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Sample records for al carbono aisi

  1. Aluminum diffusion in Al-implanted AISI 321 stainless steel using accelerator-based characterization techniques

    NASA Astrophysics Data System (ADS)

    Noli, F.; Misaelides, P.; Bethge, K.

    1998-04-01

    The aluminum diffusion in near-surface layers of Al-implanted AISI 321 austenitic stainless steel (Fe/Cr18/Ni8/Ti) was studied using ion beam analysis techniques. The implanted samples were investigated at temperatures between 450°C and 650°C (treatment times up to 144 h in vacuum and in air). The Al-profiles were determined by the 992 keV resonance of the 27Al(p,γ) 28Si nuclear reaction as well as by 4He +-Rutherford Backscattering Spectrometry (RBS). The experimental diffusion coefficients, obtained during this study using Fick's second law, were compared with corresponding literature concerning the aluminum diffusion in other relevant metallic materials. The determination of the depth profiles contributes to the interpretation of the high temperature oxidation behavior of Al-implanted stainless steel surfaces.

  2. On the Interface Generated by Hot Isostatic Pressing Compaction Process Between an AISI 304 Container and the Ti6Al4V Powders

    NASA Astrophysics Data System (ADS)

    Scherillo, Fabio; Aprea, Paolo; Astarita, Antonello; Scherillo, Antonella; Testani, Claudio; Squillace, Antonino

    2015-06-01

    In this work, the interface between a Ti6Al4V component made by Hot Isostatic Pressing and the AISI 304 container was studied in detail. The interface is dominated by interdiffusion with evident Kirkendall effect. Different intermetallic phases have been recognized. In particular, on the AISI 304 side of the interface, both ? and ? phases have been identified, whereas on the Ti6Al4V side ? phase (Laves), FeTi, (Fe,Ni)Ti, Ti2Ni, and ?-Ti are present.

  3. Tribological and mechanical properties of Ti/TiAlN/TiAlCN nanoscale multilayer PVD coatings deposited on AISI H11 hot work tool steel

    NASA Astrophysics Data System (ADS)

    AL-Bukhaiti, M. A.; Al-hatab, K. A.; Tillmann, W.; Hoffmann, F.; Sprute, T.

    2014-11-01

    A new [Ti/TiAlN/TiAlCN]5 multilayer coatings were deposited onto polished substrate AISI H11 (DIN 1.2343) steel by an industrial magnetron sputtering device. The tribological performance of the coated system was investigated by a ball-on-disk tribometer against 100Cr6 steel and Al2O3 balls. The friction coefficients and specific wear rates were measured at various normal loads (2, 5, 8, and 10 N) and sliding velocities (0.2, 0.4, and 0.8 m/s) in ambient air and dry conditions. The phase structure, composition, wear tracks morphologies, hardness, and film/substrate adhesion of the coatings were characterized by light-microscopy, scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD), 3D-surface analyzer, nanoindentation, and scratch tests. Results showed that the deposited coatings showed low wear rates in the scale of 10-15 m3/N m, low friction coefficients against 100Cr6 and Al2O3 balls in the range of 0.25-0.37, and good hardness in the range of 17-20 GPa. Results also revealed that the friction coefficients and disc wear rates decrease and increase, respectively with the increase in normal load and sliding velocity for both coating/Al2O3 and coating/100Cr6 sliding system. Compared with the uncoated-H11 substrate, the deposited coating exhibited superior tribological and mechanical properties. The dominant wear mechanism was abrasive wear for coating/Al2O3 pair, while for coating/100Cr6 pair, a combination of mild adhesive wear, severe adhesive wear, and abrasive wear (extensive plowing) were the dominant wear mechanisms at different applied normal loads.

  4. Microstructure and Corrosion Properties of AlCoCrFeNi High Entropy Alloy Coatings Deposited on AISI 1045 Steel by the Electrospark Process

    NASA Astrophysics Data System (ADS)

    Li, Q. H.; Yue, T. M.; Guo, Z. N.; Lin, X.

    2013-04-01

    Electrospark deposition (ESD) was employed to clad the AlCoCrFeNi high-entropy alloy (HEA) on AISI 1045 carbon steel. The relationship between the microstructure and corrosion properties of the HEA-coated specimens was studied and compared with that of the copper-molded cast HEA material. Two major microstructural differences were found between the cast HEA material and the HEA coatings. First, the cast material comprises both columnar and equiaxed crystals with a columnar-to-equiaxed transition (CET), whereas the HEA coatings consist of an entirely columnar crystal structure. The CET phenomenon was analyzed based on Hunt's criterion. Second, unlike the cast HEA material, there was no obvious Cr-rich interdendritic segregation and nano-sized precipitate distributed within the dendrites of the HEA coating. With regard to corrosion properties, the corrosion current of the HEA-coated specimen was significantly lower than for the 1045 steel and the cast HEA material. This was attributed to the ESD specimen having a relatively high Cr oxide and Al oxide content at the surface. Moreover, for the ESD specimen, the absence of Cr-rich interdendritic phase and second-phase precipitation resulted in a relatively uniform corrosion attack, which is different from the severe galvanic corrosion attack that occurred in the cast specimen.

  5. AISI direct steelmaking program

    SciTech Connect

    Aukrust, E.

    1991-01-09

    AISI with co-funding from DOE has initiated a research and development program aimed at the development of a new process for direct steelmaking, and the program is discussed in this document. The project is expected to cost about $30 million over a three-year period, with the government providing approximately 77 percent of the funds and AISI the balance. In contrast to current steelmaking processes which are largely open and batch, the direct steelmaking process would be closed and continuous. Further, it would use coal directly, thereby avoiding the need for coke ovens. The second year of the Direct Steelmaking Program (November 29, 1989, through November 28, 1990) was a year of significant accomplishment. The various research programs proceeded essentially on schedule and the pilot plant, the centerpiece of the program, was completed about three months behind schedule but began operation in almost a picture-perfect manner. This report presents the last years accomplishments.

  6. Effect of micro/nano-scale textures on anti-adhesive wear properties of WC/Co-based TiAlN coated tools in AISI 316 austenitic stainless steel cutting

    NASA Astrophysics Data System (ADS)

    Zhang, Kedong; Deng, Jianxin; Sun, Jialin; Jiang, Chao; Liu, Yayun; Chen, Shuai

    2015-11-01

    In cutting of stainless steel with coated tool, the steel chip adhering to tool surface is usually severe and consequently causes serious adhesive and frictional problems, which is the major reason for the failure of coated tool. To solve the problem, a surface engineering approach, namely, a highly functionalization of tool surfaces by textures may be of great importance. Thus, the effect of micro/nano-scale textures on anti-adhesive wear properties of TiAlN coated tools in AISI 316 austenitic stainless steel cutting was investigated. For this purpose, two types of surface textures were fabricated on the rake faces of WC/Co carbide tools: (i) micro-scale textures fabricated by Nd:YAG laser, (ii) micro/nano-scales textures fabricated by Nd:YAG laser and femtosecond laser. Then, these textured tools were deposited with TiAlN coatings using cathode arc-evaporation technique. Wet cutting experiments were carried out with the micro-scale textured coated tool (MCT), micro/nano-scale textured coated tool (MNCT), and the conventional coated tool (CCT). Results obtained in this work demonstrated the feasibility of fabricating micro- or micro/nano-scale textures on tools substrate surfaces to improve the anti-adhesive wear properties of TiAlN coated tool. The rake face micro/nano-scale textured tool was the most effective. Moreover, mechanisms for the anti-adhesive properties enhancement were proposed.

  7. Effect of tip relief on endurance characteristics of super nitralloy and AISI M-50 spur gears

    NASA Technical Reports Server (NTRS)

    Townsend, D. P.; Zaretsky, E. V.

    1974-01-01

    Tests were conducted with two groups of 8.89-centimeter (3.5-in.) pitch diameter spur gears with standard 20 deg involute profile with tip relief made of CVM Super-Nitralloy (5Ni-2Al) and CVM AISI M-50 at a temperature of 350 K (170 F). Super-Nitralloy gears with tip relief had a life 150 percent that of gears without tip relief. An increased scoring phenomenon was noted with the Super-Nitralloy gears with tip relief. Through-hardened AISI M-50 gears with tip relief failed due to tooth fracture. AISI M-50 gears without tip relief had a life approximately 40 times greater than the AISI M-50 gears with tip relief.

  8. Surface fatigue and failure characteristics of hot-forged powder metal AISI 4620, AISI 4640, and machined AISI 4340 steel spur gears

    NASA Technical Reports Server (NTRS)

    Townsend, Dennis P.

    1987-01-01

    Spur gear surface fatigue endurance tests were conducted to investigate hot forged powder metal AISI 4620 and 4640 steel for use as a gear material, to determine endurance characteristics and to compare the results with machined AISI 4340 and 9310 steel gear materials. The as-forged and unground AISI 4620 gear exhibited a 10 percent fatigue life that was approximately one-fourth of that for AISI 9310 and less than one-half that for the AISI 4340 gears. The forged and finish ground AISI 4620 gears exhibited a 10 percent life, approximately 70 percent that of AISI 9310 and slightly better than that of AISI 4340. The AISI 4640 hot forged gears had less fracture toughness and slightly less fatigue life than the AISI 4620 test gears.

  9. Surface fatigue and failure characteristics of hot forged powder metal AISI 4620, AISI 4640, and machined AISI 4340 steel spur gears

    NASA Technical Reports Server (NTRS)

    Townsend, D. P.

    1986-01-01

    Spur gear surface fatigue endurance tests were conducted to investigate hot forged powder metal AISI 4620 and 4640 steel for use as a gear material, to determine endurance characteristics and to compare the results with machined AISI 4340 and 9310 steel gear materials. The as-forged and unground SISI 4620 gear exhibited a 10 percent fatigue life that was approximately one-fourth of that for AISI 9310 and less than one-half that for the AISI 4340 gears. The forged and finish ground AISI 4620 gears exhibited a 10 percent life, approximately 70 percent that of AISI 9310 and slightly better than that of AISI 4340. The AISI 4640 hot forged gears had less fracture toughness and slightly less fatigue life than the AISI 4620 test gears.

  10. A life study of AISI M-50 and Super Nitralloy spur gears with and without tip relief

    NASA Technical Reports Server (NTRS)

    Townsend, D. P.; Zaretsky, E. V.

    1973-01-01

    Tests were conducted at 170 F with groups of 3.5-in.-pitch-diameter spur gear with and without tip relief made of consumable-electrode vacuum melted (CVM) Spur Nitralloy (5Ni-2Al) and CVM AISI M-50 steel. The AISI M-50 gears without tip relief had lives approximately 50 percent longer than the Super Nitralloy gears without tip relief. However, the Super Nitralloy gears with tip relief had lives equal to the AISI M-50 gears without tip relief. The difference in lives were not statistically significant. All gears failed by classical pitting fatigue at the pitch circle. However, the AIAI M-50 gears with tip relief failed by tooth fracture. AISI M-50 gear sets without tip relief having a spalled gear tooth which were deliberately overrun after spalling had occurred, failed by tooth fracture.

  11. Mechanical properties of martensitic alloy AISI 422

    SciTech Connect

    Huang, F.H.; Hu, W.L. ); Hamilton, M.L. )

    1992-09-01

    HT9 is a martensitic stainless steel that has been considered for structural applications in liquid metal reactors (LMRs) as well as in fusion reactors. AISI 422 is a commercially available martensitic stainless steel that closely resembles HT9, and was studied briefly under the auspices of the US LMR program. Previously unpublished tensile, fracture toughness and charpy impact data on AISI 422 were reexamined for potential insights into the consequences of the compositional differences between the two alloys, particularly with respect to current questions concerning the origin of the radiation-induced embrittlement observed in HT9. 8 refs, 8 figs.

  12. Mechanical properties of martensitic alloy AISI 422

    SciTech Connect

    Hamilton, M.L. ); Huang, F.H.; Hu, Wan-Liang )

    1992-06-01

    HT9 is a martensitic stainless steel that has been considered for structural applications in liquid metal reactors (LMRs) as well as in fusion reactors. AISI 422 is a commercially available martensitic stainless steel that closely resembles HT9, and was studied briefly under the auspices of the US LMR program. Previously unpublished tensile, fracture toughness and charpy impact data on AISI 422 were re-examined for potential insights into the consequences of the compositional differences between the two alloys, particularly with respect to current questions concerning the origin of the radiation-induced embrittlement observed in HT9.

  13. Mechanical properties of martensitic alloy AISI 422

    SciTech Connect

    Hamilton, M.L.; Huang, F.H.; Hu, W.

    1992-12-31

    HT9 is a martensitic stainless steel that has been considered for structural applications in liquid metal reactors (LMRs) as well as in fusion reactors. AISI 422 is a commercially available martensitic stainless steel that closely resembles HT9, and was studied briefly under the auspices of the US LMR program. Previously unpublished tensile, fracture toughness and charpy impact data on AISI 422 were reexamined for potential insights into the consequences of the compositional differences between the two alloys, particularly with respect to current questions concerning the origin of the radiation-induced embrittlement observed in HT9.

  14. High-temperature oxidation behavior of aluminized AISI 4130 steel

    NASA Astrophysics Data System (ADS)

    Badaruddin, Mohammad; Wang, Chaur Jeng; Wardono, Herry; Tarkono, Asmi, Dwi

    2016-02-01

    AISI 4130 steel was dipped into a molten aluminum bath at 700°C for 16 s to produce an aluminide coating on the steel substrate. The coating, which consisted of an Al-rich layer and an FeAl3 and Fe2Al5 intermetallic layer, strongly adhered to the steel substrate. High-temperature oxidation of the bare steel and aluminized steel was performed by thermogravimetry at 850°C for 49 h in static air. The oxidation products were characterized by scanning electron microscopy and energy-dispersive spectroscopy. The aluminide coating could increase the oxidation resistance of the bare steel by a factor of ˜19. The increase in high-temperature oxidation resistance of the aluminized steel is attributed to the formation of protective alumina scale (α-Al2O3). Although iron oxide nodules grew on the aluminide coating surface, the oxidation rate of the aluminide coatings was very low. After 49 h of oxidation, agglomerates of α-Al2O3 fine grains grew on the rod-shaped FeAl phases.

  15. Crack Arrest Toughness of Two High Strength Steels (AISI 4140 and AISI 4340)

    NASA Astrophysics Data System (ADS)

    Ripling, E. J.; Mulherin, J. H.; Crosley, P. B.

    1982-04-01

    The crack initiation toughness ( K c ) and crack arrest toughness ( K a ) of AISI 4140 and AISI 4340 steel were measured over a range of yield strengths from 965 to 1240 MPa, and a range of test temperatures from -53 to +74C. Emphasis was placed on K a testing since these values are thought to represent the minimum toughness of the steel as a function of loading rate. At the same yield strengths and test temperatures, K a for the AISI 4340 was about twice as high as it was for the AISI 4140. In addition, the K a values showed a more pronounced transition temperature than the K c values, when the data were plotted as a function of test temperature. The transition appeared to be associated with a change in fracture mechanism from cleavage to dimpled rupture as the test temperature was increased. The occurrence of a pop-in behavior at supertransition temperatures has not been found in lower strength steels, and its evaluation in these high strength steels was possible only because they are not especially tough at their supertransition temperatures. There is an upper toughness limit at which pop-in will not occur, and this was found for the AISI 4340 steel when it was tempered to its lowest yield strength (965 MPa). All the crack arrest data were identified as plane strain values, while only about one-half of the initiation values could be classified this way.

  16. Modeling of the AISI Two-Zone Smelter, Part II: Physical Modeling and the AISI Pilot Plant Trials

    SciTech Connect

    Keller, Joseph George; Zhang, X.; Fuehan, R. J.; Vassilicos, A.; Sarma, B.

    2001-06-01

    Physical modeling experiments were conducted for the American Iron and Steel Institute (AISI) two-zone smelter process. The effects of geometrical and operating parameters on backmixing flow rates were investigated. It was found that the driving force for a backmixing flow in the AISI smelter comes from gas stirring in a liquid bath. The backmixing flow rate in the AISI smelter is proportional to a bath depth and an opening area of a barrier. Based on the results of the physical modeling experiments, a dimensional analysis was performed to extrapolate the water modeling results to the operating conditions in the AISI pilot plant. Copper tracer trials were conducted at the AISI pilot plant to investigate the backmixing flow of the AISI two-zone smelter process. The results obtained from the pilot plant trials and the water modeling experiments were compared.

  17. Characterization of AISI 4140 borided steels

    NASA Astrophysics Data System (ADS)

    Campos-Silva, I.; Ortiz-Domínguez, M.; López-Perrusquia, N.; Meneses-Amador, A.; Escobar-Galindo, R.; Martínez-Trinidad, J.

    2010-02-01

    The present study characterizes the surface of AISI 4140 steels exposed to the paste-boriding process. The formation of Fe 2B hard coatings was obtained in the temperature range 1123-1273 K with different exposure times, using a 4 mm thick layer of boron carbide paste over the material surface. First, the growth kinetics of boride layers at the surface of AISI 4140 steels was evaluated. Second, the presence and distribution of alloying elements on the Fe 2B phase was measured using the Glow Discharge Optical Emission Spectrometry (GDOES) technique. Further, thermal residual stresses produced on the borided phase were evaluated by X-ray diffraction (XRD) analysis. The fracture toughness of the iron boride layer of the AISI 4140 borided steels was estimated using a Vickers microindentation induced-fracture testing at a constant distance of 25 μm from the surface. The force criterion of fracture toughness was determined from the extent of brittle cracks, both parallel and perpendicular to the surface, originating at the tips of an indenter impression. The fracture toughness values obtained by the Palmqvist crack model are expressed in the form KC( π/2) > KC > KC(0) for the different applied loads and experimental parameters of the boriding process.

  18. Hot hardness characteristics of ausformed AISI M-50, Matrix 2, WD-65, modified AISI 440-C, and Super Nitralloy

    NASA Technical Reports Server (NTRS)

    Chevalier, J. L.; Dietrich, M. W.; Zaretsky, E. V.

    1973-01-01

    Short-term hot hardness studies were performed with ausformed AISI M-50, Matrix 2, WD-65, modified AISI 440-C (14-4-1) and case hardened Super Nitralloy. Hardness levels of each material were measured at elevated temperatures in an electric furnace with a low oxygen environment. Test temperatures ranged from 294 to 877 K. The hot hardness characteristics of the ausformed AISI-M-50, Matrix 2 WD-65, and modified AISI 440-C were the same as those determined for high-speed tool steels. Hot hardness for these steels can be predicted within one point Rockwell C. The hot hardness characteristics of both the case and core of Super Nitralloy were superior to AISI 52100 but inferior to the high-speed tool steels. The short-term Rockwell C hardness at temperature for the Super Nitralloy material between 294 and 769 K can be predicted within one point Rockwell C hardness.

  19. Experimental Design and Data collection of a finishing end milling operation of AISI 1045 steel.

    PubMed

    Dias Lopes, Luiz Gustavo; de Brito, Tarcsio Gonalves; de Paiva, Anderson Paulo; Peruchi, Rogrio Santana; Balestrassi, Pedro Paulo

    2016-03-01

    In this Data in Brief paper, a central composite experimental design was planned to collect the surface roughness of an end milling operation of AISI 1045 steel. The surface roughness values are supposed to suffer some kind of variation due to the action of several factors. The main objective here was to present a multivariate experimental design and data collection including control factors, noise factors, and two correlated responses, capable of achieving a reduced surface roughness with minimal variance. Lopes et al. (2016) [1], for example, explores the influence of noise factors on the process performance. PMID:26909374

  20. Experimental Design and Data collection of a finishing end milling operation of AISI 1045 steel

    PubMed Central

    Dias Lopes, Luiz Gustavo; de Brito, Tarcsio Gonalves; de Paiva, Anderson Paulo; Peruchi, Rogrio Santana; Balestrassi, Pedro Paulo

    2016-01-01

    In this Data in Brief paper, a central composite experimental design was planned to collect the surface roughness of an end milling operation of AISI 1045 steel. The surface roughness values are supposed to suffer some kind of variation due to the action of several factors. The main objective here was to present a multivariate experimental design and data collection including control factors, noise factors, and two correlated responses, capable of achieving a reduced surface roughness with minimal variance. Lopes et al. (2016) [1], for example, explores the influence of noise factors on the process performance. PMID:26909374

  1. Laser Surface Hardening of AISI 1045 Steel

    NASA Astrophysics Data System (ADS)

    Li, Ruifeng; Jin, Yajuan; Li, Zhuguo; Qi, Kai

    2014-09-01

    The study investigates laser surface hardening in the AISI 1045 steel using two different types of industrial laser: a high-power diode laser (HPDL) and a CO2 laser, respectively. The effect of process parameters such as beam power, travel speed on structure, case depth, and microhardness was examined. In most cases, a heat-affected zone (HAZ) formed below the surface; a substantial increase in surface hardness was achieved. In addition, big differences were found between the hardened specimens after HPDL surface hardening and CO2 laser surface hardening. For HPDL, depths of the HAZ were almost equal in total HAZ o, without surface melting. For CO2 laser, the depths changed a lot in the HAZ, with surface melting in the center. To better understand the difference of laser hardening results when use these two types of laser, numerical (ANSYS) analysis of the heat conduction involved in the process was also studied. For HPDL method, a rectangular beam spot and uniform energy distribution across the spot were assumed, while for CO2 laser, a circular beam spot and Gaussian energy distribution were assumed. The results showed that the energy distribution variety altered the thermal cycles of the HAZ dramatically. The rectangular HPDL laser beam spot with uniform energy distribution is much more feasible for laser surface hardening.

  2. Colloquium on Large Scale Improvement: Implications for AISI

    ERIC Educational Resources Information Center

    McEwen, Nelly, Ed.

    2008-01-01

    The Alberta Initiative for School Improvement (AISI) is a province-wide partnership program whose goal is to improve student learning and performance by fostering initiatives that reflect the unique needs and circumstances of each school authority. It is currently ending its third cycle and ninth year of implementation. "The Colloquium on Large…

  3. Aluminum-silicon co-deposition by FB-CVD on austenitic stainless steel AISI 316

    NASA Astrophysics Data System (ADS)

    Marulanda, J. L.; Perez, F. J.; Remolina-Milln, A.

    2013-11-01

    Aluminum-silicon coatings were deposited on stainless steel AISI 316 in the temperature range of 540 to 560C by CVD-FBR. It was used a fluidized bed with 2.5% silicon and 7.5% aluminum powder and 90% inert (alumina). This bed was fluidized with Ar and as an activator a mixture of HCl/H2 in ratios of 1/10 to 1/16. Furthermore, the deposition time of the coatings was varied between 45 minutes to 1.5 hours, with a 50% active gas, neutral gases 50%. Thermodynamic simulation was conducted with the Thermocalc software to get the possible compositions and amount of material deposited for the chosen conditions. The coatings presented the follow compounds FeAl2Si, FeAl2 and Fe2Al5. Aluminum-silicon coatings were heat treated to improve its mechanical properties and its behavior against oxidation for the inter diffusion of the alloying elements. The heat treatment causes the aluminum diffuse into the substrate and the iron diffuse into coating surface. This leads to the transformation of the above compounds in FeAl, Al2FeSi, Cr3Si, AlFeNi and AlCrFe.

  4. Tribological and corrosion behaviors of carburized AISI 4340 steel

    NASA Astrophysics Data System (ADS)

    Thong-on, Atcharawadi; Boonruang, Chatdanai

    2016-01-01

    AISI 4340 steel is widely used in automotive and aircraft industries as gear components. In such applications, surface hardening processes such as carburizing are required in order to improve the life time of the components. There are many studies showing the tribological behavior of the carburized steel, but the corrosion behavior has not yet been clarified. This paper reports on both tribological and corrosion behaviors of the carburized AISI 4340 steel. Factor associated with carburizing, such as the quantities of deposited carbon, dissolved carbon, and formed Cr23C6 and Fe3C, affect the tribological and corrosion behaviors of the steel by improving hardness, friction, lubrication, and wear resistance; but corrosion resistance is reduced. The dissolved carbon affects the formation of the oxide layer of the carburized steel, by obstructing the continuous oxide layer formation and by decreasing the chromium content of the steel, leading to the decrease in the corrosion resistance of the steel.

  5. Comparison of pitting fatigue life of ausforged and standard forged AISI M-50 and AISI 9310 spur gears

    NASA Technical Reports Server (NTRS)

    Townsend, D. P.; Bamberger, E. N.; Zaretsky, E. V.

    1975-01-01

    Standard forged and ausforged spur gears made of vacuum-induction-melted, consumable-electrode, vacuum-arc-remelted AISI M-50 steel were tested under conditions that produced fatigue pitting. The gears were 8.89 cm (3.5 in.) in pitch diameter and had tip relief. The M-50 standard forged and ausforged test results were compared with each other. They were then compared with results for machined vacuum-arc-remelted AISI 9310 gears tested under identical conditions. Both types of M-50 gears had lives approximately five times that of the 9310 gears. The life at which 10 percent of the M-50 ausforged gears failed was slightly less than that at which the M-50 standard forged gears failed. The ausforged gears had a slightly greater tendency to fail by tooth fracture than did the standard forged gears, most likely because of the better forging and grain flow pattern of standard forged gears.

  6. A study of cumulative fatigue damage in AISI 4130 steel

    NASA Technical Reports Server (NTRS)

    Jeelani, S.; Musial, M.

    1986-01-01

    Experimental data were obtained using AISI 4130 steel under stress ratios of -1 and 0. A study of cumulative fatigue damage using Miner's and Kramer's equations for stress ratios of -1 and 0 for low-high, low-high-mixed, high-low, and high-low-mixed stress sequences has revealed that there is a close agreement between the theoretical and experimental values of fatigue damage and fatigue life. Kramer's equation predicts less conservative and more realistic cumulative fatigue damage than the popularly used Miner's rule does.

  7. Novel Strategies for Laser Joining of Polyamide and AISI 304

    NASA Astrophysics Data System (ADS)

    Cenigaonaindia, Asier; Libana, Fernando; Lamikiz, Aitzol; Echegoyen, Zelmar

    The increased demand for lightweight products with enhanced characteristics is driving the introduction of thermoplastic-metal hybrids in many industrial applications. However, inflexible and expensive processes, as well as difficulties in obtaining reliable joints, reduce the industrialization of hybrid products. During this work a new approach to perform the laser transmission joining (LTJ) of AISI 304 stainless steel and natural polyamide (PA6) has been studied. The proposed technology is intended to improve the strength of hybrid structures by increasing the amount of thermoplastic polymer trapped inside metal surface cavities.

  8. Formation of titanium aluminum nitride layers on AISI D2 steel by nitro-titanizing treatment

    NASA Astrophysics Data System (ADS)

    Cegil, Ozkan; Sen, Saduman

    2012-09-01

    In this study, titanium aluminum nitride coating was realized on AISI D2 steels by nitro-titanizing treatment. Steel samples were nitrided at 575 °C for 8 h in the first step of the coating process, and then titanized by thermo-reactive diffusion method in the powder mixture consisting of ferro-titanium, aluminum, ammonium chloride and alumina at 1000 °C for 2 h. The effects of the aluminum content to the coating bath were investigated. The thickness of the titanium aluminum nitride layer formed on the steel samples ranged from 6.30±0.5 to 7.89±0.34μm, depending on the aluminum content. The average micro-hardness value of the layer was 1468 ± 96 HV0.005 and 2630± 83 HV0.005. The phases formed on the coating layers are TiN, AlTi3N and Ti3Al2N2 which are characterized by XRD. EDS analysis results showed that coating layer includes titanium, aluminum and nitrogen.

  9. Residual Stress Analysis of Boronized AISI 1018 Steel

    SciTech Connect

    Payne,J.; Petrova, R.; White, H.; Chauhan, A.; Bai, J.

    2008-01-01

    AISI 1018 steel substrates were powder-pack, diffusion boronized at 850 C for 4 h, followed by air quenching. Optical microscopy in conjunction with color etching was used to obtain the average penetration depth of the iron monoboride layer (9 {mu}m) and the iron diboride layer (57 {mu}m). X-ray diffraction by synchrotron radiation, conducted at the National Synchrotron Light Source in Brookhaven National Laboratory, confirmed the presence of iron monoboride and iron diboride in the boronized plain steel substrates. The sin2 {psi} technique was employed to calculate the residual stress found in the iron monoboride layer (-237 MPa) and in the substrate layer (-150 MPa) that is intertwined with the needle-like, iron diboride penetration.

  10. Fretting of AISI 9310 and selected fretting resistant surface treatments

    NASA Technical Reports Server (NTRS)

    Bill, R. C.

    1977-01-01

    Fretting wear experiments were conducted with uncoated AISI 9310 mating surfaces, and with combinations incorporating a selected coating to one of the mating surfaces. Wear measurements and SEM observations indicated that surface fatigue, as made evident by spallation and surface crack formation, is an important mechanism in promoting fretting wear to uncoated 9310. Increasing humidity resulted in accelerated fretting, and a very noticeable difference in nature of the fretting debris. Of the coatings evaluated, alumimum bronze with a polyester additive was most effective at reducing wear and minimizing fretting damage to the mating uncoated surface, by means of a self-lubricating film that developed on the fretting surfaces. Chromium plate performed as an effective protective coating, itself resisting fretting and not accelerating damage to the uncoated surface.

  11. Fretting of AISI 9310 and selected fretting resistant surface treatments

    NASA Technical Reports Server (NTRS)

    Bill, R. C.

    1977-01-01

    Fretting wear experiments were conducted with uncoated AISI 9310 mating surfaces, and with combinations incorporating a selected coating to one of the mating surfaces. Wear measurements and SEM observations indicated that surface fatigue, as made evident by spallation and surface crack formation, is an important mechanism in promoting fretting wear to uncoated 9310. Increasing humidity resulted in accelerated fretting, and a very noticeable difference in nature of the fretting debris. Of the coatings evaluated, aluminum bronze with a polyester additive was most effective at reducing wear and minimizing fretting damage to the mating uncoated surface, by means of a selflubricating film that developed on the fretting surfaces. Chromium plate performed as an effective protective coating, itself resisting fretting and not accelerating damage to the uncoated surface.

  12. Stress Ratio Effect on Ratcheting Behavior of AISI 4340 Steel

    NASA Astrophysics Data System (ADS)

    Divya Bharathi, K.; Dutta, K.

    2016-02-01

    Ratcheting is known as accumulation of plastic strain during asymmetric cyclic loading of metallic materials under non-zero mean stress. This phenomenon reduces fatigue life of engineering materials and thus limits the life prediction capacity of Coffin-Manson relationship. This study intends to investigate the ratcheting behavior in AISI 4340 steel which is mainly used for designing of railway wheel sets, axles, shafts, aircraft components and other machinery parts. The effect of stress ratio on the ratcheting behaviour in both annealed and normalised conditions were investigated for investigated steel. Ratcheting tests were done at different stress ratios of -0.4, -0.6 and -0.8. The results showed that the material responds to hardening behavior and nature of strain accumulation is dependent on the magnitude of stress ratio. The post ratcheted samples showed increase in tensile strength and hardness which increases with increasing stress ratio and these variations in tensile properties are correlated with the induced cyclic hardening.

  13. CO2 laser welding of AISI 321stainless steel

    NASA Astrophysics Data System (ADS)

    Hussain, A.; Hamdani, A. H.; Akhter, R.

    2014-06-01

    CO2 laser welding of AISI 321austenitic stainless steel has been carried out. Bead on plate welds on 2 mm thick steel were performed with 450W CO2 laser at speeds ranging from 200 to 900 mm/min. It was observed that weld depth and width was decreased with increasing the speed at constant laser power. Butt welds on different sheet thickness of 1, 2 and 2.5 mm were performed with laser power of 450 W and at speed 750, 275 and 175 mm/min, respectively. The microstructures of the welded joints and the heat affected zones (HAZ) were examined by optical microscopy and SEM. The austenite/delta ferrite microstructure was reported in the welded zone. The microhardness and tensile strength of the welded joints were measured and found almost similar to base metal due to austenitic nature of steel.

  14. Investment cast AISI H13 tooling for automotive applications

    SciTech Connect

    Maguire, M.C.; Baldwin, M.D.; Hochanadel, P.W.; Edwards, G.R.

    1995-07-01

    While many techniques exist for production of soft tooling, for die casting there is limited recent experience with cast tooling. The most common US alloy used for manufacture of die casting tooling is wrought AISI H13. If the performance of the cast material is comparable to the wrought counterpart, the use of investment cast HI 3 tooling directly from patterns made via rapid prototyping is of considerable interest. A metallurgical study of investment cast H13 was conducted to evaluate the mechanical behavior in simulated die casting applications. Variable thickness plate investment castings of AISI H13 hot work die steel were produced and characterized in the as-cast and heat-treated conditions. The characterization included light microscopy and mechanical testing. Wrought samples of standard and premium grade H13 were heat-treated and characterized similarly for comparison. Microstructural differences were observed in as-cast samples produced in different section thicknesses. Dendrite cell size and carbide morphology constituted the most prominent microstructural differences observed. After a full heat-treatment, microstructural differences between the wrought material and cast materials were slight regardless of section thickness.The mechanical properties of the cast and heat-treated material proved similar to the properties of the standard heat-treated wrought material. A thermal fatigue testing unit was to con-elate the heat checking susceptibility of H13 steel to its processing and consequent microstructural condition. Surface hardness decreased significantly with thermal cycling, and heat checking was observed in as few as 50 cycles. Thermal softening and thermal fatigue susceptibility were quantified and discussed relative to the microstructural conditions created by processing and heat-treatment. It was found that the premium grade wrought H13 steel provided the best overall resistance to heat checking.

  15. Coated carbide drill performance under soluble coconut oil lubricant and nanoparticle enhanced MQL in drilling AISI P20

    NASA Astrophysics Data System (ADS)

    Jamil, N. A. M.; Azmi, A. I.; Fairuz, M. A.

    2016-02-01

    This research experimentally investigates the performance of a TiAlN coated carbide drill bit in drilling AISI P20 through two different kinds of lubricants, namely; soluble coconut oil (SCO) and nanoparticle-enhanced coconut oil (NECO) under minimum quantity lubrication system. The tool life and tool wear mechanism were studied using various cutting speeds of 50, 100 and 150 m/min with a constant feed of 0.01 mm/rev. Since the flank wear land was not regular along the cutting edge, the average flank wear (VB) was measured at several points using image analysis software. The drills were inspected using a scanning electron microscope to further elucidate the wear mechanism. The result indicates that drilling with the nanoparticle- enhanced lubricant was better in resisting the wear and improving the drill life to some extent

  16. A Life Study of Ausforged, Standard Forged and Standard Machined AISI M-50 Spur Gears

    NASA Technical Reports Server (NTRS)

    Townsend, D. P.; Bamberger, E. N.; Zaretsky, E. V.

    1975-01-01

    Tests were conducted at 350 K (170 F) with three groups of 8.9 cm (3.5 in.) pitch diameter spur gears made of vacuum induction melted (VIM) consumable-electrode vacuum-arc melted (VAR), AISI M-50 steel and one group of vacuum-arc remelted (VAR) AISI 9310 steel. The pitting fatigue life of the standard forged and ausforged gears was approximately five times that of the VAR AISI 9310 gears and ten times that of the bending fatigue life of the standard machined VIM-VAR AISI M-50 gears run under identical conditions. There was a slight decrease in the 10-percent life of the ausforged gears from that for the standard forged gears, but the difference is not statistically significant. The standard machined gears failed primarily by gear tooth fracture while the forged and ausforged VIM-VAR AISI M-50 and the VAR AISI 9310 gears failed primarily by surface pitting fatigue. The ausforged gears had a slightly greater tendency to fail by tooth fracture than the standard forged gears.

  17. Study on residual stress of AISI304 TIG welding line with laser shock processing by x-ray stress analyzer

    NASA Astrophysics Data System (ADS)

    Zhang, Y. K.; Kong, D. J.; Yin, S. M.; Feng, A. X.; Lu, J. Z.; Ge, T.

    2006-02-01

    The surface of AISI304 TIG welding line was processed by LSP (laser shock processing). The effects on the microstructure, hardness and residual stress of AISI304 welding line by LSP were observed, and its mechanical properties were researched by SEM (scanning electron microscope) and test device of mechanical property. Residual stresses of AISI304 TIG welding line by LSP were measured with Model X-350A X ray analyzer. The test results show that compressive residual stress values of AISI304 TIG welding line by LSP are about 110MPa. Strengthening effects of AISI304 TIG welding line by LSP is very obvious, and fatigue properties of welding line is improved, and tensile residual stresses of welding line are obviously reduced, the distribution of residual stress tends to equality, and service life of AISI304 TIG welding line is improved.

  18. Transporte electronico en nanoestructuras de carbono

    NASA Astrophysics Data System (ADS)

    Jodar Ferrandez, Esther

    The aim of this work is the study of the electronic transport properties in several structures made of carbon nanotubes. This dissertation is divided in four chapters: (1) Chapter 1: Carbon Nanotubes. This chapter is a brief review of the foundations of carbon nanotubes (CNT). Main properties of CNT are explained. The subject developed here is important for the understanding of the results obtained in the bulk of this thesis. We carry out, in the first part of this chapter, an historical review of the discovering of CNT, that includes the history of the discovering of fullerenes, the predecessors for carbon nanotubes. Afterwards, a revision of the different methods for synthesizing nanotubes is done. The main part of this chapter treats of the description of the geometry, properties and electronic structure of CNT. Many equations deduced here will be used later. Finally, we discuss some research lines related to carbon nanotubes. (2) Chapter 2: Theoretical and numerical method. In this chapter we describe the numerical method we have developed to obtain the results presented in this work. For this purpose it is necessary to describe previously the theoretical method on which our calculations are based. We extensively explain the Green's function and its properties. A large part of our calculations are based in the obtention the GF of the system under study. This chapter finishes with the application of the equations described in order to obtain electronic properties associated with pure carbon nanotubes as an example of use. Anyway, these previous results will be used later. (3) Chapter 3: Cavities made of nanotubes. We denote as a cavity to the structure formed with a carbon nanotube sandwiched between other two carbon nanotubes (contacts), provided that the central region is wider than these contacts. In this chapter we perform some calculations of the properties associated to the electronic transport in cavities, as the local density of states and the transmission function. We analyze the influence of the width of the cavity and the distance between them (in the case of multiple cavities). Some interesting results are obtained in these calculations which have been published in international journals (Jodar et al. 2006, Jodar y Perez-Garrido 2007). We emphasize the presence of quasi-localized states in the cavities, which affects to the transmission function, the behaviour of some cavities formed with semi-conductor as quantum dots, or the study of the evolution of the system with multiple cavities to the limit of infinite cavities. (4) Chapter 4: Bloch Oscillations. In this chapter we investigate the properties of carbon nanotubes under a constant electric field. This configuration show Bloch oscillations, according to the work of Bloch and Zener. We study here the dynamics of these oscillations for different geometries as a function of the electric field applied. Specially, the behaviour of the occupation probability and the averaged quadratic displacement as a function of time. We have not found bibliography that deals with this phenomenon in Carbon Nanotubes, which is the aim of this chapter. We first study the behaviour of electrons in pure carbon nanotubes in a constant electric field, for different lengths of the CNT and different values of the electric field applied. We show how wavefunctions oscillate with a period that coincides with that given by theoretical expressions of Bloch oscillations for linear chains of atoms. Besides, we show the different kind of behaviour of localized and extended waves. In the final part of this chapter we apply a constant electric field to the structure studied in the chapter 3, i.e., the cavity. We show in this case that, besides Bloch oscillations, electrons can be confined in certain regions only by inserting the nanotube in an electric field.

  19. The Forming of AISI 409 sheets for fan blade manufacturing

    SciTech Connect

    Foroni, F. D.; Menezes, M. A.; Moreira Filho, L. A.

    2007-04-07

    The necessity of adapting the standardized fan models to conditions of higher temperature has emerged due to the growth of concern referring to the consequences of the gas expelling after the Mont Blanc tunnel accident in Italy and France, where even though, with 100 fans in operation, 41 people died. The objective of this work is to present an alternative to the market standard fans considering a new technology in constructing blades. This new technology introduces the use of the stainless steel AISI 409 due to its good to temperatures of gas exhaust from tunnels in fire situation. The innovation is centered in the process of a deep drawing of metallic sheets in order to keep the ideal aerodynamic superficies for the fan ideal performance. Through the impression of circles on the sheet plane it is shown, experimentally, that, during the pressing process, the more deformed regions on the sheet plane of the blade can not reach the deformation limits of the utilized sheet material.

  20. AISI waste oxide recycling program. Final technical report

    SciTech Connect

    Aukrust, E.; Downing, K.B.; Sarma, B.

    1995-08-01

    In March 1995 AISI completed a five-year, $60 million collaborative development program on Direct Steelmaking cost-shared by DOE under the Metals Initiative. This program defined an energy-efficient and environmentally-friendly technology to produce hot metal for steelmaking directly from coal and iron ore pellets without incurring the high capital costs and environmental problems associated with traditional coke oven and blast furnace technology. As it becomes necessary to replace present capacity, this new technology will be favored because of reduced capital costs, higher energy efficiency, and lower operating costs. In April 1994, having failed to move forward with a demonstration plant for direct ironmaking, despite substantial efforts by both Stelco and Geneva Steel, an alternative opportunity was sought to commercialize this new technology without waiting until existing ironmaking capacity needed to be replaced. Recycling and resource recovery of steel plant waste oxides was considered an attractive possibility. This led to approval of a ten-month, $8.3 million joint program with DOE on recycling steel plant waste oxides utilizing this new smelting technology. This highly successful trial program was completed in December 1994. The results of the pilot plant work and a feasibility study for a recycling demonstration plant are presented in this final technical report.

  1. Abnormal grain growth in AISI 304L stainless steel

    SciTech Connect

    Shirdel, M.; Mirzadeh, H.; Parsa, M.H.

    2014-11-15

    The microstructural evolution during abnormal grain growth (secondary recrystallization) in 304L stainless steel was studied in a wide range of annealing temperatures and times. At relatively low temperatures, the grain growth mode was identified as normal. However, at homologous temperatures between 0.65 (850 °C) and 0.7 (900 °C), the observed transition in grain growth mode from normal to abnormal, which was also evident from the bimodality in grain size distribution histograms, was detected to be caused by the dissolution/coarsening of carbides. The microstructural features such as dispersed carbides were characterized by optical metallography, X-ray diffraction, scanning electron microscopy, energy dispersive X-ray analysis, and microhardness. Continued annealing to a long time led to the completion of secondary recrystallization and the subsequent reappearance of normal growth mode. Another instance of abnormal grain growth was observed at homologous temperatures higher than 0.8, which may be attributed to the grain boundary faceting/defaceting phenomenon. It was also found that when the size of abnormal grains reached a critical value, their size will not change too much and the grain growth behavior becomes practically stagnant. - Highlights: • Abnormal grain growth (secondary recrystallization) in AISI 304L stainless steel • Exaggerated grain growth due to dissolution/coarsening of carbides • The enrichment of carbide particles by titanium • Abnormal grain growth due to grain boundary faceting at very high temperatures • The stagnancy of abnormal grain growth by annealing beyond a critical time.

  2. The Forming of AISI 409 sheets for fan blade manufacturing

    NASA Astrophysics Data System (ADS)

    Foroni, F. D.; Menezes, M. A.; Moreira Filho, L. A.

    2007-04-01

    The necessity of adapting the standardized fan models to conditions of higher temperature has emerged due to the growth of concern referring to the consequences of the gas expelling after the Mont Blanc tunnel accident in Italy and France, where even though, with 100 fans in operation, 41 people died. The objective of this work is to present an alternative to the market standard fans considering a new technology in constructing blades. This new technology introduces the use of the stainless steel AISI 409 due to its good to temperatures of gas exhaust from tunnels in fire situation. The innovation is centered in the process of a deep drawing of metallic sheets in order to keep the ideal aerodynamic superficies for the fan ideal performance. Through the impression of circles on the sheet plane it is shown, experimentally, that, during the pressing process, the more deformed regions on the sheet plane of the blade can not reach the deformation limits of the utilized sheet material.

  3. The Surface Fatigue Life of Contour Induction Hardened AISI 1552 Gears

    NASA Technical Reports Server (NTRS)

    Townsend, Dennis P.; Turza, Alan; Chaplin, Mike

    1995-01-01

    Two groups of spur gears manufactured from two different materials and heat treatments were endurance tested for surface fatigue life. One group was manufactured from AISI 1552 and was finished ground to a 0.4 micron (16 micro-in.) rms surface finish and then dual frequency contour induction hardened. The second group was manufactured from CEVM AISI 9310 and was carburized, hardened, and ground to a 0.4 micron (16 micro-in.) rms surface finish. The gear pitch diameter was 8.89 cm (3.5 in.). Test conditions were a maximum Hertz stress of 1.71 GPa (248 ksi), a bulk gear temperature of approximately 350 K (170 F) and a speed of 10,000 rpm. The lubricant used for the tests was a synthetic paraffinic oil with an additive package. The test results showed that the 10 percent surface fatigue (pitting) life of the contour hardened AISI 1552 test gears was 1.7 times that of the carburized and hardened AISI 9310 test gears. Also there were two early failures of the AISI 1552 gears by bending fatigue.

  4. The surface fatigue life of contour induction hardened AISI 1552 gears

    NASA Astrophysics Data System (ADS)

    Townsend, Dennis P.; Turza, Alan; Chaplin, Mike

    1995-07-01

    Two groups of spur gears manufactured from two different materials and heat treatments were endurance tested for surface fatigue life. One group was manufactured from AISI 1552 and was finished ground to a 0.4 micron (16 micro-in.) rms surface finish and then dual frequency contour induction hardened. The second group was manufactured from CEVM AISI 9310 and was carburized, hardened, and ground to a 0.4 micron (16 micro-in.) rms surface finish. The gear pitch diameter was 8.89 cm (3.5 in.). Test conditions were a maximum Hertz stress of 1.71 GPa (248 ksi), a bulk gear temperature of approximately 350 K (170 F) and a speed of 10,000 rpm. The lubricant used for the tests was a synthetic paraffinic oil with an additive package. The test results showed that the 10 percent surface fatigue (pitting) life of the contour hardened AISI 1552 test gears was 1.7 times that of the carburized and hardened AISI 9310 test gears. Also there were two early failures of the AISI 1552 gears by bending fatigue.

  5. Surface fatigue life of CBN and vitreous ground carburized and hardened AISI 9310 spur gears

    NASA Technical Reports Server (NTRS)

    Townsend, Dennis P.; Patel, P. R.

    1988-01-01

    Spur gear surface endurance tests were conducted to investigate CBN ground AISI 9310 spur gears for use in aircraft applications, to determine their endurance characteristics and to compare the results with the endurance of standard vitreous ground AISI 9310 spur gears. Tests were conducted with VIM-VAR AISI 9310 carburized and hardened gears that were finish ground with either CBN or vitreous grinding methods. Test conditions were an inlet oil temeprature of 320 K (116 F), an outlet oil temperature of 350 K (170 F), a maximum Hertz stress of 1.71 GPa (248 ksi), and a speed of 10,000 rpm. The CBN ground gears exhibited a surface fatigue life that was slightly better than the vitreous ground gears. The subsurface residual stress of the CBN ground gears was approximately the same as that for the standard vitreous ground gears for the CBN grinding method used.

  6. Corrosion resistance of the AISI 304, 316 and 321 stainless steel surfaces modified by laser

    NASA Astrophysics Data System (ADS)

    Szubzda, B.; Antończak, A.; Kozioł, P.; Łazarek, Ł.; Stępak, B.; Łęcka, K.; Szmaja, A.; Ozimek, M.

    2016-02-01

    The article presents the analysis results of the influence of laser fluence on physical and chemical structure and corrosion resistance of stainless steel surfaces modified by irradiating with nanosecond-pulsed laser. The study was carried out for AISI 304, AISI 316 and AISI 321 substrates using Yb:glass fiber laser. All measurements were made for samples irradiated in a broad range of accumulated fluence (10÷400 J/cm2). The electrochemical composition (by EDX) and surface morphology (by SEM) of the prepared surfaces were carried out. Finally, corrosion resistance was analyzed by a potentiodynamic electrochemical test. The obtained results showed very high corrosion resistance for samples made by fluency of values lower than 100 J/cm2. In this case, higher values of corrosion potentials and breakdown potentials were observed. A correlation between corrosion phenomena, the range of laser power (fluence) and the results of chemical and structural tests were also found.

  7. Coupled Multi-Electrode Investigation of Crevice Corrosion of AISI 316 Stainless Steel

    SciTech Connect

    F. Bocher; F. Presuel-Moreno; N.D. Budinasky; J.R. Scully

    2006-06-23

    Close packed coupled multi-electrodes arrays (MEA) simulating a planar electrode were used to measure the current evolution as a function of position during initiation and propagation of crevice corrosion of AISI 316 stainless steel. Scaling laws derived from polarization data enabled the use of rescaled crevices providing spatial resolution. Crevice corrosion of AISI 316 stainless steel in 0.6 M NaCl at 50 C was found to initiate close to the crevice mouth and to spread inwards with time. The local crevice current density increased dramatically over a short period to reach a limiting value.

  8. Improvement of the Electrochemical Behavior of Steel Surfaces Using a [Ti-Al/Ti-Al-N] n Multilayer System

    NASA Astrophysics Data System (ADS)

    Ipaz, L.; Aperador, W.; Caicedo, J. C.; Esteve, J.; Zambrano, G.

    2013-05-01

    The aim of this work is to improve the corrosion resistance of AISI D3 steel surfaces using a [Ti-Al/Ti-Al-N] n multilayer system deposited with different periods (?) and bilayer numbers ( n), via magnetron co-sputtering pulsed d.c. procedure, from a metallic (Ti-Al) binary target. The multilayer coatings were characterized by cross-sectional scanning electron microscopy that showed the modulation and microstructure of the [Ti-Al/Ti-Al-N] n multilayer system. The composition of the single Ti-Al and Ti-Al-N layer films was studied via x-ray photoelectron spectroscopy, where typical signals for Ti2p1/2, Ti2p, N1s, and Al2p3/2 were detected. The electrochemical properties were evaluated by electrochemical impedance spectroscopy and Tafel polarization curves. The optimal electrochemical behavior was obtained for the [Ti-Al/Ti-Al-N] n multilayered period of ? = 25 nm (100 bilayers). At these conditions, the maximum polarization resistance (1719.32 k? cm2) and corrosion rate (0.7 ?my) were 300 and 35 times higher than that of uncoated AISI D3 steel substrate (5.61 k? cm2 and 25 ?my, respectively). Finally, scanning electron microscopy was used to analyze the [Ti-Al/Ti-Al-N] n multilayered surface after the corrosive attack. The improvement effects in the electrochemical behavior of the AISI D3 coated with the [Ti-Al/Ti-Al-N] n multilayered coatings could be attributed to the number of interfaces that act as obstacles for the inward and outward diffusions of Cl- ions, generating an increment in the energy or potential required for translating the corrosive ions across the coating/substrate interface.

  9. Studies on Direct Laser Cladding of SiC Dispersed AISI 316L Stainless Steel

    NASA Astrophysics Data System (ADS)

    Majumdar, Jyotsna Dutta; Li, Lin

    2009-12-01

    In the present study, attempts have been made to develop SiC dispersed (5 and 20 wt pct) AISI 316L stainless steel matrix composite by direct laser cladding with a high power diode laser. Direct laser cladding has been carried out by melting the powder blends of AISI 316L stainless steel and SiC (5 and 20 wt pct) and, subsequently, depositing it on mild steel (0.15 pct C steel) in a layer by layer fashion to develop a coupon of 100 mm2 10 mm dimension. A continuous, defect-free (microcracks and micro- or macroporosities), and homogeneous microstructure is formed, which consists of a dispersion of partially dissolved SiC (leading to formation of very low fraction of Cr3C2 and Fe2Si) in grain-refined austenite. The microhardness of the clad layer increases from 155 VHN to 250 to 340 VHN (for 5 wt pct SiC dispersed) and 450 to 825 VHN (for 20 wt pct SiC dispersed) as compared to 155 VHN of commercially available AISI 316L stainless steel. The corrosion rate in 3.56 wt pct NaCl solution is significantly reduced in 5 wt pct SiC dispersed steel; however, 20 wt pct SiC dispersed steel showed a similar behavior as the commercially available AISI 316L stainless steel. The processing zone for the development of a defect-free microstructure with improved properties has been established.

  10. Alberta Initiative for School Improvement: AISI Handbook for Cycle 3, 2006-2009

    ERIC Educational Resources Information Center

    Online Submission, 2006

    2006-01-01

    The purpose of the AISI (Alberta Initiative for School Improvement) Handbook for Cycle 3, 2006-2009 is to provide school authorities with the provincial and local requirements and processes for planning, funding, implementing, managing, evaluating, reporting and sharing school improvement projects. The handbook provides a framework for the

  11. Modeling and Investigation of the Wear Resistance of Salt Bath Nitrided Aisi 4140 via ANN

    NASA Astrophysics Data System (ADS)

    Ekinci, ?erafettin; Akdemir, Ahmet; Kahramanli, Humar

    2013-08-01

    Nitriding is usually used to improve the surface properties of steel materials. In this way, the wear resistance of steels is improved. We conducted a series of studies in order to investigate the microstructural, mechanical and tribological properties of salt bath nitrided AISI 4140 steel. The present study has two parts. For the first phase, the tribological behavior of the AISI 4140 steel which was nitrided in sulfinuz salt bath (SBN) was compared to the behavior of the same steel which was untreated. After surface characterization using metallography, microhardness and sliding wear tests were performed on a block-on-cylinder machine in which carbonized AISI 52100 steel discs were used as the counter face. For the examined AISI 4140 steel samples with and without surface treatment, the evolution of both the friction coefficient and of the wear behavior were determined under various loads, at different sliding velocities and a total sliding distance of 1000 m. The test results showed that wear resistance increased with the nitriding process, friction coefficient decreased due to the sulfur in salt bath and friction coefficient depended systematically on surface hardness. For the second part of this study, four artificial neural network (ANN) models were designed to predict the weight loss and friction coefficient of the nitrided and unnitrided AISI 4140 steel. Load, velocity and sliding distance were used as input. Back-propagation algorithm was chosen for training the ANN. Statistical measurements of R2, MAE and RMSE were employed to evaluate the success of the systems. The results showed that all the systems produced successful results.

  12. Studies on the Sliding Wear Performance of Plasma Spray Ni-20Cr and Ni3Al Coatings

    NASA Astrophysics Data System (ADS)

    Kaur, Maninder; Singh, Harpreet; Singh, Balraj; Singh, Bhupinder

    2010-01-01

    Two metallic powders namely Ni-20Cr and Ni3Al were coated on AISI 309 SS steel by shrouded plasma spray process. The wear behavior of the bare, Ni-20Cr and Ni3Al-coated AISI 309 SS steel was investigated according to ASTM Standard G99-03 on a Pin-on-Disc Wear Test Rig. The wear tests were carried out at normal loads of 30 and 50 N with a sliding velocity of 1 m/s. Cumulative wear rate and coefficient of friction (?) were calculated for all the cases. The worn-out surfaces were then examined by scanning electron microscopy analysis. Both the as-sprayed coatings exhibited typical splat morphology. The XRD analysis indicated the formation of Ni phase for the Ni-20Cr coating and Ni3Al phase for the Ni3Al coating. It has been concluded that the plasma-sprayed Ni-20Cr and Ni3Al coatings can be useful to reduce the wear rate of AISI 309 SS steel. The coatings were found to be adherent to the substrate steel during the wear tests. The plasma-sprayed Ni3Al coating has been recommended as a better choice to reduce the wear of AISI 309 SS steel, in comparison with the Ni-20Cr coating.

  13. Assessment of XM-19 as a Substitute for AISI 348 in ATR Service

    SciTech Connect

    F. A. Garner; L. R. Greenwood; R. E. Mizia; C. R. Tyler

    2007-11-01

    It has been proposed that XM-19 alloy be considered as a possible replacement steel for AISI 348 in the construction of Advanced Test Reactor (ATR) capsules. AISI 348 works well, but is currently very difficult to obtain commercially. The superior and desirable mechanical properties of XM-19 alloy have been proven in non-nuclear applications, but no data are available regarding its use in radiation environments. While most 300 series alloys will meet the conditions required in ATR , it cannot be confidently assumed that XM-19 can be substituted without prior qualification in a radiation test. Compared to AISI 348, XM-19 will have an enhanced tendency for phase instabilities due to its higher levels of Ni and, especially, Si. However, transmutation of important elemental components in the highly thermalized ATR spectrum may have a very pronounced effect on its performance during irradiation. Not only will strong transmutation of Mn to Fe reduce the ductility and strength advantages provided by the higher initial Mn content of XM-19, but the extensive loss of Mn will also release from solution much of the N upon which the higher strength of XM-19 depends. In addition, the combined influence of transmutation and Inverse Kirkendall processes may lead to gas-bubble-covered grain boundaries, producing a very fragile alloy after significant irradiation has accumulated. At present, there are no radiation data available to substantiate this possible scenario. An alternate proposal is therefore advanced. Since the response of AISI 348 and 347 to radiation are expected to be relatively indistinguishable, the AISI 347 might serve as an acceptable replacement. While AISI 348 is usually chosen for nuclear service in order to reduce the overall radioactivity arising from relatively small amounts of highly transmutable elements such as cobalt, these elements have very little effect on the radiation performance of the steel. In the proposed application, however, the activity induced in this highly thermalized spectrum to large doses (10 to 50 dpa) will be overwhelmed by the activation arising from the major steel components: Fe, Cr, and especially Ni. The mechanical properties, irradiation creep, and void swelling behavior of the two steels should be practically indistinguishable.

  14. Experimental Investigation of the Effect of Burnishing Force on Service Properties of AISI 1010 Steel Plates

    NASA Astrophysics Data System (ADS)

    Gharbi, F.; Sghaier, S.; Morel, F.; Benameur, T.

    2015-02-01

    This paper presents the results obtained with a new ball burnishing tool developed for the mechanical treatment of large flat surfaces. Several parameters can affect the mechanical behavior and fatigue of workpiece. Our study focused on the effect of the burnishing force on the surface quality and on the service properties (mechanical behavior, fatigue) of AISI 1010 steel hot-rolled plates. Experimental results assert that burnishing force not exceeding 300 N causes an increase in the ductility. In addition, results indicated that the effect of the burnishing force on the residual surface stress was greater in the direction of advance than in the cross-feed direction. Furthermore, the flat burnishing surfaces did not improve the fatigue strength of AISI 1010 steel flat specimens.

  15. Behavior of AISI SAE 1020 Steel Implanted by Titanium and Exposed to Bacteria Sulphate Deoxidizer

    NASA Astrophysics Data System (ADS)

    Niño, Ely Dannier V.; Garnica, Hernán; Dugar-Zhabon, Veleriy; Castillo, Genis

    2014-05-01

    A hybrid technology to treat solid surfaces with the pulse high voltage and electric arc discharges of low pressure with a three-dimensional ion implantation technique (3DII) is applied. This technology is used to protect AISI SAE 1020 steel against a microbiological corrosion. The titanium ion implanted steel samples (coupons) are subjected to a medium of bacteria sulphate deoxidizer (BSD) which are very typical of the hydrocarbon industry and are potentially harmful for structures when are in contact with petroleum and some of its derivatives. The used technology aims to find an effective hybrid procedure to minimize the harmful effects of bacteria on AISI SAE 1020 steel. The hybrid technology efficiency of superficial titanium implantation is estimated through the measurements of the point corrosion characteristics obtained after testing both the treated and non-treated coupons. The three-dimensional surface structures of the samples are reconstructed with help of a confocal microscope.

  16. An investigation of the plastic fracture of AISI 4340 and 18 nickel - 200 grade maraging steels

    NASA Technical Reports Server (NTRS)

    Cox, T. B.; Low, J. R., Jr.

    1974-01-01

    The mechanisms of plastic fracture (dimpled rupture) in high-purity and commercial 18 Ni, 200 grade maraging steels and quenched and tempered AISI 4340 steels have been studied. Plastic fracture takes place in the maraging alloys through void initiation by fracture of titanium carbo-nitride inclusions and the growth of these voids until impingement results in coalescence and final fracture. The fracture of AISI 4340 steel at a yield strength of 200 ksi occurs by nucleation and subsequent growth of voids formed by fracture of the interface between manganese sulfide inclusions and the matrix. The growth of these inclusion-nucleated voids is interrupted long before coalescence by impingement, by the formation of void sheets which connect neighboring sulfide-nucleated voids.

  17. Determination of tribological properties of ion-nitrided AISI 5140 steel

    SciTech Connect

    Alsaran, Akguen

    2002-09-15

    AISI 5140 low-alloy steel is ion-nitrided under different process parameters, including time (1, 4, and 8 h), temperature (450, 500, and 550 deg. C), and various gas mixtures at a working pressure of 5 mbar. The ion-nitriding behaviors of AISI 5140 steel have been assessed by evaluating tribological properties, surface hardness, surface roughness, compound layer thickness, and case depth by using a pin-on-disk wear machine, microhardness tester, surface profilometer, and scanning electron microscopy (SEM). It is found that ion nitriding improves the wear rate, and the presence of a hard and brittle compound layer on the surface causes an increase in wear of specimen surface. It is finally observed that ion nitriding parameters have no dominant effect on the friction coefficient.

  18. Radiation-induced evolution of austenite matrix in silicon-modified AISI 316 alloys

    SciTech Connect

    Garner, F.A.; Brager, H.R.

    1980-01-01

    The microstructures of a series of silicon-modified AISI 316 alloys irradiated to fast neutron fluences of about 2-3 and 10 x 10/sup 22/ n/cm/sup 2/ (E > 0.1 MeV at temperatures ranging from 400/sup 0/C to 600/sup 0/C have been examined. The irradiation of AISI 316 leads to an extensive repartition of several elements, particularly nickel and silicon, between the matrix and various precipitate phases. The segregation of nickel at void and grain boundary surfaces at the expense of other faster-diffusing elements is a clear indication that one of the mechanisms driving the microchemical evolution is the Inverse Kirkendall effect. There is evidence that at one sink this mechanism is in competition with the solute drag process associated with interstitial gradients.

  19. Gas tungsten arc and shielded metal arc welding of AISI 41XX steels. Welding procedure specification

    SciTech Connect

    Wodtke, C.H.; Frizzell, D.R.

    1985-08-01

    Procedure WPS-127 is qualified under Section IX of the ASME Boiler and Pressure Vessel Code for gas tungsten arc and shielded metal arc welding of AISI 4130 and 4142 steels (ASTM A519) (P-No: None), 0.438-in. wall pipe; filler metal is AMS 6457, Class 4130 MC (F-, A-No; None) (GTAW) and E8018-B2L (F-4, A-3) (GMAW); shielding gas is argon (GTAW).

  20. Creep behavior of AISI 316 stainless steel above 0. 5 T[sub M

    SciTech Connect

    Park, J.G.; Lee, D.Y. . Dept. of Materials Engineering)

    1993-09-01

    AISI 316 austenitic stainless steel possesses a number of desirable properties, such as excellent high-temperature strength and corrosion resistance, for high temperature application. On the other hand, losses in tensile strength and fracture toughness after long-term use at high temperatures limit widespread applications of 316 stainless steel. In an effort to overcome these problems, researchers have made significant efforts to develop 316 stainless steel with improved high-temperature mechanical properties and efficiency. Recently, AISI 316 stainless steel has been focused on as the leading candidate of the structural materials in fusion reactors with their ever increasing demands on materials with high-temperature capability and good compatibility with coolant and irradiation properties. The main objective of the present paper is to report the static and cyclic creep behaviors of AISI 316 stainless steel at stresses between 206 and 285 MPa above 0.5 T[sub M] (melting temperature in Kelvin), i.e., steady state creep rate, stress exponent and activation energy for creep, and Larson-Miller parameters, as well as determine the creep deformation mechanisms.

  1. Effects of Ce on Inclusions, Microstructure, Mechanical Properties, and Corrosion Behavior of AISI 202 Stainless Steel

    NASA Astrophysics Data System (ADS)

    Cai, Guojun; Li, Changsheng

    2015-10-01

    The sizes and morphologies of nonmetallic inclusions, microhardness, tensile strength, and Charpy impact toughness in AISI 202 stainless steel with different Ce contents were synthetically analyzed by means of SEM, TEM, microhardness tester, and tensile and Charpy impact tests. Effects of Ce addition on the corrosion behavior were investigated in 5 wt.% H2SO4 solution for different periods of time through measuring AC impedance. The EIS measurements indicate that the steels with Ce addition exhibit higher R p values than those without Ce, which illustrates the relative resistance to uniform corrosion is accompanied by an increasing Ce addition. Ce addition to AISI 202 stainless steel improves its uniform corrosion resistance owing to metamorphic inclusions and the improvement of electrode potential in matrix. Upon increasing Ce addition, the indentation morphology of samples transfers from sink-in types to pile-up types, explaining good machinability of steels containing Ce. It is witnessed from the fracture mode that Ce refines the grain size of steels, significantly increasing the strength; in the meantime, its plasticity is improved, thereby solving the contradiction between the strength and the plasticity of steels. It is concluded that AISI 202 stainless steel with 0.016 wt.% Ce addition in the mass fraction has the best mechanical properties and the uniform corrosion resistance.

  2. Stoichiometric titanium dioxide ion implantation in AISI 304 stainless steel for corrosion protection

    NASA Astrophysics Data System (ADS)

    Hartwig, A.; Decker, M.; Klein, O.; Karl, H.

    2015-12-01

    The aim of this study is to evaluate the applicability of highly chemically inert titanium dioxide synthesized by ion beam implantation for corrosion protection of AISI 304 stainless steel in sodium chloride solution. More specifically, the prevention of galvanic corrosion between carbon-fiber reinforced plastic (CFRP) and AISI 304 was investigated. Corrosion performance of TiO2 implanted AISI 304 - examined for different implantation and annealing parameters - is strongly influenced by implantation fluence. Experimental results show that a fluence of 5 × 1016 cm-2 (Ti+) and 1 × 1017 cm-2 (O+) is sufficient to prevent pitting corrosion significantly, while galvanic corrosion with CFRP can already be noticeably reduced by an implantation fluence of 5 × 1015 cm-2 (Ti+) and 1 × 1016 cm-2 (O+). Surface roughness, implantation energy and annealing at 200 °C and 400 °C show only little influence on the corrosion behavior. TEM analysis indicates the existence of stoichiometric TiO2 inside the steel matrix for medium fluences and the formation of a separated metal oxide layer for high fluences.

  3. A study on the control of melting ratio to increase mechanical properties of laser welded joints between AISI 440C and AISI 430F

    NASA Astrophysics Data System (ADS)

    Romoli, L.; Rashed, C. A. A.; Lovicu, G.; Ishak, R.

    2015-05-01

    Laser beam welding of dissimilar AISI 440C and AISI 430F stainless steels was investigated in a circular constrained configuration. The beam incidence angle and the offset of the focusing position respect to the contact point between the two materials were used as main control parameters to vary the melting ratio inside the seam. The objective of the study is twofold: to avoid surface microcracks related to the high percentage of carbon of the martensitic steel and to enhance the shear strength of the weld by making it less brittle. To reach this scope the effects of incidence angle and offset on weld bead geometry and melting ratio were studied by means of metallographic analyses, microstructure and microhardness characterization. As last step, the weld mechanical strength was tested by tensile-shear stress test on the whole seam. Experiments demonstrated that varying incidence angle and offsetting the focal position is a reliable method to modify the melting ratio and maintaining the expected resistance length at the material interface, as well. It was found that increasing the percentage of ferritic steel into the joint has beneficial effects on the weld quality and on the shear resistance. The critical carbon content determining the mechanical properties in the fusion zone can be calculated by taking into account the melting ratio.

  4. Endurance and failure characteristics of modified Vasco X-2, CBS 600 and AISI 9310 spur gears. [aircraft construction materials

    NASA Technical Reports Server (NTRS)

    Townsend, D. P.; Zaretsky, E. V.

    1980-01-01

    Gear endurance tests and rolling-element fatigue tests were conducted to compare the performance of spur gears made from AISI 9310, CBS 600 and modified Vasco X-2 and to compare the pitting fatigue lives of these three materials. Gears manufactured from CBS 600 exhibited lives longer than those manufactured from AISI 9310. However, rolling-element fatigue tests resulted in statistically equivalent lives. Modified Vasco X-2 exhibited statistically equivalent lives to AISI 9310. CBS 600 and modified Vasco X-2 gears exhibited the potential of tooth fracture occurring at a tooth surface fatigue pit. Case carburization of all gear surfaces for the modified Vasco X-2 gears results in fracture at the tips of the gears.

  5. Prediction of Phase Transformation and Hardness Distribution of AISI 1045 Steel After Spot Continual Induction Hardening

    NASA Astrophysics Data System (ADS)

    Zhu, Shengxiao; Wang, Zhou; Qin, Xunpeng; Mao, Huajie; Gao, Kai

    2015-10-01

    An numerical and experimental study of spot continual induction hardening (SCIH) for AISI 1045 steel was carried out to gain a better understanding of this non-stationary and transverse flux induction hardening treatment. The SCIH device was set up by assembling the single-turn coil inductor to a five-axis cooperating computer numerical control system. The influence of inductor velocity, input current, and quenching medium on temperature field was estimated via the SCIH model, and the simulated micro-hardness and microstructure were validated by experimental verification. The heating delay phenomenon appearing in the SCIH process had been analyzed.

  6. Pre- and postirradiation properties of brazed joints of AISI 316L stainless steel

    NASA Astrophysics Data System (ADS)

    Brossa, M.; Franconi, E.; Guerreschi, U.; Pierazzi, L.; Poggi, P.; Rustia, V.

    1994-09-01

    An extensive test campaign has been performed to verify the reliability and the endurance of brazed joints between AISI 316L parts for structural applications in the nuclear field. The tests, conducted for comparison with three different high melting temperature alloys, included tensile tests (normal and shear), fatigue tests (fatigue crack propagation, low cycle fatigue, 4-point bending fatigue) and impact tests; besides, tensile tests have been performed with both unirradiated and irradiated specimens. Generally, the tests demonstrated satisfactory mechanical properties of the joints and revealed occasionally strong differences in the behaviour of the different brazing alloys, thus providing important design indications.

  7. AISI/DOE Advanced Process Control Program Vol. 6 of 6: Temperature Measurement of Galvanneal Steel

    SciTech Connect

    S.W. Allison; D.L. Beshears; W.W. Manges

    1999-06-30

    This report describes the successful completion of the development of an accurate in-process measurement instrument for galvanneal steel surface temperatures. This achievement results from a joint research effort that is a part of the American Iron and Steel Institute's (AISI) Advanced Process Control Program, a collaboration between the U.S> Department of Energy and fifteen North American Steelmakers. This three-year project entitled ''Temperature Measurement of Galvanneal Steel'' uses phosphor thermography, and outgrowth of Uranium enrichment research at Oak Ridge facilities. Temperature is the controlling factor regarding the distribution of iron and zinc in the galvanneal strip coating, which in turn determines the desired product properties

  8. Wear behavior of AISI 1090 steel modified by pulse plasma technique

    SciTech Connect

    Ayday, Aysun; Durman, Mehmet

    2012-09-06

    AISI 1090 steel was pulse plasma treated (PPT) using a Molybdenum electrode. Two different pulse numbers were chosen to obtain modified layers of 20{+-}5 {mu}m thickness. The dry sliding wear studies performed on this steel with and without PPT against an alumina ball counterpart showed that the PPT improved the wear resistance. The pulse number of the PPT modified layer was found to be highly influential in imparting the wear resistance to this steel, due to enhancement of surface hardness depending on treatment time.

  9. Experimental and Analytical Load-Life Relation for AISI 9310 Steel Spur Gears

    NASA Technical Reports Server (NTRS)

    Townsend, D. P.; Coy, J. J.; Zaretsky, E. V.

    1977-01-01

    Life tests were conducted at three different loads with three groups of 8.9 cm pitch diameter spur gears made of vacuum arc remelted VAR AISI 9310 steel. Life was found to vary inversely with load to the 4.3 and 5.1 power at the L10 sub and L50 sub life levels, respectively. The Weibull slope varied linearly with maximum Hertz contact stress, having an average value of 2.5. The test data when compared to AGMA standards showed a steeper slope for the load-life diagram.

  10. Stress corrosion cracking of AISI 304 and 316 stainless steels in lithiated water at 350C

    NASA Astrophysics Data System (ADS)

    Sharkawy, S. W.; Xia, Z.; Szklarska-Smialowska, Z.

    1992-10-01

    The stress corrosion cracking susceptibility of AISI Types 304 and 316 SS tubes with different heat treatments were investigated in lithiated water at 350C. A comparison of the behaviour of these steels in the form of tubes with those made of sheets under stress corrosion cracking (SCC tests was discussed. The results showed that the sensitized conditions of both types exhibited the lowest SCC susceptibility compared to the solution-annealed conditions. The hydrogen content near the fracture surface was the highest along the gauge length of the specimens.

  11. Investigating early stages of biocorrosion with XPS: AISI 304 stainless steel exposed to Burkholderia species

    NASA Astrophysics Data System (ADS)

    Johansson, Leena-Sisko; Saastamoinen, Tuomas

    1999-04-01

    We have investigated the interactions of an exopolymer-producing bacteria, Burkholderia sp. with polished AISI 304 stainless steel substrates using X-ray photoelectron spectroscopy (XPS). Steel coupons were exposed to the pure bacteria culture in a specially designed flowcell for 6 h during which the experiment was monitored in situ with an optical microscope. XPS results verified the formation of biofilm containing extracellular polymer on all the samples exposed to bacteria. Sputter results indicated that some ions needed for metabolic processes were trapped within the biofilm. Changes in the relative Fe concentration and Fe 2p peak shape indicated that also iron had accumulated into the biofilm.

  12. Effects of biofilm formation on the electrochemical behavior of AISI 304 SS in board machine environment

    SciTech Connect

    Carp, L.; Hakkarainen, T.; Raaska, L.

    1999-11-01

    The electrochemical behavior of and biofilm formation on AISI 304 stainless steel were studied in board machine environment with natural bacteria population. Open circuit potentials, redox-potential as well as different electrochemical measurements were performed. The biofilms formed were analyzed by microbial cultivation and by epifluorescence microscopy. The results of the measurements were compared with those performed both in sterilized white water and in artificial white water. The anodic polarization behavior of just immersed specimens was very similar in biotic (real), artificial and abiotic (sterilized) white water. Pitting initiated at very low potentials and continued to very negative values. The initiation of pitting became more difficult when the immersion time increased to 7 or 8 days in real, artificial or sterilized water. When the immersion time further increased, the pitting nucleated more easily in sterilized white water as well as in artificial white water than in biotic white water. In the laboratory equipment it was possible to maintain the biofilm already formed in the board mill, but the amount of sulfate reducing bacteria decreased and the amount of biofilm did not further increase. The composition and structure of the biofilm formed in laboratory differed from that formed in board mill conditions. The preliminary results indicate that the formation of biofilm in biotic white water rather inhibits than enhances the pitting corrosion of type AISI 304 stainless steel.

  13. Variation in sessile microflora during biofilm formation on AISI-304 stainless steel coupons.

    PubMed

    de França, F P; Lutterbach, M T

    1996-07-01

    Coupons of stainless steel type AISI-304 were exposed to the industrial cooling system of a petrochemical plant fed by seawater from the Guanabara Bay, Rio de Janeiro, Brazil, in order to study the in situ formation of biofilms. Bacteria, microalgae and fungi were detected on the coupons as soon as 48 h after exposure. Their respective numbers were determined at times 48, 96 and 192 h and over the following 8 weeks. Aerobic, anaerobic and sulfate-reducing bacteria were quantified according to the technique of the most probable number, and fungi by the pour plate technique. The number of microorganisms present in the forming biofilm varied over the experimental period, reaching maximal levels of 14 x 10(11) cells cm-2, 30 x 10(13) cells cm-2, 38 x 10(11) cells cm-2 and 63 x 10(5) cells cm-2, respectively, for aerobic bacteria, anaerobic bacteria, sulfate-reducing bacteria and fungi, and the dynamics of this variation depended on the group of microorganisms. Bacillus sp, Escherichia coli, Serratia sp and Pseudomonas putrefaciens were identified among the aerobic bacteria isolated. Additionally, microalgae and bacteria of the genus Gallionella were also detected. Nonetheless, no evidence of corrosion was found on the stainless steel type AISI-304 coupons over the experimental period. PMID:8987686

  14. Microstructure, Texture, and Mechanical Property Analysis of Gas Metal Arc Welded AISI 304 Austenitic Stainless Steel

    NASA Astrophysics Data System (ADS)

    Saha, Saptarshi; Mukherjee, Manidipto; Pal, Tapan Kumar

    2015-03-01

    The present study elaborately explains the effect of welding parameters on the microstructure, texture, and mechanical properties of gas metal arc welded AISI 304 austenitic stainless steel sheet (as received) of 4 mm thickness. The welded joints were prepared by varying welding speed (WS) and current simultaneously at a fixed heat input level using a 1.2-mm-diameter austenitic filler metal (AISI 316L). The overall purpose of this study is to investigate the effect of the variation of welding conditions on: (i) Microstructural constituents using optical microscope and transmission electron microscope; (ii) Micro-texture evolution, misorientation distributions, and grain boundaries at welded regions by measuring the orientation data from electron back scattered diffraction; and (iii) Mechanical properties such as hardness and tensile strength, and their correlation with the microstructure and texture. It has been observed that the higher WS along with the higher welding current (weld metal W1) can enhance weld metal mechanical properties through alternation in microstructure and texture of the weld metal. Higher δ-ferrite formation and high-angle boundaries along with the <101> + <001> grain growth direction of the weld metal W1 were responsible for dislocation pile-ups, SFs, deformation twinning, and the induced martensite with consequent strain hardening during tensile deformation. Also, fusion boundary being the weakest link in the welded structure, failure took place mainly at this region.

  15. Determination of Proper Austenitization Temperatures for Hot Stamping of AISI 4140 Steel

    NASA Astrophysics Data System (ADS)

    Samadian, Pedram; Parsa, Mohammad Habibi; Shakeri, Amid

    2014-04-01

    High strength steels are desirable materials for use in automobile bodies in order to reduce vehicle weight and increase the safety of car passengers, but steel grades with high strength commonly show poor formability. Recently, steels with controlled microstructures and compositions are used to gain adequate strength after hot stamping while maintaining good formability during processing. In this study, microstructure evolutions and changes in mechanical properties of AISI 4140 steel sheets resulting from the hot stamping process at different austenitization temperatures were investigated. To determine the proper austenitization temperatures, the results were compared with those of the cold-worked and cold-worked plus quench-tempered specimens. Comparisons showed that the austenitization temperatures of 1000 and 1100 °C are proper for hot stamping of 3-mm-thick AISI 4140 steel sheets due to the resultant martensitic microstructure which led to the yield and ultimate tensile strength of 1.3 and 2.1 GPa, respectively. Such conditions resulted in more favorable simultaneous strength and elongation than those of hot-stamped conventional boron steels.

  16. Modelling of Tool Wear and Residual Stress during Machining of AISI H13 Tool Steel

    SciTech Connect

    Outeiro, Jose C.; Pina, Jose C.; Umbrello, Domenico; Rizzuti, Stefania

    2007-05-17

    Residual stresses can enhance or impair the ability of a component to withstand loading conditions in service (fatigue, creep, stress corrosion cracking, etc.), depending on their nature: compressive or tensile, respectively. This poses enormous problems in structural assembly as this affects the structural integrity of the whole part. In addition, tool wear issues are of critical importance in manufacturing since these affect component quality, tool life and machining cost. Therefore, prediction and control of both tool wear and the residual stresses in machining are absolutely necessary. In this work, a two-dimensional Finite Element model using an implicit Lagrangian formulation with an automatic remeshing was applied to simulate the orthogonal cutting process of AISI H13 tool steel. To validate such model the predicted and experimentally measured chip geometry, cutting forces, temperatures, tool wear and residual stresses on the machined affected layers were compared. The proposed FE model allowed us to investigate the influence of tool geometry, cutting regime parameters and tool wear on residual stress distribution in the machined surface and subsurface of AISI H13 tool steel. The obtained results permit to conclude that in order to reduce the magnitude of surface residual stresses, the cutting speed should be increased, the uncut chip thickness (or feed) should be reduced and machining with honed tools having large cutting edge radii produce better results than chamfered tools. Moreover, increasing tool wear increases the magnitude of surface residual stresses.

  17. Improvement in cavitation erosion resistance of AISI 316L stainless steel by friction stir processing

    NASA Astrophysics Data System (ADS)

    Hajian, M.; Abdollah-zadeh, A.; Rezaei-Nejad, S. S.; Assadi, H.; Hadavi, S. M. M.; Chung, K.; Shokouhimehr, M.

    2014-07-01

    Commercial AISI 316L plates with the initial grain size of 14.8 ?m were friction stir processed (FSP) with different processing parameters, resulting in two fine-grained microstructures with the grain sizes of 4.6 and 1.7 ?m. The cavitation erosion behavior, before and after FSP, was evaluated in terms of incubation time, cumulative mass loss and mean depth of erosion. A separate cavitation erosion test was performed on the transverse cross section of a FSP sample to reveal the effect of grain structure. It was observed that FSP samples, depending on their grain size, are at least 3-6 times more resistant than the base material against cavitation erosion. The improvement in cavitation erosion resistance is attributed to smaller grain structure, lower fraction of twin boundaries, and favorable crystallographic orientation of grains in FSP samples. The finer the grain size, the more cavitation erosion resistance was achieved. Moreover, the microstructures of eroded surfaces were studied using a scanning electron microscope equipped with EBSD, and an atomic force microscope. The mechanisms controlling the cavitation erosion damage in friction stir processed AISI 316L are also discussed.

  18. Modeling of the flow stress for AISI H13 Tool Steel during Hard Machining Processes

    SciTech Connect

    Umbrello, Domenico; Rizzuti, Stefania; Outeiro, Jose C.; Shivpuri, Rajiv

    2007-04-07

    In general, the flow stress models used in computer simulation of machining processes are a function of effective strain, effective strain rate and temperature developed during the cutting process. However, these models do not adequately describe the material behavior in hard machining, where a range of material hardness between 45 and 60 HRC are used. Thus, depending on the specific material hardness different material models must be used in modeling the cutting process. This paper describes the development of a hardness-based flow stress and fracture models for the AISI H13 tool steel, which can be applied for range of material hardness mentioned above. These models were implemented in a non-isothermal viscoplastic numerical model to simulate the machining process for AISI H13 with various hardness values and applying different cutting regime parameters. Predicted results are validated by comparing them with experimental results found in the literature. They are found to predict reasonably well the cutting forces as well as the change in chip morphology from continuous to segmented chip as the material hardness change.

  19. Surface modification of biomedical AISI 316L stainless steel with zirconium carbonitride coatings

    NASA Astrophysics Data System (ADS)

    Wang, L.; Zhao, X.; Ding, M. H.; Zheng, H.; Zhang, H. S.; Zhang, B.; Li, X. Q.; Wu, G. Y.

    2015-06-01

    In the paper, by using radio frequency (rf) magnetron sputtering method, a zirconium carbonitride coating was produced on AISI 316L austenitic stainless steel. The influence of substrate temperature (Ts) on microstructure, mechanical properties, corrosion resistance and hemocompatibility were then investigated. XRD and TEM results revealed that the zirconium carbonitride coatings were almost amorphous when Ts was below 400C, while nanostructured Zr2CN was formed at Ts of 400 C. The nanocrystalline formation resulted in a significant increase in the nanohardness of zirconium carbonitride coatings from 17 GPa to over 32 GPa. Electrochemical testing showed that the stable zirconium carbonitride coating had improved the corrosion resistance of AISI 316L stainless steel substrate material. The characterization of platelet adhesion indicated that the zirconium carbonitride coatings presented better hemocompatibility when Ts varied from 25 C to more than 200 C, which may be due to the lower surface roughness, interfacial tension and the rate ?sd /?sp , where ?sd and ?sp are the disperse component and polar component of the surface, respectively.

  20. Microstructural interpretation of the fluence and temperature dependence of the mechanical properties of irradiated AISI 316

    SciTech Connect

    Johnson, G.D.; Garner, F.A.; Brager, H.R.; Fish, R.L.

    1980-04-17

    The effects of neutron irradiation on the mechanical properties of annealed and 20% cold-worked AISI 316 irradiated in EBR-II were determined for the temperature regime of 370 to 760/sup 0/C for fluences up to 8.4 x 10/sup 22/ n/cm/sup 2/ (E > 0.1 MeV). At irradiation temperatures below about 500/sup 0/C, both annealed and cold-worked material exhibit a substantial increase in the flow stress with increasing fluence. Furthermore, both materials eventually exhibit the same flow stress, which is independent of fluence. At temperatures in the range of 538 to 650/sup 0/C, the cold-worked material exhibits a softening with increasing fluence. Annealed AISI 316 in this temperature regime exhibits hardening and at a fluence of 2 to 3 x 10/sup 22/ n/cm/sup 2/ (E > 0.1 MeV) reaches the same value of flow stress as the cold-worked material.

  1. Surface Treatments for Improved Performance of Spinel-coated AISI 441 Ferritic Stainless Steel

    SciTech Connect

    Stevenson, Jeffry W.; Riel, Eric M.; Stephens, Elizabeth V.; Khaleel, Mohammad A.

    2013-01-01

    Ferritic stainless steels are promising candidates for IT-SOFC interconnect applications due to their low cost and resistance to oxidation at SOFC operating temperatures. However, steel candidates face several challenges; including long term oxidation under interconnect exposure conditions, which can lead to increased electrical resistance, surface instability, and poisoning of cathodes due to volatilization of Cr. To potentially extend interconnect lifetime and improve performance, a variety of surface treatments were performed on AISI 441 ferritic stainless steel coupons prior to application of a protective spinel coating. The coated coupons were then subjected to oxidation testing at 800 and 850°C in air, and electrical testing at 800°C in air. While all of the surface-treatments resulted in improved surface stability (i.e., increased spallation resistance) compared to untreated AISI 441, the greatest degree of improvement (through 20,000 hours of testing at 800°C and 14,000 hours of testing at 850°C) was achieved by surface blasting.

  2. Niobium boride layers deposition on the surface AISI D2 steel by a duplex treatment

    SciTech Connect

    Kon, O.; Pazarlioglu, S.

    2015-03-30

    In this paper, we investigated the possibility of deposition of niobium boride layers on the surface of AISI D2 steel by a duplex treatment. At the first step of duplex treatment, boronizing was performed on AISI D2 steel samples at 1000{sup o}C for 2h and then pre-boronized samples niobized at 850°C, 900°C and 950°C using thermo-reactive deposition method for 1–4 h. The presence of the niobium boride layers such as NbB, NbB{sub 2} and Nb{sub 3}B{sub 4} and also iron boride phases such as FeB, Fe{sub 2}B were examined by X-ray diffraction analysis. Scanning electron microscope (SEM) and micro-hardness measurements were realized. Experimental studies showed that the depth of the coating layers increased with increasing temperature and times and also ranged from 0.42 µm to 2.43 µm, depending on treatment time and temperature. The hardness of the niobium boride layer was 2620±180 HV{sub 0.005}.

  3. Microstructure, Mechanical and Corrosion Properties of Friction Stir-Processed AISI D2 Tool Steel

    NASA Astrophysics Data System (ADS)

    Yasavol, Noushin; Jafari, Hassan

    2015-05-01

    In this study, AISI D2 tool steel underwent friction stir processing (FSP). The microstructure, mechanical properties, and corrosion resistance of the FSPed materials were then evaluated. A flat WC-Co tool was used; the rotation rate of the tool varied from 400 to 800 rpm, and the travel speed was maintained constant at 385 mm/s during the process. FSP improved mechanical properties and produced ultrafine-grained surface layers in the tool steel. Mechanical properties improvement is attributed to the homogenous distribution of two types of fine (0.2-0.3 ?m) and coarse (1.6 ?m) carbides in duplex ferrite-martensite matrix. In addition to the refinement of the carbides, the homogenous dispersion of the particles was found to be more effective in enhancing mechanical properties at 500 rpm tool rotation rate. The improved corrosion resistance was observed and is attributed to the volume fraction of low-angle grain boundaries produced after friction stir process of the AISI D2 steel.

  4. DAFS contribution: the influence of dislocation density and radiation on carbon activity and phase development in AISI 316. [LMFBR

    SciTech Connect

    Garner, F.A.; Wolfer, W.G.

    1980-01-01

    The objective of this effort is to identify the role of each major element in the microchemical evolution of AISI 316 and the dependence of that role on preirradiation treatment and parameters such as neutron energy and flux, temperature and stress.

  5. Studies on the determination of surface deuterium in AISI 1062, 4037, and 4140 steels by secondary ion mass spectrometry

    NASA Astrophysics Data System (ADS)

    Sastri, V. S.; Donepudi, V. S.; McIntyre, N. S.; Johnston, D.; Revie, R. W.

    1988-12-01

    The concentration of deuterium at the surface of cathodically charged high strength steels AISI 1062, 4037, and 4140 has been determined by secondary ion mass spectrometry (SIMS). The beneficial effects of pickling in NAP (a mixture of nitric, acetic, and phosphoric acids) to remove surfacebound deuterium have been observed.

  6. Surface fatigue life and failure characteristics of EX-53, CBS 1000M, and AISI 9310 gear materials

    NASA Technical Reports Server (NTRS)

    Townsend, D. P.

    1985-01-01

    Spur gear endurance tests and rolling-element surface fatigue tests are conducted to investigate EX-53 and CBS 1000M steels for use as advanced application gear materials, to determine their endurance characteristics, and to compare the results with the standard AISI 9310 gear material. The gear pitch diameter is 8.89 cm (3.50 in). Gear test conditions are an oil inlet temperature of 320 K (116 F), an oil outlet temperature of 350 K (170 F), a maximum Hertz stress of 1.71 GPa (248 ksi), and a speed of 10,000 rpm. Bench-type rolling-element fatigue tests are conducted at ambient temperature with a bar specimen speed of 12,500 rpm and a maximum Hertz stress of 4.83 GPa (700 ksi). The EX-53 test gears have a surface fatigue life of twice that of the AISI 9310 spur gears. The CBS 1000M test gears have a surface fatigue life of more than twice that of the AISI 9310 spur gears. However, the CBS 1000M gears experience a 30-percent tooth fracture failure which limits its use as a gear material. The rolling-contact fatigue lines of RC bar specimens of EX-53 and ASISI 9310 are approximately equal. However, the CBS 1000M RC specimens have a surface fatigue life of about 50 percent that of the AISI 9310.

  7. Residual Stresses in LENS-Deposited AISI 410 Stainless Steel Plates

    SciTech Connect

    Wang, L; Felicellli, S D; Pratt, Phillip R

    2008-01-01

    The residual stress in thin plate components deposited by the laser engineered net shaping (LENS{reg_sign}) process was investigated experimentally and numerically. Neutron diffraction mapping was used to characterize the residual stress in LENS-deposited AISI 410 stainless steel thin wall plates. Using the commercial welding software SYSWELD, a thermo-mechanical three-dimensional finite element model was developed, which considers also the effect of metallurgical phase transformations. The model was employed to predict the temperature history and the residual stress field during the LENS process. Several simulations were performed with the geometry and process parameters that were used to build the experimental samples. The origin of the residual stress distribution is discussed based on the thermal histories of the samples, and the modeling results are compared with measurements obtained by neutron diffraction mapping.

  8. Microstructural Evolution in Multiway Loading-Forming Process of AISI 5140 Steel Triple Valve Body

    NASA Astrophysics Data System (ADS)

    Sun, Zhichao; Yang, He

    2014-04-01

    The microstructural evolution and distribution rules, such as dynamic recrystallization (DRX) volume fraction, dynamically recrystallized grain size, and average grain size, in multiway loading-forming process of AISI 5140 steel triple valve body have been investigated using numerical simulation, combined with the analytic method by considering the influences of process parameters including loading speed of punch, initial temperature of billet, and friction. The results show that the DRX volume fraction increased, and its distribution became more uniform with the increases of punch loading speed and billet initial temperature, or the decrease of friction factor; the dynamically recrystallized grain size decreased, and its distribution was more uniform, with the increases of punch loading speed and friction factor, or the decrease of billet initial temperature; the average grain size decreased, and its distribution became more uniform with the increases of punch loading speed and billet initial temperature, or decrease of friction factor.

  9. Microstructure and Texture Evolutions in AISI 1050 Steel by Flow Forming

    SciTech Connect

    Bedekar, Vikram; Pauskar, Praveen; Shivpuri, Rajiv; Howe, Jane Y

    2014-01-01

    Hot rolled and annealed AISI 1050 steel cylindrical coupons were flow formed at different levels of deformation (66% and 90% wall thickness reduction). TEM studies revealed development of ultra fine (sub) grain cell structure due to severe plastic deformation. The transverse subgrain size changed from 10 m (beginning) to 300nm (66% deformation) to 40nm (90% deformation). EBSD study revealed decreased recrystallization fraction at 90% deformation compared with 66% deformation due to orientation pinning from preferred orientation along {002} planes. No evidence of dislocation pinning or cracking was observed on any samples. The aim of the present work is to study the deformation behaviour and microstructural evolution during conventional flow forming process. The study also sheds light on the strengthening behaviour and structural changes during severe straining.

  10. Residual Stress Analysis of Boronized AISI 1018 Steel by Synchrotron Radiation

    SciTech Connect

    Payne, J A; Petrova, R S; White, H J; Chauhan, A; Bai, Jianming

    2008-01-01

    AISI 1018 steel substrates were powder-pack, diffusion boronized at 850 C for 4 h, followed by air quenching. Optical microscopy in conjunction with color etching was used to obtain the average penetration depth of the iron monoboride layer (9 {micro}m) and the iron diboride layer (57 {micro}m). X-ray diffraction by synchrotron radiation, conducted at the National Synchrotron Light Source in Brookhaven National Laboratory, confirmed the presence of iron monoboride and iron diboride in the boronized plain steel substrates. The sin{sup 2} {Psi} technique was employed to calculate the residual stress found in the iron monoboride layer (-237 MPa) and in the substrate layer (-150 MPa) that is intertwined with the needle-like, iron diboride penetration.

  11. Characteristics of Laser Beam and Friction Stir Welded AISI 409M Ferritic Stainless Steel Joints

    NASA Astrophysics Data System (ADS)

    Lakshminarayanan, A. K.; Balasubramanian, V.

    2012-04-01

    This article presents the comparative evaluation of microstructural features and mechanical properties of friction stir welded (solid-state) and laser beam welded (high energy density fusion welding) AISI 409M grade ferritic stainless steel joints. Optical microscopy, microhardness testing, transverse tensile, and impact tests were performed. The coarse ferrite grains in the base material were changed to fine grains consisting duplex structure of ferrite and martensite due to the rapid cooling rate and high strain induced by severe plastic deformation caused by frictional stirring. On the other hand, columnar dendritic grain structure was observed in fusion zone of laser beam welded joints. Tensile testing indicates overmatching of the weld metal relative to the base metal irrespective of the welding processes used. The LBW joint exhibited superior impact toughness compared to the FSW joint.

  12. Ultrasonic and metallographic studies on AISI 4140 steel exposed to hydrogen at high pressure and temperature

    NASA Astrophysics Data System (ADS)

    Oruganti, Malavika

    This thesis conducts an investigation to study the effects of hydrogen exposure at high temperature and pressure on the behavior of AISI 4140 steel. Piezoelectric ultrasonic technique was primarily used to evaluate surface longitudinal wave velocity and defect geometry variations, as related to time after exposure to hydrogen at high temperature and pressure. Critically refracted longitudinal wave technique was used for the former and pulse-echo technique for the latter. Optical microscopy and scanning electron microscopy were used to correlate the ultrasonic results with the microstructure of the steel and to provide better insight into the steel behavior. The results of the investigation indicate that frequency analysis of the defect echo, determined using the pulse-echo technique at regular intervals of time, appears to be a promising tool for monitoring defect growth induced by a high temperature and high pressure hydrogen-related attack.

  13. Experiments on the ratchetting behavior of AISI 316L (N) austenitic steel at room temperature

    SciTech Connect

    Haupt, A.; Schinke, B.

    1996-07-01

    Uniaxial tension-compression ratchetting tests were performed on AISI 316 L(N) austenitic stainless steel at room temperature. The mean stresses were low in comparison to the stress amplitudes. Nevertheless, they have been found to be of major importance to strain accumulation. Also, the stress amplitude exerts a distinct but, under the given conditions, smaller influence. No plastic shakedown has been found in the tests with constant mean stress and stress amplitude. Tests with an increase in the maximum load after a number of cycles, due to an increase in mean stress or stress amplitude, show a behavior similar to that in tests performed with the higher load only. Tests with a decrease in maximum load exhibit immediate shakedown, although tests performed with only the lower load showed ratchetting.

  14. Comparisons of modified Vasco X-2 and AISI 9310 gear steels

    NASA Technical Reports Server (NTRS)

    Townsend, D. P.; Zaretsky, E. V.

    1980-01-01

    Endurance tests were conducted with four groups of spur gears manufactured from three heats of consumable electrode vacuum melted (CVM) modified Vasco X-2. Endurance tests were also conducted with gears manufactured from CVM AISI 9310. Bench type rolling element fatigue tests were conducted with both materials. Hardness measurements were made to 811 K. There was no statistically significant life difference between the two materials. Life differences between the different heats of modified Vasco X-2 can be attributed to heat treat variation and resultant hardness. Carburization of gear flanks only can eliminate tooth fracture as a primary failure mode for modified Vasco X-2. However, a tooth surface fatigue spall can act as a nucleus of a tooth fracture failure for the modified Vasco X-2.

  15. Effect of five lubricants on life of AISI 9310 spur gears

    NASA Technical Reports Server (NTRS)

    Townsend, D. P.; Zaretsky, E. V.

    1985-01-01

    Spur-gear surface fatigue tests were conducted with five lubricants using a single lot of consumable-electrode vacuum melted (CVM) AISI 9310 spur gears. The lot of gears was divided into five groups, each of which was tested with a different lubricant. The test lubricants are classified as either a synthetic hydrocarbon, mineral oil, or ester-based lubricant. All five lubricants have imilar viscosity and pressure-viscosity coefficients. A pentaerythritol base stock without sufficient antiwear additives produced a surface fatigue life pproximately 22 percent that of the same base stock with chlorine and phosphorus type additives. The presence of sulfur type antiwear additives in the lubricant did not appear to affect the surface fatigue life of the gears tested. No statistical difference in the 10-percent surface fatigue life was produced with four of the five lubricants.

  16. Electromagnetic nondestructive evaluation of tempering process in AISI D2 tool steel

    NASA Astrophysics Data System (ADS)

    Kahrobaee, Saeed; Kashefi, Mehrdad

    2015-05-01

    The present paper investigates the potential of using eddy current technique as a reliable nondestructive tool to detect microstructural changes during the different stages of tempering treatment in AISI D2 tool steel. Five stages occur in tempering of the steel: precipitation of ? carbides, formation of cementite, retained austenite decomposition, secondary hardening effect and spheroidization of carbides. These stages were characterized by destructive methods, including dilatometry, differential scanning calorimetry, X-ray diffraction, scanning electron microscopic observations, and hardness measurements. The microstructural changes alter the electrical resistivity/magnetic saturation, which, in turn, influence the eddy current signals. Two EC parameters, induced voltage sensed by pickup coil and impedance point detected by excitation coil, were evaluated as a function of tempering temperature to characterize the microstructural features, nondestructively. The study revealed that a good correlation exists between the EC parameters and the microstructural changes.

  17. Pitting fatigue characteristics of AISI M-50 and super nitralloy spur gears

    NASA Technical Reports Server (NTRS)

    Townsend, D. P.; Chevalier, J. L.; Zaretsky, E. V.

    1973-01-01

    Two groups of 3.50-in. pitch-diameter spur gears, without tip relief, made from consumable-electrode vacuum-melted (CVM) AISI M-50 steel and CVM super nitralloy (5Ni-2A1) were tested under conditions which produced fatigue pitting. The M-50 gears had fatigue lives approximately 50 percent longer than the super nitralloy gears. Both groups of gears failed by classical rolling-element fatigue at the pitch circle. When the gears were overrun past initial spall formation, the spalled M-50 gear teeth failed by fatigue fracture. The M-50 material had higher wear than the super nitralloy material. Differences in fatigue life and wear were not considered statistically significant.

  18. Structural, mechanical and tribological properties of duplex-treated AISI 5140 steel

    SciTech Connect

    Alsaran, Akguen . E-mail: aalsaran@atauni.edu.tr; Celik, Ayhan; Karakan, Mehmet

    2005-01-15

    The structure, hardness, adhesion, surface roughness and tribological properties of duplex-surface-treated (TiN/plasma nitrided), directly TiN-coated and ion-nitrided AISI 5140 steel were investigated using X-ray diffraction, SEM, optical microscopy, a microhardness tester, a scratch tester and a pin-on-disc tribotester. After the plasma nitriding process, the transition treatments were realized to evaluate the effect of the compound layer. It was found that the relative intensity line of TiN (200) and surface roughness increased, but the coating hardness and critical load (Lc) decreased with an increasing amount of {epsilon}-Fe{sub 2-3}N iron nitride in the compound layer. The better tribological properties were obtained with coatings applied on substrates, which included a large amount of {gamma}'-Fe{sub 4}N iron nitride after plasma nitriding.

  19. Study of the Sensitization on the Grain Boundary in Austenitic Stainless Steel Aisi 316

    NASA Astrophysics Data System (ADS)

    Kocsisov, Edina; Domnkov, Mria; Slatkovsk, Ivan; Sahul, Martin

    2014-12-01

    Intergranular corrosion (IGC) is one of the major problems in austenitic stainless steels. This type of corrosion is caused by precipitation of secondary phases on grain boundaries (GB). Precipitation of the secondary phases can lead to formation of chromium depleted zones in the vicinity of grain boundaries. Mount of the sensitization of material is characterized by the degree of sensitization (DOS). Austenitic stainless steel AISI 316 as experimental material had been chosen. The samples for the study of sensitization were solution annealed on 1100 C for 60 min followed by water quenching and then sensitization by isothermal annealing on 700 C and 650 C with holding time from 15 to 600 min. Transmission electron microscopy (TEM) was used for identification of secondary phases. Electron backscattered diffraction (EBSD) was applied for characterization of grain boundary structure as one of the factors which influences on DOS.

  20. Nitrocarburizing of AISI-304 stainless steel using high-voltage plasma immersion ion implantation

    NASA Astrophysics Data System (ADS)

    Abd El-Rahman, A. M.; Mohamed, S. H.; Ahmed, M. R.; Richter, E.; Prokert, F.

    2009-05-01

    AISI-304 austenitic stainless steel has been nitrocarburized in N 2 and C 2H 2 ambient using high-voltage plasma immersion ion implantation (PIII) technology. The use of different PIII treatment times revealed important hints with respect to the microstructural, mechanical and corrosion properties of the nitrocarburized layer. Grazing incidence X-ray diffraction (GIXRD) shows the presence of nitride ( ?N and CrN) and carbide ( ?C and Fe 3C) phases. Glow discharge optical spectroscopy (GDOS) has been used to characterize the elemental depth profiles in which the thickness of the modified layers is derived. Dynamic microindentation method is used for the study of mechanical performance of the nitrocarburized layer as well as the untreated material. The microhardness has been increased to a maximum value of more than nine times compared to that of the untreated one. The corrosion performance is characterized by potentiodynamic polarization technique and was found to be treatment time dependent.

  1. Microstructural characterization of the HAZ in AISI 444 ferritic stainless steel welds

    SciTech Connect

    Silva, Cleiton C. Farias, Jesualdo P.; Miranda, Helio C.; Guimaraes, Rodrigo F.; Menezes, John W.A.; Neto, Moises A.M.

    2008-05-15

    Ferritic stainless steel is used as a coating for equipment in the petroleum refining industry. Welding is the main manufacturing and maintenance process used. However, little information on the metallurgical alterations caused by welding of these steels is found in the literature, prompting this study. In this study the authors evaluated the HAZ microstructure of AISI 444 ferritic stainless steel welded plates, by scanning electron microscopy (SEM) and X-ray diffraction (XRD). The results indicated that a weld thermal cycle caused microphase precipitation in the HAZ of the ferritic stainless steel. Also needle-like Laves phase precipitation occurred in the HAZ, near the partially-melted zone. Other secondary phases such as chi and sigma were observed, as well as nitride, carbide and carbonitride precipitates.

  2. Microstructure evolution and texture development in a friction stir-processed AISI D2 tool steel

    NASA Astrophysics Data System (ADS)

    Yasavol, N.; Abdollah-zadeh, A.; Vieira, M. T.; Jafarian, H. R.

    2014-02-01

    Crystallographic texture developments during friction stir processing (FSP) of AISI D2 tool were studied with respect to grain sizes in different tool rotation rates. Comparison of the grain sizes in various rotation rates confirmed that grain refinement occurred progressively in higher rotation rates by severe plastic deformation. It was found that the predominant mechanism during FSP should be dynamic recovery (DRV) happened concurrently with continuous dynamic recrystallization (CDRX) caused by particle-stimulated nucleation (PSN). The developed shear texture relates to the ideal shear textures of D1 and D2 in bcc metals. The prevalence of highly dense arrangement of close-packed planes of bcc and the lowest Taylor factor showed the lowest compressive residual stress which is responsible for better mechanical properties compared with the grain-precipitate refinement.

  3. Influence of grain refinement on the electrochemical behavior of AISI 430 ferritic stainless steel in an alkaline solution

    NASA Astrophysics Data System (ADS)

    Fattah-alhosseini, A.; Vafaeian, S.

    2016-01-01

    In this paper, the effect of grain refinement on the electrochemical behavior of AISI 430 ferritic stainless steel in 0.1 M NaOH solution was investigated. Potentiodynamic polarization curves showed that fine-grained samples have less corrosion potential, higher corrosion current density, and less protective passive film in comparison to coarse-grained samples. Electrochemical impedance spectroscopy (EIS) analysis revealed that implementing the thermomechanical operation led to lower polarization resistance. Also, Mott-Schottky analysis revealed that the passive films on both fine-grained and coarse-grained samples behave as n-type and p-type semiconductors and the semiconductor character of the passive films did not change by grain refinement. Moreover, it was found that the calculated donor and acceptor densities increased with grain refinement. Thus, the presented results indicated that grain refinement weakens the corrosion and passivation behavior of AISI 430 stainless steel in this alkaline solution.

  4. Surface fatigue life of M50NiL and AISI 9310 spur gears and R C bars

    NASA Technical Reports Server (NTRS)

    Townsend, Dennis P.; Bamberger, Eric N.

    1991-01-01

    Spur gear endurance tests and rolling element surface fatigue tests were conducted to study vacuum induction melted, vacuum arc remelted (VIM-VAR) M50NiL steel for use as a gear steel in advanced aircraft applications, to determine its endurance characteristics, and to compare the results with those for standard VAR and VIM-VAR AISI 9310 gear material. Tests were conducted with spur gears and rolling contact bars manufactured from VIM-VAR M50NiL and VAR and VIM-VAR AISI 9310. The gear pitch diameter was 8.9 cm. Gear test conditions were an inlet oil temperature of 320 K, and outlet oil temperature of 350 K, a maximum Hertz stress of 1.71 GPa, and a speed of 10000 rpm. Bench rolling element fatigue tests were conducted at ambient temperatures with a bar speed of 12,500 rpm and a maximum Hertz stress of 4.83 GPa. The VIM-VAR M50NiL gears had a surface fatigue life that was 4.5 and 11.5 times that for VIM-VAR and VAR AISI 9310 gears, respectively. The surface fatigue life of the VIM-VAR M50NiL rolling contact bars was 13.2 and 21.6 times that for the VIM-VAR and VAR AISI 9310, respectively. The VIM-VAR M50NiL material was shown to have good resistance to fracture through a fatigue spall and superior fatigue life to both other gears.

  5. Microstructure and Mechanical Properties of Laser Clad and Post-cladding Tempered AISI H13 Tool Steel

    NASA Astrophysics Data System (ADS)

    Telasang, Gururaj; Dutta Majumdar, Jyotsna; Wasekar, Nitin; Padmanabham, G.; Manna, Indranil

    2015-05-01

    This study reports a detailed investigation of the microstructure and mechanical properties (wear resistance and tensile strength) of hardened and tempered AISI H13 tool steel substrate following laser cladding with AISI H13 tool steel powder in as-clad and after post-cladding conventional bulk isothermal tempering [at 823 K (550 C) for 2 hours] heat treatment. Laser cladding was carried out on AISI H13 tool steel substrate using a 6 kW continuous wave diode laser coupled with fiber delivering an energy density of 133 J/mm2 and equipped with a co-axial powder feeding nozzle capable of feeding powder at the rate of 13.3 10-3 g/mm2. Laser clad zone comprises martensite, retained austenite, and carbides, and measures an average hardness of 600 to 650 VHN. Subsequent isothermal tempering converted the microstructure into one with tempered martensite and uniform dispersion of carbides with a hardness of 550 to 650 VHN. Interestingly, laser cladding introduced residual compressive stress of 670 15 MPa, which reduces to 580 20 MPa following isothermal tempering. Micro-tensile testing with specimens machined from the clad zone across or transverse to cladding direction showed high strength but failure in brittle mode. On the other hand, similar testing with samples sectioned from the clad zone parallel or longitudinal to the direction of laser cladding prior to and after post-cladding tempering recorded lower strength but ductile failure with 4.7 and 8 pct elongation, respectively. Wear resistance of the laser surface clad and post-cladding tempered samples (evaluated by fretting wear testing) registered superior performance as compared to that of conventional hardened and tempered AISI H13 tool steel.

  6. The tensile properties of AISI 316L and OPTIFER in various conditions irradiated in a spallation environment

    NASA Astrophysics Data System (ADS)

    Chen, J.; Rödig, M.; Carsughi, F.; Dai, Y.; Bauer, G. S.; Ullmaier, H.

    2005-08-01

    Tensile specimens, prepared from AISI 316L austenitic stainless steel in three conditions (solution-annealed, cold-worked and electron-beam welded) and from OPTIFER martensitic stainless steel in tempered condition, were irradiated in the Swiss spallation neutron source (SINQ) at 90-400 °C to displacement doses from 3 dpa to 11 dpa. The mechanical properties were measured by tensile testing at room temperature and 250 °C, respectively, and subsequent metallographic analysis was employed. The tensile results indicated that the strength of AISI 316L-SA is quite similar or a little higher than in 316L-EBW but elongation of SA 316L is somewhat larger than EBW for both unirradiated and irradiated samples. The cold-worked specimens revealed much higher strength but almost zero strain-to-necking after irradiation. The results from OPTIFER samples showed that irradiation hardening increases with dose, which is accompanied by a dramatic reduction of uniform elongation beginning at very low dose. The metallographic analysis showed that the samples of AISI 316L-EBW failed in the welded zone.

  7. Formation of Expanded Austenite on a Cold-Sprayed AISI 316L Coating by Low-Temperature Plasma Nitriding

    NASA Astrophysics Data System (ADS)

    Adachi, Shinichiro; Ueda, Nobuhiro

    2015-07-01

    Low-temperature plasma nitriding at temperatures below 450 C is commonly applied to austenitic stainless steels to enhance wear resistance, while maintaining corrosion resistance, by forming expanded austenite (known as the S-phase). In this work, low-temperature plasma nitriding of cold-sprayed AISI 316L coatings was examined. A cold-spray technique was developed to produce metal coatings with less oxidation. However, the cold-sprayed AISI 316L coating obtained by use of nitrogen gas as propellant contained many interconnected pores and cracks, and was, consequently, unsuitable as an anticorrosive coating. Therefore, laser post-treatment was used to modify the coating and increase its density to similar to that of bulk steel. The anticorrosive performance of this coating on a carbon steel substrate in NaCl solution was substantially improved. Subsequent low-temperature plasma nitriding enhanced the wear resistance by two orders of magnitude. It is concluded that cold-sprayed AISI 316L coatings treated by laser post-treatment and subsequent low-temperature plasma nitriding could be used as protective coatings under severe wear and corrosion conditions.

  8. Plasma nitriding process by direct current glow discharge at low temperature increasing the thermal diffusivity of AISI 304 stainless steel

    SciTech Connect

    Prandel, L. V.; Somer, A.; Assmann, A.; Camelotti, F.; Costa, G.; Bonardi, C.; Jurelo, A. R.; Rodrigues, J. B.; Cruz, G. K.

    2013-02-14

    This work reports for the first time on the use of the open photoacoustic cell technique operating at very low frequencies and at room temperature to experimentally determine the thermal diffusivity parameter of commercial AISI304 stainless steel and AISI304 stainless steel nitrided samples. Complementary measurements of X-ray diffraction and scanning electron microscopy were also performed. The results show that in standard AISI 304 stainless steel samples the thermal diffusivity is (4.0 {+-} 0.3) Multiplication-Sign 10{sup -6} m{sup 2}/s. After the nitriding process, the thermal diffusivity increases to the value (7.1 {+-} 0.5) Multiplication-Sign 10{sup -6} m{sup 2}/s. The results are being associated to the diffusion process of nitrogen into the surface of the sample. Carrying out subsequent thermal treatment at 500 Degree-Sign C, the thermal diffusivity increases up to (12.0 {+-} 2) Multiplication-Sign 10{sup -6} m{sup 2}/s. Now the observed growing in the thermal diffusivity must be related to the change in the phases contained in the nitrided layer.

  9. Formation of Expanded Austenite on a Cold-Sprayed AISI 316L Coating by Low-Temperature Plasma Nitriding

    NASA Astrophysics Data System (ADS)

    Adachi, Shinichiro; Ueda, Nobuhiro

    2015-12-01

    Low-temperature plasma nitriding at temperatures below 450 °C is commonly applied to austenitic stainless steels to enhance wear resistance, while maintaining corrosion resistance, by forming expanded austenite (known as the S-phase). In this work, low-temperature plasma nitriding of cold-sprayed AISI 316L coatings was examined. A cold-spray technique was developed to produce metal coatings with less oxidation. However, the cold-sprayed AISI 316L coating obtained by use of nitrogen gas as propellant contained many interconnected pores and cracks, and was, consequently, unsuitable as an anticorrosive coating. Therefore, laser post-treatment was used to modify the coating and increase its density to similar to that of bulk steel. The anticorrosive performance of this coating on a carbon steel substrate in NaCl solution was substantially improved. Subsequent low-temperature plasma nitriding enhanced the wear resistance by two orders of magnitude. It is concluded that cold-sprayed AISI 316L coatings treated by laser post-treatment and subsequent low-temperature plasma nitriding could be used as protective coatings under severe wear and corrosion conditions.

  10. Linking anisotropy with Fe3C distribution in AISI 1045 steel

    NASA Astrophysics Data System (ADS)

    Shen, Ke-chang; Li, Gui-hua; Sun, Yi-min; Wang, Yong-gang; Li, Ying-jie; Cao, Guang-hui; Wang, Wei-min

    2015-12-01

    The anisotropy of the microstructure, thermal expansion behavior, corrosion resistance and magnetic properties of AISI 1045 steel was investigated. The distribution of Fe3C lamellae in the investigation plane parallel to the radial directions of molds was observed to differ from that in the investigation plane perpendicular to the radial directions by transmission electron microscopy. The lattice constants a 0 of ?-Fe deduced from the XRD patterns of samples prepared using a sand (S)-mold and cut parallel to the radial direction of the mold (S//) and using a metal (M)-mold and cut parallel to the radial direction (M//), the corrosion resistance measured using an electrochemical workstation, and the magnetic permeability obtained by vibrating sample magnetometry also indicated the existence of anisotropy in the tested samples. The anisotropic change of corrosion potential ( E corr), pitting potential ( E pit) and magnetic permeability ( ) of the samples was observed to depend on the orientation factor F 200 of ?-Fe in the measured samples, which is controlled by the distribution of Fe3C lamellae in the eutectoid structure.

  11. Niobized AISI 304 stainless steel bipolar plate for proton exchange membrane fuel cell

    NASA Astrophysics Data System (ADS)

    Wang, Lixia; Sun, Juncai; Li, Pengbin; Jing, Bo; Li, Song; Wen, Zhongsheng; Ji, Shijun

    2012-06-01

    AISI 304 stainless steel (SS) has been niobized by a plasma surface diffusion alloying method. A 3 ?m niobized layer with dominant niobium elements has been formed on the 304 SS surface and the performances of the niobized 304 SS has been examined and evaluated as bipolar plate for proton exchange membrane fuel cell (PEMFC). Results show that the average contact angle with water for the niobized 304 SS is about 90.4, demonstrating better hydrophobicity as compared with the untreated 304 SS (68.1). The corrosion resistance of the 304 SS is considerably improved by the niobized layer with the corrosion current densities decreased at 0.2 and 0.4 ?A cm-2 in simulated PEMFC anode purged with hydrogen and the cathode purged with air condition (0.05 M H2SO4 + 2 ppm F- solution at 70 C), respectively. The interfacial contact resistance (ICR) for the as-prepared niobized 304 SS is 10.53 m? cm2 at the compaction of 140 N cm-2. Furthermore, after 4 h potentiostatic tests, the niobizied specimens exhibit much lower ICR than that for the untreated ones. Thus, the niobized layer can act as a conductively protective layer of the 304 SS bipolar plate for PEMFC.

  12. Effect of Surface Integrity of Hard Turned AISI 52100 Steel on Fatigue Performance

    SciTech Connect

    Lara-Curzio, Edgar; Watkins, Thomas R; Allard Jr, Lawrence Frederick; Riester, Laura

    2007-01-01

    This paper addresses the relationship between surface integrity and fatigue life of hard turned AISI 52100 steel (60-62 HRC), with grinding as a benchmark. The impact of superfinishing on the fatigue performance of hard turned and ground surfaces is also discussed. Specifically, the surface integrity and fatigue life of the following five distinct surface conditions are examined: hard turned with continuous white layer, hard turned with no white layer, ground, and superfinished hard turned and ground specimens. Surface integrity of the specimens is characterized via surface topography measurement, metallography, residual stress measurements, transmission electron microscopy (TEM), and nano-indentation tests. High cycle tension-tension fatigue tests show that the presence of white layer does not adversely affect fatigue life and that, on average, the hard turned surface performs as well or better than the ground surface. The effect of superfinishing is to exaggerate these differences in performance. The results obtained from this study suggest that the effect of residual stress on fatigue life is more significant than the effect of white layer. For the hard turned surfaces, the fatigue life is found to be directly proportional to both the surface compressive residual stress and the maximum compressive residual stress. Possible explanations for the observed effects are discussed.

  13. Some Temperature Effects on AISI-304 Nitriding in an Inductively Coupled RF Plasma

    NASA Astrophysics Data System (ADS)

    Valencia-Alvarado, R.; de la Piedad-Beneitez, A.; de la Rosa-Vzquez, J.; Lpez-Callejas, R.; Barocio, S. R.; Godoy-Cabrera, O. G.; Mercado-Cabrera, A.; Pea-Eguiluz, R.; Muoz-Castro, A. E.

    2006-12-01

    Some recent results obtained from nitriding AISI 304 stainless steel samples, 1.2 cm in diameter and 0.5 cm thick are reported here in the case of an 85% hydrogen and 15% nitrogen mixture work gas. The process was carried out from 300 to 400 W for (13.56 MHz) inductively coupled plasma within a 60 cm long pyrex glass tube 3.5 cm in diameter where the samples were biased up to -300 V with respect to earth. The resulting hardness appears to be a function of the substrate temperature which varied from 200 C at a 0 V bias to 550 C at -300 V. The plasma density at 400 W reached 31010 cm-3 with a 4 eV electron temperature. Prior to nitriding, all the samples were polished with 0.05 ?m diamond paste, leading to a 30 nm average roughness (Ra). After nitriding at -300 V, the Ra rose until 400 nm while hardness values of 1500 HV under 300 g loads were measured. X ray diffraction indicates that the extended phase amplitude (?N), Fe and Cr nitride depends on the substrate temperature.

  14. Some Temperature Effects on AISI-304 Nitriding in an Inductively Coupled RF Plasma

    SciTech Connect

    Valencia-Alvarado, R.; Barocio, S. R.; Mercado-Cabrera, A.; Pena-Eguiluz, R.; Munoz-Castro, A. E.; Piedad-Beneitez, A. de la; Rosa-Vazquez, J. de la; Lopez-Callejas, R.; Godoy-Cabrera, O. G.

    2006-12-04

    Some recent results obtained from nitriding AISI 304 stainless steel samples, 1.2 cm in diameter and 0.5 cm thick are reported here in the case of an 85% hydrogen and 15% nitrogen mixture work gas. The process was carried out from 300 to 400 W for (13.56 MHz) inductively coupled plasma within a 60 cm long pyrex glass tube 3.5 cm in diameter where the samples were biased up to -300 V with respect to earth. The resulting hardness appears to be a function of the substrate temperature which varied from 200 deg. C at a 0 V bias to 550 deg. C at -300 V. The plasma density at 400 W reached 3x1010 cm-3 with a 4 eV electron temperature. Prior to nitriding, all the samples were polished with 0.05 {mu}m diamond paste, leading to a 30 nm average roughness (Ra). After nitriding at -300 V, the Ra rose until {approx}400 nm while hardness values of 1500 HV under 300 g loads were measured. X ray diffraction indicates that the extended phase amplitude ({gamma}N), Fe and Cr nitride depends on the substrate temperature.

  15. Effect of lubricant extreme-pressure additives on surface fatigue life of AISI 9310 spur gears

    NASA Technical Reports Server (NTRS)

    Scibbe, H. W.; Townsend, D. P.; Aron, P. R.

    1984-01-01

    Surface fatigue tests were conducted with AISI 9310 spur gears using a formulated synthetic tetraester oil (conforming to MIL-L-23699 specifications) as the lubricant containing either sulfur or phosphorus as the EP additive. Four groups of gears were tested. One group of gears tested without an additive in the lubricant acted as the reference oil. In the other three groups either a 0.1 wt % sulfur or phosphorus additive was added to the tetraester oil to enhance gear surface fatigue life. Test conditions included a gear temperature of 334 K (160 F), a maximum Hertz stress of 1.71 GPa (248 000 psi), and a speed of 10,000 rpm. The gears tested with a 0.1 wt % phosphorus additive showed pitting fatigue life 2.6 times the life of gears tested with the reference tetraester based oil. Although fatigue lives of two groups of gears tested with the sulfur additive in the oil showed improvement over the control group gear life, the results, unlike those obtained with the phosphorus oil, were not considered to be statistically significant.

  16. Effect of Hydrogen and Magnetic Field on the Mechanical Behavior of High Strength AISI 4340 Steel

    NASA Astrophysics Data System (ADS)

    Ramanathan, Meenakshisundaram; Saha, Biswadeep; Ren, Chai; Guruswamy, Sivaraman; McCarter, Michael

    2013-04-01

    Presence of hydrogen in materials is known to affect their mechanical properties due to hydrogen embrittlement problem. Steels used in various applications are prone to be exposed to aqueous electrochemical environments, which may introduce hydrogen into the alloy. These alloys are also prone to be simultaneously exposed to magnetic field, which may affect the hydrogen embrittlement susceptibility of these alloys. Therefore, it is important to examine the effect of hydrogen and magnetic field on the mechanical behavior of iron-based alloys. In this work, the effect of hydrogen and magnetic field on the fracture behavior of high strength AISI 4340 steel was examined. Three-point bend test was used to study the fracture behavior. In all the cases, the samples tested with hydrogen charging show a drastic reduction in ductility and fracture stress values. The effect of magnetic field was seen to be negligible. The hydrogen embrittlement was characterized by a change in the fracture surface from a ductile-type fracture to a brittle cleavage-type fracture. Acoustic emission signals collected during the test corresponds to the fracture behavior.

  17. Phase Transformations During the Low-Temperature Nitriding of AISI 2205 Duplex Stainless Steel

    NASA Astrophysics Data System (ADS)

    Yan, Jing; Gu, Tan; Qiu, Shaoyu; Wang, Jun; Xiong, Ji; Fan, Hongyuan

    2015-02-01

    Liquid nitriding of type AISI 2205 duplex stainless steel was conducted at 723 K (450 C), using one type of novel low-temperature liquid chemical thermo-treatment. The transformation of the nitrided surface microstructure was systematically studied. Experimental results revealed that a nitrided layer formed on the sample surface with the thickness ranging from 3 to 28 ?m, depending on nitriding time. After the 2205 duplex stainless steel was subjected to liquid nitriding 723 K (450 C) for less than 8 hours, the pre-existing ferrite region on the surface transformed into the expanded austenite (S phase) by the infusion of nitrogen atoms, most of which stay in the interstitial sites. Generally, the dominant phase of the nitrided layer was the expanded austenite. When the nitriding time prolonged up to 16 hours, some pre-existing ferrite in expanded austenite was decomposed and ?-nitride precipitated subsequently. When the treatment time went up to 40 hours, large amount of ?-nitride and CrN precipitates were observed in the pre-existing ferritic region in the expanded austenite. Furthermore, many nitrides precipitated from the pre-austenite region. Acicular nitride was identified by transmission electron microscopy. The thickness of the nitrided layer increased with increasing nitriding time. The growth of the nitrided layer is mainly due to nitrogen diffusion in accordance with the expected parabolic rate law. Liquid nitriding effectively increased the surface hardness of 2205 duplex stainless steel by a factor of 3.

  18. The Meta-Lax method of stress reduction in welds. [ASTM A36; AISI 4140

    SciTech Connect

    Smith, S.M.

    1992-07-31

    This study is the second phase of ongoing research into the mechanics and feasibility of using the Meta-Lax method of vibratory stress relief in place of thermal methods of stress relief. The first phase of this research revealed results that were similar to, and even superior to those achieved using thermal methods. The testing here was designed to eliminate the effects of interbead tempering by utilizing single pass bead-on-plate welds only. A metallurgical explanation for the success of the Meta-Lax method was not found. No significant structure or chemical changes were noted when used with ASTM A36 or AISI 4140 materials, and the phenomena noted in phase I was apparently due to interbead tempering. The theory of accelerated aging has been proposed and studies exist which observed dislocation motion as a result of vibratory treatment. It is evident that the vibratory stress relief system does not impart sufficient energy to bring about the magnitude of change seen with thermal methods. however the physical improvement is a reality, and vibratory methods should be evaluated further.

  19. Characterization of irradiated AISI 316L stainless steel disks removed from the Spallation Neutron Source

    SciTech Connect

    Vevera, Bradley J; Hyres, James W; McClintock, David A; Riemer, Bernie

    2014-01-01

    Irradiated AISI 316L stainless steel disks were removed from the Spallation Neutron Source (SNS) for post-irradiation examination (PIE) to assess mechanical property changes due to radiation damage and erosion of the target vessel. Topics reviewed include high-resolution photography of the disk specimens, cleaning to remove mercury (Hg) residue and surface oxides, profile mapping of cavitation pits using high frequency ultrasonic testing (UT), high-resolution surface replication, and machining of test specimens using wire electrical discharge machining (EDM), tensile testing, Rockwell Superficial hardness testing, Vickers microhardness testing, scanning electron microscopy (SEM), and energy dispersive spectroscopy (EDS). The effectiveness of the cleaning procedure was evident in the pre- and post-cleaning photography and permitted accurate placement of the test specimens on the disks. Due to the limited amount of material available and the unique geometry of the disks, machine fixturing and test specimen design were critical aspects of this work. Multiple designs were considered and refined during mock-up test runs on unirradiated disks. The techniques used to successfully machine and test the various specimens will be presented along with a summary of important findings from the laboratory examinations.

  20. Fe-Based Amorphous Coatings on AISI 4130 Structural Steel for Corrosion Resistance

    NASA Astrophysics Data System (ADS)

    Katakam, Shravana; Santhanakrishnan, S.; Dahotre, Narendra B.

    2012-06-01

    The current study focuses on synthesizing a novel functional coating for corrosion resistance applications, via laser surface alloying. The iron-based (Fe48Cr15Mo14Y2C15B) amorphous precursor powder is used for laser surface alloying on AISI 4130 steel substrate, with a continuous wave ytterbium Nd-YAG fiber laser. The corrosion resistance of the coatings is evaluated for different processing conditions. The microstructural evolution and the response of the microstructure to the corrosive environment is studied using x-ray diffraction, scanning electron microscopy, and transmission electron microscopy. Microstructural studies indicate the presence of face-centered cubic Fe-based dendrites intermixed within an amorphous matrix along with fine crystalline precipitates. The corrosion resistance of the coatings decrease with an increase in laser energy density, which is attributed to the precipitation and growth of chromium carbide. The enhanced corrosion resistance of the coatings processed with low energy density is attributed to the self-healing mechanism of this amorphous system.

  1. Computational Modeling of Microstructural-Evolution in AISI 1005 Steel During Gas Metal Arc Butt Welding

    NASA Astrophysics Data System (ADS)

    Grujicic, M.; Ramaswami, S.; Snipes, J. S.; Yavari, R.; Arakere, A.; Yen, C.-F.; Cheeseman, B. A.

    2013-05-01

    A fully coupled (two-way), transient, thermal-mechanical finite-element procedure is developed to model conventional gas metal arc welding (GMAW) butt-joining process. Two-way thermal-mechanical coupling is achieved by making the mechanical material model of the workpiece and the weld temperature-dependent and by allowing the potential work of plastic deformation resulting from large thermal gradients to be dissipated in the form of heat. To account for the heat losses from the weld into the surroundings, heat transfer effects associated with natural convection and radiation to the environment and thermal-heat conduction to the adjacent workpiece material are considered. The procedure is next combined with the basic physical-metallurgy concepts and principles and applied to a prototypical (plain) low-carbon steel (AISI 1005) to predict the distribution of various crystalline phases within the as-welded material microstructure in different fusion zone and heat-affected zone locations, under given GMAW-process parameters. The results obtained are compared with available open-literature experimental data to provide validation/verification for the proposed GMAW modeling effort.

  2. Effect of superheat on the solidification structures of AISI 310S austenitic stainless steel

    SciTech Connect

    Ozbayraktar, S.; Koursaris, A.

    1996-04-01

    An experimental study was carried out to investigate the evolution of macrostructure and microstructure in AISI 310S stainless steel during solidification. Experimental findings suggested that the macrostructure a/nd the microstructure of the cast material responded differently to variations in casting temperature. As the casting temperature decreased, the macrostructure was refined, as expected, but the microstructure coarsened. A relationship was established between the proportion of equiaxed zone and superheat as follows: pct equiaxed zone = a + b ln (1/{Delta}T), where a and b are constants. The relationship between grain width and superheat could be expressed by the equation: gw = e(c+d/{Delta}T), where c and d are constants determined by the distance from the edge of the ingot. The relationship between primary arm spacing and superheat could be expressed by the equation: {lambda}{sub 1} = p + q ln (1/{Delta}T), where p and q are constants determined by the distance from the edge of the ingot. The parameter grain width ratio has been introduced to describe the relationship between the shape and the nucleation and growth kinetics of the columnar grains.

  3. Nano- and Macro-wear of Bio-carbo-nitrided AISI 8620 Steel Surfaces

    NASA Astrophysics Data System (ADS)

    Arthur, Emmanuel Kwesi; Ampaw, Edward; Zebaze Kana, M. G.; Adetunji, A. R.; Olusunle, S. O. O.; Adewoye, O. O.; Soboyejo, W. O.

    2015-12-01

    This paper presents the results of an experimental study of nano- and macro-scale wear in a carbo-nitrided AISI 8620 steel. Carbo-nitriding is carried out using a novel method that involves the use of dried, cyanide-containing cassava leaves, as sources of carbon and nitrogen. These are used in a pack cementation that is used to diffuse carbon and nitrogen into case layers at intermediate temperatures [673.15 K, 723.15 K, 773.15 K, and 823.15 K (400 °C, 450 °C, 500 °C, and 550 °C)]. Nano- and macro-scale wear properties are studied in the case-hardened surfaces, using a combination of nano-scratch and pin-on-disk experiments. The measured wear volumes (at both nano- and macro-length scales) are shown to increase with decreasing pack cyaniding temperature. The nano- and macro-wear resistances are also shown to be enhanced by the in situ diffusion of carbon and nitrogen from cyanide-containing bio-processed waste. The underlying wear mechanisms are also elucidated via atomic force microscopy and scanning electron microscopy observations of the wear tracks. The implications of the results are discussed for the design of hardened carbo-nitrided steel surfaces with improved wear resistance.

  4. An Electrochemical Processing Strategy for Improving Tribological Performance of Aisi 316 Stainless Steel Under Grease Lubrication

    NASA Astrophysics Data System (ADS)

    Zou, Jiaojuan; Li, Maolin; Lin, Naiming; Zhang, Xiangyu; Qin, Lin; Tang, Bin

    2014-12-01

    In order to improve the tribological performance of AISI 316 stainless steel (316 SS) under grease lubrication, electrochemical processing was conducted on it to obtain a rough (surface texturing-like) surface by making use of the high sensitivity of austenitic stainless steel to pitting corrosion in Cl--rich environment. Numerous corrosion pits or micro-ditches acted as micro-reservoirs on the obtained surface. While the grease could offer consistent lubrication, and then improve the tribological performance of 316 SS. Tribological behaviors of raw 316 SS and the treated sample were measured using a reciprocating type tribometer sliding against GCr15 steel counterpart under dry and grease lubrication conditions. The results showed that the mass losses of the two samples were in the same order of magnitude, and the raw sample exhibited lower friction coefficient in dry sliding. When the tests were conducted under grease lubrication condition, the friction coefficients and mass losses of the treated sample were far lower than those of the raw 316 SS. The tribological performance of 316 SS under grease lubrication was drastically improved after electrochemical processing.

  5. Strengthening of an AISI 1020 steel by aluminum-microalloying during liquid dynamic compaction

    SciTech Connect

    Matsuo, S.; Ando, T.; Zody, M.C.; Grant, N.J. . Dept. of Materials Science and Engineering)

    1991-01-01

    Grain size refinement was achieved in an AISI 1020 steel alloyed with 0.06 wt. % aluminum by liquid dynamic compaction (LDC), a rapid solidification spray deposition process. Atomization was done with nitrogen which resulted in incorporation of about 0.05 wt. % nitrogen in the spray deposited steel. The spray deposit showed a fine (10--40 {mu}m), equiaxed ferrite plus pearlite structure and a high as-deposited density of about 95% of theoretical. Minor reductions up to 70% in hot rolling plus annealing, both at low austenitic temperatures (850--900{degrees}C), fully densified the deposit and produced significantly finer (3--4 {mu}m) ferritic grains with uniformly distributed fine pearlite colonies. The grain size refinement resulted from pinning of prior austenitic grain boundaries by fine AIN particles which precipitated during the thermomechanical treatments (TMT). Room temperature yield and ultimate tensile strength values exceeding 80 and 90 ksi (550 and 620 MPa), respectively, were achieved at high ductility levels. The fine microstructures were stabilized by AIN precipitates even on reheating to temperatures up to 1100{degrees}C. 19 refs., 6 figs., 1 tab.

  6. Experimental Investigation and Analytical Prediction of ?-Phase Precipitation in AISI 316L Austenitic Stainless Steel

    NASA Astrophysics Data System (ADS)

    Sahlaoui, Habib; Sidhom, Habib

    2013-07-01

    The phase precipitation in industrial AISI 316L stainless steel during aging for up to 80,000 hours between 823 K and 1073 K (550 C and 800 C) has been studied using transmission electron microscopy, scanning transmission electron microscopy, and carbon replica energy-dispersive X-ray microanalysis. Three phases were identified: Chromium carbides (M23C6), Laves phase ( ?), and ?-phase (Fe-Cr). M23C6 carbide precipitation occurred firstly and was followed by the ? and ?-phases at grain boundaries when the aging temperature is higher than 873 K (600 C). Precipitation and growth of M23C6 create chromium depletion zones at the grain boundaries and also retard the ?-phase formation. Thus, the ?-phase is controlled by the kinetic of chromium bulk diffusion and can appear only when the chromium reaches, at grain boundaries and at the M23C6/ ? and M23C6/ ?/ ? interfaces, content higher than a critical value obtained by self-healing. An analytical model, based on equivalent chromium content, has been established in this study and successfully validated to predict the time-temperature-precipitation diagram of the ?-phase. The obtained diagram is in good agreement with the experimental results.

  7. Structural analysis and intergranular corrosion tests of AISI 316L steel.

    PubMed

    Stonawsk, Z; Svoboda, M; Soza?ska, M; Krstkov, M; Sojka, J; Dagbert, C; Hyspeck, L

    2006-10-01

    Pure AISI 316L steel is investigated after solution heat treatment (1050 degrees C/H(2)O) and structural sensitization (650 degrees C). Two quite different intergranular corrosion tests are used to determine the degree of structural sensitization due to the precipitation of secondary phases along the grain boundaries (mainly the M(23)C(6) and sigma-phase): the oxalic acid etch test and the electrochemical potentio-kinetic reactivation test. Generally, the dissolution of chromium-rich carbides (M(23)C(6)) is provoked by oxalic acid etch tests, whereas the chromium-depleted zones, in the vicinity of chromium-rich carbides (M(23)C(6)), are attacked by electrochemical potentio-kinetic reactivation tests. Both intergranular corrosion tests are used to determine the maximum degree of structural sensitization. Thus structural analysis by carbon replicas reveals the Laves phase, and both the M(23)C(6) and (Cr,Mo)(x)(Fe,Ni)(y) phases. The results of intergranular corrosion tests are related to the findings of the structural analysis. PMID:17100908

  8. Microstructure Characterization and Corrosion Properties of Nitrocarburized AISI 4140 Low Alloy Steel

    NASA Astrophysics Data System (ADS)

    Fattah, M.; Mahboubi, F.

    2012-04-01

    Plasma nitrocarburizing treatments of AISI 4140 low alloy steel have been carried out in a gas mixture of 85% N2-12% H2-3% CO2. All treatments were performed for 5 h at a chamber pressure of 4 mbar. Different treatment temperatures varying from 520 to 620 C have been used to investigate the effect of treatment temperature on the corrosion and hardness properties and also microstructure of the plasma nitrocarburized steel. Scanning electron and optical microscopy, x-ray diffraction, microhardness measurement, and potentiodynamic polarization technique in 3.5% NaCl solution were used to study the treated surfaces. The results revealed that plasma nitrocarburizing at temperatures below 570 C can readily produce a monophase ? compound layer. The compound layer formed at 620 C is composed of two sub-layers and is supported by an austenite zone followed by the diffusion layer. The thickest diffusion layer was related to the sample treated at 620 C. Microhardness results showed a reduction of surface hardness with increasing the treatment temperature from 520 to 620 C. It has also been found that with increasing treatment temperature from 520 to 545 C the corrosion resistance increases up to a maximum and then decreases with further increasing treatment temperature from 545 to 620 C.

  9. Influence of gas pressure and substrate temperature on PIII nitrocarburizing process of AISI 304 stainless steel

    NASA Astrophysics Data System (ADS)

    Abd El-Rahman, A. M.; El-Hossary, F. M.; Negm, N. Z.; Prokert, F.; Richter, E.; Mller, W.

    2004-12-01

    Plasma immersion ion implantation (PIII) has been used to modify the surface properties of 304 austenitic stainless steel (AISI). The influence of working gas pressure, 0.2-1.0 Pa, and substrate temperature, 300-500 C, on the microstructure, treating rate, nitrogen/carbon concentration depth profile, and surface microhardness was investigated. A gas composition of 25% C2H2, 75% N2, r.f. plasma power input of 350 W, and a negatively biased potential of 30 kV were fixed during the experiment. The experimental results show that the substrate temperature and the diffusion process of nitrogen and carbon depend on the gas pressure inside the plasma chamber. The thickness of the modified layer has been found to be more than 30 ?m for samples were treated in the plasma for 60 min. The results show also that the values of diffusion coefficient and surface microhardness of the treated samples are high to be 3.4 10-1 ?m2/s and 1880 kg/mm2, respectively.

  10. Effect of welding parameters on the heat-affected zone of AISI409 ferritic stainless steel

    NASA Astrophysics Data System (ADS)

    Ranjbarnodeh, Eslam; Hanke, Stefanie; Weiss, Sabine; Fischer, Alfons

    2012-10-01

    One of the main problems during the welding of ferritic stainless steels is severe grain growth within the heat-affected zone (HAZ). In the present study, the microstructural characteristics of tungsten inert gas (TIG) welded AISI409 ferritic stainless steel were investigated by electron backscattered diffraction (EBSD), and the effects of welding parameters on the grain size, local misorientation, and low-angle grain boundaries were studied. A 3-D finite element model (FEM) was developed to predict the effects of welding parameters on the holding time of the HAZ above the critical temperature of grain growth. It is found that the base metal is not fully recrystallized. During the welding, complete recrystallization is followed by severe grain growth. A decrease in the number of low-angle grain boundaries is observed within the HAZ. FEM results show that the final state of residual strains is caused by competition between welding plastic strains and their release by recrystallization. Still, the decisive factor for grain growth is heat input.

  11. Effect of shot peening on surface fatigue life of carburized and hardened AISI 9310 spur gears

    NASA Technical Reports Server (NTRS)

    Townsend, D. P.; Zaretsky, E. V.

    1982-01-01

    Surface fatigue tests were conducted on two groups of AISI 9310 spur gears. Both groups were manufactured with standard ground tooth surfaces, with the second group subjected to an additional shot peening process on the gear tooth flanks. The gear pitch diameter was 8.89 cm (3.5 in.). Test conditions were a gear temperature of 350 K (170 F), a maximum Hertz stress of 1.71 billion N/sq m (248,000 psi), and a speed of 10,000 rpm. The shot peened gears exhibited pitting fatigue lives 1.6 times the life of standard gears without shot peening. Residual stress measurements and analysis indicate that the longer fatigue life is the result of the higher compressive stress produced by the shot peening. The life for the shot peened gear was calculated to be 1.5 times that for the plain gear by using the measured residual stress difference for the standard and shot peened gears. The measured residual stress for the shot peened gears was much higher than that for the standard gears.

  12. Carburization behavior of AISI 316LN austenitic stainless steel - Experimental studies and modeling

    NASA Astrophysics Data System (ADS)

    Sudha, C.; Sivai Bharasi, N.; Anand, R.; Shaikh, H.; Dayal, R. K.; Vijayalakshmi, M.

    2010-07-01

    AISI type 316LN austenitic stainless steel was exposed to flowing sodium at 798 K for 16,000 h in the bi-metallic (BIM) sodium loop. A modified surface layer of 10 ?m width having a ferrite structure was detected from X-ray diffraction and electron micro probe based analysis. Beneath the modified surface layer a carburized zone of 60 ?m width was identified which was found to consist of M 23C 6 carbides. A mathematical model based on finite difference technique was developed to predict the carburization profiles in sodium exposed austenitic stainless steel. In the computation, effect of only chromium on carbon diffusion was considered. Amount of carbon remaining in solution was determined from the solubility parameter. The predicted profile showed a reasonably good match with the experimental profile. Calculations were extended to simulate the thickness of the carburized layer after exposure to sodium for a period of 40 years. Attempt was also made to predict the carburization profiles based on equilibrium calculations using Dictra and Thermocalc which contain both thermodynamic and kinetic databases for the system under consideration.

  13. Optimizing Multi Characterstics in Machining of AISI 4340 Steel Using Taguchi's Approach and Utility Concept

    NASA Astrophysics Data System (ADS)

    Gupta, Munish Kumar; Sood, Pardeep Kumar

    2016-01-01

    This paper aims to develop the multi response optimization technique for predict and select the optimal setting of machining parameters while machining AISI 4340 steel using utility concept. The experimental studies in machining were carried out under varying conditions of process parameters, such as cutting speed (v), feed (f) and different cooling conditions (i.e. dry, wet and cryogenic in which liquid nitrogen used as a coolant) by using uncoated tungsten carbide insert tool. Experiments were carried out as per Taguchi's L9 orthogonal array with the utility concept and multi response optimization were performed for minimization of specific cutting force ( K S ) and surface roughness ( R a ). Further statistical analysis of variation (ANOVA) and analysis of mean (ANOM) were used to determine the effect of process parameters on responses K S and R a based on their P value and F value at 95 % confidence level. The optimization results proved that, cutting speed 57 m/min, feed 0.248 mm/min and cryogenic cooling is required for minimizes K S and R a .

  14. Prediction of Cutting Forces Using ANNs Approach in Hard Turning of AISI 52100 steel

    SciTech Connect

    Makhfi, Souad; Habak, Malek; Velasco, Raphael; Haddouche, Kamel; Vantomme, Pascal

    2011-05-04

    In this study, artificial neural networks (ANNs) was used to predict cutting forces in the case of machining the hard turning of AISI 52100 bearing steel using cBN cutting tool. Cutting forces evolution is considered as the key factors which affect machining. Predicting cutting forces evolution allows optimizing machining by an adaptation of cutting conditions. In this context, it seems interesting to study the contribution that could have artificial neural networks (ANNs) on the machining forces prediction in both numerical and experiment studies. Feed-forward multi-layer neural networks trained by the error back-propagation (BP) algorithm are used. Levenberg-Marquardt (LM) optimization algorithm was used for finding out weights. The training of the network is carried out with experimental machining data.The input dataset used are cutting speed, feed rate, cutting depth and hardness of the material. The output dataset used are cutting forces (Ft-cutting force, Fa- feed force and Fr- radial force).Results of the neural networks approach, in comparison with experimental data are discussed in last part of this paper.

  15. Corrosion behavior of ASTM A106 and AISI 316SS in KOH and nickel acetate solutions

    SciTech Connect

    Gonzalez, J.J.; Baron, E.; Saldeho, J.

    1999-11-01

    The present work is concerned with the corrosion behavior of ASTM A106 B grade and AISI 316 stainless steel in the presence of three different environments: a mixture or an emulsion formed by oil-KOH-nickel acetate solution, a KOH (40 wt. %) solution and a nickel acetate (14 wt. %) solution, which are representative fluids used during a PDVSA proprietary process for improving heavy crude oils. Corrosion rate measurements and stress corrosion cracking (SCC) behavior were evaluated through weight loss (in the laboratory and in situ measurements), and mechanical testing (constant load and slow strain rate tests). In the emulsion the corrosion rate was almost undetectable for both steels and the evidence suggested that no SCC had taken place. However, the corrosion rate of the carbon steel in 40wt.% KOH solution at 130 C was 2.8 mm/y, showing the presence of pitting corrosion. On the other hand, the stainless steel showed an undetectable corrosion rate. Though SCC was not observed in any of the materials tested in presence of KOH at both 30 and 130 C, a deterioration in the mechanical properties was found for the high temperature case for carbon steel. During nickel acetate solution tests at 130 C, the A 106 steel showed a relatively high corrosion rate (5.9 mm/y) and the formation of pits. For the stainless steel case, acetate solution had no corrosive effect whatsoever. This last environment offered no SCC susceptibility for any material at both temperatures tested.

  16. The effect of Pseudomonas NCIMB 2021 biofilm on AISI 316 stainless steel.

    PubMed

    Beech, I B; Zinkevich, V; Hanjangsit, L; Gubner, R; Avci, R

    2000-01-01

    A bioreactor system operating in a continuous mode was designed to generate biofilms on polished and as-received surfaces of AISI 316 stainless steel coupons exposed for 36 d to a pure culture of marine Pseudomonas NCIMB 2021. Scanning electron microscopy (SEM) and atomic force microscopy were employed to determine the degree of surface colonisation and to examine corrosion damage of the steel. X-ray photoelectron spectroscopy analysis was carried out to characterise the chemistry of the passive layers on polished steel stored for a period of time, freshly re-polished coupons, and as-received steel. The effect of biofilms on the composition of layers formed on the steel specimens was evaluated. SEM revealed that the surfaces of polished and stored steel appeared to accumulate more biofilm compared to as-received specimens. Micropitting of steel occurred underneath the biofilm, regardless of surface finish. The concentration of elements in the passive layers differed significantly between freshly re-polished and as-received or polished and stored coupons. In the presence of Pseudomonas NCIMB 2021 biofilm, the composition of the passive layer on the as-received steel surface was considerably altered compared to unexposed steel or steel exposed to abiotic medium. PMID:22115287

  17. Optimizing Multi Characterstics in Machining of AISI 4340 Steel Using Taguchi's Approach and Utility Concept

    NASA Astrophysics Data System (ADS)

    Gupta, Munish Kumar; Sood, Pardeep Kumar

    2015-10-01

    This paper aims to develop the multi response optimization technique for predict and select the optimal setting of machining parameters while machining AISI 4340 steel using utility concept. The experimental studies in machining were carried out under varying conditions of process parameters, such as cutting speed (v), feed (f) and different cooling conditions (i.e. dry, wet and cryogenic in which liquid nitrogen used as a coolant) by using uncoated tungsten carbide insert tool. Experiments were carried out as per Taguchi's L9 orthogonal array with the utility concept and multi response optimization were performed for minimization of specific cutting force (K S ) and surface roughness (R a ). Further statistical analysis of variation (ANOVA) and analysis of mean (ANOM) were used to determine the effect of process parameters on responses K S and R a based on their P value and F value at 95 % confidence level. The optimization results proved that, cutting speed 57 m/min, feed 0.248 mm/min and cryogenic cooling is required for minimizes K S and R a .

  18. Evaluation of AISI 4140 Steel Repair Without Post-Weld Heat Treatment

    NASA Astrophysics Data System (ADS)

    Silva, Cleiton C.; de Albuquerque, Victor H. C.; Moura, Ccero R. O.; Aguiar, Willys M.; Farias, Jesualdo P.

    2009-04-01

    The present work evaluates the two-layer technique on the heat affected zone (HAZ) of AISI 4140 steel welded with different heat input levels between the first and second layer. The weld heat input levels selected by the Higuchi test were 5/5, 5/10, and 15/5 kJ/cm. The evaluation of the refining and/or tempering of the coarsened grain HAZ of the first layer was carried out using metallographic tests, microhardness measurements, and the Charpy-V impact test. The tempering of the first layer was only reached when the weld heat input ratio was 5/5 kJ/cm. The results of the Charpy-V impact test showed that the two-layer technique was efficient, from the point of view of toughness, since the toughness values reached were greater than the base metal for all weld heat input ratios applied. The results obtained indicate that the best performance of the two-layer deposition technique was for the weld heat input ratio 5/5 kJ/cm employing low heat input.

  19. Investigation of Low-Cycle Bending Fatigue of AISI 9310 Steel Spur Gears

    NASA Technical Reports Server (NTRS)

    Handschuh, Robert F.; Krantz, Timothy L.; Lerch, Bradley A.; Burke, Christopher S.

    2007-01-01

    An investigation of the low-cycle bending fatigue of spur gears made from AISI 9310 gear steel was completed. Tests were conducted using the single-tooth bending method to achieve crack initiation and propagation. Tests were conducted on spur gears in a fatigue test machine using a dedicated gear test fixture. Test loads were applied at the highest point of single tooth contact. Gear bending stresses for a given testing load were calculated using a linear-elastic finite element model. Test data were accumulated from 1/4 cycle to several thousand cycles depending on the test stress level. The relationship of stress and cycles for crack initiation was found to be semi-logarithmic. The relationship of stress and cycles for crack propagation was found to be linear. For the range of loads investigated, the crack propagation phase is related to the level of load being applied. Very high loads have comparable crack initiation and propagation times whereas lower loads can have a much smaller number of cycles for crack propagation cycles as compared to crack initiation.

  20. Investigation of Low-Cycle Bending Fatigue of AISI 9310 Steel Spur Gears

    NASA Technical Reports Server (NTRS)

    Handschuh, Robert F.; Krantz, Timothy L.; Lerch, Bradley A.; Burke, Christopher S.

    2007-01-01

    An investigation of the low-cycle bending fatigue of spur gears made from AISI 9310 gear steel was completed. Tests were conducted using the single-tooth bending method to achieve crack initiation and propagation. Tests were conducted on spur gears in a fatigue test machine using a dedicated gear test fixture. Test loads were applied at the highest point of single tooth contact. Gear bending stresses for a given testing load were calculated using a linear-elastic finite element model. Test data were accumulated from 1/4 cycle to several thousand cycles depending on the test stress level. The relationship of stress and cycles for crack initiation was found to be semilogarithmic. The relationship of stress and cycles for crack propagation was found to be linear. For the range of loads investigated, the crack propagation phase is related to the level of load being applied. Very high loads have comparable crack initiation and propagation times whereas lower loads can have a much smaller number of cycles for crack propagation cycles as compared to crack initiation.

  1. Diagnosing ALS

    MedlinePLUS

    ... ChallengeALS About This Site Site Map Link Policy Privacy Policy Pay tribute to those fighting ALS with a ... the National Office . Site Map | Press Room | FAQ | Privacy Policy | Link Policy | RSS | Contact Us The ALS Association - ...

  2. Preparation of Datex-Ohmeda Aestiva and Aisys anaesthetic machines for use in malignant hyperthermia susceptible patients.

    PubMed

    Jones, C; Bennett, K; Kim, T W; Bulger, T F; Pollock, N

    2012-05-01

    Preparation of anaesthesia machines for use by malignant hyperthermia susceptible patients requires purging the machines of halogenated anaesthetic agents. The endpoint of this process is to reach a gas concentration of 5 ppm or less, which has been arbitrarily chosen as the safe limit of exposure to avoid triggering a malignant hyperthermia event. We examined the washout characteristics of sevoflurane and desflurane from the Datex-Ohmeda Aestiva Anaesthesia System and Aisys Anaesthesia Carestation anaesthetic machines. The machines were contaminated for two hours using either sevoflurane 2 vol% or desflurane 6 vol%. At the end of the priming period, the patient breathing circuit and reservoir bag, carbon dioxide absorbent, sampling line and test lung were replaced with uncontaminated components. During the test period, machines were purged using oxygen flows of 10 l/minute. The average time to reach 5 ppm with the Aestiva machines was 51 minutes with sevoflurane and 71 minutes with desflurane. The average time to reach 5 ppm for the Aisys machines was 55 minutes with sevoflurane and 69 minutes with desflurane. All configurations of machines and anaesthetic gases demonstrated a rebound effect in agent concentration above 5 ppm when the fresh gas flow was subsequently reduced from 10 to 2 l/minute. Aestiva and Aisys anaesthetic machines require a prolonged period to adequately purge them of halogenated volatile anaesthetic agent. The rebound effect poses a serious concern, suggesting that after the purging period, fresh gas flows of 10 l/minute should be maintained for the duration of anaesthesia care of the malignant hyperthermia susceptible patient. PMID:22577915

  3. Effect of martensite to austenite reversion on the formation of nano/submicron grained AISI 301 stainless steel

    SciTech Connect

    Karimi, M.; Najafizadeh, A.; Kermanpur, A.; Eskandari, M.

    2009-11-15

    The martensite to austenite reversion behavior of 90% cold rolled AISI 301 stainless steel was investigated in order to refine the grain size. Cold rolled specimens were annealed at 600-900 deg. C, and subsequently characterized by scanning electron microscopy, X-ray diffraction, Feritscope, and hardness measurements. The effects of annealing parameters on the formation of fully-austenitic nano/submicron grained structure and the mechanisms involved were studied. It was found that annealing at 800 deg. C for 10 s exhibited the smallest average austenite grain size of 240 {+-} 60 nm with an almost fully-austenitic structure.

  4. Effect of low-melting-point eutectic on solidification cracking susceptibility of boron-added AISI 304 stainless steel welds

    SciTech Connect

    Matsumoto, T.; Kanai, H.; Shinoda, T.; Miyake, H.; Matsuzaka, T.

    1995-12-01

    This study was conducted to clarify the effects of low-temperature eutectic on solidification cracking of boron-added AISI 304 austenitic stainless steel welds. This steel is often used in the fabrication of nuclear shields and reactor control rods. Experimental results confirmed that the lower solidification cracking susceptibility of high B steels is mainly due to the healing of cracks by the abundant amounts of low-melting-point eutectic liquid of (Cr, Fe){sub 2}B and {gamma}-Fe. This was directly observed in the hot-stage microscope. It was also confirmed that high P- and S-content welds show high solidification cracking susceptibility.

  5. Machining Performance and Surface Integrity of AISI D2 Die Steel Machined Using Electrical Discharge Surface Grinding Process

    NASA Astrophysics Data System (ADS)

    Choudhary, Rajesh; Kumar, Harmesh; Singh, Shankar

    2013-12-01

    The aim of this study is to establish optimum machining conditions for EDSG of AISI D2 die steel through an experimental investigation using Taguchi Methodology. To achieve combined grinding and electrical discharge machining, metal matrix composite electrodes (Cu-SiCp) were processed through powder metallurgy route. A rotary spindle attachment was developed to perform the EDSG experimental runs on EDM machine. Relationships were developed between various input parameters such as peak current, speed, pulse-on time, pulse-off time, abrasive particle size, and abrasive particle concentration, and output characteristics such as material removal rate and surface roughness. The optimized parameters were further validated by conducting confirmation experiments.

  6. Mechanical behavior of AISI 304SS determined by miniature test methods after neutron irradiation to 28 dpa

    SciTech Connect

    Ellen M. Rabenberg; Brian J. Jaques; Bulent H. Sencer; Frank A. Garner; Paula D. Freyer; Taira Okita; Darryl P. Butt

    2014-05-01

    The mechanical properties of AISI 304 stainless steel irradiated for over a decade in the Experimental Breeder Reactor (EBR-II) were measured using miniature mechanical testing methods. The shear punch method was used to evaluate the shear strengths of the neutron-irradiated steel and a correlation factor was empirically determined to predict its tensile strength. The strength of the stainless steel slightly decreased with increasing irradiation temperature, and significantly increased with increasing dose until it saturated above approximately 5 dpa. Ferromagnetic measurements were used to observe and deduce the effects of the stress-induced austenite to martensite transformation as a result of shear punch testing.

  7. Morphology, topography, and hardness of diffusion bonded sialon to AISI 420 at different bonding time

    NASA Astrophysics Data System (ADS)

    Ibrahim, Nor Nurulhuda Md.; Hussain, Patthi; Awang, Mokhtar

    2015-07-01

    Sialon and AISI 420 martensitic stainless steel were diffusion bonded in order to study the effect of bonding time on reaction layer's growth. Joining of these materials was conducted at 1200°C under a uniaxial pressure of 17 MPa in a vacuum ranging from 5.0 to 8.0×10-6 Torr with bonding time varied for 0.5, 2, and 3 h. Thicker reaction layer was formed in longer bonded sample since the elements from sialon could diffuse further into the steel. Sialon retained its microstructure but it was affected at the initial contact with the steel to form the new interface layer. Diffusion layer grew toward the steel and it was segregated with the parent steel as a result of the difference in properties between these regions. The segregation formed a stream-like structure and its depth decreased when the bonding time was increased. The microstructure of the steel transformed into large grain size with precipitates. Prolonging the bonding time produced more precipitates in the steel and reduced the steel thickness as well. Interdiffusions of elements occurred between the joined materials and the concentrations were decreasing toward the steel and vice versa. Silicon easily diffused into the steel because it possessed lower ionization potential compared to nitrogen. Formation of silicide and other compounds such as carbides were detected in the interface layer and steel grain boundary, respectively. These compounds were harmful due to silicide brittleness and precipitation of carbides in the grain boundary might cause intergranular corrosion cracking. Sialon retained its hardness but it dropped very low at the interface layer. The absence of crack at the joint in all samples could be contributed from the ductility characteristic of the reaction layer which compensated the residual stress that was formed upon the cooling process.

  8. Investigation of AISI 441 Ferritic Stainless Steel and Development of Spinel Coatings for SOFC Interconnect Applications

    SciTech Connect

    Yang, Zhenguo; Xia, Guanguang; Wang, Chong M.; Nie, Zimin; Templeton, Joshua D.; Singh, Prabhakar; Stevenson, Jeffry W.

    2008-05-30

    As part of an effort to develop cost-effective ferritic stainless steel-based interconnects for solid oxide fuel cell (SOFC) stacks, both bare and spinel coated AISI 441 were studied in terms of metallurgical characteristics, oxidation behavior, and electrical performance. The conventional melt metallurgy used for the bulk alloy fabrication leads to significant processing cost reduction and the alloy chemistry with the presence of minor alloying additions of Nb and Ti facilitate the strengthening by precipitation and formation of Laves phase both inside grains and along grain boundaries during exposure in the intermediate SOFC operating temperature range. The Laves phase formed along the grain boundaries also ties up Si and prevents the formation of an insulating silica layer at the scale/metal interface during prolonged exposure. The substantial increase in ASR during long term oxidation due to oxide scale growth suggested the need for a conductive protection layer, which could also minimize Cr evaporation. In particular, Mn1.5Co1.5O4 based surface coatings on planar coupons drastically improved the electrical performance of the 441, yielding stable ASR values at 800ºC for over 5,000 hours. Ce-modified spinel coatings retained the advantages of the unmodified spinel coatings, and also appeared to alter the scale growth behavior beneath the coating, leading to a more adherent scale. The spinel protection layers appeared also to improve the surface stability of 441 against the anomalous oxidation that has been observed for ferritic stainless steels exposed to dual atmosphere conditions similar to SOFC interconnect environments. Hence, it is anticipated that, compared to unmodified spinel coatings, the Ce-modified coatings may lead to superior structural stability and electrical performance.

  9. ALS - resources

    MedlinePLUS

    Resources - ALS ... The following organizations are good resources for information on amyotrophic lateral sclerosis : Muscular Dystrophy Association -- mda.org/disease/amyotrophic-lateral-sclerosis National Amyotrophic Lateral Sclerosis (ALS) Registry -- ...

  10. Wear resistance of TiAlSiN thin coatings.

    PubMed

    Silva, F J G; Martinho, R P; Alexandre, R J D; Baptista, A P M

    2012-12-01

    In the last decades TiAIN coatings deposited by PVD techniques have been extensively investigated but, nowadays, their potential development for tribological applications is relatively low. However, new coatings are emerging based on them, trying to improve wear behavior. TiAlSiN thin coatings are now investigated, analyzing if Si introduction increases the wear resistance of PVD films. Attending to the application, several wear test configurations has been recently used by some researchers. In this work, TiAISiN thin coatings were produced by PVD Unbalanced Magnetron Sputtering technique and they were conveniently characterized using Scanning Electron Microscopy (SEM) provided with Energy Dispersive Spectroscopy (EDS), Atomic Force Microscopy (AFM), Electron Probe Micro-Analyzer (EPMA), Micro Hardness (MH) and Scratch Test Analysis. Properties as morphology, thickness, roughness, chemical composition and structure, hardness and film adhesion to the substrate were investigated. Concerning to wear characterization, two very different ways were chosen: micro-abrasion with ball-on-flat configuration and industrial non-standardized tests based on samples inserted in a feed channel of a selected plastic injection mould working with 30% (wt.) glass fiber reinforced polypropylene. TiAISiN coatings with a small amount of about 5% (wt.) Si showed a similar wear behavior when compared with TiAIN reported performances, denoting that Si addition does not improve the wear performance of the TiAIN coatings in these wear test conditions. PMID:23447962

  11. Tribological Characteristics of Single-phase AlMgB14 and Nanocomposite AlMgB14-TiB2 Superhard Coatings

    SciTech Connect

    Qu, Jun; Blau, Peter Julian; Zhu, Dong; Cook, Bruce A; Elmoursi, Alaa A

    2008-01-01

    This study investigated the friction and wear characteristics of AlMgB14 and AlMgB14-TiB2 superhard coatings, produced by pulse laser deposition (PLD) and physical vapor deposition (PVD), respectively. Tests were conducted under unidirectional and reciprocating sliding against AISI 52100 bearing steel in both dry and oil-lubricated conditions. The AlMgB14 coating exhibited an encouraging but short-lived low friction stage (u = 0.2) in dry sliding. The AlMgB14-TiB2 coating reduced the wear rates by one order of magnitude for itself and three orders of magnitude for the counterface compared with the uncoated M2 tool steel in dry sliding. This nanocomposite coating also demonstrated significant extension (>2.5X) of the low friction (non-scuffing) stage in a lubricant starvation sliding.

  12. Tribological properties of CrN coatings deposited by nitro-chromizing treatment on AISI D2 steel

    NASA Astrophysics Data System (ADS)

    Durmaz, M.; Kilinc, B.; Abakay, E.; Sen, U.; Sen, S.

    2015-03-01

    In this work, the wear test of uncoated and chromium nitride coated AISI D2 cold work tool steel against alumina ball realized at 0.1 m/s sliding speeds and under the loads of 2.5N, 5N and 10N. Steel samples were nitrided at 575C for 8 h in the first step of the coating process, and then chromium nitride coating was performed thermo-reactive deposition technique (TRD) in a powder mixture consisting of ferro-chromium, ammonium chloride and alumina at 1000C for 2 h. Nitro-chromized samples were characterized by X-Ray diffraction analysis (XRD), scanning electron microscopy (SEM), micro-hardness and ball on disk wear tests. The coating layer formed on the AISI D2 steel was compact and homogeneous. X-ray studies showed that the phase formed in the coated layer is Cr2N. The depth of the layer was 8.15 m. The average hardness of the layer was 216015 HV0.025. For uncoated and chromium nitride materials, wear rate increased with increasing load. The results of friction coefficient and wear rate of the tested materials showed that the CrN coating presents the lowest results.

  13. Wear behavior of the surface alloyed AISI 1020 steel with Fe-Nb-B by TIG welding technique

    NASA Astrophysics Data System (ADS)

    Kilinc, B.; Durmaz, M.; Abakay, E.; Sen, U.; Sen, S.

    2015-03-01

    Weld overlay coatings also known as hardfacing is a method which involves melting of the alloys and solidification for applied coatings. Recently hardfacing by welding has become a commonly used technique for improvement of material performance in extreme (high temperature, impact/abrasion, erosion, etc.) conditions.In the present study, the coatings were produced from a mixture of ferrous niobium, ferrous boron and iron powders in the ranges of -45m particle size with different ratio. Fe12Nb5B3 and Fe2NbBalloys were coated on the AISI 1020 steel surface by TIG welding. The phases formed in the coated layer are Fe2B, NbB2, NbFeB and Fe0,2 Nb0,8 phases. The hardness of the presence phases are changing between 168985 HV0.01, and 1817 HV0.1. Microstructural examinations were realized by optical and scanning electron microscopy. The wear and friction behaviors of Fe12Nb5B3 and Fe2NbB realized on the AISI 1020 steel were investigated by the technique of TIG welding by using ball-on-disk arrangement against alumina ball.

  14. Tribological properties of CrN coatings deposited by nitro-chromizing treatment on AISI D2 steel

    SciTech Connect

    Durmaz, M. Abakay, E.; Sen, U.; Sen, S.; Kilinc, B.

    2015-03-30

    In this work, the wear test of uncoated and chromium nitride coated AISI D2 cold work tool steel against alumina ball realized at 0.1 m/s sliding speeds and under the loads of 2.5N, 5N and 10N. Steel samples were nitrided at 575°C for 8 h in the first step of the coating process, and then chromium nitride coating was performed thermo-reactive deposition technique (TRD) in a powder mixture consisting of ferro-chromium, ammonium chloride and alumina at 1000°C for 2 h. Nitro-chromized samples were characterized by X-Ray diffraction analysis (XRD), scanning electron microscopy (SEM), micro-hardness and ball on disk wear tests. The coating layer formed on the AISI D2 steel was compact and homogeneous. X-ray studies showed that the phase formed in the coated layer is Cr{sub 2}N. The depth of the layer was 8.15 µm. The average hardness of the layer was 2160±15 HV{sub 0.025}. For uncoated and chromium nitride materials, wear rate increased with increasing load. The results of friction coefficient and wear rate of the tested materials showed that the CrN coating presents the lowest results.

  15. Wear behavior of the surface alloyed AISI 1020 steel with Fe-Nb-B by TIG welding technique

    SciTech Connect

    Kilinc, B. Durmaz, M.; Abakay, E.; Sen, U.; Sen, S.

    2015-03-30

    Weld overlay coatings also known as hardfacing is a method which involves melting of the alloys and solidification for applied coatings. Recently hardfacing by welding has become a commonly used technique for improvement of material performance in extreme (high temperature, impact/abrasion, erosion, etc.) conditions.In the present study, the coatings were produced from a mixture of ferrous niobium, ferrous boron and iron powders in the ranges of -45µm particle size with different ratio. Fe{sub 12}Nb{sub 5}B{sub 3} and Fe{sub 2}NbBalloys were coated on the AISI 1020 steel surface by TIG welding. The phases formed in the coated layer are Fe{sub 2}B, NbB{sub 2}, NbFeB and Fe0,2 Nb{sub 0,8} phases. The hardness of the presence phases are changing between 1689±85 HV{sub 0.01}, and 181±7 HV{sub 0.1}. Microstructural examinations were realized by optical and scanning electron microscopy. The wear and friction behaviors of Fe{sub 12}Nb{sub 5}B{sub 3} and Fe2NbB realized on the AISI 1020 steel were investigated by the technique of TIG welding by using ball-on-disk arrangement against alumina ball.

  16. High temperature oxidation behavior of austenitic stainless steel AISI 304 in steam of nanofluids contain nanoparticle ZrO2

    SciTech Connect

    Prajitno, Djoko Hadi Syarif, Dani Gustaman

    2014-03-24

    The objective of this study is to evaluate high temperature oxidation behavior of austenitic stainless steel SS 304 in steam of nanofluids contain nanoparticle ZrO{sub 2}. The oxidation was performed at high temperatures ranging from 600 to 800°C. The oxidation time was 60 minutes. After oxidation the surface of the samples was analyzed by different methods including, optical microscope, scanning electron microscope (SEM) and X-ray diffraction (XRD). X-ray diffraction examination show that the oxide scale formed during oxidation of stainless steel AISI 304 alloys is dominated by iron oxide, Fe{sub 2}O{sub 3}. Minor element such as Cr{sub 2}O{sub 3} is also appeared in the diffraction pattern. Characterization by optical microscope showed that cross section microstructure of stainless steel changed after oxidized with the oxide scale on the surface stainless steels. SEM and x-ray diffraction examination show that the oxide of ZrO{sub 2} appeared on the surface of stainless steel. Kinetic rate of oxidation of austenite stainless steel AISI 304 showed that increasing oxidation temperature and time will increase oxidation rate.

  17. In vitro performance of prefilled CO2 absorbers with the Aisys(®).

    PubMed

    Hendrickx, Jan F A; De Ridder, Simon P A J; Dehouwer, Alexander; Carette, Rik; De Cooman, Sofie; De Wolf, Andre M

    2016-04-01

    Low flow anesthesia increases the use of CO2 absorbents, but independent data that compare canister life of the newest CO2 absorbents are scarce. Seven different pre-packed CO2 canisters were tested in vitro: Amsorb Plus, Spherasorb, LoFloSorb, Medisorb, Medisorb EF, LithoLyme, and SpiraLith. CO2 (160 mL min(-1)) flowed into the tip of a 2 L breathing bag that was ventilated with a tidal volume of 500 mL, a respiratory rate of 10/min, and an I:E ratio of 1:1 using the controlled mechanical ventilation mode of the Aisys (®) (GE, Madison, WI, USA). In part I, canister life of each brand (all of the same lot) was tested with 12 different fresh gas flows (FGF) ranging from 0.25 to 4 L min(-1). In part II, canister life of six canisters each of two different lots of each brand were tested with a 350 mL min(-1) FGF. Canister life is presented as "FCU", fractional canister usage, the fraction of a canister used per hour, and is defined for the inspired CO2 concentration (FICO2) that denotes exhaustion. In part III, canister life per 100 g fresh granule content was calculated. FCU decreased linearly with increasing FGF. The relative position of the FCU-FGF curves of the different brands depends on the FICO2 threshold because the exhaustion rate (the rate of rise once FICO2 starts to increase) differs among the brands. Intra-lot variability was 18 % or less. The different prepacks can be ranked according their efficiency (least to most efficient) as follows: Amsorb Plus = Medisorb EF < LoFloSorb < Medisorb = Spherasorb = LithoLyme < SpiraLith (all for an FICO2 threshold = 0.5 %). Canister life per 100 g fresh granule content is almost twice as long when LiOH is used as the primary absorbent. The most important factors that determine canister life of prepacks in a circle breathing system are the chemical composition of the canister, the absolute amount of absorbent present in the canister, and the FICO2 replacement threshold. The use of the fractional canister usage allows cost comparisons among different prepacks. Results should not be extrapolated to prepacks that fit onto other anesthesia machines. PMID:25953416

  18. Surface fatigue life of carburized and hardened M50NiL and AISI 9310 spur gears and rolling-contact test bars

    NASA Technical Reports Server (NTRS)

    Townsend, Dennis P.; Bamberger, Eric N.

    1989-01-01

    Spur gear endurance tests and rolling-element surface tests were conducted to investigate vacuum-induction-melted, vacuum-arc-melted (VIM-VAR) M50NiL steel for use as a gear steel in advanced aircraft applications, to determine its endurance characteristics, and to compare the results with those for standard VAR and VIM-VAR AISI 9310 gear material. Tests were conducted with spur gears and rolling-contact bars manufactured from VIM-VAR M50NiL and VAR and VIM-VAR AISI 9310. The gear pitch diameter was 8.9 cm (3.5 in.). Gear test conditions were an inlet oil temperature of 320 K (116 F), and outlet oil temperature of 350 K (170 F), a maximum Hertz stress of 1.71 GPa (248 ksi), and a speed of 10,000 rpm. Bench rolling-element fatigue tests were conducted at ambient temperatures with a bar speed of 12,500 rpm and a maximum Hertz stress of 4.83 GPA (700 ksi). The VIM-VAR M50NiL gears had a surface fatigue life that was 4.5 and 11.5 times that for VIM-VAR and VAR AISI 9310 gears, respectively. The surface fatigue life of the VIM-VAR M50NiL rolling-contact bars was 13.2 and 21.6 times that for the VIM-VAR and VAR AISI 9310, respectively. The VIM-VAR M50NiL material was shown to have good resistance to fracture through a fatigue spall and to have fatigue life far superior to that of both VIM-VAR and VAR AISI 9310 gears and rolling-contact bars.

  19. Corrosion resistance of multilayer hybrid sol-gel coatings deposited on the AISI 316L austenitic stainless steel

    NASA Astrophysics Data System (ADS)

    Caballero, Y. T.; Rondón, E. A.; Rueda, L.; Hernández Barrios, C. A.; Coy, A.; Viejo, F.

    2016-02-01

    In the present work multilayer hybrid sol-gel coatings were synthesized on the AISI 316L austenitic stainless steel employed in the fabrication of orthopaedic implants. Hybrid sols were obtained from a mixture of inorganic precursor, TEOS, and organic, GPTMS, using ethanol as solvent, and acetic acid as catalyst. The characterization of the sols was performed using pH measurements, rheological tests and infrared spectroscopy (FTIR) for different ageing times. On the other hand, the coatings were characterized by scanning electron microscopy (SEM), while the corrosion resistance was evaluated using anodic potentiodynamic polarization in SBF solution at 37±2°C. The results confirmed that sol-gel synthesis employing TEOS-GPTMS systems produces uniform and homogeneous coatings, which enhanced the corrosion resistance with regard to the parent alloy. Moreover, corrosion performance was retained after applying more than one layer (multilayer coatings).

  20. Evaluation of Microstructure and Toughness of AISI D2 Steel by Bright Hardening in Comparison with Oil Quenching

    NASA Astrophysics Data System (ADS)

    Torkamani, H.; Raygan, Sh.; Rassizadehghani, J.

    2011-12-01

    AISI D2 is used widely in the manufacture of blanking and cold-forming dies, on account of its excellent hardness and wear behavior. Increasing toughness at a fixed high level of hardness is growing requirement for this kind of tool steel. Improving microstructure characteristics, especially refinement of coarse carbides, is an appropriate way to meet such requirement. In this study, morphology and size of carbides in martensite matrix were compared between two kinds of samples, which were bright hardened (quenching in hot alkaline salt bath consisting of 60% KOH and 40% NaOH) at 230 C and quenched in oil bath at 60 C. Results showed that morphology and distribution of carbides in samples performed by bright hardening were finer and almost spherical compared to that of oil quenched. This microstructure resulted in an improvement in toughness and tensile properties of alloy.

  1. Tribo-electrochemical characterization of hafnium multilayer systems deposited on nitride/vanadium nitride AISI 4140 steel

    NASA Astrophysics Data System (ADS)

    Mora, M.; Vera, E.; Aperador, W.

    2016-02-01

    In this work is presented the synergistic behaviour among corrosion/wear (tribocorrosion) of the multilayer coatings hafnium nitride/vanadium nitride [HfN/VN]n. The multilayers were deposited on AISI 4140 steel using the technique of physical vapor deposition PVD magnetron sputtering, the tests were performed using a pin-on-disk tribometer, which has an adapted potentiostat galvanostat with three-electrode electrochemical cell. Tribocorrosive parameters such as: Friction coefficient between the coating and the counter body (100 Cr6 steel ball); Polarization resistance by means of electrochemical impedance spectroscopy technique and corrosion rate by polarization curves were determined. It was observed an increase in the polarization resistance, a decrease in the corrosion rate and a low coefficient of friction in comparison with the substrate, due to an increase on the number of bilayers.

  2. Corrosion-fatigue behavior of an annealed AISI 1045 carbon steel coated with electroless nickel-phosphorus

    SciTech Connect

    Pertuz, A.; Chitty, J.A.; Puchi, E.S. ); Hintermann, H. . Faculty of Sciences)

    1999-08-01

    The influence of an industrial electroless nickel-phosphorus deposit on the corrosion-fatigue properties of an annealed AISI 1045 steel has been investigated. For this purpose, three corrosive media were selected: distilled water and two NaCl solutions of different concentration (3 and 5%) in distilled water. Corrosion-fatigue tests were conducted at alternating stress levels ranging between 219 and 329 MPa at a frequency of 50 Hz. The corrosion-fatigue properties of the coated and uncoated substrates are very similar when testing is conducted in salty water. However, for testing in distilled water the corrosion-fatigue properties of coated substrates were diminished in relation to the uncoated material. The fractographic analysis of the fracture surfaces revealed the presence of fatigue marks within the electroless nickel-phosphorus deposit, which indicate that the fracture mechanism of the coating is associated to the cyclic loading of the material.

  3. Application of strainrange partitioning to the prediction of creep-fatigue lives of AISI types 304 and 316 stainless steel

    NASA Technical Reports Server (NTRS)

    Saltsman, J. F.; Halford, G. R.

    1976-01-01

    As a demonstration of the predictive capabilities of the method of Strainrange Partitioning, published high-temperature, low cycle, creep-fatigue test results on AISI Types 304 and 316 stainless steel were analyzed and calculated, cyclic lives compared with observed lives. Predicted lives agreed with observed lives within factors of two for 76 percent, factors of three for 93 percent, and factors of four for 98 percent of the laboratory tests analyzed. Agreement between observed and predicted lives is judged satisfactory considering that the data are associated with a number of variables (two alloys, several heats and heat treatments, a range of temperatures, different testing techniques, etc.) that are not directly accounted for in the calculations.

  4. Application of Strainrange Partitioning to the prediction of creep-fatigue lives of AISI Types 304 and 316 stainless steel

    NASA Technical Reports Server (NTRS)

    Saltsman, J. F.; Halford, G. R.

    1977-01-01

    As a demonstration of the predictive capabilities of the method of Strainrange Partitioning, published high-temperature, low cycle, creep-fatigue test results on AISI Types 304 and 316 stainless steel were analyzed and calculated cyclic lives compared with observed lives. Predicted lives agreed with observed lives within factors of two for 76 percent, factors of three for 93 percent, and factors of four for 98 percent of the laboratory tests analyzed. Agreement between observed and predicted lives is judged satisfactory considering that the data are associated with a number of variables (two alloys, several heats and heat treatments, a range of temperatures, different testing techniques, etc.) that are not directly accounted for in the calculations.

  5. Effect of postweld treatment on the fatigue crack growth rate of electron-beam-welded AISI 4130 steel

    SciTech Connect

    Wang, C.C.; Chang, Y.

    1996-10-01

    This article studies the effect of in-chamber electron beam and ex-chamber furnace postweld treatments on the fatigue crack growth rate of electron-beam-welded AISI 4130 steel. Mechanical properties of the weldment are evaluated by tensile testing, while the fatigue properties are investigated by a fatigue crack propagation method. Microstructural examination shows that both postweld treatments temper the weldment by the appropriate control of beam pattern width, input beam energy, and furnace temperature. In addition, the ductility, strength, and microhardness of the weldment also reflect this tempering effect. The fatigue crack growth rate is decreased after both postweld treatments. This is mainly caused by the existence of a toughened microstructure and relief of the residual stress due to the fact that (1) the residual stress becomes more compressive as more beam energy is delivered into the samples and (2) postweld furnace tempering effectively releases the tensile stress into a compressive stress state.

  6. Near surface chemistry and corrosion behavior of excimer laser surface-melted AISI type 304 stainless steel

    SciTech Connect

    Baer, D.R.; Frydrych, D.J.; Jervis, T.R.

    1988-05-01

    The effects of excimer laser surface melting on the near-surface chemistry, and corrosion behavior of AISI 304 stainless steel have been examined as a function of total energy deposited on the specimen. The surface chemistry resulting from the laser treatments has been examined using Auger electron spectroscopy. Electrochemical methods were used to monitor the corrosion behavior of the specimens in deaerated 0.1 M NaCl. Electron microscopy was used to characterize the extent of local corrosion of the specimens. Laser treatment was observed to increase the chromium concentration of the surface oxide and to reduce the number of pits. Two types of pits were observed on untreated material, but only one type of pit occurred after laser treatment. 7 refs., 5 figs.

  7. Experimental investigations on effects of frequency in ultrasonically-assisted end-milling of AISI 316L: A feasibility study.

    PubMed

    Maurotto, A; Wickramarachchi, C T

    2016-02-01

    The effects of frequency in ultrasonic vibration assisted milling (UVAM) with axial vibration of the cutter is investigated in this paper. A series of face-mill experiment in dry conditions were conducted on AISI 316L, an alloy of widespread use in industry. The finished surfaces roughness were studied along with basic considerations on tool wear for both conventional milling and an array of frequencies for UVAM (204060 kHz) in a wide range of cutting conditions. Surface residual stresses and cross-cut metallographic slides were used to investigate the hidden effects of UVAM. Experimental results showed competitive results for both surface roughness and residual stress in UVAM when compared with conventional milling especially in the low range of frequency with similar trend for tool wear. PMID:26601562

  8. Comparison of Roller Burnishing Method with Other Hole Surface Finishing Processes Applied on AISI 304 Austenitic Stainless Steel

    NASA Astrophysics Data System (ADS)

    Akkurt, Adnan

    2011-08-01

    Component surface quality and selection of the optimum material are the main factors determining the performance of components used in machine manufacturing. The level of hole surface quality can be evaluated by the measurements regarding surface roughness, micro-hardness, and cylindricity. In this study, data had been obtained for different hole drilling methods. The characteristics of materials obtained after applications were compared for different hole-finishing processes to identify best hole drilling method. AISI 304 austenitic stainless steel material was used. Surface finishing of holes were performed using drilling, turning, reaming, grinding, honing, and roller burnishing methods. The results of the study show that the roller burnishing method gives the best results for mechanical, metallurgical properties, and hole surface quality of the material. On the other hand, the worst characteristics were obtained in the drilling method.

  9. Fractographic evaluation of creep effects on strain-controlled fatigue-cracking of AISI 304LC and 316 stainless steel

    NASA Technical Reports Server (NTRS)

    Oldrieve, R. E.

    1978-01-01

    Analysis of high temperature low cycle fatigue of AISI 304LC and 316 stainless steels by the method of strainrange partitioning results in four separate strainrange versus life relationships, depending upon the way in which creep-strain and plastic strain are combined within a cycle. Fractography is used in this investigation of the creep-fatigue interaction associated with these cycles. The PP and PC-cycle fractures were transgranular. The PC-cycle resulted in fewer cycles of initiation and shorter total cyclic life for the same applied inelastic strainrange. The CC-cycle had mixed transgranular and intergranular fracture, fewer cycles of initiation and shorter cycle life than PP or PC. The CP-cycle had fully integranular cracking, and failed in fewer cycles than were required for cracks to initate for PP,PC, and CC.

  10. Experimental Investigation of Machining AISI 1040 Medium Carbon Steel Under Cryogenic Machining: A Comparison with Dry Machining

    NASA Astrophysics Data System (ADS)

    Gupta, Munish Kumar; Singh, Gauravdeep; Sood, Pardeep Kumar

    2015-10-01

    This experimental work was carried out by turning of AISI 1040 medium carbon steel in which the effect of cryogenic cooling (LN2) used as a cutting fluid is compared to that of dry machining with respect to tool wear i.e. crater and flank wear, surface roughness, cutting forces (feed and cutting forces) and cutting temperature. Experiments were performed using uncoated tungsten carbide insert tool having various feed rate and constant cutting speed. Compared to dry machining, in LN2 machining, overall the tool wear were reduced to 55.45 and 65.53 %, surface roughness was reduced to 125.90 % and forces were reduced to 61.94 and 96.60 %. The experimental results proved that the application of cryogenic coolant overall increases the machining performance as compared to dry machining.

  11. Quantifying Cutting and Wearing Behaviors of TiN- and CrN-Coated AISI 1070 Steel

    PubMed Central

    Cakan, Ahmet; Ozkaner, Vedat; Yildirim, Mustafa M.

    2008-01-01

    Hard coatings such as titanium nitride (TiN) and chromium nitride (CrN) are widely used in cutting and forming tools against wear and corrosion. In the present study, hard coating films were deposited onto AISI 1070 steels by a cathodic arc evaporation plating (CAVP) technique. These samples were subjected to wear in a conventional lathe for investigating the tribological behaviour of coating structure, and prenitrided subsurface composition was characterized using scanning electron microscopy (SEM), line scan analyses and X-ray diffraction (XRD). The wear properties of TiN- and CrN-coated samples were determined using an on-line monitoring system. The results show that TiN-coated samples demonstrate higher wear resistance than CrN-coated samples.

  12. Influence of dissolved hydrogen on the fatigue crack growth behaviour of AISI 4140 steel

    NASA Astrophysics Data System (ADS)

    Ramasagara Nagarajan, Varun

    Many metallic structural components come into contact with hydrogen during manufacturing processes or forming operations such as hot stamping of auto body frames and while in service. This interaction of metallic parts with hydrogen can occur due to various reasons such as water molecule dissociation during plating operations, interaction with atmospheric hydrogen due to the moisture present in air during stamping operations or due to prevailing conditions in service (e.g.: acidic or marine environments). Hydrogen, being much smaller in size compared to other metallic elements such as Iron in steels, can enter the material and become dissolved in the matrix. It can lodge itself in interstitials locations of the metal atoms, at vacancies or dislocations in the metallic matrix or at grain boundaries or inclusions (impurities) in the alloy. This dissolved hydrogen can affect the functional life of these structural components leading to catastrophic failures in mission critical applications resulting in loss of lives and structural component. Therefore, it is very important to understand the influence of the dissolved hydrogen on the failure of these structural materials due to cyclic loading (fatigue). For the next generation of hydrogen based fuel cell vehicles and energy systems, it is very crucial to develop structural materials for hydrogen storage and containment which are highly resistant to hydrogen embrittlement. These materials should also be able to provide good long term life in cyclic loading, without undergoing degradation, even when exposed to hydrogen rich environments for extended periods of time. The primary focus of this investigation was to examine the influence of dissolved hydrogen on the fatigue crack growth behaviour of a commercially available high strength medium carbon low alloy (AISI 4140) steel. The secondary objective was to examine the influence of microstructure on the fatigue crack growth behaviour of this material and to determine the hydrogen induced failure mechanism in this material during cyclic loading. The secondary objective of this investigation was to determine the role of inclusions and their influence in affecting the fatigue crack growth rate of this material. Compact tension and tensile specimens were prepared as per ASTM E-647, E-399 and E-8 standards. The specimens were tested in three different heat treated conditions i.e. annealed (as received) as well as two austempered conditions. These specimens were precharged with hydrogen (ex situ) using cathodic charging method at a constant current density at three different time periods ranging from 150 to 250 hours before conducting fatigue crack growth tests. Mode 1 type fatigue tests were then performed in ambient atmosphere at constant amplitude using load ratio R of 0.1. The near threshold fatigue crack growth rate, fatigue threshold and the fatigue crack growth rate in the linear region were determined. Fatigue crack growth behaviour of specimens without any dissolve hydrogen were then compared with the specimens with different concentration of dissolved hydrogen. The test results show that the dissolved hydrogen concentration increases with the increase in charging time in all three heat treated conditions and the hydrogen uptake shows a strong dependence on the microstructure of the alloy. It was also observed that the microstructure has a significant influence of on the fatigue crack growth and SCC behaviour of the alloy with dissolved hydrogen. As the dissolved hydrogen concentration increases, the fatigue threshold was found to decrease and the near threshold crack growth rate increases in all three heat treated conditions showing the deleterious effect of hydrogen, but to a different extent in each condition. Current test results also indicate that the fatigue crack growth rates in the linear region increases as the dissolved hydrogen content increases in all three heat treated conditions. It is also observed that increasing the austempering temperature decreases the resistance to hydrogen embrittlement. An interesting phenomenon was also observed in annealed specimen charged with hydrogen for 250 h which had an unusually high fatigue threshold (DeltaKth).

  13. Electron Backscatter Diffraction Analysis of Joints Between AISI 316L Austenitic/UNS S32750 Dual-Phase Stainless Steel

    NASA Astrophysics Data System (ADS)

    Shamanian, Morteza; Mohammadnezhad, Mahyar; Amini, Mahdi; Zabolian, Azam; Szpunar, Jerzy A.

    2015-08-01

    Stainless steels are among the most economical and highly practicable materials widely used in industrial areas due to their mechanical and corrosion resistances. In this study, a dissimilar weld joint consisting of an AISI 316L austenitic stainless steel (ASS) and a UNS S32750 dual-phase stainless steel was obtained under optimized welding conditions by gas tungsten arc welding technique using AWS A5.4:ER2594 filler metal. The effect of welding on the evolution of the microstructure, crystallographic texture, and micro-hardness distribution was also studied. The weld metal (WM) was found to be dual-phased; the microstructure is obtained by a fully ferritic solidification mode followed by austenite precipitation at both ferrite boundaries and ferrite grains through solid-state transformation. It is found that welding process can affect the ferrite content and grain growth phenomenon. The strong textures were found in the base metals for both steels. The AISI 316L ASS texture is composed of strong cube component. In the UNS S32750 dual-phase stainless steel, an important difference between the two phases can be seen in the texture evolution. Austenite phase is composed of a major cube component, whereas the ferrite texture mainly contains a major rotated cube component. The texture of the ferrite is stronger than that of austenite. In the WM, Kurdjumov-Sachs crystallographic orientation relationship is found in the solidification microstructure. The analysis of the Kernel average misorientation distribution shows that the residual strain is more concentrated in the austenite phase than in the other phase. The welding resulted in a significant hardness increase in the WM compared to initial ASS.

  14. Comparison of Austenite Decomposition Models During Finite Element Simulation of Water Quenching and Air Cooling of AISI 4140 Steel

    NASA Astrophysics Data System (ADS)

    Babu, K.; Prasanna Kumar, T. S.

    2014-08-01

    An indigenous, non-linear, and coupled finite element (FE) program has been developed to predict the temperature field and phase evolution during heat treatment of steels. The diffusional transformations during continuous cooling of steels were modeled using Johnson-Mehl-Avrami-Komogorov equation, and the non-diffusion transformation was modeled using Koistinen-Marburger equation. Cylindrical quench probes made of AISI 4140 steel of 20-mm diameter and 50-mm long were heated to 1123 K (850 °C), quenched in water, and cooled in air. The temperature history during continuous cooling was recorded at the selected interior locations of the quench probes. The probes were then sectioned at the mid plane and resultant microstructures were observed. The process of water quenching and air cooling of AISI 4140 steel probes was simulated with the heat flux boundary condition in the FE program. The heat flux for air cooling process was calculated through the inverse heat conduction method using the cooling curve measured during air cooling of a stainless steel 304L probe as an input. The heat flux for the water quenching process was calculated from a surface heat flux model proposed for quenching simulations. The isothermal transformation start and finish times of different phases were taken from the published TTT data and were also calculated using Kirkaldy model and Li model and used in the FE program. The simulated cooling curves and phases using the published TTT data had a good agreement with the experimentally measured values. The computation results revealed that the use of published TTT data was more reliable in predicting the phase transformation during heat treatment of low alloy steels than the use of the Kirkaldy or Li model.

  15. Hydrogen Uptake Enhancement and Accelerated Hydrogen Re-embrittlement of Cd-plated AISI 4340 Steel Bolts Coupled with IN718 Nuts

    NASA Astrophysics Data System (ADS)

    Lovicu, Gian Franco; Colombo, Costanza; de Sanctis, Massimo; Valentini, Renzo

    2011-12-01

    Hydrogen re-embrittlement on anodically coated high strength steels could be of great concern because the uptake of hydrogen from the corrosion process can cause component failure. A scratched Cd-coated AISI 4340 steel membrane has been coupled with different materials reproducing crevice conditions, and the hydrogen uptake has been measured using a modified Devanathan-Stachurski permeation apparatus. Experimental tests proved that, in presence of a crevice, metals nobler than cadmium strongly enhance local hydrogen reduction on exposed steel areas, thus possibly favoring brittle failure of high strength steel components during service. Therefore, the coupling of uncoated nuts made of noble passive alloys (like Inconel) to Cd-plated AISI 4340 steel bolts should be avoided.

  16. Welding procedure specification. Supplement 1. Records of procedure qualification tests. Gas tungsten arc and shielded metal arc welding of AISI 41XX steels. [4130 and 4142 steels

    SciTech Connect

    Wodtke, C.H.; Frizzell, D.R.

    1986-06-01

    Procedure WPS-127 is qualified under Section IX of the ASME Boiler and Pressure Vessel Code for gas tungsten arc and shielded metal arc welding of AISI 4130 and 4142 steels (ASTM A519) (P-No: None), 0.438-inch wall pipe; filler metal is AMS 6457, Class 4130 MC (F-, A-No: None) (GTAW) and E8018-B2L (F-4, A-3) (GMAW): shielding gas is argon (GTAW).

  17. In vitro response of human peripheral blood mononuclear cells to AISI 316L austenitic stainless steel subjected to nitriding and collagen coating treatments.

    PubMed

    Stio, Maria; Martinesi, Maria; Treves, Cristina; Borgioli, Francesca

    2015-02-01

    Surface modification treatments can be used to improve the biocompatibility of austenitic stainless steels. In the present research two different modifications of AISI 316L stainless steel were considered, low temperature nitriding and collagen-I coating, applied as single treatment or in conjunction. Low temperature nitriding produced modified surface layers consisting mainly of S phase, which enhanced corrosion resistance in PBS solution. Biocompatibility was assessed using human peripheral blood mononuclear cells (PBMC) in culture. Proliferation, lactate dehydrogenase (LDH) levels, release of cytokines (TNF-?, IL-1?, IL-12, IL-10), secretion of metalloproteinase (MMP)-9 and its inhibitor TIMP-1, and the gelatinolytic activity of MMP-9 were determined. While the 48-h incubation of PBMC with all the sample types did not negatively influence cell proliferation, LDH and MMP-9 levels, suggesting therefore a good biocompatibility, the release of the pro-inflammatory cytokines was always remarkable when compared to that of control cells. However, in the presence of the nitrided and collagen coated samples, the release of the pro-inflammatory cytokine IL-1? decreased, while that of the anti-inflammatory cytokine IL-10 increased, in comparison with the untreated AISI 316L samples. Our results suggest that some biological parameters were ameliorated by these surface treatments of AISI 316L. PMID:25655502

  18. Al Composites

    NASA Astrophysics Data System (ADS)

    Chandanayaka, Tharaka; Azarmi, Fardad

    2014-05-01

    In the present study, cold spraying technique was used to fabricate a metal matrix composite (MMC) that consists of Ni matrix and 20 vol.% Ni3Al particles at two different particle sizes as reinforcement. This study intends to investigate the effect of reinforcement particle size on microstructural and mechanical properties of cold sprayed MMCs. Two different Ni3Al powders with nominal particle size of -45 to +5 and +45 to 100 ?m were used as reinforcement in this study. Cold sprayed Ni-Ni3Al samples were subjected to the microstructural observation and characterization prior to any mechanical testing. Then, samples were tested using nano-indentation, Knoop hardness, Vickers hardness, and Resonance frequency to evaluate their mechanical properties. No significant changes were observed in microstructural characteristics due to different particle sizes. The results obtained from a variety of mechanical testings indicated that the increasing reinforcement particle size resulted in the slight reduction of mechanical properties such as elastic modulus and hardness in cold sprayed MMCs. The mechanical interlock between deposited particles defines the bonding strength in cold sprayed samples. Small size particles have a higher velocity and impact resulting in stronger interlock between deformed particles.

  19. Exploration of surface hydrophilic properties on AISI 304 stainless steel and silicon wafer against aging after atmospheric pressure plasma treatment

    NASA Astrophysics Data System (ADS)

    Chuang, Shang-I.; Duh, Jenq-Gong

    2014-11-01

    The aim of this work is to seek the enhanced surface hydrophilic properties on AISI 304 stainless steel and silicon wafer after atmospheric pressure plasma treatment using a specifically designed atmospheric pressure plasma jet. The aging tendency of surface hydrophilic property under air is highlighted. It is concluded that both of the silicon wafer and stainless steel treated with plasma generated from supply gas of argon 15 slm mixed with oxygen 40 sccm shows a better tendency on remaining high water contact angle as compared to that with pure argon and nitrogen addition. Additional peaks of O I (777, 844 nm), O II (408 nm) are detected by optical emission spectroscope indicating the presence of the oxygen radicals and ionic species, which interact with surfaces and thus contribute to low water contact angle (WCA) surfaces. Moreover, the result acquired from X-ray photoelectron spectroscopy (XPS) indicates that the increase in the oxygen-related bonding exhibits a better contribution on remaining high surface energy over a period of time.

  20. Selection of Wire Electrical Discharge Machining Process Parameters on Stainless Steel AISI Grade-304 using Design of Experiments Approach

    NASA Astrophysics Data System (ADS)

    Lingadurai, K.; Nagasivamuni, B.; Muthu Kamatchi, M.; Palavesam, J.

    2012-06-01

    Wire electrical discharge machining (WEDM) is a specialized thermal machining process capable of accurately machining parts of hard materials with complex shapes. Parts having sharp edges that pose difficulties to be machined by the main stream machining processes can be easily machined by WEDM process. Design of Experiments approach (DOE) has been reported in this work for stainless steel AISI grade-304 which is used in cryogenic vessels, evaporators, hospital surgical equipment, marine equipment, fasteners, nuclear vessels, feed water tubing, valves, refrigeration equipment, etc., is machined by WEDM with brass wire electrode. The DOE method is used to formulate the experimental layout, to analyze the effect of each parameter on the machining characteristics, and to predict the optimal choice for each WEDM parameter such as voltage, pulse ON, pulse OFF and wire feed. It is found that these parameters have a significant influence on machining characteristic such as metal removal rate (MRR), kerf width and surface roughness (SR). The analysis of the DOE reveals that, in general the pulse ON time significantly affects the kerf width and the wire feed rate affects SR, while, the input voltage mainly affects the MRR.

  1. Correlation of microstructure and surface roughness of disc drums fabricated by hot forging of an AISI 430F stainless steel

    NASA Astrophysics Data System (ADS)

    Kim, Dong-Kuk; Lee, Dong-Geon; Lee, Sunghak

    2001-05-01

    The surface roughness of disc drums fabricated by hot forging of an AISI 430F stainless steel was investigated. Emphasis was placed on the role of microstructural changes, which depend on postforging annealing conditions. In the forged drum specimens, MnS inclusions were heavily elongated, and a large amount of martensite was found. Three different annealing conditions were used on the forged drum specimens to completely or partially decompose martensite. The surface roughness tests were conducted on these specimens, and then the test data were compared via hardness and microstructures. The top plane of disc drums, where MnS inclusions were elongated perpendicular to the machined surface, showed a good surface roughness because of the free-machining effect of MnS. However, the side plane, where MnS inclusions were aligned parallel to the machined surface, showed an increased surface roughness due to reduction of the MnS effect. These findings suggested that a proper amount of martensite formed during forging and annealing would be beneficial for cost efficiency, as well as machinability of the 430F stainless steel products.

  2. Effect of metallurgical factors on the electrochemical noise measured on AISI Type 430 stainless steels in chloride-containing media

    SciTech Connect

    Gorse, D.; Boulleret, C.; Baroux, B.

    1996-12-31

    Potentiostatic noise measurements are performed on a series of AISI 430 type ferritic stainless steels containing controlled amounts of sulfur (from 8 up to 47 ppm) and titanium (up to 0.37 wt%), in 0.02M sodium chloride (NaCl) aqueous solution (pH 6.6), in a range of potentials below the pitting potential. The authors focus on the evolution of the shape of the current transients, going from a titanium (Ti) free and 41-ppm sulfur-containing alloy to different Ti-bearing alloys with comparable amount of sulfur ({approximately}40 ppm). The results are compared to the case of a Ti-free and low sulfur (8-ppm) containing alloy. The shape of the anodic current transients obeys a power law, t{sup n}. The authors distinguish two different situations, with n either less or larger than 1, which can be associated with the Ti and sulfur content in the steel. The influence of the exposure time under polarization is also discussed. It appears that for the manganese sulfide (MnS)-containing alloys, after prolonged polarization, the shape of the metastable pitting events evolves toward that found for MnS-free alloys (Ti-bearing), or low-sulfur-containing alloys. Attention is drawn to the possible relationship between the shape of the current transients and the metallurgical defects acting as pitting initiation sites.

  3. Influence of sulfate-reducing bacteria on the passive film formed on austenitic stainless steel AISI 304

    SciTech Connect

    Chen, G.; Clayton, C.R.; Sadowski, R.A.; Kearns, J.R.; Gillow, J.B.; Francis, A.J.

    1995-03-01

    The influence of sulfate-reducing bacteria (SRB) on the passivity of a stainless steel, AISI 304, was investigated with X-ray photoelectron spectroscopy (XPS) and electrochemical techniques. Samples were exposed to SRB in growth media for 5 days. Potentiodynamic polarization tests were then conducted in deaerated 0.1 M HCl to determine if prior exposure to SRB compromised the passivity of the steel. The surface chemistry was analyzed with XPS, immediately after the exposure and following subsequent anodic polarization in 0.1 M HCl. Excess biomass generated by SRB could be rinsed from the steel with deaerated deionized water. Therefore, electrochemical and surface analysis were performed on both rinsed and unrinsed samples. Comparisons were made with control samples which were immersed in uninoculated media. The status of a newly polished sample at each stage of the investigation was given as an basis for comparison. It was found that SRB caused a loss of passivity in the 0.1 M HCl solution, due to the formation of sulfides. The following sulfides were observed: FeS, FeS{sub 2}, NiS, Cr{sub 2}S{sub 3} and possibly Fe{sub 1{minus}x}S{sub x}. The sulfides developed into the sublayer of the substrate during exposure to SRB and remained to hinder repassivation in the test electrolyte.

  4. Influence of sulfate-reducing bacteria on the passive film formed on austenitic stainless steel AISI 304

    SciTech Connect

    Chen, G.; Clayton, C.R.; Sadowski, R.A.; Kearns, J.R.; Gillow, J.B.; Francis, A.J.

    1995-10-01

    The influence of sulfate-reducing bacteria (SRB) on the passivity of a stainless steel, AISI 304, was investigated with X-ray photoelectron spectroscopy (XPS) and electrochemical techniques. Samples were exposed to SRB in growth media for 5 days. Potentiodynamic polarization tests were then conducted in deaerated 0.1 M HCl to determine if prior exposure to SRB compromised the passivity of the steel. The surface chemistry was analyzed with XPS, immediately after the exposure and following subsequent anodic polarization in 0.1 M HCl. Excess biomass generated by SRB could be rinsed from the steel with deaerated deionized water. Therefore, electrochemical and surface analysis were performed on both rinsed and unrinsed samples. Comparisons were made with control samples which were immersed in uninoculated media. The status of a newly polished sample at each stage of the investigation was given as a basis for comparison. It was found that SRB caused a loss of passivity in the 0.1 M HCl solution, due to the formation of sulfides. The following sulfides were observed: FeS, FeS{sub 2}, NiS, Cr{sub 2}S{sub 3} and possibly Fe{sub 1{minus}x}S{sub x}. The sulfides developed into the sublayer of the substrate during exposure to SRB and remained to hinder repassivation in the test electrolyte.

  5. Corrosion behavior and tensile properties of AISI 316LN stainless steel exposed to flowing sodium at 823 K

    SciTech Connect

    Pillai, S.R.; Barasi, N.S.; Khatak, H.S.; Terrance, A.L.E.; Kale, R.D.; Rajan, M.; Rajan, K.K.

    2000-02-01

    Austenitic stainless steel of the grade AISI 316 LN was exposed to flowing sodium in a loop at 823 K for 6,000 h to examine the corrosion and mass-transfer behavior. The specimens were incorporated in specially designed sample holders in the loop. These were retrieved and examined by various metallurgical techniques. Specimens were also subjected to thermal aging in the same sample holder to aid in separating the consequences of exposure to sodium from those cause by mere thermal effects. Microstructural investigations have revealed that thermal aging caused the precipitation of carbides at the grain boundaries. Exposure to sodium caused the leaching of elements such as chromium and nickel from the specimen. Loss of nickel from the austenite phase promoted the generation of ferrite phase. Microhardness investigation revealed the hardening of the sodium-exposed surface. Analysis using an electron Probe Microanalyzer revealed that the surface of the steel was both carburized and nitrided. Tensile tests indicated that there is no appreciable difference in the yield strength (YS) and ultimate tensile strength (UTS) of the thermally aged and sodium-exposed specimens when compared with the material in the as-received condition. However, the thermally aged and sodium-exposed specimens showed a decrease in the uniform elongation and total elongation at rupture, perhaps due to carburization and nitridation.

  6. Cobalt-Free Laser Cladding on AISI Type 316L Stainless Steel for Improved Cavitation and Slurry Erosion Wear Behavior

    NASA Astrophysics Data System (ADS)

    Paul, C. P.; Gandhi, B. K.; Bhargava, P.; Dwivedi, D. K.; Kukreja, L. M.

    2014-12-01

    Laser cladding of Colmonoy-5 (a nickel base alloy) and Metco-41C (an iron base alloy) on AISI type 316L stainless steel (SS316L) and their wear behaviors were investigated to establish Co-free clad layers for potential applications in nuclear industry. A 3.5 kW CO2 laser-based system was used to optimize the laser cladding on SS316L substrate. The observed optimum parameters were: laser power of 1.6 kW, scan speed of 0.6 m/min, and powder feed rate of 8 g/min with 60% overlapping. The microstructure studies revealed that the clad layers primarily comprise very fine columnar dendritic structures, while clad-substrate interface exhibited planar and non-epitaxial mode of solidification due to high cooling rates. The cavitation and slurry erosion behaviors of laser clad layers were also compared to that of Stellite-6 for potential direct replacement. The cavitation erosion resistance was improved by a factor of 1.6, 3.7, and 4.1, while the slurry erosion resistances at an impingement angle of 30 were 1.5, 4.8, and 1.8 times better for laser clad surfaces of Colmonoy-5, Metco-41C, and Stellite-6, respectively, as compared to that of bare SS316L substrate. The study demonstrated that Metco-41C is a better choice as Co-free clad material for potential nuclear applications.

  7. Cobalt-Free Laser Cladding on AISI Type 316L Stainless Steel for Improved Cavitation and Slurry Erosion Wear Behavior

    NASA Astrophysics Data System (ADS)

    Paul, C. P.; Gandhi, B. K.; Bhargava, P.; Dwivedi, D. K.; Kukreja, L. M.

    2014-09-01

    Laser cladding of Colmonoy-5 (a nickel base alloy) and Metco-41C (an iron base alloy) on AISI type 316L stainless steel (SS316L) and their wear behaviors were investigated to establish Co-free clad layers for potential applications in nuclear industry. A 3.5 kW CO2 laser-based system was used to optimize the laser cladding on SS316L substrate. The observed optimum parameters were: laser power of 1.6 kW, scan speed of 0.6 m/min, and powder feed rate of 8 g/min with 60% overlapping. The microstructure studies revealed that the clad layers primarily comprise very fine columnar dendritic structures, while clad-substrate interface exhibited planar and non-epitaxial mode of solidification due to high cooling rates. The cavitation and slurry erosion behaviors of laser clad layers were also compared to that of Stellite-6 for potential direct replacement. The cavitation erosion resistance was improved by a factor of 1.6, 3.7, and 4.1, while the slurry erosion resistances at an impingement angle of 30 were 1.5, 4.8, and 1.8 times better for laser clad surfaces of Colmonoy-5, Metco-41C, and Stellite-6, respectively, as compared to that of bare SS316L substrate. The study demonstrated that Metco-41C is a better choice as Co-free clad material for potential nuclear applications.

  8. Microstructure and Mechanical Properties of Plasma Arc Brazed AISI 304L Stainless Steel and Galvanized Steel Plates

    NASA Astrophysics Data System (ADS)

    Jin, Yajuan; Li, Ruifeng; Yu, Zhishui; Wang, Yu

    2016-03-01

    Plasma arc brazing is used to join the AISI 304L stainless steel and galvanized steel plate butt joints with the CuSi3Mn1 filler wire. The effect of parameters on weld surface appearance, interfacial microstructure, and composition distribution in the joint was studied. The microhardness and mechanical tests were conducted to determine the mechanical properties of the welded specimens. The results indicated that good appearance, bead shape, and sufficient metallurgical bonding could be obtained when the brazing process was performed with a wire feeding speed of 0.8 m/min, plasma gas flow rate of 3.0 l/min, welding current of 100 A, and welding speed of 27 cm/min. During plasma arc brazing process, the top corner of the stainless steel and galvanized steel plate were heated and melted, and the melted quantity of stainless steel was much more than that of the galvanized steel due to the thermal conductivity coefficient difference between the dissimilar materials. The microhardness test results shows that the microhardness value gradually increased from the side of the galvanized steel to the stainless steel in the joint, and it is good for improving the mechanical properties of joint. The tensile strength was a little higher than that of the brazing filler, and the fracture position of weld joint was at the base metal of galvanized steel plate.

  9. Nanosecond laser surface modification of AISI 304L stainless steel: Influence the beam overlap on pitting corrosion resistance

    NASA Astrophysics Data System (ADS)

    Pacquentin, Wilfried; Caron, Nadge; Oltra, Roland

    2014-01-01

    Surface modifications of AISI 304L stainless steel by laser surface melting (LSM) were investigated using a nanosecond pulsed laser-fibre doped by ytterbium at different overlaps. The objective was to study the change in the corrosion properties induced by the treatment of the outer-surface of the stainless steel without modification of the bulk material. Different analytical techniques such as scanning electron microscopy (SEM), X-ray diffraction (XRD), and glow discharge optical emission spectrometry (GDOES) were used to characterize the laser-melted surface. The corrosion resistance was evaluated in a chloride solution at room temperature by electrochemical tests. The results showed that the crystallographic structure, the chemical composition, the properties of the induced oxide layer and consequently the pitting corrosion resistance strongly depend on the overlap rate. The most efficient laser parameters led to an increase of the pitting potential by more than 300 mV, corresponding to a quite important improvement of the corrosion resistance. This latter was correlated to chromium enrichment (47 wt.%) at the surface of the stainless steel and the induced absence of martensite and ferrite phases. However, these structural and chemical modifications were not sufficient to explain the change in corrosion behaviour: defects and adhesion of the surface oxide layer must have been taken into consideration.

  10. Influences of Processing Time and Discharge Current Density During Pulsed Plasma-Oxidizing process of AISI 316L

    NASA Astrophysics Data System (ADS)

    Daz-Guilln, J. C.; Vargas-Gutirrez, G.; Granda-Gutirrez, E. E.; Aguilar-Martnez, J. A.; Gonzlez-Albarrn, M. A.; lvarez-Contreras, L.

    2015-06-01

    The influences of discharge current density and oxidation process duration on surface morphology, crystalline phase composition, and electrochemical corrosion performance of pulsed plasma-oxidized AISI 316L stainless steel were studied. Analysis of results shows that samples treated through DC pulsed plasma oxidation (0.5 mA/cm2, 60 min) exhibit corrosion current values of 2.0 10-4 mA/cm2 which represent one eighth of the corrosion current obtained for untreated samples and one half that of chemically passivated samples. Scanning electron microscopy, grazing incidence x-ray diffraction, and Raman analysis show that the improved corrosion performance of oxidized samples could be attributed to morphological changes of the oxidized layer which is composed of hematite and magnetite iron oxides. Corrosion performances of DC plasma-oxidized samples suggest that through this technique, it is possible to obtain comparable or even better corrosion performance than techniques, such as inductively coupled plasma-oxidizing process, but without the inherent higher instrumental requirements of radiofrequency plasma processes.

  11. Effects of strain and strain-induced ?'-martensite on passive films in AISI 304 austenitic stainless steel.

    PubMed

    Lv, Jinlong; Luo, Hongyun

    2014-01-01

    In this paper, the effects of strain and heat treatment on strain-induced ?'-martensite of AISI 304 stainless steel tubes were measured by X-ray diffraction. Moreover, the effects of strain and content of ?'-martensite on passivated property on the surface of the material in borate buffer solution were evaluated by electrochemical technique. The results showed that the volume fraction of ?'-martensite increased gradually with the increase of tensile strain for as-received and solid solution samples. However, ?'-martensite in as-received sample was more than that in the solid solution sample. The electrochemical impedance spectroscopy results showed that the solid solution treatment improved corrosion resistance of the steel, especially for samples with small strain. Moreover, acceptor densities were always higher than donor densities for as-received and solid solution samples. With the increase of strain, the increase tendency of acceptor density was more significant than that of donor density. We also found that the total density of the acceptor and donor almost increased linearly with the increase of ?'-martensite. The present results indicated that the increased acceptor density might lead to the decreased corrosion resistance of the steel. PMID:24268285

  12. Influence of Sigma Phase on Pitting Resistance Depending on Solidification Mode in AISI316L Weld Metal

    NASA Astrophysics Data System (ADS)

    Jang, A. Y.; Lee, H. W.

    2012-06-01

    The pitting corrosion resistances were investigated in the AISI 316L stainless steel weld metals with respect to the sigma phase precipitation in a 0.1 M NaCl solution. The modified flux-cored arc welding filler wires were fabricated at various chromium and nickel equivalent ratios using the flux-cored arc welding process. As the Cr/Ni equivalent ratio increased, the precipitated ? phase content increased in the temperature range of 923 K to 1123 K (650 C to 850 C), and the specimen that was aged at 1123 K (850 C) precipitated the ? phase rapidly. The hardness increased with increasing sigma contents. During the potentiodynamic anodic polarization test, the specimens that were aged at 923 K to 1123 K (650 C to 850 C) exhibited lower pitting potentials than the as-weld metal. Additionally, the specimens that were aged for longer times exhibited lower pitting potentials. The pits occurred preferentially in the ductility dip cracking in specimen 1, whereas intergranular pits occurred in the sigma phase regions along the vermicular ferrite and acicular ferrite grain boundaries in specimens 2 and 3.

  13. Determination of Neutron Exposure of AISI 304 Stainless Steel from a BWR Top Guide using Retrospective Dosimetry

    SciTech Connect

    Greenwood, Lawrence R.; Garner, Francis A.; Oliver, Brian M.; Bruemmer, Stephen M.

    2007-03-31

    Retrospective dosimetry was used to determine the accumulated neutron exposure of AISI 304 stainless steel removed from the top guide of a boiling water reactor located at the Oyster Creek nuclear power station. The material was removed from areas adjacent to cracks that were observed after ~20 years of operation. Using the plant operational history and a variety of measurements of various radioisotopes or non-radioactive transmutation products produced by irradiation, it was possible to determine the integrated flux spectra experienced by the cracked region and to specify the accumulated displacement dose. Dose estimates on two separate specimens adjacent to the cracks were found to average 1.5 0.2 dpa, possibly reflecting some uncertainty in measurement but more likely suggesting a small gradient in neutron flux-spectra within the section from which the various analysis specimens were cut. This report demonstrates that it is possible to examine defective components lying outside of the core region and where neutron flux-spectra are not well known, and to use the induced transmutation products to determine the neutron exposure with some confidence by using the examined specimen as its own dosimeter.

  14. Employing Ti nano-powder dielectric to enhance surface characteristics in electrical discharge machining of AISI D2 steel

    NASA Astrophysics Data System (ADS)

    Marashi, Houriyeh; Sarhan, Ahmed A. D.; Hamdi, Mohd

    2015-12-01

    Manufacturing components with superior surface characteristics is challenging when electrical discharge machining (EDM) is employed for mass production. The aim of this research is to enhance the characteristics of AISI D2 steel surface machined with EDM through adding Ti nano-powder to dielectric under various machining parameters, including discharge duration (Ton) and peak current (I). Surface roughness profilometer, FESEM and AFM analysis were utilized to reveal the machined surface characteristics in terms of surface roughness, surface morphology and surface micro-defects. Moreover, EDX analysis was performed in order to evaluate the atomic deposition of Ti nano-powder on the surface. The concentration of Ti nano-powder in dielectric was also examined using ESEM and EDX. According to the results, the addition of Ti nano-powder to dielectric notably enhanced the surface morphology and surface roughness at all machining parameters except Ton = 340 μs. Of these parameters, maximum enhancement was observed at Ton = 210 μs, where the material removal rate and average surface roughness improved by ∼69 and ∼35% for peak current of 6 and 12 A, respectively. Elemental analysis signified negligible Ti deposition on the machined surface while the atomic concentration of Ti was increased around the crack areas.

  15. Correlation between surface physicochemical properties and the release of iron from stainless steel AISI 304 in biological media.

    PubMed

    Hedberg, Yolanda; Karlsson, Maria-Elisa; Blomberg, Eva; Odnevall Wallinder, Inger; Hedberg, Jonas

    2014-10-01

    Stainless steel is widely used in biological environments, for example as implant material or in food applications, where adsorption-controlled ligand-induced metal release is of importance from a corrosion, health, and food safety perspective. The objective of this study was to elucidate potential correlations between surface energy and wettability of stainless steel surfaces and the release of iron in complexing biological media. This was accomplished by studying changes in surface energies calculated from contact angle measurements, surface oxide composition (X-ray photoelectron spectroscopy), and released iron (graphite furnace atomic absorption spectroscopy) for stainless steel grade AISI 304 immersed in fluids containing bovine serum albumin or citric acid, and non-complexing fluids such as NaCl, NaOH, and HNO3. It was shown that the surface wettability and polar surface energy components were all influenced by adventitious atmospheric carbon (surface contamination of low molecular weight), rather than differences in surface oxide composition in non-complexing solutions. Adsorption of both BSA and citrate, which resulted in ligand-induced metal release, strongly influenced the wettability and the surface energy, and correlated well with the measured released amount of iron. PMID:25048358

  16. Fracture prediction in hydraulic bulging of AISI 304 austenitic steel sheets based on a modified ductile fracture criterion

    NASA Astrophysics Data System (ADS)

    Xu, Y.; Song, H. W.; Zhang, S. H.; Cheng, M.

    2011-08-01

    The demand for weight reduction in modern vehicle construction has resulted in an increase in the application of hydroforming processes for the manufacture of automotive lightweight components. This trend led to the research of evaluation on formability of the sheet or tube hydroforming to be noted, particularly the prediction of fracture. In this study, a new proposed approach based on damage theory for fracture prediction considering the deformation history was introduced. And the modified ductile fracture criterion was applied to predict the failure for hydraulic bulging of AISI 304 austenitic steel sheets. The material parameters in terms of the function of strain rate in the failure criterion were determined from the equivalent fracture strains corresponding tensile tests under different stress conditions. Then, in the finite element simulation the effect of strain rates and their distribution as well during practical sheet metal forming process was considered. The hydraulic bulging tests were carried out to identify the fracture behavior predicted from FE analysis. A comparison between the prediction and experimental results showed that the proposed approach with a modified ductile fracture criteria can give better fracture predictions than traditional ways.

  17. Surface oxidation phenomenon and mechanism of AISI 304 stainless steel induced by Nd:YAG pulsed laser

    NASA Astrophysics Data System (ADS)

    Cui, C. Y.; Cui, X. G.; Ren, X. D.; Qi, M. J.; Hu, J. D.; Wang, Y. M.

    2014-06-01

    Surface oxidation phenomenon of AISI 304 stainless steel induced by Nd:YAG pulsed laser in air was investigated using scanning electron spectroscopy (SEM), high resolution transmission electron microscope (HRTEM), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). The results showed that there were different morphologies and phase compositions in one laser spot from the center to the edge on stainless steel surface after pulsed laser oxidation. The morphologies were mainly nano-spheres and hexagons. It was proved using XRD that they were basically ?-Fe, Cr2O3, Fe2O3 and a small amount of MnO2. The elemental compositions in the edge region were rich in Cr and deficient in Fe, while it had an opposite distribution trend in the center of the laser spot. XPS measurement confirmed the formed oxides on the stainless steel surface, indicating that most of the elements were in oxidation states. Moreover, the oxidation behavior of the stainless steel in one laser spot was assessed using thermodynamics and kinetics of laser oxidation process. And the oxidation mechanism was also clearly revealed.

  18. The corrosion protection of AISI(TM) 1010 steel by organic and inorganic zinc-rich primers

    NASA Technical Reports Server (NTRS)

    Danford, M. D.; Mendrek, M. J.

    1995-01-01

    The behavior of zinc-rich primer-coated AISI 1010 steel in 3.5-percent Na-Cl was investigated using electrochemical techniques. The alternating current (ac) method of electrochemical impedance spectroscopy (EIS), in the frequency range of 0.001 to 40,000 Hz, and the direct current (dc) method of polarization resistance (PR), were used to evaluate the characteristics of an organic, epoxy zinc-rich primer and an inorganic, ethyl silicate zinc-rich primer. A dc electromechanical galvanic corrosion test was also used to determine the corrosion current of each zinc-rich primer anode coupled to a 1010 steel cathode. Duration of the EIS/PR and galvanic testing was 21 days and 24 h, respectively. The galvanic test results demonstrated a very high current between the steel cathode and both zinc-rich primer anodes (38.8 and 135.2 microns A/sq cm for the organic and inorganic primers, respectively). The results of corrosion rate determinations demonstrated a much higher corrosion rate of the zinc in the inorganic primer than in the organic primer, due primarily to the higher porosity in the former. EIS equivalent circuit parameters confirmed this conclusion. Based on this investigation, the inorganic zinc-rich primer appears to provide superior galvanic protection and is recommended for additional study for application on solid rocket booster steel hardware.

  19. Microchemical and microstructural evolution of AISI 304 stainless steel irradiated in EBR-II at PWR-relevant dpa rates

    NASA Astrophysics Data System (ADS)

    Dong, Y.; Sencer, B. H.; Garner, F. A.; Marquis, E. A.

    2015-12-01

    AISI 304 stainless steel was irradiated at 416 °C and 450 °C at a 4.4 × 10-9 and 3.05 × 10-7 dpa/s to ∼0.4 and ∼28 dpa, respectively, in the reflector of the EBR-II fast reactor. Both unirradiated and irradiated conditions were examined using standard and scanning transmission electron microscopy, energy dispersive spectroscopy, and atom probe tomography on very small specimens produced by focused ion beam milling. These results are compared with previous electron microscopy examination of 3 mm disks from essentially the same material. By comparing a very low dose specimen with a much higher dose specimen, both derived from a single reactor assembly, it has been demonstrated that the coupled microstructural and microchemical evolution of dislocation loops and other sinks begins very early, with elemental segregation producing at these sinks what appears to be measurable precursors to fully formed precipitates found at higher doses. The nature of these sinks and their possible precursors are examined in detail.

  20. Influence of electroless nickel-phosphorus deposits on the corrosion-fatigue life of notched and unnotched samples of an AISI 1045 steel

    SciTech Connect

    Chitty, J.A.; Pertuz, A.; Puchi, E.S.; Hintermann, H.

    1999-02-01

    Electroless nickel-phosphorus deposits of approximately 10% phosphorus and about 20 {micro}m thickness are shown either to have no effect or sometimes to increase the corrosion-fatigue properties of a quenched and tempered AISI 1045 steel in the stress amplitude range of 481 to 687 MPa, in the presence of an aqueous solution of 3% sodium chloride. Such an increase is produced when the stress amplitude is below 516 MPa. For the notched specimens, no substantial differences are found between the fatigue life of the coated and uncoated specimens.

  1. Metal objects mapping after small charge explosions. A study on AISI 304Cu steel with two different grain sizes.

    PubMed

    Firrao, Donato; Matteis, Paolo; Scavino, Giorgio; Ubertalli, Graziano; Ienco, Maria G; Pellati, Gabriella; Piccardo, Paolo; Pinasco, Maria R; Stagno, Enrica; Costanza, Girolamo; Montanari, Roberto; Tata, Maria E; Brandimarte, Giovanni; Petralia, Santo

    2006-05-01

    Evidence of exposure of a metal component to a small charge explosion can be detected by observing microstructural modifications; they may be present even if the piece does not show noticeable overall plastic deformations. Particularly, if an austenitic stainless steel (or another metal having a face-centered cubic structure and a low stacking fault energy) is exposed to an explosive shock wave, high-speed deformation induces primarily mechanical twinning, whereas, in nonexplosive events, a lower velocity plastic deformation first induces slip. The occurrence of mechanical twins can be detected even if the surface is damaged or oxidized in successive events. In the present research, optical metallography (OM) and scanning electron microscopy (SEM), and scanning tunneling microscopy (STM) were used to detect microstructural modifications caused on AISI 304Cu steel disks by small-charge explosions. Spherical charges of 54.5 or 109 g TNT equivalent mass were used at explosive-to-target distances from 6.5 to 81.5 cm, achieving peak pressures from 160 to 0.5 MPa. Explosions induced limited or no macro-deformation. Two alloy grain sizes were tested. Surface OM and SEM evidenced partial surface melting, zones with recrystallization phenomena, and intense mechanical twinning, which was also detected by STM and X-ray diffraction. In the samples' interior, only twins were seen, up to some distance from the explosion impinged surface and again, at the shortest charge-to-sample distances, in a thin layer around the reflecting surface. For forensic science locating purposes after explosions, the maximum charge-to-target distance at which the phenomena disappear was singled out for each charge or grain size and related to the critical resolved shear stress for twinning. PMID:16696699

  2. AISI/DOE Technology Roadmap Program: A Technology of Low Coal Rate and High Productivity of RHF Ironmaking

    SciTech Connect

    Wei-Kao Lu

    2002-09-15

    An economical and environment-friendly ironmaking process based on heating the chemiexecy self-sufficient green balls of iron ore and coal in a hearth furnace is being developed with financial support from AISI members and DOE. DRI, which is hot (1400 C), dense (3.2 g/cm) and of high degree of metallization (95%), has been produced in laboratory and in a pilot plant in Genoa, Italy. Products of such quality have been made from American and Brazilian ores, BOF sludge, EAF dust/BOF sludge mixtures and millscale. The removal of zinc and lead from green balls by this process is essentially complete. In comparison with typical blast furnace operation, the new technology with a melter would have a lower total coal rate by 200kg.THM. The elimination of cokemaking and high temperature agglomeration steps, and a simpler gas handling system would lead to lower capital and operating costs. In comparison with commercial RHF practice it is different in atmosphere (fully oxidized at 1600 to 1650 C), in bed height (120 mm instead of 20-25 mm) and in pellet composition (much less coal but of higher VM). The combined effect leads to three times higher furnace productivity, lower coal consumption and superior DRI quality. The risk of re-oxidation (slag formation) and dusty operation are practiexecy eliminated. The process is stable, tolerant and independent of the size, shape and movement of the hearth. However, materials handling (e.g., discharge of hot DRI) and the exact energy savings have to be established in a larger furnace, straight or rotary, and in a continuous mode of operation.

  3. Brazed joints of CBN grains and AISI 1045 steel with AgCuTi-TiC mixed powder as filler materials

    NASA Astrophysics Data System (ADS)

    Ding, Wen-Feng; Xu, Jiu-Hua; Chen, Zhen-Zhen; Su, Hong-Hua; Fu, Yu-Can

    2011-12-01

    The brazing process of cubic boron nitride (CBN) grains and AISI 1045 steel with AgCuTi-TiC mixed powder as a filler material was carried out. The joining strength and the interfacial microstructure were investigated. The experimental results indicate that the spreading of the molten filler material on AISI 1045 steel is decreased with the increase of TiC content. A good interface is formed between the TiC particulates and AgCuTi alloy through the wetting behavior. In the case of AgCuTi+16wt% TiC, the strength of the brazed steel-to-steel joints reached the highest value of 95 MPa dependent upon the reinforcement effect of TiC particles within the filler layer. Brazing resultants of TiB2, TiB, and TiN are produced at the interface of the CBN grains and the AgCuTi-TiC filler layer by virtue of the interdiffusion of B, N, and Ti atoms.

  4. The effect of microstructure on the thermal fatigue resistance of investment cast and wrought AISI H13 hot work die steel

    SciTech Connect

    Hochanadel, P.W.; Edwards, G.R.; Maguire, M.C.; Baldwin, M.D.

    1995-07-01

    Variable thickness plate investment castings of AISI H13 hot work die steel were pour and characterized in the as-cast and heat treated conditions. The characterization included light microscopy and mechanical testing. Wrought samples of standard and premium grade H13 steel were heat treated and characterized similarly for comparison. Microstructural differences were observed in as-cast samples poured to different section thicknesses. Dendrite cell size and carbide morphology constituted the most prominent microstructural differences observed. After a full heat treatment, however, Microstructural differences between the wrought material and cast materials were slight regardless of section thickness. The mechanical properties of the cast and heat treated material proved similar to the properties of the standard heat treated wrought material. A thermal fatigue testing unit was designed and built to correlate the heat checking susceptibility of AISI H13 steel to its processing and consequent microstructural condition. Surface hardness decreased significantly with thermal cycling, and heat checking was noticed in as few as 50 cycles. Thermal softening and thermal fatigue susceptibility were quantified and discussed relative to the microstructural conditions created by processing and heat treatment. It was found that the premium grade wrought H13 steel provided the best overall resistance to heat checking; however, the heat-treat cast and as-cast H13 tool steel (made from standard grade wrought H13 tool steel) provided comparable resistance to heat checking in terms Of area fraction of heat checking and maximum crack length.

  5. Effects of Deep Cryogenic Treatment on the Wear Resistance and Mechanical Properties of AISI H13 Hot-Work Tool Steel

    NASA Astrophysics Data System (ADS)

    Çiçek, Adem; Kara, Fuat; Kıvak, Turgay; Ekici, Ergün; Uygur, İlyas

    2015-11-01

    In this study, a number of wear and tensile tests were performed to elucidate the effects of deep cryogenic treatment on the wear behavior and mechanical properties (hardness and tensile strength) of AISI H13 tool steel. In accordance with this purpose, three different heat treatments (conventional heat treatment (CHT), deep cryogenic treatment (DCT), and deep cryogenic treatment and tempering (DCTT)) were applied to tool steel samples. DCT and DCTT samples were held in nitrogen gas at -145 °C for 24 h. Wear tests were conducted on a dry pin-on-disk device using two loads of 60 and 80 N, two sliding velocities of 0.8 and 1 m/s, and a wear distance of 1000 m. All test results showed that DCT improved the adhesive wear resistance and mechanical properties of AISI H13 steel. The formation of small-sized and uniformly distributed carbide particles and the transformation of retained austenite to martensite played an important role in the improvements in the wear resistance and mechanical properties. After cleavage fracture, the surfaces of all samples were characterized by the cracking of primary carbides, while the DCT and DCTT samples displayed microvoid formation by decohesion of the fine carbides precipitated during the cryo-tempering process.

  6. A Simple Kinetic Model for the Growth of Fe2B Layers on AISI 1026 Steel During the Powder-pack Boriding

    NASA Astrophysics Data System (ADS)

    Flores-Rentería, M. A.; Ortiz-Domínguez, M.; Keddam, M.; Damián-Mejía, O.; Elias-Espinosa, M.; Flores-González, M. A.; Medina-Moreno, S. A.; Cruz-Avilés, A.; Villanueva-Ibañez, M.

    2015-02-01

    This work focused on the determination of boron diffusion coefficient through the Fe2B layers on AISI 1026 steel using a mathematical model. The suggested model solves the mass balance equation at the (Fe2B/substrate) interface. This thermochemical treatment was carried out in the temperature range of 1123-1273 K for a treatment time ranging from 2 to 8 h. The generated boride layers were characterized by different experimental techniques such as light optical microscopy, scanning electron microscopy, XRD analysis and the Daimler-Benz Rockwell-C indentation technique. As a result, the boron activation energy for AISI 1026 steel was estimated as 178.4 kJ/mol. Furthermore, this kinetic model was validated by comparing the experimental Fe2B layer thickness with the predicted one at a temperature of 1253 K for 5 h of treatment. A contour diagram relating the layer thickness to the boriding parameters was proposed to be used in practical applications.

  7. Ion Beam Analysis, structure and corrosion studies of nc-TiN/a-Si3N4 nanocomposite coatings deposited by sputtering on AISI 316L

    NASA Astrophysics Data System (ADS)

    Garca, J.; Canto, C. E.; Flores, M.; Andrade, E.; Rodrguez, E.; Jimnez, O.; Solis, C.; de Lucio, O. G.; Rocha, M. F.

    2014-07-01

    In this work, nanocomposite coatings of nc-TiN/a-Si3N4, were deposited on AISI 316L stainless steel substrate by a DC and RF reactive magnetron co-sputtering technique using an A-N2 plasma. The structure of the coatings was characterized by means of XRD (X-ray Diffraction). The substrate and coating corrosion resistance were evaluated by potentiodynamic polarization using a Ringer solution as electrolyte. Corrosion tests were conducted with the purpose to evaluate the potential of this coating to be used on biomedical alloys. IBA (Ion Beam Analysis) techniques were applied to measure the elemental composition profiles of the films and, XPS (X-ray Photoelectron Spectroscopy) were used as a complementary technique to obtain information about the compounds present in the films. The nanocomposite coatings of nc-TiN/a-Si3N4 show crystalline (TiN) and amorphous (Si3N4) phases which confer a better protection against the corrosion effects compared with that of the AISI 316L.

  8. Improvement of Electrochemical Surface Properties in Steel Substrates Using a Nanostructured CrN/AlN Multilayer Coating

    NASA Astrophysics Data System (ADS)

    Cabrera, G.; Torres, F.; Caicedo, J. C.; Aperador, W.; Amaya, C.; Prieto, P.

    2012-01-01

    Improvement of corrosion properties on AISI D3 steel surfaces coated with [CrN/AlN] n multilayered system deposited for various periods (?) via magnetron sputtering has been studied in this work exhaustively. For practical effects compared were the latter properties with CrN and AlN single layers deposited with the same conditions as the multilayered systems. The coatings were characterized in terms of crystal phase; chemical composition, micro-structural, and electrochemical properties by x-ray diffractometry, energy dispersive x-ray, Fourier transforming infrared spectroscopy, atomic force microscopy, scanning electron microscopy, Tafel polarization curves, and electrochemical impedance spectroscopy. Corrosion evolution was observed via optical microscopy. Results from x-ray diffractometry analysis revealed that the crystal structure of [CrN/AlN] n multilayered coatings has an NaCl-type lattice structure and hexagonal structure (wurtzite-type) for CrN and AlN, respectively, i.e., it was made non-isostructural multilayered. The best behavior was obtained by the multilayered period: ? = 60 nm (50 bilayers), showing the maximum corrosion resistance (polarization resistance of 1.18 K?, and corrosion rate of 1.02 mpy). Those results indicated an improvement of anticorrosive properties, compared to the CrN/AlN multilayer system with 1 bilayer at 98 and 80%, respectively. Furthermore, the corrosion resistance of steel AISI D3 is improved beyond 90%. These improvement effects in multilayered coatings could be attributed to the number of interfaces that act as obstacles for the inward and outward diffusions of ion species, generating an increment in the energy or potential required for translating the corrosive ions across the coating/substrate interface. Moreover, the interface systems affect the means free path on the ions toward the metallic substrate, due to the decreasing of the defects presented in the multilayered coatings.

  9. Influence of cold plastic deformation on critical pitting potential of AISI 316 L and 304 L steels in an artificial physiological solution simulating the aggressiveness of the human body.

    PubMed

    Cigada, A; Mazza, B; Pedeferri, P; Sinigaglia, D

    1977-07-01

    The effect of cold working on critical pitting potential of AISI 316 L and 304 L steels in a buffered physiological solution has been studied. In particular, the importance of deformation degree, orientation of the specimen surface to the deformation direction, and cold working temperature in lowering the critical pitting potential is shown. PMID:873942

  10. Microstructure and corrosion resistance of nanocrystalline TiZrN films on AISI 304 stainless steel substrate

    SciTech Connect

    Lin, Yu-Wei; Huang, Jia-Hong; Yu, Ge-Ping

    2010-07-15

    This study investigated the microstructure and properties of nanocrystalline TiZrN films on AISI 304 stainless steel substrate. TiZrN films were prepared by reactive magnetron sputtering based on the previous optimum coating conditions (substrate temperature, system pressure, nitrogen flow, etc.) for TiN and ZrN thin films. The composition ratio of TiZrN coatings were adjusted by changing the Zr target power, while keeping the Ti target power constant. Experiments were conduced to find the optimum composition with desired properties. The ratio of TiZrN composition was analyzed by x-ray photoelectron spectroscopy and Rutherford backscattering spectrometer. In terms of phase formation, there were two types of coatings that were considered: single-phase solid solutions of TiZrN and interlacing nuclei of TiZr in the matrix of TiZrN. The thickness of all TiZrN films as measured by the secondary ion mass spectroscopy was about 500 nm, and the composition depth profiles indicated that the compositions in the TiZrN films were uniform from the film surface to the 304 stainless steel substrate. The crystal structure of the TiZrN films was determined by x-ray diffraction using a M18XHF-SRA diffractometer with Cu K{sub {alpha}} radiation. A diffraction peak of TiZrN (002) was observed between that of TiN (002) and ZrN (002); similarly, a diffraction peak of TiZrN (111) was observed between that of TiN(111) and ZrN(111), respectively. The corrosion resistance of the TiZrN film deposited on the 304 stainless steel has been investigated by electrochemical measurement. The electrolyte, 0.5M H{sub 2}SO{sub 4} containing 0.05M KSCN, was used for the potentiodynamic polarization. The potentiodynamic scan was conducted from -800 to 800 mV standard calomel electrode (SCE).

  11. Wear and Corrosion Behavior of CoNiCrAlY Bond Coats

    NASA Astrophysics Data System (ADS)

    Rathod, W. S.; Khanna, A. S.; Rathod, R. C.; Sapate, S. G.

    2014-07-01

    The present study focusses on the wear and microstructural properties of CoNiCrAlY coatings fabricated on AISI 316L stainless steel substrate by using the (HVOF) and (CGDS) methods. A triobiological test was performed on the samples in order to understand the wear behaviour of thermally sprayed coatings. The microstructures of as-sprayed and worn out coatings were investigated by scanning electron microscopy. Coating hardness measurements were performed with nanoindentation. HVOF coating revealed lower hardness value in comparison with CGDS. Studies depicted better wear resistance of the CGDS sprayed with He, when compared to CGDS N2 and HVOF processing. Potentiodynamic polarization curves and tafel extrapolation experiments were carried at 7.5 pH value using 3.5 % NaCl as an electrolyte. Electrochemical studies depicted better corrosion resistance of the He processed coating when compared to N2 and HVOF processing.

  12. Impact of localized surface preheating on the microstructure and crack formation in laser direct deposition of Stellite 1 on AISI 4340 steel

    NASA Astrophysics Data System (ADS)

    Fallah, Vahid; Alimardani, Masoud; Corbin, Stephen F.; Khajepour, Amir

    2010-12-01

    Crack formation in laser cladding of the hardfacing alloy Stellite 1 on AISI-SAE 4340 steel was prevented through locally preheating the substrate prior to the deposition process. Numerical analysis showed that the preheating process helps developing a relatively steadier melt temperature as well as decreasing the cooling rates and consequently the thermal stresses during the subsequent deposition process. Microstructural analysis revealed a thicker cross-section with smoother surface profile, more uniform surface hardness and even distribution of a dendritic morphology in the preheated sample. This confirmed the presence of a well-developed melt pool with a homogeneous composition at solidification. The microstructure of non-preheated sample was, however, considerably non-uniform consisting of macro-scale colonies of dendritic and lamellar (eutectic) structures. The experimental observations, as implied through the numerical results, showed that the preheated sample, in general, reveals more uniform structure and properties making it less prone to cracking during the deposition process.

  13. Improvement of localised corrosion resistance of AISI 2205 Duplex Stainless Steel joints made by gas metal arc welding under electromagnetic interaction of low intensity

    NASA Astrophysics Data System (ADS)

    García-Rentería, M. A.; López-Morelos, V. H.; García-Hernández, R.; Dzib-Pérez, L.; García-Ochoa, E. M.; González-Sánchez, J.

    2014-12-01

    The resistance to localised corrosion of AISI 2205 duplex stainless steel plates joined by Gas Metal Arc Welding (GMAW) under the effect of electromagnetic interaction of low intensity (EMILI) was evaluated with sensitive electrochemical methods. Welds were made using two shielding gas mixtures: 98% Ar + 2% O2 (M1) and 97% Ar + 3% N2 (M2). Plates were welded under EMILI using the M1 gas with constant welding parameters. The modified microstructural evolution in the high temperature heat affected zone and at the fusion zone induced by application of EMILI during welding is associated with the increase of resistance to localised corrosion of the welded joints. Joints made by GMAW using the shielding gas M2 without the application of magnetic field presented high resistance to general corrosion but high susceptibility to undergo localised attack.

  14. Friction and wear of selected metals and alloys in sliding contact with AISI 440 C stainless steel in liquid methane and in liquid natural gas

    NASA Technical Reports Server (NTRS)

    Wisander, D. W.

    1978-01-01

    Aluminum, titanium, beryllium, nickel, iron, copper, and several copper alloys were run in sliding contact with AISI 440C in liquid methane and natural gas. All of the metals run except copper and the copper alloys of tin and tin-lead showed severely galled wear scars. Friction coefficients varied from 0.2 to 1.0, the lowest being for copper, copper-17 wt. % tin, and copper-8 wt. % tin-22 wt. % lead. The wear rate for copper was two orders of magnitude lower than that of the other metals run. An additional order of magnitude of wear reduction was achieved by the addition of tin and/or lead to copper.

  15. Effect of Beam Energy on Weld Geometric Characteristics in Nd:YAG Laser Overlapping Spot Welding of Thin AISI 304 Stainless Steel Sheets

    NASA Astrophysics Data System (ADS)

    Lapsanska, Hana; Chmelickova, Hana; Hrabovsky, Miroslav

    2010-10-01

    Weld geometric characteristics in laser overlapping spot welding of 0.6-mm AISI 304 stainless steel sheets were investigated. A pulsed Nd:YAG laser with maximal average power of 150 W was used for welding experiments with different laser beam energies in the range of 3.5 J to 6.2 J, keeping all other processing parameters constant. The main objective of these experiments was to study the effect of energy changes and to identify the welding mode in dependency on the beam effective peak power density. Each weld surface and its cross section were analyzed using a laser scanning confocal microscope. The spot diameter on the specimen, weld width, and penetration depth were measured. Three-dimensional surface reconstruction was realized to describe the effect of energy changes on weld surface properties.

  16. Combined bending-torsion fatigue reliability of AISI 4340 steel shafting with K sub t = 2.34. [stress concentration factor

    NASA Technical Reports Server (NTRS)

    Kececioglu, D.; Chester, L. B.; Dodge, T. M.

    1974-01-01

    Results generated by three, unique fatigue reliability research machines which can apply reversed bending loads combined with steady torque are presented. Six-inch long, AISI 4340 steel, grooved specimens with a stress concentration factor of 2.34 and R sub C 35/40 hardness were subjected to various combinations of these loads and cycled to failure. The generated cycles-to-failure and stress-to-failure data are statistically analyzed to develop distributional S-N and Goodman diagrams. Various failure theories are investigated to determine which one represents the data best. The effect of the groove and of the various combined bending-torsion loads on the S-N and Goodman diagrams are determined. Three design applications are presented. The third one illustrates the weight savings that may be achieved by designing for reliability.

  17. AISI Direct Steelmaking Program

    SciTech Connect

    Aukrust, E.

    1993-01-01

    Pilot plant trials with the horizontal vessel were completed. Design of a third pressurized vessel and an offgas cleaning and tempering system was completed. Installation is now underway. A basic study and a pre-engineering design of a 350,000-metric ton/y demonstration plant were completed, and efforts are underway to develop such a demonstration plant at a host steel company. Foreign filings have been prepared for the two-zone countercurrent smelter (patent applied for). Work with a water model of two-zone smelter was completed. The horizontal smelter program was completed. Trials were conducted to determine how sulfur is partitioned among the hot metal, slag, and offgas. Design of offgas cleaning and tempering loop was completed.

  18. Application of orthogonal array technique and particle swarm optimization approach in surface roughness modification when face milling AISI1045 steel parts

    NASA Astrophysics Data System (ADS)

    Azadi Moghaddam, Masoud; Kolahan, Farhad

    2015-12-01

    Face milling is an important and common machining operation because of its versatility and capability to produce various surfaces. Face milling is a machining process of removing material by the relative motion between a work piece and rotating cutter with multiple cutting edges. It is an interrupted cutting operation in which the teeth of the milling cutter enter and exit the work piece during each revolution. This paper is concerned with the experimental and numerical study of face milling of AISI1045. The proposed approach is based on statistical analysis on the experimental data gathered using Taguchi design matrix. Surface roughness is the most important performance characteristics of the face milling process. In this study the effect of input face milling process parameters on surface roughness of AISI1045 steel milled parts have been studied. The input parameters are cutting speed (v), feed rate (f z ) and depth of cut (a p ). The experimental data are gathered using Taguchi L9 design matrix. In order to establish the relations between the input and the output parameters, various regression functions have been fitted on the data based on output characteristics. The significance of the process parameters on the quality characteristics of the process was also evaluated quantitatively using the analysis of variance method. Then, statistical analysis and validation experiments have been carried out to compare and select the best and most fitted models. In the last section of this research, mathematical model has been developed for surface roughness prediction using particle swarm optimization (PSO) on the basis of experimental results. The model developed for optimization has been validated by confirmation experiments. It has been found that the predicted roughness using PSO is in good agreement with the actual surface roughness.

  19. Mechanical Characterization of CrN/CrAlN Multilayer Coatings Deposited by Magnetron Sputtering System

    NASA Astrophysics Data System (ADS)

    Kaouther, Khlifi; Hafedh, Dhiflaoui; Lassaad, Zoghlami; Ahmed, Ben Cheikh Larbi

    2015-10-01

    Chromium-based coatings are deposited on a 100Cr6 (AISI 52100) substrate by a physical vapor deposition magnetron sputtering system. The coatings have different structures, such as a CrN monolayer and CrAlN multilayer. The structural and morphological compositions of the coatings were evaluated using glow discharge optical emission spectroscopy, atomic force microscopy, and cross-sectional scanning electron microscopy. Nano-indentation tests were performed to investigate the mechanical properties. Domes and craters are shown to be uniformly distributed over the entire surfaces of the two coatings. Additionally, the CrN/CrAlN multilayer coating exhibits a rough surface, attractive mechanical properties, a high compressive stress, and a high plastic and elastic deformation resistance. The improvement of the mechanical properties of the CrN/CrAlN coating is mainly attributed to a reduction in the crystallite size. We found that this reduction was related to three factors: (1) the compositional change resulting from the substitution of aluminum for chromium, which can produce a decrease in the interatomic distance; (2) the structure of CrN/CrAlN, which was characterized by grain size refinement; and (3) the high number of interfaces, which explains the widely accepted concept of dislocation blocking by the layer interfaces.

  20. Long-term evaluation of solid oxide fuel cell candidate materials in a 3-cell generic stack test fixture, part III: Stability and microstructure of Ce-(Mn,Co)-spinel coating, AISI441 interconnect, alumina coating, cathode and anode

    NASA Astrophysics Data System (ADS)

    Chou, Yeong-Shyung; Stevenson, Jeffry W.; Choi, Jung-Pyung

    2014-07-01

    A generic solid oxide fuel cell stack test fixture was developed to evaluate candidate materials and processing under realistic conditions. Part III of the work investigated the stability of Ce-(Mn,Co) spinel coating, AISI441 metallic interconnect, alumina coating, and cell's degradation. After 6000 h test, the spinel coating showed densification with some diffusion of Cr. At the metal interface, segregation of Si and Ti was observed, however, no continuous layer formed. The alumina coating for perimeter sealing areas appeared more dense and thick at the air side than the fuel side. Both the spinel and alumina coatings remained bonded. EDS analysis of Cr within the metal showed small decrease in concentration near the coating interface and would expect to cause no issue of Cr depletion. Inter-diffusion of Ni, Fe, and Cr between spot-welded Ni wire and AISI441 interconnect was observed and Cr-oxide scale formed along the circumference of the weld. The microstructure of the anode and cathode was discussed relating to degradation of the top and middle cells. Overall, the Ce-(Mn,Co) spinel coating, alumina coating, and AISI441 steel showed the desired long-term stability and the developed generic stack fixture proved to be a useful tool to validate candidate materials for SOFC.

  1. /Cu-Al System

    NASA Astrophysics Data System (ADS)

    Kish, Orel; Froumin, Natalya; Aizenshtein, Michael; Frage, Nachum

    2014-05-01

    Wettability and interfacial interaction of the Ta2O5/Cu-Al system were studied. Pure Cu does not wet the Ta2O5 substrate, and improved spreading is achieved when relatively a high fraction of the active element (~40 at.% Al) was added. The Al2O3 and AlTaO4 phases were observed at the Ta2O5/Cu-Al interface. A thermodynamic evaluation allowed us to suggest that the lack of wetting bellow 40 at.% Al is due to the presence of a native oxide, which covers the drop. The conditions of the native oxide decomposition and the formation of the volatile Al2O suboxide strongly depend on the vacuum level during sessile drop experiments and the composition of the Cu-Al alloy. In our case, Al contents greater than 40% provides thermodynamic conditions for the formation of Al2O (as a result of Al reaction with Al2O3) and the drop spreading. It was suggested that the final contact angle in the Ta2O5/Cu-Al system (50) is determined by Ta adsorption on the newly formed alumina interlayer.

  2. Initial Symptoms of ALS

    MedlinePLUS

    ... world without ALS Start an Event Combine your passion and commitment to finding a cure for ALS while achieving ... 1275 K Street NW - Suite 250 - Washington, DC 20005 All content and works posted on this website are owned and copyrighted ...

  3. Who Gets ALS?

    MedlinePLUS

    ... world without ALS Start an Event Combine your passion and commitment to finding a cure for ALS while achieving ... 1275 K Street NW - Suite 250 - Washington, DC 20005 All content and works posted on this website are owned and copyrighted ...

  4. MDA ALS Caregiver's Guide

    MedlinePLUS

    ... MDA Partners in Progress Search form Search MDA ALS Caregiver's Guide March 2013 Download a printable PDF ... probably because someone you care about deeply has ALS. This guide will help you to help your ...

  5. The effect of CO2 laser beam welded AISI 316L austenitic stainless steel on the viability of fibroblast cells, in vitro.

    PubMed

    Köse, Ceyhun; Kaçar, Ramazan; Zorba, Aslı Pınar; Bağırova, Melahat; Allahverdiyev, Adil M

    2016-03-01

    It has been determined by the literature research that there is no clinical study on the in vivo and in vitro interaction of the cells with the laser beam welded joints of AISI 316L biomaterial. It is used as a prosthesis and implant material and that has adequate mechanical properties and corrosion resistance characteristics. Therefore, the interaction of the CO2 laser beam welded samples and samples of the base metal of AISI 316L austenitic stainless steel with L929 fibroblast cells as an element of connective tissue under in vitro conditions has been studied. To study the effect of the base metal and the laser welded test specimens on the viability of the fibroblast cells that act as an element of connective tissues in the body, they were kept in DMEMF-12 medium for 7, 14, 28days and 18months. The viability study was experimentally studied using the MTT method for 7, 14, 28days. In addition, the direct interaction of the fibroblast cells seeded on 6 different plates with the samples was examined with an inverted microscope. The MTT cell viability experiment was repeated on the cells that were in contact with the samples. The statistical relationship was analyzed using a Tukey test for the variance with the GraphPad statistics software. The data regarding metallic ion release were identified with the ICP-MS method after the laser welded and main material samples were kept in cell culture medium for 18months. The cell viability of the laser welded sample has been detected to be higher than that of the base metal and the control based on 7th day data. However, the laser welded sample's viability of the fibroblast cells has diminished by time during the test period of 14 and 28days and base metal shows better viability when compared to the laser welded samples. On the other hand, the base metal and the laser welded sample show better cell viability effect when compared to the control group. According to the ICP-MS results of the main material and laser welded samples which were kept in the cell culture medium for 18months, it was determined that the Fe, Ni and Cr ion concentration released to the cell culture medium from the laser welded test sample was less than that of the main material. PMID:26706524

  6. Microstructures and Mechanical Performance of Plasma-Nitrided Al0.3CrFe1.5MnNi0.5 High-Entropy Alloys

    NASA Astrophysics Data System (ADS)

    Tang, Wei-Yeh; Chuang, Ming-Hao; Lin, Su-Jien; Yeh, Jien-Wei

    2012-07-01

    This study investigates the effect of plasma nitriding at 798 K (525 °C) on microstructures and the mechanical performance of Al0.3CrFe1.5MnNi0.5 high-entropy alloys (HEAs) obtained using different cast and wrought processing. All the alloys can be well nitride, with a thickness of around 80 μm, and attain a peak hardness level around Hv 1300 near the surface. The main nitride phases are CrN, AlN, and (Mn, Fe)4N. Those of the substrates are bcc, fcc, Al-, and Ni-rich B2 precipitates, and ρ phase. Their relative amounts depend on the prior processing and also change under the heat treatment during nitriding. The formation of ρ phase during nitriding could in-situ harden the substrate to attain the suitable level required for wear applications. This gives the advantage in simplifying the processing for making a wear-resistance component or a mold since austenitizing, quench hardening, and tempering required for steels such as SACM and SKD steels are no longer required and final finishing can be accomplished before nitriding. Nitrided Al0.3CrFe1.5MnNi0.5 samples have much better wear resistance than un-nitrided ones by 49 to 80 times and also exhibit superior adhesive wear resistance to conventional nitrided alloys: nitriding steel SACM-645 (AISI 7140), 316 stainless steel, and hot-mold steel SKD-61 (AISI H13) by 22 to 55 times depending on prior processing. The superiority is due to the fact that the present nitrided alloys possess a much thicker highly hardened layer than the conventional alloys.

  7. Wear Behavior and Mechanism of Fe-Al Intermetallic Coating Prepared by Hot-Dip Aluminizing and Diffusion

    NASA Astrophysics Data System (ADS)

    Zhang, Q. Y.; Zhou, Y.; Liu, J. Q.; Chen, K. M.; Mo, J. G.; Cui, X. H.; Wang, S. Q.

    2016-03-01

    A Fe-Al intermetallic compound coating was prepared on AISI H13 steel by hot-dip aluminizing and subsequent high-temperature diffusion. Dry sliding wear tests of the Fe-Al intermetallic coating were performed at 298 K to 873 K (25 °C to 600 °C). The wear behavior of the Fe-Al intermetallic coating was noticed to vary markedly with the temperature and load. At 298 K (25 °C), the wear rate rapidly increased with an increase of the load. As the temperature was elevated, the wear rate dramatically decreased except for the cases under 300 N at 473 K and 673 K (200 °C and 400 °C). The Fe-Al intermetallic coating possessed an excellent elevated-temperature wear performance, especially at 673 K to 873 K (400 °C to 600 °C), but worse room-temperature one, which were noticed to be attributed to the existence and inexistence of thin tribo-oxide layers, respectively. Such a thin tribo-oxide layer was considered to provide a protection for the intermetallic compound. When the tribo-oxide layer did not form at room temperature or the formed one was massively delaminated above the critical load at elevated temperatures, Fe-Al intermetallic coating possessed poor wear resistance.

  8. The Microstructures and Wear Resistance of Gas-Nitrided and Ionically Nitrided AISI H10 Dies with Narrow Gaps Designed for the Hot Extrusion of Aluminium

    NASA Astrophysics Data System (ADS)

    Tercelj, Milan; Smolej, Anton; Vecko-Pirtovsek, Tatjana; Turk, Rado

    Dies made from AISI H10 die steel with narrow and deep gaps were nitrided by various manufacturers of equipment for ionic and gas nitriding. The manufacturers chose the optimum nitriding parameters themselves, based on their experience with extrusion dies. The resulting microstructures showed differences in terms of the presence or absence of a compound layer, the thickness of the layer and its ?/?? phase ratio (XRD), the nitriding depth and the microhardness values. The obtained nitriding depths, the maximum microhardness of the nitrided surfaces and the ? /?? phase ratio were usually similar for dies from the same manufacturer, while the dies from different manufacturers tended to have different values. Samples with various nitrided microstructures were laboratory tested for wear resistance with a newly designed test rig that provided a simulation of the tribological conditions for the hot extrusion of aluminium. The results of the study indicate that dies with a greater nitriding depth in combination with a compound layer composed primarily of just one phase (in our case the ? phase) exhibited better wear resistance than those dies with a small nitriding depth and with an equal share of the two phases.

  9. Microstructural Characterization and Wear Behavior of Nano-Boride Dispersed Coating on AISI 304 Stainless Steel by Hybrid High Velocity Oxy-Fuel Spraying Laser Surface Melting

    NASA Astrophysics Data System (ADS)

    Sharma, Prashant; Majumdar, Jyotsna Dutta

    2015-07-01

    The current study concerns the detailed microstructural characterization and investigation of wear behavior of nano-boride dispersed coating developed on AISI 304 stainless steel by high velocity oxy-fuel spray deposition of nickel-based alloy and subsequent laser melting. There is a significant refinement and homogenization of microstructure with improvement in microhardness due to laser surface melting (1200 VHN as compared to 945 VHN of as-sprayed and 250 VHN of as-received substrate). The high temperature phase stability of the as-coated and laser melted surface has been studied by differential scanning calorimeter followed by detailed phase analysis at room and elevated temperature. There is a significant improvement in wear resistance of laser melted surface as compared to as-sprayed and the as-received one due to increased hardness and reduced coefficient of friction. The mechanism of wear has been investigated in details. Corrosion resistance of the coating in a 3.56 wt pct NaCl solution is significantly improved (4.43 E-2 mm/year as compared to 5 E-1 mm/year of as-sprayed and 1.66 mm/year of as-received substrate) due to laser surface melting as compared to as-sprayed surface.

  10. Prediction of scuffing failure based on competitive kinetics of oxide formation and removal: Application to lubricated sliding of AISI 52100 steel on steel

    NASA Astrophysics Data System (ADS)

    Cutiongco, Eric C.; Chung, Yip-Wah

    1994-07-01

    A method for predicting scuffing failure based on the competitive kinetics of oxide formation and removal has been developed and applied to the sliding of AISI 52100 steel on steel with poly-alpha-olefin as the lubricant. Oxide formation rates were determining using static oxidation tests on coupons of 52100 steel covered with poly-alpha-olefin at temperatures of 140 C to 250 C. Oxide removal rates were determined at different combinations of initial average nominal contact pressures (950 MPa to 1578 MPa) and sliding velocities (0.4 m/s to 1.8 m/s) using a ball-on-disk vacuum tribotester. The nominal asperity flash temperatures generated during the wear tests were calculated and the temperatures corresponding to the intersection of the the Arrhenius plots of oxide formation and removal rates were determined and taken as the critical failure temperatures. The pressure-velocity failure transition diagram was constructed by plotting the critical failure temperatures along isotherms of average nominal asperity flash temperatures calculated at different combinations of contact stress and sliding speed. The predicted failure transition curve agreed well with experimental scuffing data.

  11. Finite Element Modelling of the effect of tool rake angle on tool temperature and cutting force during high speed machining of AISI 4340 steel

    NASA Astrophysics Data System (ADS)

    Sulaiman, S.; Roshan, A.; Ariffin, M. K. A.

    2013-12-01

    In this paper, a Finite Element Method (FEM) based on the ABAQUS explicit software which involves Johnson-Cook material model was used to simulate cutting force and tool temperature during high speed machining (HSM) of AISI 4340 steel. In this simulation work, a tool rake angle ranging from 0 to 20 and a range of cutting speeds between 300 to 550 m/min was investigated. The purpose of this simulation analysis was to find optimum tool rake angle where cutting force is smallest as well as tool temperature is lowest during high speed machining. It was found that cutting forces to have a decreasing trend as rake angle increased to positive direction. The optimum rake angle observed between 10 and 18 due to decrease of cutting force as 20% for all simulated cutting speeds. In addition, increasing cutting tool rake angle over its optimum value had negative influence on tool's performance and led to an increase in cutting temperature. The results give a better understanding and recognition of the cutting tool design for high speed machining processes.

  12. Effect of Welding Current and Time on the Microstructure, Mechanical Characterizations, and Fracture Studies of Resistance Spot Welding Joints of AISI 316L Austenitic Stainless Steel

    NASA Astrophysics Data System (ADS)

    Kianersi, Danial; Mostafaei, Amir; Mohammadi, Javad

    2014-09-01

    This article aims at investigating the effect of welding parameters, namely, welding current and welding time, on resistance spot welding (RSW) of the AISI 316L austenitic stainless steel sheets. The influence of welding current and welding time on the weld properties including the weld nugget diameter or fusion zone, tensile-shear load-bearing capacity of welded materials, failure modes, energy absorption, and microstructure of welded nuggets was precisely considered. Microstructural studies and mechanical properties showed that the region between interfacial to pullout mode transition and expulsion limit is defined as the optimum welding condition. Electron microscopic studies indicated different types of delta ferrite in welded nuggets including skeletal, acicular, and lathy delta ferrite morphologies as a result of nonequilibrium phases, which can be attributed to a fast cooling rate in the RSW process. These morphologies were explained based on Shaeffler, WRC-1992, and pseudo-binary phase diagrams. The optimum microstructure and mechanical properties were achieved with 8-kA welding current and 4-cycle welding time in which maximum tensile-shear load-bearing capacity or peak load of the welded materials was obtained at 8070 N, and the failure mode took place as button pullout with tearing from the base metal. Finally, fracture surface studies indicated that elongated dimples appeared on the surface as a result of ductile fracture in the sample welded in the optimum welding condition.

  13. Weldability Characteristics of Sintered Hot-Forged AISI 4135 Steel Produced through P/M Route by Using Pulsed Current Gas Tungsten Arc Welding

    NASA Astrophysics Data System (ADS)

    Joseph, Joby; Muthukumaran, S.; Pandey, K. S.

    2016-01-01

    Present investigation is an attempt to study the weldability characteristics of sintered hot-forged plates of AISI 4135 steel produced through powder metallurgy (P/M) route using matching filler materials of ER80S B2. Compacts of homogeneously blended elemental powders corresponding to the above steel were prepared on a universal testing machine (UTM) by taking pre-weighed powder blend with a suitable die, punch and bottom insert assembly. Indigenously developed ceramic coating was applied on the entire surface of the compacts in order to protect them from oxidation during sintering. Sintered preforms were hot forged to flat, approximately rectangular plates, welded by pulsed current gas tungsten arc welding (PCGTAW) processes with aforementioned filler materials. Microstructural, tensile and hardness evaluations revealed that PCGTAW process with low heat input could produce weldments of good quality with almost nil defects. It was established that PCGTAW joints possess improved tensile properties compared to the base metal and it was mainly attributed to lower heat input, resulting in finer fusion zone grains and higher fusion zone hardness. Thus, the present investigation opens a new and demanding field in research.

  14. Influence of Surface Position along the Working Range of Conoscopic Holography Sensors on Dimensional Verification of AISI 316 Wire EDM Machined Surfaces

    PubMed Central

    Fernández, Pedro; Blanco, David; Rico, Carlos; Valiño, Gonzalo; Mateos, Sabino

    2014-01-01

    Conoscopic holography (CH) is a non-contact interferometric technique used for surface digitization which presents several advantages over other optical techniques such as laser triangulation. Among others, the ability for the reconstruction of high-sloped surfaces stands out, and so does its lower dependence on surface optical properties. Nevertheless, similarly to other optical systems, adjustment of CH sensors requires an adequate selection of configuration parameters for ensuring a high quality surface digitizing. This should be done on a surface located as close as possible to the stand-off distance by tuning frequency (F) and power (P) until the quality indicators Signal-to-Noise Ratio (SNR) and signal envelope (Total) meet proper values. However, not all the points of an actual surface are located at the stand-off distance, but they could be located throughout the whole working range (WR). Thus, the quality of a digitized surface may not be uniform. The present work analyses how the quality of a reconstructed surface is affected by its relative position within the WR under different combinations of the parameters F and P. Experiments have been conducted on AISI 316 wire EDM machined flat surfaces. The number of high-quality points digitized as well as distance measurements between different surfaces throughout the WR allowed for comparing the metrological behaviour of the CH sensor with respect to a touch probe (TP) on a CMM. PMID:24662452

  15. Improvement in wear and corrosion resistance of AISI 1020 steel by high velocity oxy-fuel spray coating containing Ni-Cr-B-Si-Fe-C

    NASA Astrophysics Data System (ADS)

    Prince, M.; Thanu, A. Justin; Gopalakrishnan, P.

    2012-04-01

    In this investigation, AISI 1020 low carbon steel has been selected as the base material. The Ni based super alloy powder NiCrBSiFeC was sprayed on the base material using high velocity oxy-fuel spraying (HVOF) technique. The thickness of the coating was approximately 0.5 mm (500 μm). The coating was characterized using optical microscopy, Vickers microhardness testing, X-ray diffraction technique and scanning electron microscopy. Dry sliding wear tests were carried out at 3 m/s sliding speed under the load of 10 N for 1000 m sliding distance at various temperatures i.e., 35° C, 250° C and 350° C. The corrosion test was carried out in 1 M copper chloride in acetic acid solution. The polarization studies were also conducted for both base material and coating. The improvement in microhardness from 1.72 GPa (175 HV0.05) to 10.54 GPa (1075 HV0.05) was observed. The coatings exhibited 3-6 times improved wear resistance as compared with base material. Also, the corrosion rate was reduced by 3.5 times due to the presence of coatings.

  16. Effect of pulse laser parameters on TiC reinforced AISI 304 stainless steel composite coating by laser surface engineering process

    NASA Astrophysics Data System (ADS)

    Sahoo, Chinmaya Kumar; Masanta, Manoj

    2015-04-01

    In this work, TiC reinforced steel composite layer has been produced by laser scanning over the preplaced TiC powder on AISI 304 steel substrate, using a pulse Nd:YAG laser. Depending on the pulse laser parameters, TiC either deposited or dispersed on the surface of steel substrate. Depth and width of laser processed TiC-steel composite layer has been deliberated from the SEM images at the transverse cross section of the laser scanned samples. Hardness of the laser processed composite layer has been measured through Vickers micro-hardness tester. Effect of pulsed laser parameters i.e. peak power, pulse duration, overlapping factor (corresponding to scan speed and frequency) on micro-hardness, composite layer profile (depth and width) and microstructure of the laser processed TiC-steel composite layer has been studied. From the experimental analysis, it is revealed that, laser peak power and overlapping factor have significant effect on the TiC-steel composite layer profile and its hardness value.

  17. Experimental Evaluation and Optimization of Flank Wear During Turning of AISI 4340 Steel with Coated Carbide Inserts Using Different Cutting Fluids

    NASA Astrophysics Data System (ADS)

    Lawal, S. A.; Choudhury, I. A.; Nukman, Y.

    2015-01-01

    The understanding of cutting fluids performance in turning process is very important in order to improve the efficiency of the process. This efficiency can be determined based on certain process parameters such as flank wear, cutting forces developed, temperature developed at the tool chip interface, surface roughness on the work piece, etc. In this study, the objective is to determine the influence of cutting fluids on flank wear during turning of AISI 4340 with coated carbide inserts. The performances of three types of cutting fluids were compared using Taguchi experimental method. The results show that palm kernel oil based cutting fluids performed better than the other two cutting fluids in reducing flank wear. Mathematical models for cutting parameters such as cutting speed, feed rate, depth of cut and cutting fluids were obtained from regression analysis using MINITAB 14 software to predict flank wear. Experiments were conducted based on the optimized values to validate the regression equations for flank wear and 5.82 % error was obtained. The optimal cutting parameters for the flank wear using S/N ratio were 160 m/min of cutting speed (level 1), 0.18 mm/rev of feed (level 1), 1.75 mm of depth of cut (level 2) and 2.97 mm2/s palm kernel oil based cutting fluid (level 3). ANOVA shows cutting speed of 85.36 %; and feed rate 4.81 %) as significant factors.

  18. The Effect of Surface Roughness on the Corrosion Properties of Type AISI 304 Stainless Steel in Diluted NaCl and Urban Rain Solution

    NASA Astrophysics Data System (ADS)

    Leban, Mirjam Bajt; Mikyka, ?rt; Kosec, Tadeja; Markoli, Botjan; Kova?, Janez

    2014-05-01

    Due to their good corrosion resistance, favorable mechanical properties, and reasonable price regarding their excellent properties, austenitic stainless steels have, over recent decades, become one of the alloys that are increasingly used in civil engineering and building, as well as for specific architectural purposes. Architects often design stainless steel exterior elements with higher surface roughnesses, which are not resistant to corrosion processes. The aim of this work was to investigate the influence of different types of surface finishes to stainless steel of quality AISI 304 on the corrosion properties of this steel. In order to achieve this goal, electrochemical tests were performed on different surface finishes in two different environments: in an NaCl aqueous solution, and in simulated urban rain which contained no chlorides. In addition to the electrochemical methods used, surface roughness was also measured, and XPS surface analyses were performed. The results of the investigation showed that surface roughness affects the growth of the passive layer in urban rain significantly; however, the growth of such a film is retarded in the case of the NaCl aqueous solution. Based on the results of the performed analyses, it was found that, in the NaCl solution, the pitting potential depended strongly upon the surface roughness and the surface finish, but this was not true for the samples tested in urban rain.

  19. In vitro corrosion study by EIS of an equiatomic NiTi alloy and an implant quality AISI 316 stainless steel.

    PubMed

    Rondelli, G; Torricelli, P; Fini, M; Rimondini, L; Giardino, R

    2006-11-01

    The electrochemical impedance spectroscopy (EIS) technique was used for the study of the electrochemical behavior of an equiatomic NiTi alloy and an implant quality AISI 316 stainless steel type ASTM F138. Experiments were carried out using four different different test solutions: phosphate buffered saline (PBS), Dulbecco minimum essential medium (MEM), MEM + fetal calf serum (FCS), and MEM + fetal calf serum + fibroblast cell (CELL). Specimens were finished to 600-grit SiC paper and were tested in conditions that did not provoke abrupt mechanical damage of the passive film. Bode-phase spectra showed the presence of two maxima and were fitted with an equivalent circuit characterized by two parallel combinations (R, resistance; CPE, constant phase element). The R(1) and CPE(1) branch was assigned to the inner compact passive film and the R(2) and CPE(2) branch to the external porous film. The resistance of the inner film R(1), roughly corresponding to the polarization resistance (R(p)), which is inversely proportional to the material's corrosion rate, increased with the immersion time and was generally greater in PBS than in other media. With the exception of FCS solution, R(1) for NiTi alloy is better or similar to that of ASTM F138. PMID:16850480

  20. Ventilatory Control in ALS

    PubMed Central

    Nichols, Nicole L.; Van Dyke, J.; Nashold, L.; Satriotomo, I.; Suzuki, M.; Mitchell, G.S.

    2015-01-01

    Amyotrophic lateral sclerosis (ALS) is a fatal, progressive neurodegenerative disease. ALS selectively causes degeneration in upper and lower (spinal) motor neurons, leading to muscle weakness, paralysis and death by ventilatory failure. Although ventilatory failure is generally the cause of death in ALS, little is known concerning the impact of this disorder on respiratory motor neurons, the consequences of respiratory motor neuron cell death, or the ability of the respiratory control system to fight back via mechanisms of compensatory respiratory plasticity. Here we review known effects of ALS on breathing, including possible effects on rhythm generation, respiratory motor neurons, and their target organs: the respiratory muscles. We consider evidence for spontaneous compensatory plasticity, preserving breathing well into disease progression despite dramatic loss of spinal respiratory motor neurons. Finally, we review current and potential therapeutic approaches directed toward preserving the capacity to breathe in ALS patients. PMID:23692930

  1. Laser welding of NiTi shape memory alloy: Comparison of the similar and dissimilar joints to AISI 304 stainless steel

    NASA Astrophysics Data System (ADS)

    Mirshekari, G. R.; Saatchi, A.; Kermanpur, A.; Sadrnezhaad, S. K.

    2013-12-01

    The unique properties of NiTi alloy, such as its shape memory effect, super-elasticity and biocompatibility, make it ideal material for various applications such as aerospace, micro-electronics and medical device. In order to meet the requirement of increasing applications, great attention has been given to joining of this material to itself and to other materials during past few years. Laser welding has been known as a suitable joining technique for NiTi shape memory alloy. Hence, in this work, a comparative study on laser welding of NiTi wire to itself and to AISI 304 austenitic stainless steel wire has been made. Microstructures, mechanical properties and fracture morphologies of the laser joints were investigated using optical microscopy, scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), X-ray diffraction analysis (XRD), Vickers microhardness (HV0.2) and tensile testing techniques. The results showed that the NiTi-NiTi laser joint reached about 63% of the ultimate tensile strength of the as-received NiTi wire (i.e. 835 MPa) with rupture strain of about 16%. This joint also enabled the possibility to benefit from the pseudo-elastic properties of the NiTi component. However, tensile strength and ductility decreased significantly after dissimilar laser welding of NiTi to stainless steel due to the formation of brittle intermetallic compounds in the weld zone during laser welding. Therefore, a suitable modification process is required for improvement of the joint properties of the dissimilar welded wires.

  2. [Environmental factors in ALS].

    PubMed

    Juntas-Morales, Raul; Pageot, Nicolas; Corcia, Philippe; Camu, William

    2014-05-01

    ALS is likely to be a disorder of multifactorial origin. Among all the factors that may increase the risk of ALS, environmental ones are being studied for many years, but in the recent years, several advances have pointed to a new interest in their potential involvement in the disease process, especially for the cyanotoxin BMAA. Food containing BMAA has been found on Guam, a well-known focus of ALS/parkinsonism/dementia and high levels of BMAA have been identified into the brain of these patients. The BMAA cyanotoxin is potentially ubiquitous and have also been found into the food of patients who died from ALS both in Europe and USA. BMAA can be wrongly integrated into the protein structure during mRNA traduction, competing with serine. This may induce abnormal protein folding and a subsequent cell death. Heavy metals, such as lead or mercury may be directly toxic for neuronal cells. Several works have suggested an increased risk of ALS in individuals chronically exposed to these metals. Exposure to pesticides has been suggested to be linked to an increased risk of developing ALS. The mechanism of their toxicity is likely to be mediated by paraoxonases. These proteins are in charge of detoxifying the organism from toxins, and particularly organophosphates. To date, there are insufficient scientific data to suggest that exposure to electromagnetic fields may increase the risk of having ALS. We are particularly missing longitudinal cohorts to demonstrate that risk. PMID:24703731

  3. ALS2 mutations

    PubMed Central

    Schneider, Susanne A.; Carr, Lucinda; Deuschl, Guenther; Hopfner, Franziska; Stamelou, Maria; Wood, Nicholas W.; Bhatia, Kailash P.

    2014-01-01

    Objective: To determine the genetic etiology in 2 consanguineous families who presented a novel phenotype of autosomal recessive juvenile amyotrophic lateral sclerosis associated with generalized dystonia. Methods: A combination of homozygosity mapping and whole-exome sequencing in the first family and Sanger sequencing of candidate genes in the second family were used. Results: Both families were found to have homozygous loss-of-function mutations in the amyotrophic lateral sclerosis 2 (juvenile) (ALS2) gene. Conclusions: We report generalized dystonia and cerebellar signs in association with ALS2-related disease. We suggest that the ALS2 gene should be screened for mutations in patients who present with a similar phenotype. PMID:24562058

  4. Genetic Testing for ALS

    MedlinePLUS

    ... Involved Donate Familial Amyotrophic Lateral Sclerosis (FALS) and Genetic Testing By Deborah Hartzfeld, MS, CGC, Certified Genetic ... guarantee a person will develop symptoms of ALS. Genetic Counseling If there is more than one person ...

  5. All About ALS

    MedlinePLUS

    ... External link, please review our exit disclaimer . Subscribe All About ALS Understanding a Devastating Disorder In the ... a coffee pot, or button a shirt. Eventually, all muscles under voluntary control are affected, and people ...

  6. MDA ALS Caregiver's Guide

    MedlinePLUS

    ... for an official diagnosis of FTD. Most people’s perceptions of “dementia” include the dramatic memory loss, confusion ... for those with ALS. The seat’s width and depth adjustments are indexed and clearly marked for a ...

  7. What Is ALS?

    MedlinePLUS

    ... scarring or hardening ("sclerosis") in the region. Motor neurons reach from the brain to the spinal cord ... the body. The progressive degeneration of the motor neurons in ALS eventually leads to their demise. When ...

  8. About ALS: FAQ

    MedlinePLUS

    ... Hall of Fame basketball player George Yardley , pro football player Glenn Montgomery , golfer Jeff Julian , golf caddie ... in physical therapy, speech, occupational therapy, nursing, psychology, social work, nutrition and other fields, the ALS neurologist ...

  9. Leakage current behaviors of Al/ZrO2/Al and Al/YSZ/Al devices

    NASA Astrophysics Data System (ADS)

    Yeh, Tsung-Her; Lin, Ruei-De; Cherng, Bo-Ruei; Cherng, Jyh-Shiarn

    2015-01-01

    The leakage current behaviors of Al/ZrO2/Al and Al/yttria stabilized zirconia (YSZ)/Al devices are investigated for resistive random access memory (RRAM) applications. A silicon oxide layer (450 nm) is first formed on a Si wafer by thermal oxidation. Onto it an Al bottom electrode (270 nm), a ZrO2 or YSZ nano-film (75 nm), and an Al top electrode (270 nm) are sequentially deposited by sputtering. These RRAM devices exhibit ohmic behaviors in the low-field region, while Schottky and Poole-Frenkel emissions take over in the high-field regions. Both the Schottky and trap barrier levels are decreased when monoclinic ZrO2 is replaced by cubic YSZ in the metal/oxide/metal structure. This is attributed not only to the higher symmetry crystal structure and lower binding energy of YSZ, but also to the formation of more oxygen vacancies and their re-distribution associated with yttria doping.

  10. Frequently Asked Questions about ALS and the ALS Registry

    MedlinePLUS

    ... long do people with familial ALS live? Do clusters of ALS possibly exist? (I have been told ... related?) What are the problems with studying possible clusters of ALS? What are motor neuron (nerve cell) ...

  11. Antimicrobial and mutagenic activity of some carbono- and thiocarbonohydrazone ligands and their copper(II), iron(II) and zinc(II) complexes.

    PubMed

    Bacchi, A; Carcelli, M; Pelagatti, P; Pelizzi, C; Pelizzi, G; Zani, F

    1999-06-15

    Several mono- and bis- carbono- and thiocarbonohydrazone ligands have been synthesised and characterised; the X-ray diffraction analysis of bis(phenyl 2-pyridyl ketone) thiocarbonohydrazone is reported. The coordinating properties of the ligands have been studied towards Cu(II), Fe(II), and Zn(II) salts. The ligands and the metal complexes were tested in vitro against Gram positive and Gram negative bacteria, yeasts and moulds. In general, the bisthiocarbonohydrazones possess the best antimicrobial properties and Gram positive bacteria are the most sensitive microorganisms. Bis(ethyl 2-pyridyl ketone) thiocarbonohydrazone, bis(butyl 2-pyridyl ketone)thiocarbonohydrazone and Cu(H2nft)Cl2 (H2nft, bis(5-nitrofuraldehyde)thiocarbonohydrazone) reveal a strong activity with minimum inhibitory concentrations of 0.7 microgram ml-1 against Bacillus subtilis and of 3 micrograms ml-1 against Staphylococcus aureus. Cu(II) complexes are more effective than Fe(II) and Zn(II) ones. All bisthiocarbono- and carbonohydrazones are devoid of mutagenic properties, with the exception of the compounds derived from 5-nitrofuraldehyde. On the contrary a weak mutagenicity, that disappears in the copper complexes, is exhibited by monosubstituted thiocarbonohydrazones. PMID:10450607

  12. ALS superbend magnet performance

    SciTech Connect

    Marks, Steve; Zbasnik, John; Byrne, Warren; Calais, Dennis; Chin, Michael; DeMarco, Richard; Fahmie, Michael; Geyer, Alan; Krupnick, Jim; Ottens, Fred; Paterson, James A.; Pipersky, Paul; Robin, David S.; Schlueter, RossD.; Steier, Christoph; Wandesforde, Alan

    2001-12-10

    The Lawrence Berkeley National Laboratory has been engaged in the design, construction and testing of four superconducting dipoles (Superbends) that are installed in three arcs of the Advanced Light Source (ALS), with the fourth magnet as a spare. This represents a major upgrade to the ALS providing an enhanced flux and brightness at photon energies above 10 keV. In preparation for installation, an extensive set of tests and measurements have been conducted to characterize the magnetic and cryogenic performance of the Superbends and to fiducialize them for accurate placement in the ALS storage ring. The magnets are currently installed, and the storage ring is undergoing final commissioning. This paper will present the results of magnetic and cryogenic testing.

  13. Fosetyl-al

    Integrated Risk Information System (IRIS)

    Fosetyl - al ; CASRN 39148 - 24 - 8 Human health assessment information on a chemical substance is included in the IRIS database only after a comprehensive review of toxicity data , as outlined in the IRIS assessment development process . Sections I ( Health Hazard Assessments for Noncarcinogenic Ef

  14. Al Shanker Remembers.

    ERIC Educational Resources Information Center

    American Educator, 2000

    2000-01-01

    In a 1996 interview shortly before his death, Al Shanker, longtime president of the American Federation of Teachers, discussed such topics as: his own educational experiences; how he learned about political fighting in the Boy Scouts; the appeal of socialism; multinational corporations and the nation state; teaching tough students; and John Dewey

  15. Al Shanker Remembers.

    ERIC Educational Resources Information Center

    American Educator, 2000

    2000-01-01

    In a 1996 interview shortly before his death, Al Shanker, longtime president of the American Federation of Teachers, discussed such topics as: his own educational experiences; how he learned about political fighting in the Boy Scouts; the appeal of socialism; multinational corporations and the nation state; teaching tough students; and John Dewey…

  16. Wear behavior of Al{sub 2}O{sub 3}-TiCN composite ceramic sliding on stainless steel

    SciTech Connect

    Zhao, X.Z.; Liu, J.J.; Zhu, B.L.; Luo, Z.B.; Miao, H.Z.

    1996-08-01

    It is well known that austenitic stainless steel AISI 302 is relatively difficult to cut. In order to investigate the wear behavior of Al{sub 2}O{sub 3}-TiCN composite ceramic when machining austenitic stainless steels, a block-on-ring tribometer was used to simulate a real machining process. The test results showed that the wear of both the ceramic and the stainless steel increased rapidly with increasing load and speed. The boundary lubrication actions of water and oil used in this test could not reduce the wear of the rubbing materials. Scanning electron microscopy and energy-dispersive x-ray spectroscopy analyses identified material transferred between the ceramic and the stainless steel surfaces in rubbing process. On the one hand, stainless steel transferred on the ceramic surface because of adhesion; on the other, some ceramic fragments caused by microfracture of the ceramic were found to be embedded in the worn stainless steel surface. The wear of Al{sub 2}O{sub 3}-TiCN ceramic sliding against stainless steel was caused primarily by adhesion between the rubbing surfaces and the microfracture of the ceramic.

  17. Mechanical, tribological, and electrochemical behavior of Cr 1- xAl xN coatings deposited by r.f. reactive magnetron co-sputtering method

    NASA Astrophysics Data System (ADS)

    Sanchz, J. E.; Sanchz, O. M.; Ipaz, L.; Aperador, W.; Caicedo, J. C.; Amaya, C.; Landaverde, M. A. Hernndez; Beltran, F. Espinoza; Muoz-Saldaa, J.; Zambrano, G.

    2010-02-01

    Chromium aluminum nitride (Cr 1- xAl xN) coatings were deposited onto AISI H13 steel and silicon substrates by r.f. reactive magnetron co-sputtering in (Ar/N 2) gas mixture from chromium and aluminum targets. Properties of deposited Cr 1- xAl xN coatings such as compositional, structural, morphological, electrochemical, mechanical and tribological, were investigated as functions of aluminum content. X-ray diffraction patterns of Cr 1- xAl xN coatings with different atomic concentrations of aluminum (0.51 < x < 0.69) showed the presence and evolution of (1 1 1), (2 0 0), and (1 0 2) crystallographic orientations associated to the Cr 1- xAl xN cubic and w-AlN phases, respectively. The rate of corrosion of the steel coated with Cr 1- xAl xN varied with the applied power; however, always being clearly lower when compared to the uncoated substrate. The behavior of the protective effect of the Cr 1- xAl xN coatings is based on the substitution of Cr for Al, when the power applied to the aluminum target increases. The mechanical properties were also sensitive to the power applied, leading to a maximum in hardness and a reduced elastic modulus of 30 and 303 GPa at 350 W and a monotonic decrease to 11 and 212 GPa at 450 W, respectively. Finally, the friction coefficient measured by pin-on disk revealed values between 0.45 and 0.70 in humid atmosphere.

  18. /Al-Si Composite

    NASA Astrophysics Data System (ADS)

    Li, Wei; Chen, Jian; Hu, Yongle; Cong, Li; Sun, YouPing; Yang, JiMing

    2014-08-01

    The cyclic fatigue characteristics of spray-deposited SiCp/Al-Si composite were investigated in comparison with the unreinforced Al-Si alloy. The as-extruded specimens were cyclically deformed with fully reversed loading under a range of total strain amplitudes. The results show that the cyclic response characteristics for the reinforced and unreinforced materials are similar to each other. Both the composite and matrix alloys display cyclic hardening under total strain amplitude of 0.35-0.5%. Otherwise, the composite exhibits higher degree of strain hardening than that of the matrix alloy. Dislocation substructure developed during cyclic deformation was analyzed using transmission electron microscopy. The discrepancy between dislocation substructures obtained from processing compared to its development during cyclic strain loading is thought to give rise to the observed cyclic stress response behavior. Fractographic analysis shows that particle/matrix debonding and particle cracking are the main mechanisms of failure in the SiC particle-reinforced composite.

  19. ALS Project Management Manual

    SciTech Connect

    Krupnick, Jim; Harkins, Joe

    2000-05-01

    This manual has been prepared to help establish a consistent baseline of management practices across all ALS projects. It describes the initial process of planning a project, with a specific focus on the production of a formal project plan. We feel that the primary weakness in ALS project management efforts to date stems from a failure to appreciate the importance of ''up-front'' project planning. In this document, we present a guide (with examples) to preparing the documents necessary to properly plan, monitor, and control a project's activities. While following the manual will certainly not guarantee good project management, failure to address the issues we raise will dramatically reduce the chance of success. Here we define success as meeting the technical goals on schedule and within the prescribed budget.

  20. ALS insertion devices

    SciTech Connect

    Hoyer, E.; Chin, J.; Halbach, K.; Hassenzahl, W.V.; Humphries, D.; Kincaid, B.; Lancaster, H.; Plate, D.

    1990-11-01

    The Advanced Light Source (ALS), the first US third generation synchrotron radiation source, is currently under construction at the Lawrence Berkeley Laboratory. The low-emittance, 1.5 GeV electron storage ring and the insertion devices are specifically designed to produce high brightness beams in the UV to soft X-Ray range. The planned initial complement of insertion devices includes four 4.6 m long undulators, with period lengths of 3.9 cm, 5.0 cm (2) and 8.0 cm, and a 2.9 m long wiggler of 16 cm period length. Undulator design is well advanced and fabrication has begun on the 5.0 cm and 8.0 cm period length undulators. This paper discusses ALS insertion device requirements; general design philosophy; and design of the magnetic structure, support structure/drive systems, control system and vacuum system. 18 refs., 9 figs., 5 tabs.

  1. Jasechko et al. reply.

    PubMed

    Jasechko, Scott; Sharp, Zachary D; Gibson, John J; Birks, S Jean; Yi, Yi; Fawcett, Peter J

    2014-02-13

    replying to A. M. J. Coenders-Gerrits et al. 506, http://dx.doi.org/10.1038/nature12925 (2014)In their Comment, Coenders-Gerrits et al. suggest that our conclusion that transpiration dominates the terrestrial water cycle is biased by unrepresentative input data and optimistic uncertainty ranges related to runoff, interception and the isotopic compositions of transpired and evaporated moisture. We clearly presented the uncertainties applied in our Monte-Carlo sensitivity analysis, we reported percentile ranges of results rather than standard deviations to best communicate the nonlinear nature of the isotopic evaporation model, and we highlighted that the uncertainty in our calculation remains large, particularly in humid catchments (for example, figure 2 in our paper). PMID:24522604

  2. Multiaxial fatigue criteria for AISI 304 and 2-1/4 Cr-1 Mo steel at 538/sup 0/C with applications to strain-range partitioning and linear summation of creep and fatigue damage

    SciTech Connect

    Blass, J.J.

    1982-01-01

    An improved multiaxial fatigue failure criterion was developed based on the results of combined axial-torsional strain cycling tests of AISI 304 and 2-1/4 Cr-1 Mo steel conducted at 538/sup 0/C (1000/sup 0/F). The formulation of this criterion involves the shear and normal components of inelastic strain range on the planes of maximum inelastic shear strain range. Optimum values of certain parameters contained in the formulation were obtained for each material by the method of least squares. The ability of this criterion to correlate the test results was compared with that of the usual (Mises) equivalent inelastic strain range criterion. An improved definition of equivalent inelastic strain range resulting from these considerations was used to generalize the theory of Strain Range Partitioning to multiaxial stress-strain conditions and was also applied to the linear summation of creep and fatigue damage.

  3. The Influence of Cold-work Level on the Irradiation Creep and Swelling of AISI 316 Stainless Steel Irradiated as Pressurized Tubes in the EBR-II Fast Reactor

    SciTech Connect

    Gilbert, Edgar R.; Garner, Francis A.

    2007-08-01

    Pressurized tubes of AISI 316 stainless steel irradiated in the P-1 experiment in the EBR-II fast reactor have been measured to determine the dependence of irradiation-induced strains resulting from plastic deformation, irradiation creep, void swelling and precipitation. It is shown that the Soderberg relation predicting no axial creep strains in biaxially-loaded tubes is correct for both plastic and creep strains. Swelling strains are shown to be isotropically distributed both for stress-free and stress-affected swelling, while precipitation strains are somewhat anisotropic in their distribution. When corrected for stress-enhancement of swelling, the derived irradiation creep strains appear to be identical for both annealed and 20% cold-worked specimens, and also for tubes strained by rise to power increases in pressure. For relatively small creep strains it is often

  4. A progress report on the use of electrochemical noise to investigate the effects of zebra mussel attachment on the corrosion resistance of AISI Type 304 stainless steel and carbon steel in lake water

    SciTech Connect

    Brennenstuhl, A.M.; Sim, B.; Claudi, R.

    1996-12-31

    The electrochemical noise technique was used to determine the effect of zebra mussel settlement on the corrosion performance of AISI Type 304 stainless steel and carbon steel (ASTM A53 Grade B). These materials represent alloys commonly used for handling untreated Great Lakes water at Ontario Hydro`s power generating plants. This work was motivated by a concern that zebra mussel settlement will lead to accelerated attack of these materials as a result of the establishment of stable crevice conditions and the growth of corrosion influencing anaerobic sulfate-reducing bacteria (SRB). Corrosion monitoring was carried out in a field test facility that uses the same untreated Lake Erie water as Ontario Hydro`s Nanticoke Thermal Generating Station. The test program extended from May through December 1993. During this period, a number of electrochemical parameters were monitored simultaneously, including coupling current, electrochemical potential noise (EPN), electrochemical current noise (ECN), degree of localization (DoL), and resistance noise (R{sub n}). Differences were observed in the performance of the control samples and the samples to which mussels were attached. The results for the AISI Type 304 stainless steel suggested that over the period monitored, mussel attachment reduced corrosion activity. Similarly, signals from carbon steel, samples exposed to mussels, although initially displaying relatively high corrosion rates, exhibited less corrosion damage than did control samples over the longer term. The reason for this difference in performance is not known but is considered to have resulted from a change in the surface environment as a result of mussel attachment, which appeared to diminish corrosion. One possible explanation may be the generation of inhibitive species by the mussels.

  5. Al Jazirah, Sudan

    NASA Technical Reports Server (NTRS)

    2008-01-01

    Al Jazirah (also Gezira) is one of the 26 states of Sudan. The state lies between the Blue Nile and the White Nile in the east-central region of the country. It is a well populated area suitable for agriculture. The area was at the southern end of Nubia and little is known about its ancient history and only limited archaeological work has been conducted in this area. The region has benefited from the Gezira Scheme, a program to foster cotton farming begun in 1925. At that time the Sennar Dam and numerous irrigation canals were built. Al Jazirah became the Sudan's major agricultural region with more than 2.5 million acres (10,000 km) under cultivation. The initial development project was semi-private, but the government nationalized it in 1950. Cotton production increased in the 1970s but by the 1990s increased wheat production has supplanted a third of the land formerly seeded with cotton.

    The image was acquired December 25, 2006, covers an area of 56 x 36.4 km, and is located near 14.5 degrees north latitude, 33.1 degrees east longitude.

    The U.S. science team is located at NASA's Jet Propulsion Laboratory, Pasadena, Calif. The Terra mission is part of NASA's Science Mission Directorate.

  6. Al(+)-ligand binding energies

    NASA Technical Reports Server (NTRS)

    Sodupe, M.; Bauschlicher, Charles W., Jr.

    1991-01-01

    Ab initio calculations are used to optimize the structure and determine the binding energies of Al(+) to a series of ligands. For Al(+)-CN, the bonding was found to have a large covalent component. For the remaining ligands, the bonding is shown to be electrostatic in origin. The results obtained for Al(+) are compared with those previously reported for Mg(+).

  7. Studies of 27Al NMR in EuAl4

    NASA Astrophysics Data System (ADS)

    Niki, H.; Nakamura, S.; Higa, N.; Kuroshima, H.; Toji, T.; Yogi, M.; Nakamura, A.; Hedo, M.; Nakama, T.; ?nuki, Y.; Harima, H.

    2015-03-01

    EuAl4 orders antiferromagnetically at TN ? 16 K with an effective magnetic moment of 8.02 ?B. In the paramagnetic phase, the magnetic susceptibility of EuAl4 follows the Curie-Weiss law with a positive Curie-Weiss temperature ?P = +14 K. The antiferromagnetic state is changed into the field induced ferromagnetic state at a critical field Hc of approximately 2 T. In order to microscopically investigate the magnetic and electronic properties in EuAl4, the NMR measurements of EuAl4 have been carried out at temperatures between 2 and 300 K, applying an external magnetic field of approximately 6.5 T. The 27Al NMR spectra corresponding to Al(I) and Al(II) sites are obtained. From the 27Al NMR spectra, the isotropic part Kiso and anisotropic part Kaniso of Knight shift, and nuclear quadrupole frequncy ?Q are obtained. The Kiso and Kaniso shift to negative side with decreasing temperature due to the RKKY interaction. These temperature dependences follow the Curie-Weiss law with ?P = +14 K, which is consistent with that of the magnetic susceptibility. From the K - ? plot, the values of the hyperfine fields Hhf_iso and Hhf_aniso are -3.231 and -0.162 kOe/?B for Al(I) site, and -1.823 and -0.264 kOe/?B for Al(II) site, respectively. The values of ?Q of 27Al nucleus for Al(I) and Al(II) sites are approximately 0.865 and 0.409 MHz, respectively. The nuclear relaxation time T1 of 27Al NMR for both sites is almost constant in the paramagnetic phase, while the value of 1/T1 is abruptly decreased in the ordered ferromagnetic state.

  8. Growth and Optical Properties of Al rich AlN/AlGaN Quantum Wells

    NASA Astrophysics Data System (ADS)

    Tahtamouni, T. M. Al; Nepal, N.; Nakarmi, M. L.; Lin, J. Y.; Jiang, H. X.

    2006-03-01

    Al rich AlGaN alloys are promising materials for the applications in the optoelectronic devices such as deep ultraviolet (UV) emitters and detectors in the spectral range down to 200 nm. AlGaN based UV emitters (?<340nm) has applications in bio-chemical agent detection and medical research/ health care. To realize deep UV emission (?< 280 nm) Al rich AlGaN based quantum wells (QWs) are required. We report here the growth of AlN/AlxGa1-xNQWs (x>0.65) on AlN/sapphire templates by metalorganic chemical vapor deposition (MOCVD). Deep UV photoluminescence (PL) was employed to study the optical properties of the QWs. Well width (Al composition) dependence was studied by varying the QW thickness (Al composition) with fixed x 0.65 (well width at 3 nm). Optical properties of these QWs such as the effects of alloy fluctuation, temperature, strain and piezoelectric field, carrier and exciton localizations on the quantum efficiency have been studied. Carrier and exciton dynamics were probed. Implications of our findings on the applications of Al rich AlN/AlGaN QWs for UV emitters and detectors will also be discussed.

  9. Analysis of Wear Mechanisms in Low Friction, Nanocomposite AlMgB14-TiB2 Coatings

    SciTech Connect

    Cook, Bruce A; Harringa, J; Anderegg, A; Russell, A M; Qu, Jun; Blau, Peter Julian; Higdon, Clifton; Elmoursi, Alaa A

    2010-01-01

    Recent developments in coating science and technology offer new opportunities to enhance the energy-efficiency and performance of industrial machinery such as hydraulic fluid pumps and motors. The lubricated friction and wear characteristics of two wear-resistant coatings, diamond-like carbon and a nanocomposite material based on AlMgB{sub 14}-50 vol.% TiB{sub 2}, were compared in pin-on-disk tribotests using Mobil DTE-24{trademark} oil as the lubricant. In each case, the pins were fixed 9.53 mm diameter spheres of AISI 52100 steel, the load was 10 N, and the speed 0.5 m/s in all tests. Average steady-state friction coefficient values of 0.10 and 0.08 were measured for the DLC and nanocomposite, respectively. The coatings and their 52100 steel counterfaces were analyzed after the tests by X-ray photoelectron and Auger spectroscopy for evidence of material transfer or tribo-chemical reactions. The low-friction behavior of the boride nanocomposite coating is due to the formation of lubricative boric acid, B(OH){sub 3}. In contrast, the low-friction behavior of the DLC coating is related to the relatively low dielectric constant of the oil-based lubricant, leading to desorption of surface hydrogen from the coating.

  10. Theoretical studies of AlF, AlCl, and AlBr

    NASA Technical Reports Server (NTRS)

    Langhoff, Stephen R.; Bauschlicher, Charles W., Jr.; Taylor, Peter R.

    1988-01-01

    Spectroscopic constants have been obtained for the lowest six singlet and lowest five triplet states of AlF and AlCl. The results suggest that the correct ordering of the triplet manifold in these molecules is: a 3Pi, b 3Sigma(+), c 3Sigma(+), d 3Pi, and e 3Delta. Radiative lifetimes have been determined for the excited states, and the A 1Pi to X 1Sigma(+) transition in AlF, AlCl, and AlBr has been examined in detail. A-X transition moment functions, Einstein coefficients, and A 1Pi vibrational lifetimes have been obtained for AlF and AlCl.

  11. Rub' al Khali, Arabia

    NASA Technical Reports Server (NTRS)

    2008-01-01

    The Rub' al Khali is one of the largest sand deserts in the world, encompassing most of the southern third of the Arabian Peninsula. It includes parts of Oman, United Arab Emirates, and Yemen. The desert covers 650,000 square kilometers, more than the area of France. Largely unexplored until recently, the desert is 1000 km long and 500 km wide. The first documented journeys made by Westerners were those of Bertram Thomas in 1931 and St. John Philby in 1932. With daytime temperatures reaching 55 degrees Celsius, and dunes taller than 330 meters, the desert may be one of the most forbidding places on Earth.

    The image was acquired December 2, 2005, covers an area of 54.8 x 61.9 km, and is located near 20.7 degrees north latitude, 53.6 degrees east longitude.

    The U.S. science team is located at NASA's Jet Propulsion Laboratory, Pasadena, Calif. The Terra mission is part of NASA's Science Mission Directorate.

  12. Interfacial reactions and oxidation behavior of Al 2O 3 and Al 2O 3/Al coatings on an orthorhombic Ti 2AlNb alloy

    NASA Astrophysics Data System (ADS)

    Li, H. Q.; Wang, Q. M.; Gong, J.; Sun, C.

    2011-02-01

    The uniform and dense Al2O3 and Al2O3/Al coatings were deposited on an orthorhombic Ti2AlNb alloy by filtered arc ion plating. The interfacial reactions of the Al2O3/Ti2AlNb and Al2O3/Al/Ti2AlNb specimens after vacuum annealing at 750 C were studied. In the Al2O3/Ti2AlNb specimens, the Al2O3 coating decomposed significantly due to reaction between the Al2O3 coating and the O-Ti2AlNb substrate. In the Al2O3/Al/Ti2AlNb specimens, a ?-TiAl layer and an Nb-rich zone came into being by interdiffusion between the Al layer and the O-Ti2AlNb substrate. The ?-TiAl layer is chemically compatible with Al2O3, with no decomposition of Al2O3 being detected. No internal oxidation or oxygen and nitrogen dissolution zone was observed in the O-Ti2AlNb alloy. The Al2O3/Al/Ti2AlNb specimens exhibited excellent oxidation resistance at 750 C.

  13. Effects of Si content on microstructure and mechanical properties of TiAlN/Si3N4-Cu nanocomposite coatings

    NASA Astrophysics Data System (ADS)

    Feng, Changjie; Hu, Shuilian; Jiang, Yuanfei; Wu, Namei; Li, Mingsheng; Xin, Li; Zhu, Shenglong; Wang, Fuhui

    2014-11-01

    TiAlN/Si3N4-Cu nanocomposite coatings of various Si content (0-5.09 at.%) were deposited on AISI-304 stainless steel by DC reactive magnetron sputtering technique. The chemical composition, microstructure, mechanical and tribological properties of these coatings were systematically investigated by means of X-ray diffraction (XRD), field emission scanning electron microscope (FESEM), nanoindentation tester, a home-made indentation system, a scratch tester and a wear tester. Results indicated that with increasing Si content in these coatings, a reduction of grain size and surface roughness, a transformation of the (1 1 1) preferred orientation was detected by XRD and FESEM. Furthermore the hardness of these coatings increase from 9.672 GPa to 18.628 GPa, and the elastic modulus reveal the rising trend that increase from 224.654 GPa to 251.933 GPa. However, the elastic modulus of TiAlN/Si3N4-Cu coating containing 3.39 at.% Si content dropped rapidly and changed to about 180.775 GPa. The H3/E2 ratio is proportional to the film resistance to plastic deformation. The H3/E2 ratio of the TiAlN/Si3N4-Cu coating containing 3.39 at.% Si content possess of the maximum of 0.11 GPa, and the indentation test indicate that few and fine cracks were observed from its indentation morphologies. The growth pattern of cracks is mainly bending growing. The present results show that the best toughness is obtained for TiAlN/Si3N4-Cu nanocomposite coating containing 3.39 at.% Si content. In addition, the TiAlN/Si3N4-Cu coating containing 3.39 at.% Si content also has good adhesion property and superior wear resistance, and the wear mechanism is mainly adhesion wear.

  14. Dynamic nanomechanical properties of novel Si-rich intermetallic coatings growth on a medical 316 LVM steel by hot dipping in a hypereutectic Al-25Si alloy.

    PubMed

    Frutos, E; Gonzlez-Carrasco, J L

    2015-06-01

    This aim of this study is to determine the elastoplastic properties of Ni-free Al3FeSi2 intermetallic coatings grown on medical stainless steel under different experimental conditions. Elastoplastic properties are defined by the plasticity index (PI), which correlates the hardness and the Young's modulus. Special emphasis is devoted to correlate the PI with the wear resistance under sliding contact, determined by scratch testing, and fracture toughness, determined by using a novel method based on successive impacts with small loads. With regard to the substrate, the developed coatings are harder and exhibit a lower Young's reduced modulus, irrespective of the experimental conditions. It has been shown that preheating of the samples prior to hot dipping and immersion influences the type and volume fraction of precipitates, which in turn also affect the nanomechanical properties. The higher the preheating temperature is, the greater the Young's reduced modulus is. For a given preheating condition, an increase of the immersion time yields a decrease in hardness. Although apparent friction coefficients of coated specimens are smaller than those obtained on AISI 316 LVM, they increase when using preheating or higher immersion times during processing, which correlates with the PI. The presence of precipitates produces an increase in fracture toughness, with values greater than those presented by samples processed on melted AlSi alloys with lower Si content (12 wt%). Therefore, these intermetallic coatings could be considered "hard but tough", suitable to enhance the wear resistance, especially when using short periods of immersion. PMID:25778350

  15. Characteristics of CeCoIn5/Al/AlOx/Nb and CeCoIn5/Al/AlOx/Al Tunnel Junctions

    SciTech Connect

    Petrovic, C.; Nevirkovets, I.P.; Chernyashevskyy, O.; Hu, R.; Ketterson, J.B.; Sarma, B.K.

    2009-03-03

    We report characteristics of CeCoIn{sub 5}/Al/AlO{sub x}/Nb and CeCoIn{sub 5}/Al/AlO{sub x}/Al tunnel junctions fabricated on the (0 0 1) surface of CeCoIn{sub 5} crystal platelets. The main result of this work is the observation of a low Josephson current (as compared with that expected from the Ambegaokar-Baratoff formula), which is consistent with idea that the order parameter in the heavy-fermion superconductor CeCoIn{sub 5} has unconventional pairing symmetry.

  16. Finite-element modelling of low-temperature autofrettage of thick-walled tubes of the austenitic stainless steel AISI 304 L: Part II. Thick-walled tube with cross-bore

    NASA Astrophysics Data System (ADS)

    Feng, H.; Donth, B.; Mughrabi, H.

    1998-01-01

    In part I, the autofrettage of a smooth thick-walled tube of the austenitic stainless steel AISI 304 L was studied by finite-element (FE) modelling. It was shown that low- temperature autofrettage is more efficient than autofrettage at room temperature, since it produces a larger beneficial compressive residual tangential (hoop) stress at the inner bore of the tube and hence permits a more significant enhancement of the fatigue resistance against pulsating internal pressure. The objective of the present study (part II) was to investigate the technically more relevant case of a thick-walled tube with a cross-bore made of the same steel. For this purpose, three-dimensional FE calculations were performed in order to characterize the influences of the autofrettage pressure and temperature on the stress and strain changes, in particular at the site of the cross-bore, also taking into account the effects of work hardening and reverse yielding. The results indicate that low-temperature autofrettage can also be applied advantageously in the case of thick-walled tubes with a cross-bore by virtue of the significantly larger residual compressive stresses, compared to room temperature autofrettage. From the quantitative FE calculations, the optimal combination of autofrettage temperature and pressure were concluded to lie in the range of 0965-0393/6/1/007/img1 to 0965-0393/6/1/007/img2, respectively. The calculated results were found to be in fair agreement with the measured values.

  17. Finite-element modelling of low-temperature autofrettage of thick-walled tubes of the austenitic stainless steel AISI 304 L: Part I. Smooth thick-walled tubes

    NASA Astrophysics Data System (ADS)

    Feng, H.; Mughrabi, H.; Donth, B.

    1998-01-01

    The stresses and strains introduced by low-temperature autofrettage of smooth thick-walled tubes made of the austenitic stainless steel AISI 304 L were modelled by the finite-element (FE) method. The objective was to show that low-temperature autofrettage is much more efficient than autofrettage at room temperature in enhancing the fatigue resistance by introducing a higher beneficial tangential (hoop) residual compressive stress at the inner part of the tube. Attention was paid to the influences of the autofrettage temperature and pressure, the work hardening and the reverse yielding on the residual stress components and on the total strain components of the tube. The FE calculations confirmed that more beneficial residual stress patterns can be attained by autofrettage at low rather than at room temperature. From the quantitative calculations, the optimal autofrettage temperature and pressure of the tube were concluded to be about 0965-0393/6/1/006/img1 and 4000 bar, respectively. The results of the calculations were shown to be in good agreement with recently measured data.

  18. Changes in Microstructural and Mechanical Properties of AISI Type 316LN Stainless Steel and Modified 9Cr-1Mo Steel on Long-Term Exposure to Flowing Sodium in a Bi-Metallic Sodium Loop

    NASA Astrophysics Data System (ADS)

    Sivai Bharasi, N.; Pujar, M. G.; Thyagarajan, K.; Mallika, C.; Kamachi Mudali, U.; Dhaul, Anuradha; Nandagopal, M.; Moitra, A.; Chandramouli, S.; Rajan, K. K.

    2015-12-01

    AISI Type 316LN stainless steel (SS) and modified 9Cr-1Mo steel were exposed to flowing sodium at 798 K (525 °C) for 30000 hours in a bi-metallic sodium loop. The changes in microchemical, microstructural, and mechanical properties were evaluated and compared with the as-received and thermally aged specimens. Effective carbon diffusion coefficient {( {D_{C}^{eff} } )} was calculated to be 6.8 × 10-19 m2/s. Depth of carburization analyzed by secondary ion mass spectroscopy technique was around 100 µm for sodium-exposed 316LN SS. Selective leaching of nickel occurred across depth from the surface of sodium-exposed 316LN SS with the formation of 10 µm ferrite layer, and it showed an increase in yield strength by 15 pct, reduction in ductility by 60 pct, and a decrease in impact energy by 15 pct vis-a-vis the as-received and thermally aged specimens. This reduction in ductility occurred due to extensive precipitation of sigma phase as a result of long-term thermal aging. No significant changes were observed in the sodium/modified 9Cr-1Mo steel interfacial microstructure as well as tensile properties of sodium-exposed modified 9Cr-1Mo steel. Although modified 9Cr-1Mo neither showed carburization nor decarburization on sodium exposure, it showed a drastic reduction in the impact strength, which was attributed to the presence of Laves phase, observed in X-ray diffraction patterns.

  19. Medical application of 26Al

    NASA Astrophysics Data System (ADS)

    Steinhausen, C.; Gerisch, P.; Heisinger, B.; Hohl, Ch.; Kislinger, G.; Korschinek, G.; Niedermayer, M.; Nolte, E.; Dumitru, M.; Alvarez-Brckmann, M.; Schneider, M.; Ittel, T. H.

    1996-06-01

    Accelerator mass spectrometry (AMS) measurements with 26Al as tracer were performed in order to study the aluminium metabolism and anomalies in the human body and in rats. In particular, the differences between healthy volunteers and patients with renal failure were investigated. The obtained data points of 26Al in blood and urine were described by an open compartment model with three peripheral compartments. It was found that the minimum of peripheral compartments needed to describe 26Al concentrations in blood and urine over a time period of three years is at least three.

  20. Influence of the substrate bias voltage on the crystallographic structure and mechanical properties of Ti6Al4V coatings deposited by rf magnetron

    NASA Astrophysics Data System (ADS)

    Alfonso, J. E.; Pacheco, Fernando; Castro P., Alvaro; Torres, J.

    2005-08-01

    Physical and mechanical properties of pure titanium are improved when the material is mixed with aluminum and vanadium at specific concentrations. Specifically, the alloy composed by 90% of titanium, 6% of aluminum and 4% of vanadium (Ti-6Al-4V) is highly resistant to fatigue and corrosion titanium and their alloys can be deposited by two techniques: Chemical Vapor Deposition (CVD) and Physical Vapor Deposition (PVD). However, some problems are generated when carbonated steel substrates are used under the CVD technique, mainly because those substrates lost its carbon as a result of the high substrate temperature used during the deposition process. Alternatively, PVD (magnetron sputtering, ion plating) is a low temperature substrate process and also has the advantage that substrate bias can promote structure refinement through resputtering effects.Substrate bias influence on the crystalline structure of Ti6Al4V thin films prepared by rf magnetron sputtering are presented in this work. Samples were grown onto common glass and AISI 420 steel substrates using a Ti6Al4V (99.9 %) target. Substrate bias was varied from -100 V to -200 V. Samples were characterized by X-ray Diffraction (XRD), Energy Dispersive X-ray Spectroscopy (EDXS), Scanning Electron Microscopy (SEM), and Atomic Force Microscopy (AFM). Thin films stoichiometry were studied by EDX in agreement with the Ti-6Al-4V target. Finally, the studies of the mechanical behavior of the films on steel showed that the hardness increased 1100 Knoop when the bias voltage is raised to -160 V.

  1. Understanding ALS: new therapeutic approaches.

    PubMed

    Musar, Antonio

    2013-09-01

    Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disease associated with motor neuron degeneration, muscle atrophy and paralysis. Although numerous pathological mechanisms have been elucidated, ALS remains an invariably fatal disease in the absence of any effective therapy. The heterogeneity of the disease and the failure to develop satisfactory therapeutic protocols reinforce the view that ALS is a multi-factorial and multi-systemic disease. Thus, a better understanding of the pathogenic mechanisms and study of the potential pathological relationship between the various cellular processes is required to ensure efficacious therapy. The pathogenic mechanisms associated with ALS are reviewed, and the strengths and limitations of some new therapeutic approaches are discussed. PMID:23217177

  2. Reply to Fischer et al.

    PubMed

    Watson, Stuart K; Townsend, Simon W; Schel, Anne M; Wilke, Claudia; Wallace, Emma K; Cheng, Leveda; West, Victoria; Slocombe, Katie E

    2015-11-01

    We welcome the correspondence from Fischer and colleagues regarding our recent paper on vocal learning in chimpanzee food grunts [1]. Fischer et al. make two challenges to our paper's conclusions, which we address here. PMID:26528741

  3. Reply to Gopalswamy et al.

    NASA Technical Reports Server (NTRS)

    Cane, H. V.; Richardson, I. G.

    2003-01-01

    The comment of Gopalswamy et al. (thereafter GMY) relates to a letter discussing coronal mass ejections (CMEs), interplanetary ejecta and geomagnetic storms. GMY contend that Cane et al. incorrectly identified ejecta (interplanetary CMEs) and hypothesize that this is because Cane et al. fail to understand how to separate ejecta from "shock sheaths" when interpreting solar wind and energetic particle data sets. They (GMY) are wrong be cause the relevant section of the paper was concerned with the propagation time to 1 AU of any potentially geoeffective structures caused by CMEs, i.e. upstream compression regions with or without shocks, or ejecta. In other words, the travel times used by Cane et al. were purposefully and deliberately distinct from ejecta travel times (except for those slow ejecta, approx. 30% of their events, which generated no upstream features), and no error in identification was involved. The confusion of GMY stems from the description did not characterize the observations sufficiently clearly.

  4. In memory of Al Cameron

    NASA Astrophysics Data System (ADS)

    Cowan, John; Truran, James W.

    Al Cameron, who died recently (October 3, 2005) at 80, was one of the giants in astrophysics. His insights were profound and his interests were wide-ranging. Originally trained as a nuclear physicist, he made major contributions in a number of fields, including nuclear reactions in stars, nucleosynthesis, the abundances of the elements in the Solar System, and the origin of the Solar System and the Moon. In 1957, Cameron and, independently, Burbidge, Burbidge, Fowler and Hoyle, wrote seminal papers on nuclear astrophysics. Most of our current ideas concerning ele- ment formation in stars have followed from those two pioneering and historical works. Al also made many contributions in the field of Solar System physics. Particularly noteworthy in this regard was Cameron's work on the formation of the Moon. Al was also a good friend and mentor of young people. Al Cameron will be missed by many in the community both for his scientific contributions and for his friendship.

  5. Transcranial magnetic stimulation in ALS

    PubMed Central

    Floyd, A G.; Yu, Q P.; Piboolnurak, P; Tang, M X.; Fang, Y; Smith, W A.; Yim, J; Rowland, L P.; Mitsumoto, H; Pullman, S L.

    2009-01-01

    Objective: To investigate transcranial magnetic stimulation (TMS) measures as clinical correlates and longitudinal markers of amyotrophic lateral sclerosis (ALS). Methods: We prospectively studied 60 patients with ALS subtypes (sporadic ALS, familial ALS, progressive muscular atrophy, and primary lateral sclerosis) using single pulse TMS, recording from abductor digiti minimi (ADM) and tibialis anterior (TA) muscles. We evaluated three measures: 1) TMS motor response threshold to the ADM, 2) central motor conduction time (CMCT), and 3) motor evoked potential amplitude (correcting for peripheral changes). Patients were evaluated at baseline, compared with controls, and followed every 3 months for up to six visits. Changes were analyzed using generalized estimation equations to test linear trends with time. Results: TMS threshold, CMCT, and TMS amplitude correlated (p < 0.05) with clinical upper motor neuron (UMN) signs at baseline and were different (p < 0.05) from normal controls in at least one response. Seventy-eight percent of patients with UMN (41/52) and 50% (4/8) of patients without clinical UMN signs had prolonged CMCT. All three measures revealed significant deterioration over time: TMS amplitude showed the greatest change, decreasing 8% per month; threshold increased 1.8% per month; and CMCT increased by 0.9% per month. Conclusions: Transcranial magnetic stimulation (TMS) findings, particularly TMS amplitude, can objectively discriminate corticospinal tract involvement in amyotrophic lateral sclerosis (ALS) from controls and assess the progression of ALS. While central motor conduction time and response threshold worsen by less than 2% per month, TMS amplitude decrease averages 8% per month, and may be a useful objective marker of disease progression. GLOSSARY ADM = abductor digiti minimi; ALS = amyotrophic lateral sclerosis; ANOVA = analysis of variance; CI = confidence interval; CMAP = compound motor action potential; CMCT = central motor conduction time; DTR = deep tendon stretch reflex; fALS = familial ALS; GEE = generalized estimation equations; LMN = lower motor neuron; MEP = motor evoked potential; PLS = primary lateral sclerosis; PMA = progressive muscular atrophy; sALS = sporadic ALS; TA = tibialis anterior; TMS = transcranial magnetic stimulation; UMN = upper motor neuron. PMID:19204259

  6. ALS: focus on purinergic signalling.

    PubMed

    Volont, Cinzia; Apolloni, Savina; Carr, Maria Teresa; D'Ambrosi, Nadia

    2011-10-01

    Amyotrophic lateral sclerosis (ALS) is one of the most common neuromuscular diseases. It is devastating and fatal, causing progressive paralysis of all voluntary muscles and eventually death, while sparing cognitive functions. A pathological hallmark of ALS is neuroinflammation mediated by non-neuronal cells in the nervous system, such as microglia and astrocytes that accelerate the disease progression. Scientists have neither found a unique key mechanism, nor an effective treatment against ALS, supposedly because it is a multi-factorial and multi-systemic disease. Extracellular purines and pyrimidines are widespread and powerful physiopathological molecules, signalling to most cell types and directing cell-to-cell communication networks. They are instrumental for instance for neurotransmission, muscle contraction and immune surveillance. Recent work has reported the crucial involvement of purinergic pathways in many neurodegenerative and neuroinflammatory diseases, comprising ALS. Especially P2 receptors for ATP, P1 receptors for adenosine, and nucleotide transporters were found to be modulated in ALS cells and tissues, playing a potential role in the disease. Given the composite cellular cross-talk occurring during ALS and the established action of extracellular purines/pyrimidines as neuron-to-glia alarm signal in the nervous system, a mutual query in these two fields should now be whether, how and when purinergic would meet ALS. In this review, we will highlight the early cellular and molecular purinergic cross-talk that participates to ALS etiopathology, with the conviction that better understanding of purinergic dynamics might provide original research perspectives, stimulate alternative disease modelling, and the design and testing of more powerful targeted therapeutics against this relentlessly progressive disorder. PMID:21704075

  7. Comparing the Thermodynamic Behaviour of Al(1)+ZrO2(s) to Al(1)+Al2O3(s)

    NASA Technical Reports Server (NTRS)

    Copland, Evan

    2004-01-01

    In an effort to better determine the thermodynamic properties of Al(g) and Al2O(g). the vapor in equilibrium with Al(l)+ZrO2(s) was compared to the vapor in equilibrium with Al(l)+Al2O3(s) over temperature range 1197-to-1509K. The comparison was made directly by Knudsen effusion-cell mass spectrometry with an instrument configured for a multiple effusion-cell vapor source (multi-cell KEMS). Second law enthalpies of vaporization of Al(g) and Al2O(g) together with activity measurements show that Al(l)+ZrO2(s) is thermodynamically equivalent to Al(l)+Al2O3(s), indicating Al(l) remained pure and Al2O3(s) was present in the ZrO2-cell. Subsequent observation of the Al(l)/ZrO2 and vapor/ZrO2 interfaces revealed a thin Al2O3-layer had formed, separating the ZrO2-cell from Al(l) and Al(g)+Al2O(g), effectively transforming it into an Al2O3 effusion-cell. This behavior agrees with recent observations made for Beta-NiAl(Pt) alloys measured in ZrO2 effusion-cell.

  8. Corrosion Behavior of Al-Al3Ni and Al-Al2Cu Functionally Graded Materials Fabricated by a Centrifugal Method

    NASA Astrophysics Data System (ADS)

    Noda, Kazuhiko; Miyahara, Keita; Watanabe, Yoshimi

    2008-02-01

    Intermetallic compounds, such as Al3Ni and Al2Cu, are effective for enhancing the mechanical properties of an alloy. Al-Al3Ni and Al-Al2Cu functionally graded materials (FGMs) might be attractive materials for advanced materials. Al-Al3Ni and Al-Al2Cu FGMs were fabricated by a centrifugal method; the centrifugal method is an extremely effective method for fabricating FGMs. Al-Al3Ni and Al-Al2Cu FGMs that had a graded distribution of intermetallic compounds could be produced by this in-situ centrifugal method. Particle size, particle shape and the distribution of intermetallic compounds were controlled by varying the content of the alloy element (Ni, Cu) in the master alloy, the cooling rate in casting and the gravity number. The casting mechanism is explained in terms of the microstructures of the Al-Al3Ni and Al-Al2Cu FGMs fabricated by this method. The corrosion behavior of the FGMs was investigated by electrochemical analysis. Polarization curves of the FGMs in a borate solution were measured by a potentiodynamic method. The presence of Al2Cu exerted a larger effect on the corrosion behavior of the FGMs than Al3Ni. Analysis of the polarization curve parameters was effective for evaluating the corrosion resistance of the FGMs.

  9. High Density Sliding at Ta/Al and Al/Al Interfaces

    SciTech Connect

    Hammerberg, J. E.; Germann, T. C.; Ravelo, R.

    2006-07-28

    We present 3D-nonequilibrium molecular dynamics results for the velocity dependence of the frictional force at smooth sliding interfaces for Ta and Al single crystals. For Ta/Al we consider Al(100)/Ta(100) and Al(111)/Ta(110) interfaces sliding along [001] and [11(bar sign)0]fcc /[001]bcc respectively. These are compared with Al(111)/Al(100) interfaces at the same loads, corresponding to a pressure of 15 GPa. Both interfacial pairs show similar behavior in the velocity dependence of the frictional force: a low velocity regime with an increasing frictional force followed by a strain induced transformation regime at velocities above approximately 1/10 the transverse sound speed, followed by a fluidized interface at high velocities. For both interfacial pairs, the high velocity dependence of the frictional force exhibits power law behavior, Ft {proportional_to} v-{beta} with {beta}=3/4. We discuss the structural changes that influence dissipation in each of these regimes.

  10. Everyday Life with ALS: A Practical Guide

    MedlinePLUS

    ... likely be affected by ALS. An astonish- ing array of assistive technology is now available to help ... neuromuscular diseases. MDA’s ALS Division provides a vast array of services to people with ALS, one of ...

  11. Modeling of the ALS linac

    SciTech Connect

    Kim, C.H.

    1996-08-01

    The ALS injector linac is used for the Beam Test Facility (BTF) and the Damping Experiments when it is available in between the ALS filings. These experiments usually require higher quality beams and a better characterization than is normally required for ALS operations. This paper focuses on the beam emittance, energy tilt, and especially the longitudinal variation of the beam parameters. For instance, the authors want to avoid longitudinal variations at the low beta section of the BTF. On the other hand, a large energy tilt is required for post-acceleration compression of the bunch using an alpha magnet. The PARMELA code was modified to calculate and display longitudinal variations of the emittance ellipse. Using the Microsoft Development Studio under Windows NT environment the code can handle a much larger number of particles than was previously possible.

  12. AlN/Fe/AlN nanostructures for magnetooptic magnetometry

    SciTech Connect

    Likov-Jakubisov, E. Vi?ovsk, .; irok, P.; Hrabovsk, D.; Pitora, J.

    2014-05-07

    AlN/Fe/AlN/Cu nanostructures with ultrathin Fe grown by sputtering on Si substrates are evaluated as probes for magnetooptical (MO) mapping of weak currents. They are considered for a laser wavelength of ??=?410?nm (3.02?eV) and operate at oblique light incidence angles, ?{sup (0)}, to enable detection of both in-plane and out-of-plane magnetization. Their performance is evaluated in terms of MO reflected wave electric field amplitudes. The maximal MO amplitudes in AlN/Fe/AlN/Cu are achieved by a proper choice of layer thicknesses. The nanostructures were characterized by MO polar Kerr effect at ?{sup (0)}???5 and longitudinal Kerr effect spectra (?{sup (0)}?=?45) at photon energies between 1 and 5?eV. The nominal profiles were refined using a model-based analysis of the spectra. Closed form analytical expressions are provided, which are useful in the search for maximal MO amplitudes.

  13. 27Al NMR study in ZrNiAl.

    PubMed

    Nowak, B; Hayashi, S

    2000-01-01

    We have studied the microscopic properties of the hexagonal ZrNiAl, a model compound for a wide family of intermetallic compounds crystallizing in this type of structure, by using 27Al NMR spectroscopy. We have investigated the lineshape of static and MAS NMR spectra as a function of magnetic field strength (4.7-9.4 T) and temperature (5-300 K). Our data indicate that the 27Al NMR spectra result from a combined effect of quadrupole and anisotropic shift interactions. The 27Al nuclei are in an environment characterized by the quadrupole coupling constant e2qQ/h of 3.3 MHz, asymmetry parameter etaQ of 0.42, isotropic shift delta(iso) of 393 ppm, shift anisotropy delta(anis) = delta(zz) - (delta(xx) + delta(yy))/2 of 150 ppm, and asymmetry factor etaS of 0.5. They are found to be temperature independent. The spin-lattice relaxation rate measured at 7.05 T is proportional to the temperature with T1T = 135 s K. The mechanisms responsible for observed values of delta(iso), delta(anis), T1T, and the enhanced Korringa constant are discussed. PMID:11270742

  14. Effect of microscale texture on cutting performance of WC/Co-based TiAlN coated tools under different lubrication conditions

    NASA Astrophysics Data System (ADS)

    Zhang, Kedong; Deng, Jianxin; Xing, Youqiang; Li, Shipeng; Gao, Huanhuan

    2015-01-01

    Commonly known the severe friction between the tool and chip affects the tool life and the quality of the machined surfaces. Introducing a lubricant into the tool-chip interface can be used to alleviate the friction, the effectiveness of which may be improved by surface texturing of the tools. Thus, surface textures were fabricated using laser on the rake of the cemented carbide (WC/Co) inserts, then TiAlN films were coated on the textured tools. The effect of the textures on the cutting performance was investigated using the textured coated tools and conventional coated tools in cutting AISI 1045 hardened steel tests. Two batches of cutting tests were carried out, in regimes of full and starved lubrication. The machining performance was assessed in terms of the cutting forces, friction coefficient at the tool-chip interface, surface roughness of machined workpiece and tool wear on the rake face. Results show that the cutting performance of textured tools was enhanced, especially under the full lubrication condition.

  15. Long term corrosion on T91 and AISI1 316L steel in flowing lead alloy and corrosion protection barrier development: Experiments and models

    NASA Astrophysics Data System (ADS)

    Weisenburger, A.; Schroer, C.; Jianu, A.; Heinzel, A.; Konys, J.; Steiner, H.; Mller, G.; Fazio, C.; Gessi, A.; Babayan, S.; Kobzova, A.; Martinelli, L.; Ginestar, K.; Balbaud-Clerier, F.; Martn-Muoz, F. J.; Soler Crespo, L.

    2011-08-01

    Considering the status of knowledge on corrosion and corrosion protection and especially the need for long term compatibility data of structural materials in HLM a set of experiments to generate reliable long term data was defined and performed. The long term corrosion behaviour of the two structural materials foreseen in ADS, 316L and T91, was investigated in the design relevant temperature field, i.e. from 300 to 550 C. The operational window of the two steels in this temperature range was identified and all oxidation data were used to develop and validate the models of oxide scale growth in PbBi. A mechanistic model capable to predict the oxidation rate applying some experimentally fitted parameters has been developed. This model assumes parabolic oxidation and might be used for design and safety relevant investigations in future. Studies on corrosion barrier development allowed to define the required Al content for the formation of thin alumina scales in LBE. These results as well as future steps and required improvements are discussed. Variation of experimental conditions clearly showed that specific care has to be taken with respect to local flow conditions and oxygen concentrations.

  16. Microstructure Evolution and Mechanical Properties of Al/Al-Mg/Al composite sheet metals

    NASA Astrophysics Data System (ADS)

    Cho, Jaehyung; Kim, Su-Hyeon; Kim, Hyoung-Wook; Lim, Cha-Yong; Kim, Eun-Young; Choi, Shi-Hoon

    2011-08-01

    Two different types of aluminum alloys of AA1050 and AA5182 were used to manufacture Al/Al-Mg/Al composite sheet metals by roll bonding technology at room temperature. The composite sheet metals were annealed at 400 C and carried out uniaxial tension tests to investigate mechanical properties. Macroscopic mechanical properties are strongly dependent on the volume (or thickness) fraction of two component layers. Microstructure and texture evolution were also investigated during roll bonding process. The AA1050 sheets located in the outer layer mainly consist of shear texture components and the AA5182 sheet located in the center layer consists of plane strain texture components. With differential speeds of the top and bottom rolls, roll bonding was also carried out. Elongation along the RD and TD was improved at a speed difference of approximately 10%-20%.

  17. Cdk5 sinks into ALS.

    PubMed

    Patzke, Holger; Tsai, Li Huei

    2002-01-01

    Recent research points to an involvement of deregulated cdk5 activity in the pathogenesis of mutant SOD1-mediated disease. In addition, inhibition of this activity might promote motor neuron survival. These observations have opened the door to further research into the role of cdk5 in ALS and other neurodegenerative diseases. PMID:11801324

  18. Dynamic Modeling of ALS Systems

    NASA Technical Reports Server (NTRS)

    Jones, Harry

    2002-01-01

    The purpose of dynamic modeling and simulation of Advanced Life Support (ALS) systems is to help design them. Static steady state systems analysis provides basic information and is necessary to guide dynamic modeling, but static analysis is not sufficient to design and compare systems. ALS systems must respond to external input variations and internal off-nominal behavior. Buffer sizing, resupply scheduling, failure response, and control system design are aspects of dynamic system design. We develop two dynamic mass flow models and use them in simulations to evaluate systems issues, optimize designs, and make system design trades. One model is of nitrogen leakage in the space station, the other is of a waste processor failure in a regenerative life support system. Most systems analyses are concerned with optimizing the cost/benefit of a system at its nominal steady-state operating point. ALS analysis must go beyond the static steady state to include dynamic system design. All life support systems exhibit behavior that varies over time. ALS systems must respond to equipment operating cycles, repair schedules, and occasional off-nominal behavior or malfunctions. Biological components, such as bioreactors, composters, and food plant growth chambers, usually have operating cycles or other complex time behavior. Buffer sizes, material stocks, and resupply rates determine dynamic system behavior and directly affect system mass and cost. Dynamic simulation is needed to avoid the extremes of costly over-design of buffers and material reserves or system failure due to insufficient buffers and lack of stored material.

  19. AlN/Al dual protective coatings on NdFeB by DC magnetron sputtering

    NASA Astrophysics Data System (ADS)

    Li, Jinlong; Mao, Shoudong; Sun, Kefei; Li, Xiaomin; Song, Zhenlun

    2009-11-01

    AlN/Al dual protective coatings were prepared on NdFeB by DC magnetron sputtering in a home-made industrial apparatus. Comparing with Al coating, AlN/Al coatings have a denser structure of an outmost AlN amorphous layer following an inner Al columnar crystal layer. The coatings and NdFeB substrate combine well, and moreover, there is occurrence of metallurgy bonding in the interface layer. Both Al and AlN/Al coatings have a good protective ability to NdFeB. Especially, the corrosion resistance of AlN/Al coated NdFeB is improved largely. AlN/Al and Al protective coatings not only do not deteriorate the magnetic properties of NdFeB, but contribute to their slight increase.

  20. Large rectification magnetoresistance in nonmagnetic Al/Ge/Al heterojunctions.

    PubMed

    Zhang, Kun; Li, Huan-Huan; Grnberg, Peter; Li, Qiang; Ye, Sheng-Tao; Tian, Yu-Feng; Yan, Shi-Shen; Lin, Zhao-Jun; Kang, Shi-Shou; Chen, Yan-Xue; Liu, Guo-Lei; Mei, Liang-Mo

    2015-01-01

    Magnetoresistance and rectification are two fundamental physical properties of heterojunctions and respectively have wide applications in spintronics devices. Being different from the well known various magnetoresistance effects, here we report a brand new large magnetoresistance that can be regarded as rectification magnetoresistance: the application of a pure small sinusoidal alternating-current to the nonmagnetic Al/Ge Schottky heterojunctions can generate a significant direct-current voltage, and this rectification voltage strongly varies with the external magnetic field. We find that the rectification magnetoresistance in Al/Ge Schottky heterojunctions is as large as 250% at room temperature, which is greatly enhanced as compared with the conventional magnetoresistance of 70%. The findings of rectification magnetoresistance open the way to the new nonmagnetic Ge-based spintronics devices of large rectification magnetoresistance at ambient temperature under the alternating-current due to the simultaneous implementation of the rectification and magnetoresistance in the same devices. PMID:26387967

  1. Large rectification magnetoresistance in nonmagnetic Al/Ge/Al heterojunctions

    PubMed Central

    Zhang, Kun; Li, Huan-huan; Grnberg, Peter; Li, Qiang; Ye, Sheng-tao; Tian, Yu-feng; Yan, Shi-shen; Lin, Zhao-jun; Kang, Shi-shou; Chen, Yan-xue; Liu, Guo-lei; Mei, Liang-mo

    2015-01-01

    Magnetoresistance and rectification are two fundamental physical properties of heterojunctions and respectively have wide applications in spintronics devices. Being different from the well known various magnetoresistance effects, here we report a brand new large magnetoresistance that can be regarded as rectification magnetoresistance: the application of a pure small sinusoidal alternating-current to the nonmagnetic Al/Ge Schottky heterojunctions can generate a significant direct-current voltage, and this rectification voltage strongly varies with the external magnetic field. We find that the rectification magnetoresistance in Al/Ge Schottky heterojunctions is as large as 250% at room temperature, which is greatly enhanced as compared with the conventional magnetoresistance of 70%. The findings of rectification magnetoresistance open the way to the new nonmagnetic Ge-based spintronics devices of large rectification magnetoresistance at ambient temperature under the alternating-current due to the simultaneous implementation of the rectification and magnetoresistance in the same devices. PMID:26387967

  2. Thermodynamic modeling of Pt-Al and Pd-Al

    NASA Astrophysics Data System (ADS)

    Carr, Derek

    2011-03-01

    Pure platinum and pure palladium are too soft for typical jewelry applications. Adding small amounts of other metals can significantly increase their performance. However, international hallmarking standards require the alloys to be 95% pure by weight. How does one achieve significant improvements in performance adding only small amounts (5 wt-%) of other metals? Significant improvements are possible even with small additions if precipitate hardening can be induced. Using a combination of first-principles, cluster expansion, and Monte Carlo modeling, we have identified new Pt-rich/Pd-rich phases in Pt-Al and Pd-Al that should be useful in precipitate hardening. Thermodynamical modeling indicates that the phases are experimentally feasible (not kinetically inhibited).

  3. Large rectification magnetoresistance in nonmagnetic Al/Ge/Al heterojunctions

    NASA Astrophysics Data System (ADS)

    Zhang, Kun; Li, Huan-Huan; Grnberg, Peter; Li, Qiang; Ye, Sheng-Tao; Tian, Yu-Feng; Yan, Shi-Shen; Lin, Zhao-Jun; Kang, Shi-Shou; Chen, Yan-Xue; Liu, Guo-Lei; Mei, Liang-Mo

    2015-09-01

    Magnetoresistance and rectification are two fundamental physical properties of heterojunctions and respectively have wide applications in spintronics devices. Being different from the well known various magnetoresistance effects, here we report a brand new large magnetoresistance that can be regarded as rectification magnetoresistance: the application of a pure small sinusoidal alternating-current to the nonmagnetic Al/Ge Schottky heterojunctions can generate a significant direct-current voltage, and this rectification voltage strongly varies with the external magnetic field. We find that the rectification magnetoresistance in Al/Ge Schottky heterojunctions is as large as 250% at room temperature, which is greatly enhanced as compared with the conventional magnetoresistance of 70%. The findings of rectification magnetoresistance open the way to the new nonmagnetic Ge-based spintronics devices of large rectification magnetoresistance at ambient temperature under the alternating-current due to the simultaneous implementation of the rectification and magnetoresistance in the same devices.

  4. CO oxidation mechanism on AlAun

    NASA Astrophysics Data System (ADS)

    Guo, Ling; An, Xiaoyu; Li, Shuying; Li, Aixia

    2015-04-01

    CO oxidation via LH mechanism on AlAun (n = 1-12) have been studied by density functional theory calculations with the aim to shed light on reaction mechanism and catalytic activity of AlAu alloy. The AlAun molecular structures and adsorption energies of a single CO or O2 molecule as well as coadsorption energies of CO + O2, CO2 + O, and CO + O on various distinctive sites of each AlAun are predicted. The calculated results show that the overall LH, AlAun + O2(gas) + CO(gas) ?A lAun-O2(ads) + CO(ads) ? AlAun-OOCO(ads) ? AlAun-O(ads) + CO2(gas) ? AlAun-O(ads) + CO(ads) ? AlAun-OCO(ads) ? AlAun + CO2(gas) is calculated to by exothermic by -144.8 kcal/mol. It suggests that the CO oxidation catalyzed by the AlAu6 and AlAu12 is likely to occur at or even below room temperature. AlAu6 and AlAu12 exhibit a larger catalytic activity for CO oxidation by O2 molecule.

  5. Synthesis of AlN/Al Polycrystals along with Al Nanoparticles Using Thermal Plasma Route

    SciTech Connect

    Kanhe, Nilesh S.; Nawale, A. B.; Kulkarni, N. V.; Bhoraskar, S. V.; Mathe, V. L.; Das, A. K.

    2011-07-15

    This paper for the first time reports the (200) oriented growth of hexagonal Aluminum nitride crystals during synthesis of aluminum nanoparticles in dc transferred arc thermal plasma reactor by gas phase condensation in nitrogen plasma. The structural and morphological study of as synthesized AlN crystal and aluminium nanoparticles was done by using the x-ray diffraction method, scanning electron microscopy and transmission electron microscopy.

  6. Synthesis of AlN/Al Polycrystals along with Al Nanoparticles Using Thermal Plasma Route

    NASA Astrophysics Data System (ADS)

    Kanhe, Nilesh S.; Nawale, A. B.; Kulkarni, N. V.; Bhoraskar, S. V.; Mathe, V. L.; Das, A. K.

    2011-07-01

    This paper for the first time reports the (200) oriented growth of hexagonal Aluminum nitride crystals during synthesis of aluminum nanoparticles in dc transferred arc thermal plasma reactor by gas phase condensation in nitrogen plasma. The structural and morphological study of as synthesized AlN crystal and aluminium nanoparticles was done by using the x-ray diffraction method, scanning electron microscopy and transmission electron microscopy.

  7. NiAl-base composite containing high volume fraction of AlN for advanced engines

    NASA Technical Reports Server (NTRS)

    Hebsur, Mohan (Inventor); Whittenbeger, John D. (Inventor); Lowell, Carl F. (Inventor)

    1994-01-01

    A particulate reinforced NiAl-AlN composite alloy has a NiAl matrix and greater than about 13 volume percent fine particles of AlN within the matrix. The particles preferably have a diameter from about 15 nanometers to about 50 nanometers. The particulate reinforced NiAl-AlN composite alloy may be prepared by cryomilling prealloyed NiAl in liquid nitrogen using grinding media having a diameter of from about 2 to 6 mm at an impeller speed of from about 450 RPM to about 800 RPM. The cryomilling may be done for a duration of from about 4 hours to about 20 hours to obtain a cryomilled powder. The cryomilled powder may be consolidated to form the particulate reinforced NiAl-AlN composite alloy. The particulate reinforced alloy can further include a toughening alloy. The toughening alloy may include NiCrAlY, FeCrAlY, and FeAl.

  8. Everyday Life with ALS: A Practical Guide

    MedlinePLUS

    ... in Progress Search form Search Everyday Life with ALS: A Practical Guide March 2010 Download a printable ... in this one. Back to top Resources MDA ALS Division The Muscular Dystrophy Association, one of the ...

  9. Benefits for Military Veterans with ALS

    MedlinePLUS

    ... Get Involved Donate Military Veterans Resources for Military Veterans, Families & Survivors The ALS Association is working everyday to ... not served. This site is designed specifically for veterans with ALS, their families and survivors. Here you will learn what benefits ...

  10. New synthetic route to Al4O4C reinforced Al-Al2O3 composite materials

    NASA Astrophysics Data System (ADS)

    Jiang, Peng; Sun, Jialin; Xue, Wendong; Chen, Junhong; Vasant Kumar, R.; Li, Yong

    2015-08-01

    Carbon free Al-Al2O3 composite sliding gate materials were successfully prepared by adding excess amount of Al powders through carbon burial sintering at 1450 C for 6 h. Physical properties including apparent porosity, bulk density, ambient temperature crushing strength and hot rupture modulus were characterized for all the samples and addition of 9 at% aluminum powder was proved to exhibit optimal properties. The XRD and SEM results reveal that Al4O4C and AlN phases shown in the product samples are serving as reinforcement phase, contributing to better physical performances.

  11. Photoelectrical, photophysical and photocatalytic properties of Al based MOFs: MIL-53(Al) and MIL-53-NH2(Al)

    NASA Astrophysics Data System (ADS)

    An, Yang; Li, Huiliang; Liu, Yuanyuan; Huang, Baibiao; Sun, Qilong; Dai, Ying; Qin, Xiaoyan; Zhang, Xiaoyang

    2016-01-01

    Two Al based MOFs (MIL-53(Al) and MIL-53-NH2 (Al)) were synthesized, and their photoelectrical, photophysical and photocatalytic properties towards oxygen evolution from water were investigated. Different from the ligand to metal charge transfer process previously reported, we proposes a new photocatalytic mechanism based on electron tunneling according to the results of theoretical calculation, steady state and time resolved fluorescence spectra. The organic linkers absorb photons, giving rise to electrons and holes. Then, the photogenerated electrons tunnel through the AlO6-octahedra, which not only inhibit the recombination of photogenerated charge carriers, but also is a key factor to the photocatalytic activity of Al based MOFs.

  12. Al-Co-Fe (Aluminium - Cobalt - Iron)

    NASA Astrophysics Data System (ADS)

    Materials Science International Team MSIT

    This document is part of Subvolume A1 'Light Metal Systems. Part 1: Selected Systems from Ag-Al-Cu to Al-Cu-Er' of Volume 11 'Ternary Alloy Systems - Phase Diagrams, Crystallographic and Thermodynamic Data critically evaluated by MSIT' of Landolt-Brnstein - Group IV Physical Chemistry. It provides the data for the ternary system Al-Co-Fe (Aluminium - Cobalt - Iron).

  13. Framework Al zoning in zeolite ECR-1.

    PubMed

    Shin, Jiho; Ahn, Nak Ho; Cho, Sung June; Ren, Limin; Xiao, Feng-Shou; Hong, Suk Bong

    2014-02-25

    Rietveld analyses of the synchrotron X-ray diffraction data for various cation forms of zeolite ECR-1 have demonstrated framework Al zoning, which parallels the alternation of Al-rich maz and Al-poor mor layers. This can be further supported by notable differences in the average bond valence of its 10 crystallographically distinct tetrahedral sites. PMID:24409461

  14. Nonstoichiometry of Al-Zr intermetallic phases

    SciTech Connect

    Radmilovic, V.; Thomas, G.

    1994-06-01

    Nonstoichiometry of metastable cubic {beta}{prime} and equilibrium tetragonal {beta} Al-Zr intermetallic phases of the nominal composition Al{sub 3}Zr in Al-rich alloys has been extensively studied. It is proposed that the ``dark contrast`` of {beta}{prime} core in {beta}{prime}/{sigma}{prime} complex precipitates, in Al-Li-Zr based alloys, is caused by incorporation of Al and Li atoms into the {beta}{prime} phase on Zr sublattice sites, forming nonstoichiometric Al-Zr intermetallic phases, rather than by Li partitioning only. {beta}{prime} particles contain very small amounts of Zr, approximately 5 at.%, much less than the stoichiometric 25 at.% in the Al{sub 3}Zr metastable phase. These particles are, according to simulation of high resolution images, of the Al{sub 3}(Al{sub 0.4}Li{sub 0.4}Zr{sub 0.2}) type. Nonstoichiometric particles of average composition Al{sub 4}Zr and Al{sub 6}Zr are observed also in the binary Al-Zr alloy, even after annealing for several hours at 600{degree}C.

  15. Aluminium distribution in ZSM-5 revisited: The role of Al-Al interactions

    SciTech Connect

    Ruiz-Salvador, A. Rabdel; Grau-Crespo, Ricardo; Gray, Aileen E.; Lewis, Dewi W.

    2013-02-15

    We present a theoretical study of the distribution of Al atoms in zeolite ZSM-5 with Si/Al=47, where we focus on the role of Al-Al interactions rather than on the energetics of Al/Si substitutions at individual sites. Using interatomic potential methods, we evaluate the energies of the full set of symmetrically independent configurations of Al siting in a Si{sub 94}Al{sub 2}O{sub 192} cell. The equilibrium Al distribution is determined by the interplay of two factors: the energetics of the Al/Si substitution at an individual site, which tends to populate particular T sites (e.g., the T14 site), and the Al-Al interaction, which at this Si/Al maximises Al-Al distances in general agreement with Dempsey's rule. However, it is found that the interaction energy changes approximately as the inverse of the square of the distance between the two Al atoms, rather than the inverse of the distance expected if this were merely charge repulsion. Moreover, we find that the anisotropic nature of the framework density plays an important role in determining the magnitude of the interactions, which are not simply dependent on Al-Al distances. - Graphical abstract: Role of Al-Al interactions in high silica ZSM-5 is shown to be anisotropic in nature and not dependent solely on Coulombic interactions. Highlights: Black-Right-Pointing-Pointer Si-Al distribution in ZSM-5 is revisited, stressing the role of the Al-Al interaction. Black-Right-Pointing-Pointer Coulomb interactions are not the key factors controlling the Al siting. Black-Right-Pointing-Pointer Anisotropy of the framework is identified as a source of departure from Dempsey's rule.

  16. Opportunity's 'Rub al Khali' Panorama

    NASA Technical Reports Server (NTRS)

    2005-01-01

    [figure removed for brevity, see original site] Click on the image for Opportunity's 'Rub al Khali' Panorama (QTVR)

    This panoramic image, dubbed 'Rub al Khali,' was acquired by NASA's Mars Exploration Rover Opportunity on the plains of Meridiani during the period from the rover's 456th to 464th sols on Mars (May 6 to May 14, 2005). Opportunity was about 2 kilometers (1.2 miles) south of 'Endurance Crater' at a place known informally as 'Purgatory Dune.'

    The rover was stuck in the dune's deep fine sand for more than a month. 'Rub al Khali' (Arabic translation: 'the empty quarter') was chosen as the name for this panorama because it is the name of a similarly barren, desolate part of the Saudi Arabian desert on Earth.

    The view spans 360 degrees. It consists of images obtained in 97 individual pointings of the panoramic camera. The camera took images with five camera filters at each pointing. This 22,780-by-6,000-pixel mosaic is an approximately true-color rendering generated using the images acquired through filters admitting light wavelengths of 750, 530, and 480 nanometers.

    Lighting varied during the nine sols it took to acquire this panorama, resulting in some small image seams within the mosaic. These seams have been smoothed in sky parts of the mosaic to better simulate the vista that a person would see if able to view it all at the same time on Mars.

    Opportunity's tracks leading back to the north (center of the panorama) are a reminder of the rover's long trek from Endurance Crater. The deep ruts dug by Opportunity's wheels as it became stuck in the sand appear in the foreground. The crest and trough of the last ripple the rover crossed before getting stuck is visible in the center. These wind-formed sand features are only about 10 to 15 centimeters (4 to 6 inches) tall. The crest of the actual ripple where the rover got stuck can be seen just to the right of center. The tracks and a few other places on and near ripple crests can be seen in this color image to be dustier than the undisturbed or 'normal' plains soils in Meridiani. Since the time these ruts were made, some of the dust there has been blown away by the wind, reaffirming the dynamic nature of the martian environment, even in this barren, ocean-like desert of sand.

  17. Cyclic oxidation resistance of a reaction milled NiAl-AlN composite

    NASA Technical Reports Server (NTRS)

    Lowell, Carl E.; Barrett, Charles A.; Whittenberger, J. D.

    1990-01-01

    Based upon recent mechanical property tests a NiAl-AlN composite produced by cryomilling has very attractive high temperature strength. This paper focuses on the oxidation resistance of the NiAl-AlN composite at 1473 and 1573 K as compared to that of Ni-47Al-0.15Zr, one of the most oxidation resistant intermetallics. The results of cyclic oxidation tests show that the NiAl-AlN composite has excellent properties although not quite as good as those of Ni-47Al-0.15Zr. The onset of failure of the NiAl-AlN was unique in that it was not accompanied by a change in scale composition from alumina to less protective oxides. Failure in the composite appears to be related to the entrapment of AlN particles within the alumina scale.

  18. Instandhaltungsmanagement als Gestaltungsfeld Ganzheitlicher Produktionssysteme

    NASA Astrophysics Data System (ADS)

    Dombrowski, Uwe; Schulze, Sven; Otano, Isabel Crespo

    Sich kontinuierlich verändernde Rahmenbedingungen, wie beispielsweise eine steigende Variantenvielfalt, verkürzte Produktlebenszyklen sowie Kundenforderungen nach höherer Qualität, kürzeren Lieferzeiten und geringeren Kosten, fordern von produzierenden Unternehmen eine stetige Anpassung der Prozesse, der Organisation und der Strukturen. Seit den 90er Jahren versuchen immer mehr deutsche Unternehmen diesen veränderten Anforderungen mit der Einführung eines Ganzheitlichen Produktionssystems (GPS) zu begegnen. Ganzheitliche Produktionssysteme sind dabei in ihren Grundlagen an das Toyota Produktionssystem angelehnt, vereinigen aber auch weitere Methoden zu einem unternehmensspezifischen Regelwerk. Im Rahmen des langfristigen Trends zu unternehmensindividuellen Produktionssystemen wird sowohl in der Industrie als auch in der Forschung intensiv über das Toyota Produktionssystem, Lean Production, Lean Management und Ganzheitliche Produktionssysteme diskutiert, werden Konzepte zu Implementierung und Betrieb erstellt und die Wirtschaftlichkeit untersucht.

  19. Systems Engineering Techniques for ALS Decision Making

    NASA Technical Reports Server (NTRS)

    Rodriquez, Luis F.; Drysdale, Alan E.; Jones, Harry; Levri, Julie A.

    2004-01-01

    The Advanced Life Support (ALS) Metric is the predominant tool for predicting the cost of ALS systems. Metric goals for the ALS Program are daunting, requiring a threefold increase in the ALS Metric by 2010. Confounding the problem, the rate new ALS technologies reach the maturity required for consideration in the ALS Metric and the rate at which new configurations are developed is slow, limiting the search space and potentially giving the perspective of a ALS technology, the ALS Metric may remain elusive. This paper is a sequel to a paper published in the proceedings of the 2003 ICES conference entitled, "Managing to the metric: an approach to optimizing life support costs." The conclusions of that paper state that the largest contributors to the ALS Metric should be targeted by ALS researchers and management for maximum metric reductions. Certainly, these areas potentially offer large potential benefits to future ALS missions; however, the ALS Metric is not the only decision-making tool available to the community. To facilitate decision-making within the ALS community a combination of metrics should be utilized, such as the Equivalent System Mass (ESM)-based ALS metric, but also those available through techniques such as life cycle costing and faithful consideration of the sensitivity of the assumed models and data. Often a lack of data is cited as the reason why these techniques are not considered for utilization. An existing database development effort within the ALS community, known as OPIS, may provide the opportunity to collect the necessary information to enable the proposed systems analyses. A review of these additional analysis techniques is provided, focusing on the data necessary to enable these. The discussion is concluded by proposing how the data may be utilized by analysts in the future.

  20. Wear behavior of Al-Al{sub 3}Ti composite manufactured by a centrifugal method

    SciTech Connect

    Watanabe, Yoshimi; Yamanaka, Noboru; Fukui, Yasuyoshi

    1999-12-01

    The purpose of the present study was to develop a wear-resistant, light Al-Al{sub 3}Ti composite material. An Al-Al{sub 3}Ti composite specimen was machined from a thick-walled tube of Al-Al{sub 3}Ti functionally graded material (FGM) manufactured by the centrifugal method from a commercial ingot of Al-5 mass% Ti master alloy. The alloy was heated to a temperature where solid Al{sub 3}Ti particles resided in a liquid Al matrix, and then the centrifugal method was carried out. Al{sub 3}Ti particles in a commercial alloy ingot exist as platelets, and this shape was maintained through the casting. Three kinds of wear specimens were prepared, taking into account the morphology of the Al{sub 3}Ti particles in the thick-walled FGM tube; the Al{sub 3}Ti particles were arranged with their platelet planes nearly normal to the radial direction as a result of the applied centrifugal force. The wear resistance of the Al-Al{sub 3}Ti composite was significantly higher than that of pure Al. Wear-resistance anisotropy and dissolution of the Al{sub 3}Ti into the Al matrix at the near-surface region, around 100 {micro}m in depth, were also observed. The mechanism of the supersaturated-layer formation and the origin of the anisotropic wear resistance are discussed.

  1. Oxidation induced softening in Al nanowires

    NASA Astrophysics Data System (ADS)

    Sen, Fatih G.; Qi, Yue; van Duin, Adri C. T.; Alpas, Ahmet T.

    2013-02-01

    The mechanical properties of metallic nanowires depend dramatically on the atmospheric conditions. Molecular-dynamics simulations with ReaxFF were conducted to study tensile elastic deformation of oxidized Al nanowires. The thin amorphous oxide shell formed around Al nanowires had a very low Young's modulus of 26 GPa, due to its low density and low Al-O coordination. Consequently, for diameters less than 100 nm, the composite Young's modulus of oxide-covered Al nanowires showed a size dependence implying that in this case "smaller is softer." The model developed also explained the discrepancies in the reported modulus values of nanometer-scale Al thin films.

  2. THE INFLUENCE OF COLD?WORK LEVEL ON THE IRRADIATION CREEP AND The Influence of Cold?Work Level on The Irradiation Creep and Swelling of AISI 316 Stainless Steel Irradiated as Pressurized Tubes In The EBR-II Fast Reactor

    SciTech Connect

    Gilbert, Edgar R.; Garner, Francis A.

    2006-09-01

    Pressurized tubes of AISI 316 stainless steel irradiated in the P-1 experiment in the EBR-II fast reactor have been measured to determine the dependence of irradiation-induced strains resulting from plastic deformation, irradiation creep, void swelling and precipitation. It is shown that the Soderberg relation predicting no axial creep strains in biaxially-loaded tubes is correct for both plastic and creep strains. Swelling strains are shown to be isotropically distributed both for stress-free and stress-affected swelling, while precipitation strains are somewhat anisotropic in their distribution. When corrected for stress-enhancement of swelling, the derived irradiation creep strains appear to be identical for both annealed and 20% cold-worked specimens, and also for tubes strained by rise to power increases in pressure. For relatively small creep strains it is often difficult to separate the creep and non-creep components of deformation.

  3. Nucleation and Precipitation Strengthening in Dilute Al-Ti and Al-Zr Alloys

    NASA Astrophysics Data System (ADS)

    Knipling, Keith E.; Dunand, David C.; Seidman, David N.

    2007-10-01

    Two conventionally solidified Al-0.2Ti alloys (with 0.18 and 0.22 at. pct Ti) exhibit no hardening after aging up to 3200 hours at 375 C or 425 C. This is due to the absence of Al3Ti precipitation, as confirmed by electron microscopy and electrical conductivity measurements. By contrast, an Al-0.2Zr alloy (with 0.19 at. pct Zr) displays strong age hardening at both temperatures due to precipitation of Al3Zr (L12) within Zr-enriched dendritic regions. This discrepancy between the two alloys is explained within the context of the equilibrium phase diagrams: (1) the disparity in solid and liquid solubilities of Ti in ?-Al is much greater than that of Zr in ?-Al; and (2) the relatively small liquid solubility of Ti in ?-Al limits the amount of solute retained in solid solution during solidification, while the comparatively high solid solubility reduces the supersaturation effecting precipitation during post-solidification aging. The lattice parameter mismatch of Al3Ti (L12) with ?-Al is also larger than that of Al3Zr (L12), further hindering nucleation of Al3Ti. Classical nucleation theory indicates that the minimum solute supersaturation required to overcome the elastic strain energy of Al3Ti nuclei cannot be obtained during conventional solidification of Al-Ti alloys (unlike for Al-Zr alloys), thus explaining the absence of Al3Ti precipitation and the presence of Al3Zr precipitation.

  4. Reactive Plasma Spraying of Fine Al2O3/AlN Feedstock Powder

    NASA Astrophysics Data System (ADS)

    Shahien, Mohammed; Yamada, Motohiro; Yasui, Toshiaki; Fukumoto, Masahiro

    2013-12-01

    Reactive plasma spraying (RPS) is a promising technology for in situ formation of aluminum nitride (AlN) coatings. Recently, AlN-based coatings were fabricated by RPS of alumina (Al2O3) powder in N2/H2 thermal plasma. This study investigated the feasibility of RPS of a fine Al2O3/AlN mixture and the influence of the plasma gases (N2, H2) on the nitriding conversion, and coating microstructure and properties. Thick AlN/Al2O3 coatings with high nitride content were successfully fabricated. The coatings consist of h-AlN, c-AlN, Al5O6N, γ-Al2O3, and a small amount of α-Al2O3. Use of fine particles enhanced the nitriding conversion and the melting tendency by increasing the surface area. Furthermore, the AlN additive improved the AlN content in the coatings. Increasing the N2 gas flow rate improved the nitride content and complete crystal growth to the h-AlN phase, and enhanced the coating thickness. On the other hand, though the H2 gas is required for plasma nitriding of the Al2O3 particles, increasing its flow rate decreased the nitride content and the coating thickness. Remarkable influence of the plasma gases on the coating composition, microstructure, and properties was observed during RPS of the fine particles.

  5. Mg isotopic heterogeneity, Al-Mg isochrons, and canonical 26Al/27Al in the early solar system

    NASA Astrophysics Data System (ADS)

    Wasserburg, G. J.; Wimpenny, Josh; Yin, Qing-Zhu

    2012-12-01

    Abstract-There is variability in the Mg isotopic composition that is a reflection of the widespread heterogeneity in the isotopic composition of the elements in the solar system at approximately 100 ppm. Measurements on a single calcium-aluminum-rich inclusion (CAI) gave a good correlation of 26Mg/24Mg with 27<span class="hlt">Al</span>/24Mg, yielding an isochron corresponding to an initial (26<span class="hlt">Al</span>/27<span class="hlt">Al</span>)o = (5.27 ± 0.18) × 10-5 and an initial (26Mg/24Mg)o = -0.127 ± 0.032‰ relative to the standard. This isochron is parallel to that obtained by <link href="#b41 #b42">Jacobsen et <span class="hlt">al</span>. (2008), but is distinctively offset. This demonstrates that there are different initial Mg isotopic compositions in different samples with the same 26<span class="hlt">Al</span>/27<span class="hlt">Al</span>. No inference about uniformity/heterogeneity of 26<span class="hlt">Al</span>/27<span class="hlt">Al</span> on a macro scale can be based on the initial (26Mg/24Mg)o values. Different values of 26<span class="hlt">Al</span>/27<span class="hlt">Al</span> for samples representing the same point in time would prove heterogeneity of 26<span class="hlt">Al</span>/27<span class="hlt">Al</span>. The important issue is whether the bulk solar inventory of 26<span class="hlt">Al</span>/27<span class="hlt">Al</span> was approximately 5 × 10-5 at some point in the early solar system. We discuss ultra refractory phases of solar type oxygen isotope composition with 26<span class="hlt">Al</span>/27<span class="hlt">Al</span> from approximately 5 × 10-5 to below 0.2 × 10-5. We argue that the real issues are: intrinsic heterogeneity in the parent cloud; mechanism and timing for the later production of 16O-poor material; and the relationship to earlier formed 16O-rich material in the disk. 26<span class="hlt">Al</span>-free refractories can be produced at a later time by late infall, if there is an adequate heat source, or from original heterogeneities in the placental molecular cloud from which the solar system formed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/10177889','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/10177889"><span id="translatedtitle"><span class="hlt">AISI</span> Direct Steelmaking Program. Final technical report</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Aukrust, E.</p> <p>1994-08-01</p> <p>This final report deals with the results of a 5-yr project for developing a more energy-efficient, environmentally friendly, less costly process for producing hot metal than current coke ovens and blast furnaces. In the process, iron ore pellets are smelted in a foamy slag created by reaction of coal char with molten slag to produce CO. The CO further reacts with oxygen, which also reacts with coal volatile matter, to produce the heat necessary to sustain the endothermic reduction reaction. The uncombusted CO and H{sub 2} from the coal are used to preheat and prereduce hematite pellets for the most efficient use of the energy in the coal. Laboratory programs confirmed that the process steps worked. Pilot plant studies were successful. Economic analysis for a 1 million tpy plant is promising.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013ApPhL.102k1603M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013ApPhL.102k1603M"><span id="translatedtitle">Atom probe analysis of <span class="hlt">Al</span>N interlayers in <span class="hlt">AlGaN/Al</span>N/GaN heterostructures</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Mazumder, Baishakhi; Kaun, Stephen W.; Lu, Jing; Keller, Stacia; Mishra, Umesh K.; Speck, James S.</p> <p>2013-03-01</p> <p>Atom probe tomography was used to characterize <span class="hlt">Al</span>N interlayers in <span class="hlt">AlGaN/Al</span>N/GaN heterostructures grown by plasma-assisted molecular beam epitaxy (PAMBE), NH3-based molecular beam epitaxy (NH3-MBE), and metal-organic chemical vapor deposition (MOCVD). The PAMBE-grown <span class="hlt">Al</span>N interlayer had the highest purity, with nearly 100% of group-III sites occupied by <span class="hlt">Al</span>. The group-III site concentrations of <span class="hlt">Al</span> for interlayers grown by NH3-MBE and MOCVD were 85% and 47%, respectively. Hall measurements were performed to determine the two-dimensional electron gas mobility and sheet concentration. Sheet concentrations were 25%-45% higher with molecular beam epitaxy than with MOCVD, and these results matched well with atom probe data.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/22162790','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/22162790"><span id="translatedtitle">Atom probe analysis of <span class="hlt">Al</span>N interlayers in <span class="hlt">AlGaN/Al</span>N/GaN heterostructures</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Mazumder, Baishakhi; Kaun, Stephen W.; Speck, James S.; Lu, Jing; Keller, Stacia; Mishra, Umesh K.</p> <p>2013-03-18</p> <p>Atom probe tomography was used to characterize <span class="hlt">Al</span>N interlayers in <span class="hlt">AlGaN/Al</span>N/GaN heterostructures grown by plasma-assisted molecular beam epitaxy (PAMBE), NH{sub 3}-based molecular beam epitaxy (NH{sub 3}-MBE), and metal-organic chemical vapor deposition (MOCVD). The PAMBE-grown <span class="hlt">Al</span>N interlayer had the highest purity, with nearly 100% of group-III sites occupied by <span class="hlt">Al</span>. The group-III site concentrations of <span class="hlt">Al</span> for interlayers grown by NH{sub 3}-MBE and MOCVD were {approx}85% and {approx}47%, respectively. Hall measurements were performed to determine the two-dimensional electron gas mobility and sheet concentration. Sheet concentrations were {approx}25%-45% higher with molecular beam epitaxy than with MOCVD, and these results matched well with atom probe data.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/443755','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/443755"><span id="translatedtitle">Reply to Vance et <span class="hlt">al</span>.</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Woon-Chee Yee; Elliott, J.L; Kwon, J.M.; Goodfellow, P.</p> <p>1996-07-01</p> <p>In our report of a family with a motor and sensory polyneuropathy that was linked to chromosome 3q, we classified this neuropathy as a form of hereditary motor and sensory neuropathy II (HMSN II, also known as {open_quotes}CMT2{close_quotes}). Doubts have been raised by Vance et <span class="hlt">al</span>. as to whether this neuropathy should be classified as hereditary sensory autonomic neuropathy I (HSAN I) instead of HMSN II. While it is reasonable to raise such doubts, we believe that the neuropathy is best designated as HMSN II for the reasons described below. The group of disorders described as HSAN are characterized by primary or predominant involvement of sensory and autonomic neurons that fail to develop or that undergo atrophy and degeneration. These disorders were extensively reviewed by Dyck and Ohta, who initially described them as the hereditary sensory neuropathies (HSN). It was Dyck who subsequently suggested that these disorders be designated HSAN rather than HSN, because of the presence of autonomic involvement. 8 refs.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/15510857','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/15510857"><span id="translatedtitle">Development of <span class="hlt">Al</span>2O3 fiber-reinforced <span class="hlt">Al</span>2O3-based ceramics.</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Tanimoto, Yasuhiro; Nemoto, Kimiya</p> <p>2004-09-01</p> <p>The purpose of this study was to use a tape casting technique to develop an <span class="hlt">Al</span>2O3 fiber-reinforced <span class="hlt">Al</span>2O3-based ceramic material (<span class="hlt">Al</span>2O3-fiber/<span class="hlt">Al</span>2O3 composite) into a new type of dental ceramic. The <span class="hlt">Al</span>2O3-based ceramic used a matrix consisting of 60 wt% <span class="hlt">Al</span>2O3 powder and 40 wt% SiO2-B2O3 powder. The prepreg sheets of <span class="hlt">Al</span>2O3-fiber/<span class="hlt">Al</span>2O3 composite (in which uniaxially aligned <span class="hlt">Al</span>2O3 fibers were infiltrated with the <span class="hlt">Al</span>2O3-based matrix) were fabricated continuously using tape casting technique with a doctor blade system. Multilayer preforms of <span class="hlt">Al</span>2O3-fiber/<span class="hlt">Al</span>2O3 composite sheets were then sintered at a maximum temperature of 1000 degrees C under an atmospheric pressure in a furnace. The results showed that the shrinkage and bending properties of <span class="hlt">Al</span>2O3-fiber/<span class="hlt">Al</span>2O3 composite exceeded those of unreinforced <span class="hlt">Al</span>2O3--hence demonstrating the positive effects of fiber reinforcement. In conclusion, the tape casting technique has been utilized to successfully develop a new type of dental ceramic material. PMID:15510857</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/8817656','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/8817656"><span id="translatedtitle">Structure and regulation of the <span class="hlt">ALS</span> gene.</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Ooi, G T; Cohen, F J; Hsieh, S; Seto, D; Rechler, M M; Boisclair, Y R</p> <p>1995-01-01</p> <p>The mouse <span class="hlt">ALS</span> gene spans at least 6 kb. It contains 2 exons which encode a protein highly homologous to human and rat <span class="hlt">ALS</span>. It was localized to mouse chromosome 17 by flourescent in situ hybridization. The 5' flanking region lacks a TATA box but contains GC boxes that may be recognised by transcription factors such as Spl. Hepatic <span class="hlt">ALS</span> mRNA is decreased in rats following hypophysectomy, and restored by stimulated <span class="hlt">ALS</span> promoter activity in a rat hepatoma cell line, but not in 3T3-F442A mouse preadipocyte fibroblasts, suggesting that utilisation of the <span class="hlt">ALS</span> promoter is cell-type specific. The rat hepatoma system is a promising system to study the regulation of <span class="hlt">ALS</span> gene expression, and the signalling pathways of CH regulation. PMID:8817656</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4683522','PMC'); return false;" href="http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4683522"><span id="translatedtitle">Growth and Stress-induced Transformation of Zinc blende <span class="hlt">Al</span>N Layers in <span class="hlt">Al-Al</span>N-TiN Multilayers</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Li, Nan; Yadav, Satyesh K.; Wang, Jian; Liu, Xiang-Yang; Misra, Amit</p> <p>2015-01-01</p> <p><span class="hlt">Al</span>N nanolayers in sputter deposited {111}<span class="hlt">Al/Al</span>N/TiN multilayers exhibit the metastable zinc-blende-structure (z-<span class="hlt">Al</span>N). Based on density function theory calculations, the growth of the z-<span class="hlt">Al</span>N is ascribed to the kinetically and energetically favored nitridation of the deposited aluminium layer. In situ nanoindentation of the as-deposited {111}<span class="hlt">Al/Al</span>N/TiN multilayers in a high-resolution transmission electron microscope revealed the z-<span class="hlt">Al</span>N to wurzite <span class="hlt">Al</span>N phase transformation through collective glide of Shockley partial dislocations on every two {111} planes of the z-<span class="hlt">Al</span>N. PMID:26681109</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015NatSR...518554L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015NatSR...518554L"><span id="translatedtitle">Growth and Stress-induced Transformation of Zinc blende <span class="hlt">Al</span>N Layers in <span class="hlt">Al-Al</span>N-TiN Multilayers</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Li, Nan; Yadav, Satyesh K.; Wang, Jian; Liu, Xiang-Yang; Misra, Amit</p> <p>2015-12-01</p> <p><span class="hlt">Al</span>N nanolayers in sputter deposited {111}<span class="hlt">Al/Al</span>N/TiN multilayers exhibit the metastable zinc-blende-structure (z-<span class="hlt">Al</span>N). Based on density function theory calculations, the growth of the z-<span class="hlt">Al</span>N is ascribed to the kinetically and energetically favored nitridation of the deposited aluminium layer. In situ nanoindentation of the as-deposited {111}<span class="hlt">Al/Al</span>N/TiN multilayers in a high-resolution transmission electron microscope revealed the z-<span class="hlt">Al</span>N to wurzite <span class="hlt">Al</span>N phase transformation through collective glide of Shockley partial dislocations on every two {111} planes of the z-<span class="hlt">Al</span>N.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/26681109','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/26681109"><span id="translatedtitle">Growth and Stress-induced Transformation of Zinc blende <span class="hlt">Al</span>N Layers in <span class="hlt">Al-Al</span>N-TiN Multilayers.</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Li, Nan; Yadav, Satyesh K; Wang, Jian; Liu, Xiang-Yang; Misra, Amit</p> <p>2015-01-01</p> <p><span class="hlt">Al</span>N nanolayers in sputter deposited {111}<span class="hlt">Al/Al</span>N/TiN multilayers exhibit the metastable zinc-blende-structure (z-<span class="hlt">Al</span>N). Based on density function theory calculations, the growth of the z-<span class="hlt">Al</span>N is ascribed to the kinetically and energetically favored nitridation of the deposited aluminium layer. In situ nanoindentation of the as-deposited {111}<span class="hlt">Al/Al</span>N/TiN multilayers in a high-resolution transmission electron microscope revealed the z-<span class="hlt">Al</span>N to wurzite <span class="hlt">Al</span>N phase transformation through collective glide of Shockley partial dislocations on every two {111} planes of the z-<span class="hlt">Al</span>N. PMID:26681109</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015JMEP...24.4083L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015JMEP...24.4083L"><span id="translatedtitle">Effects of <span class="hlt">Al</span> Contents on Carburization Behavior and Corrosion Resistance of Ti<span class="hlt">Al</span> Alloys</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Liao, Cui Jiao; He, Yue Hui; Ming, Xing Zu</p> <p>2015-10-01</p> <p>Ti<span class="hlt">Al</span> alloys with <span class="hlt">Al</span> contents of 30.7, 37, 46.5, and 54.2 at.% were carburized. Corrosion resistance of the untreated and the carburized Ti<span class="hlt">Al</span> alloys was comparatively analyzed. The phase and microstructure of the carburized Ti<span class="hlt">Al</span> alloys were studied by x-ray diffraction and scanning electron microscopy, respectively. Electrochemical corrosion behavior of the untreated and the carburized Ti<span class="hlt">Al</span> alloys was investigated using potentiodynamic polarization and electrochemical impedance spectroscopy. Experimental results indicate that different <span class="hlt">Al</span> contents bring about distinct microstructure of the carburized layers. The lower <span class="hlt">Al</span> content leads to the formation of the thicker binary carbides and the thinner Ti2<span class="hlt">Al</span>C phase. Additionally, the lower <span class="hlt">Al</span> content leads to higher corrosion resistance in the untreated and the carburized states.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19970023021','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19970023021"><span id="translatedtitle">Tensile Behavior of <span class="hlt">Al</span>2o3/feal + B and <span class="hlt">Al</span>2o3/fecraly Composites</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Draper, S. L.; Eldridge, J. I.; Aiken, B. J. M.</p> <p>1995-01-01</p> <p>The feasibility of <span class="hlt">Al</span>2O3/Fe<span class="hlt">Al</span> + B and <span class="hlt">Al</span>2O3/FeCr<span class="hlt">Al</span>Y composites for high-temperature applications was assessed. The major emphasis was on tensile behavior of both the monolithics and composites from 298 to 1100 K. However, the study also included determining the chemical compatibility of the composites, measuring the interfacial shear strengths, and investigating the effect of processing on the strength of the single-crystal <span class="hlt">Al</span>2O3 fibers. The interfacial shear strengths were low for <span class="hlt">Al</span>203/Fe<span class="hlt">Al</span> + B and moderate to high for <span class="hlt">Al</span>203/FeCr<span class="hlt">Al</span>Y. The difference in interfacial bond strengths between the two systems affected the tensile behavior of the composites. The strength of the <span class="hlt">Al</span>203 fiber was significantly degraded after composite processing for both composite systems and resulted in poor composite tensile properties. The ultimate tensile strength (UTS) values of the composites could generally be predicted with either rule of mixtures (ROM) calculations or existing models when using the strength of the etched-out fiber. The <span class="hlt">Al</span>2O3/Fe<span class="hlt">Al</span> + B composite system was determined to be unfeasible due to poor interfacial shear strengths and a large mismatch in coefficient of thermal expansion (CTE). Development of the <span class="hlt">Al</span>2O3/FeCr<span class="hlt">Al</span>Y system would require an effective diffusion barrier to minimize the fiber strength degradation during processing and elevated temperature service.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ClinicalTrials.gov/ct2/show/study/NCT00821132','CLINICALTRIALS'); return false;" href="https://ClinicalTrials.gov/ct2/show/study/NCT00821132"><span id="translatedtitle">Genetics of Familial and Sporadic <span class="hlt">ALS</span></span></a></p> <p><a target="_blank" href="http://www.clinicaltrials.gov/ct/screen/SimpleSearch">ClinicalTrials.gov</a></p> <p></p> <p>2016-03-21</p> <p>Amyotrophic Lateral Sclerosis (<span class="hlt">ALS</span>); Familial Amyotrophic Lateral Sclerosis; Amyotrophic Lateral Sclerosis With Frontotemporal Dementia; Lou Gehrig's Disease; Motor Neuron Disease; Primary Lateral Sclerosis</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/20425287','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/20425287"><span id="translatedtitle">Psychiatric aspects of amyotrophic lateral sclerosis (<span class="hlt">ALS</span>).</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Norris, Lorenzo; Que, Guinevere; Bayat, Elham</p> <p>2010-06-01</p> <p>Amyotrophic lateral sclerosis (<span class="hlt">ALS</span>) is a progressive disorder characterized by degeneration of motor neurons. Given the severe nature of <span class="hlt">ALS</span>, many believed that patients would suffer from a high level of depression and a low quality of life. However, research into the psychological health of patients with <span class="hlt">ALS</span> has shown that this is not the case. This article reviews the state of current knowledge as it pertains to the psychological health of <span class="hlt">ALS</span> patients in four broad areas: quality of life, personality characteristics, emotional reactions, and end-of-life choices. PMID:20425287</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1994PhyB..193...25W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1994PhyB..193...25W"><span id="translatedtitle">Antiferromagnetic properties of Eu<span class="hlt">Al</span> 2</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Wada, H.; Shiga, M.</p> <p>1994-01-01</p> <p>The magnetization, specific heat, thermal expansion and electrical resistivity have been measured for Eu<span class="hlt">Al</span> 2. Anomalies associated with the antiferromagnetic transition were observed in their temperature dependence at or below 30 K. The thermal and transport properties were analyzed by the effective Debye temperature model, in which the temperature dependence of ? D is taken into account. It is shown that the s-f exchange interaction of Eu<span class="hlt">Al</span> 2 is considerably smaller than in Gd<span class="hlt">Al</span> 2. The anomalous magnetization process of Eu<span class="hlt">Al</span> 2 is also presented and discussed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/26053104','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/26053104"><span id="translatedtitle">Hepatocyte growth factor measurement in <span class="hlt">AL</span> amyloidosis.</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Abraham, Julie; Desport, Estelle; Rigaud, Charlotte; Marin, Benoit; Bender, Sbastien; Lacombe, Corinne; Moreau, Stphane; Yagoubi, Fatima; Bordessoule, Dominique; Lavergne, David; Bridoux, Frank; Jaccard, Arnaud</p> <p>2015-01-01</p> <p>Hepatocyte growth factor (HGF) is a pro-angiogenic cytokine activated by tissue-type plasminogen activator (tPA) that might play a role in the progression of multiple myeloma (MM). Preliminary studies indicated that serum HGF levels were higher in patients with <span class="hlt">AL</span> amyloidosis (<span class="hlt">AL</span>) compared to those with MM. The aim of the present study was to determine whether HGF is a relevant marker of diagnosis and prognosis in <span class="hlt">AL</span>. HGF serum levels were measured at diagnosis in patients with monoclonal gammopathy (MG) without <span class="hlt">AL</span> (76 controls), or with biopsy-proven systemic <span class="hlt">AL</span> (69 patients). HGF serum levels were significantly higher in patients with <span class="hlt">AL</span> compared to controls, respectively, 11.2?ng/mL [min: 0.95-max: 200.4] versus 1.4?ng/mL [min: 0.82-max: 6.2] (p?<?0.0001). The threshold value of 2.2?ng/mL conferred optimal sensitivity (88%) and specificity (95%) to differentiate <span class="hlt">AL</span> and monoclonal gammopathy of undetermined significance (MGUS) patients. Serum HGF concentrations were correlated positively with the severity of cardiac involvement and the serum level of monoclonal light chains. These data suggest that HGF measurement could be used in patients with MG to detect <span class="hlt">AL</span> or to reinforce a clinical suspicion of <span class="hlt">AL</span> and to guide indications for diagnostic tissue biopsies. PMID:26053104</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li class="active"><span>17</span></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_17 --> <div id="page_18" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li class="active"><span>18</span></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="341"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010JaJAP..49a0201S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010JaJAP..49a0201S"><span id="translatedtitle">Dissolution Behavior of <span class="hlt">Al</span> and Formation Process of Zn<span class="hlt">Al</span>2O4 Phases in <span class="hlt">Al</span>2O3-Doped ZnO Sintered Bodies</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Shirouzu, Keita; Kawamoto, Tohru; Enomoto, Naoya; Hojo, Junichi</p> <p>2010-01-01</p> <p><span class="hlt">Al</span>-doped ZnO sintered bodies, which were doped with 0-2 mol % <span class="hlt">Al</span>2O3, were prepared from a powder mixture. <span class="hlt">Al</span> could dissolve in ZnO grains uniformly and a fraction of <span class="hlt">Al</span> tended to segregate along ZnO grain boundaries when the <span class="hlt">Al</span> concentration was low. The decrease in the [c/a] lattice ratio suggested that the solubility of <span class="hlt">Al</span> in ZnO increased with increasing concentration of <span class="hlt">Al</span>2O3. The solubility of <span class="hlt">Al</span> reached the limit when <span class="hlt">Al</span>2O3 was doped at more than 1 mol %. Zn<span class="hlt">Al</span>2O4 particles appeared before the solubility of <span class="hlt">Al</span> reached the limit, indicating that the dissolution of <span class="hlt">Al</span> and the formation of Zn<span class="hlt">Al</span>2O4 phases occurred simultaneously in the <span class="hlt">Al</span>2O3-ZnO sintering process.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19970022133','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19970022133"><span id="translatedtitle">Processing and Mechanical Properties of Directionally Solidified Ni<span class="hlt">Al/NiAl</span>Ta Alloys</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Johnson, D. R.; Oliver, B. F.; Noebe, R. D.; Whittenberger, J. D.</p> <p>1994-01-01</p> <p>Promising creep strengths were found for a directionally solidified Ni<span class="hlt">Al-NiAl</span>Ta alloy when compared to other Ni<span class="hlt">Al</span> based intermetallics. The directionally solidified alloy had an off-eutectic composition that resulted in microstructures consisting of Ni<span class="hlt">Al</span> dendrites surrounded by aligned eutectic regions. The room temperature toughness of the two phase alloy was similar to that of polycrystalline Ni<span class="hlt">Al</span> even with the presence of the brittle Laves phase Ni<span class="hlt">Al</span>Ta. Alloying additions that may improve the room temperature toughness by producing multiphase alloys are discussed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015JMBM...24...18F','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015JMBM...24...18F"><span id="translatedtitle">Strengthening of <span class="hlt">Al</span> and <span class="hlt">Al</span>-Mg alloy wires by melt inoculation with <span class="hlt">Al</span>/MgB2 nanocomposite</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Florián-Algarín, David; Marrero, Raúl; Padilla, Alexandra; Suárez, Oscar Marcelo</p> <p>2015-12-01</p> <p>This study hinges on the feasibility of strengthening <span class="hlt">Al</span> and <span class="hlt">Al</span>-Mg wires by adding <span class="hlt">Al</span> nanocomposite pellets containing MgB2 nanoparticles into the melt upon fabrication. These MgB2 nanoparticles were obtained by fragmentation using a high-energy ball mill, and were, afterward, mechanically alloyed with pure aluminum. The resulting MgB2/<span class="hlt">Al</span> nanocomposite pellets were sintered at 260°C to be subsequently added into molten aluminum and an <span class="hlt">Al</span>-Mg alloy melt. Cold rolling intercalated with stepwise annealing allowed the fabrication of 1 mm diameter wires with a final area reduction of 96%. Mechanical and physical properties of the treated wire specimens were compared to those of similarly processed pure aluminum wire. The ultimate tensile strength of the treated wires increased approximately double fold with respect to untreated wires at the expense of some loss in electrical conductivity.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015JMEP...24..426N','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015JMEP...24..426N"><span id="translatedtitle">Evaluation of Methods of Soldering <span class="hlt">Al</span>Si and <span class="hlt">Al</span>Si-SiC Particle Composite <span class="hlt">Al</span> Foams</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Nowacki, Jerzy; Moraniec, Kacper</p> <p>2015-01-01</p> <p>The cellular structure and unique properties of aluminum foams are the reason of their numerous applications and interests in respect of their joining. The paper includes the characterization of the essence of properties and application of aluminum and aluminum composite foams, the limitations, and possibilities of their soldering. The aim of the research is the consideration of methods of soldering <span class="hlt">Al</span>Si foams and <span class="hlt">Al</span>Si-SiC composite foams, and the joint structure. EDS and XRD investigations of the <span class="hlt">Al</span>Si-SiC composite foams' joints were done. The possibility of soldering <span class="hlt">Al</span>Si9 foams and <span class="hlt">Al</span>Si9-SiC composite foams using S-Bond 220 solder was confirmed, and higher tensile strength of the joint than the parent material was also ascertained</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2000MMTA...31.2369X','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2000MMTA...31.2369X"><span id="translatedtitle">Design and fabrication of W-Mo-Ti-Ti<span class="hlt">Al-Al</span> system functionally graded material</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Xiong, Huaping; Zhang, Lianmeng; Chen, Lidong; Hirai, Toshio; Yuan, Runzhang</p> <p>2000-09-01</p> <p>To obtain a kind of functionally graded material (FGM) with a density gradient, the W-Mo-Ti-Ti<span class="hlt">Al-Al</span> system graded material was designed, and the powder metallurgy method was chosen for its fabrication. The sintering of W, W-Mo, and Mo-Ti alloys at low temperature was studied, and then the approximately wholly dense W-Mo-Ti-Ti<span class="hlt">Al</span> system FGM was achieved by one-step sintering at 1473 K for 1 hour under a pressure of 30 MPa. It was found that through sintering at 1473 K, mainly the mechanical mixtures of W and Mo were formed in W-Mo alloys. In Mo-Ti alloys, the newly designed Fe-<span class="hlt">Al</span> sintering aids not only have an important effect on the densification of the alloys, but also contribute to the formation of the (Mo, Ti) solid solution. However, the solid-solution reaction that occurred in Mo-Ti alloys was still insufficient. During the sintering of Ti + Ti<span class="hlt">Al</span>, the chemical reaction of Ti + Ti<span class="hlt">Al</span> ? <span class="hlt">Al</span>Ti2 was induced within the sintered body. The W-Mo-Ti-Ti<span class="hlt">Al-Al</span> system FGM was finally fabricated by joining of the Ti<span class="hlt">Al</span> side of the sintered W-Mo-Ti-Ti<span class="hlt">Al</span> system FGM to metal <span class="hlt">Al</span> with an <span class="hlt">Al</span>-based brazing filler metal, and its density changed quasi-continuously within the large range from 17.15 to 2.70 g/cm3.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/1149231','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/1149231"><span id="translatedtitle">Quantitatively Probing the <span class="hlt">Al</span> Distribution in Zeolites</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Vjunov, Aleksei; Fulton, John L.; Huthwelker, Thomas; Pin, Sonia; Mei, Donghai; Schenter, Gregory K.; Govind, Niranjan; Camaioni, Donald M.; Hu, Jian Z.; Lercher, Johannes A.</p> <p>2014-06-11</p> <p>The degree of substitution of Si4+ by <span class="hlt">Al</span>3+ in the oxygen-terminated tetrahedra (<span class="hlt">Al</span> T-sites) of zeolites determines the concentration of ion-exchange and Brnsted acid sites. As the location of the tetrahedra and the associated subtle variations in bond angles influence the acid strength, quantitative information about <span class="hlt">Al</span> T-sites in the framework is critical to rationalize catalytic properties and to design new catalysts. A quantitative analysis is reported that uses a combination of extended X-ray absorption fine structure (EXAFS) analysis and 27<span class="hlt">Al</span> MAS NMR spectroscopy supported by DFT-based molecular dynamics simulations. To discriminate individual <span class="hlt">Al</span> atoms, sets of ab initio EXAFS spectra for various T-sites are generated from DFT-based molecular dynamics simulations allowing quantitative treatment of the EXAFS single- and multiple-photoelectron scattering processes out to 3-4 atom shells surrounding the <span class="hlt">Al</span> absorption center. It is observed that identical zeolite types show dramatically different <span class="hlt">Al</span>-distributions. A preference of <span class="hlt">Al</span> for T-sites that are part of one or more 4-member rings in the framework over those T-sites that are part of only 5- and 6-member rings in the HBEA150 sample has been determined from a combination of these methods. This work was supported by the U. S. Department of Energy (DOE), Office of Basic Energy Sciences, Division of Chemical Sciences, Geosciences & Biosciences.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://eric.ed.gov/?q=%22youth+population+growth%22+OR+%22u.s.+national+security%22+OR+%22potential+impacts%22+OR+%22presidential+administration%22+OR+%22middle+east%22&pg=6&id=EJ997797','ERIC'); return false;" href="http://eric.ed.gov/?q=%22youth+population+growth%22+OR+%22u.s.+national+security%22+OR+%22potential+impacts%22+OR+%22presidential+administration%22+OR+%22middle+east%22&pg=6&id=EJ997797"><span id="translatedtitle">Diana <span class="hlt">Al</span>-Hadid: Identity and Heritage</span></a></p> <p><a target="_blank" href="http://www.eric.ed.gov/ERICWebPortal/search/extended.jsp?_pageLabel=advanced">ERIC Educational Resources Information Center</a></p> <p>Jungerberg, Tom; Smith, Anna; Borsh, Colleen</p> <p>2012-01-01</p> <p>Diana <span class="hlt">Al</span>-Hadid's sculptures reflect the many locations, cultures, histories, and mythologies that have shaped her as an artist. In large-scale works which have the appearance of architectural ruins, <span class="hlt">Al</span>-Hadid employs imagery drawn from many diverse interests including science and technology, history, and literature. She also incorporates images and</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/25193032','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/25193032"><span id="translatedtitle">Sporadic and hereditary amyotrophic lateral sclerosis (<span class="hlt">ALS</span>).</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Ajroud-Driss, Senda; Siddique, Teepu</p> <p>2015-04-01</p> <p>Genetic discoveries in <span class="hlt">ALS</span> have a significant impact on deciphering molecular mechanisms of motor neuron degeneration. The identification of SOD1 as the first genetic cause of <span class="hlt">ALS</span> led to the engineering of the SOD1 mouse, the backbone of <span class="hlt">ALS</span> research, and set the stage for future genetic breakthroughs. In addition, careful analysis of <span class="hlt">ALS</span> pathology added valuable pieces to the <span class="hlt">ALS</span> puzzle. From this joint effort, major pathogenic pathways emerged. Whereas the study of TDP43, FUS and C9ORF72 pointed to the possible involvement of RNA biology in motor neuron survival, recent work on P62 and UBQLN2 refocused research on protein degradation pathways. Despite all these efforts, the etiology of most cases of sporadic <span class="hlt">ALS</span> remains elusive. Newly acquired genomic tools now allow the identification of genetic and epigenetic factors that can either increase <span class="hlt">ALS</span> risk or modulate disease phenotype. These developments will certainly allow for better disease modeling to identify novel therapeutic targets for <span class="hlt">ALS</span>. This article is part of a Special Issue entitled: Neuromuscular Diseases: Pathology and Molecular Pathogenesis. PMID:25193032</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20080047349','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20080047349"><span id="translatedtitle">Durability Assessment of Ti<span class="hlt">Al</span> Alloys</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Draper, Susan L.; Lerch, Bradley A.</p> <p>2008-01-01</p> <p>The durability of Ti<span class="hlt">Al</span> is a prime concern for the implementation of Ti<span class="hlt">Al</span> into aerospace engines. Two durability issues, the effect of high temperature exposure on mechanical properties and impact resistance, have been investigated and the results are summarized in this paper. Exposure to elevated temperatures has been shown to be detrimental to the room temperature ductility of gamma alloys with the most likely mechanisms being the ingress of interstitials from the surface. Fluorine ion implantation has been shown to improve the oxidation resistance of gamma alloys, and ideally it could also improve the environmental embrittlement of high Nb content Ti<span class="hlt">Al</span> alloys. The effect of F ion implantation on the surface oxidation and embrittlement of a third generation, high Nb content Ti<span class="hlt">Al</span> alloy (Ti-45<span class="hlt">Al</span>-5Nb-B-C) were investigated. Additionally, the ballistic impact resistance of a variety of gamma alloys, including Ti-48<span class="hlt">Al</span>-2Cr- 2Nb, Ti-47<span class="hlt">Al</span>-2Cr-2Nb, ABB-2, ABB-23, NCG359E, 95A and Ti-45<span class="hlt">Al</span>-5Nb-B-C was accessed. Differences in the ballistic impact properties of the various alloys will be discussed, particularly with respect to their manufacturing process, microstructure, and tensile properties.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://eric.ed.gov/?q=+%22youth+population+growth%22+OR+%22u.s.+national+security%22++OR+%22potential+impacts%22++OR+%22presidential+administration%22++OR+%22middle+east%22+&pg=6&id=EJ997797','ERIC'); return false;" href="http://eric.ed.gov/?q=+%22youth+population+growth%22+OR+%22u.s.+national+security%22++OR+%22potential+impacts%22++OR+%22presidential+administration%22++OR+%22middle+east%22+&pg=6&id=EJ997797"><span id="translatedtitle">Diana <span class="hlt">Al</span>-Hadid: Identity and Heritage</span></a></p> <p><a target="_blank" href="http://www.eric.ed.gov/ERICWebPortal/search/extended.jsp?_pageLabel=advanced">ERIC Educational Resources Information Center</a></p> <p>Jungerberg, Tom; Smith, Anna; Borsh, Colleen</p> <p>2012-01-01</p> <p>Diana <span class="hlt">Al</span>-Hadid's sculptures reflect the many locations, cultures, histories, and mythologies that have shaped her as an artist. In large-scale works which have the appearance of architectural ruins, <span class="hlt">Al</span>-Hadid employs imagery drawn from many diverse interests including science and technology, history, and literature. She also incorporates images and…</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016MS%26E..116a2012G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016MS%26E..116a2012G"><span id="translatedtitle">Contact hardening of <span class="hlt">Al</span> interlayer in laminated Mg/<span class="hlt">Al</span> composites during compressive and tensile loading</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Gurevich, L.; Pronichev, D.; Trunov, M.</p> <p>2016-02-01</p> <p>The study presents result of the FEM simulation of Mg alloy/<span class="hlt">Al</span>/Ti alloy composite under tensile and compression loads. The simulation revealed the strength of <span class="hlt">Al</span> interlayer at its various thickness values.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19940007975','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19940007975"><span id="translatedtitle">Ni<span class="hlt">Al</span> alloys for structural uses</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Koss, D. A.</p> <p>1991-01-01</p> <p>Alloys based on the intermetallic compound Ni<span class="hlt">Al</span> are of technological interest as high temperature structural alloys. These alloys possess a relatively low density, high melting temperature, good thermal conductivity, and (usually) good oxidation resistance. However, Ni<span class="hlt">Al</span> and Ni<span class="hlt">Al</span>-base alloys suffer from poor fracture resistance at low temperatures as well as inadequate creep strength at elevated temperatures. This research program explored macroalloying additions to Ni<span class="hlt">Al</span>-base alloys in order to identify possible alloying and processing routes which promote both low temperature fracture toughness and high temperature strength. Initial results from the study examined the additions of Fe, Co, and Hf on the microstructure, deformation, and fracture resistance of Ni<span class="hlt">Al</span>-based alloys. Of significance were the observations that the presence of the gamma-prime phase, based on Ni3<span class="hlt">Al</span>, could enhance the fracture resistance if the gamma-prime were present as a continuous grain boundary film or 'necklace'; and the Ni-35<span class="hlt">Al</span>-20Fe alloy was ductile in ribbon form despite a microstructure consisting solely of the B2 beta phase based on Ni<span class="hlt">Al</span>. The ductility inherent in the Ni-35<span class="hlt">Al</span>-20Fe alloy was explored further in subsequent studies. Those results confirm the presence of ductility in the Ni-35<span class="hlt">Al</span>-20Fe alloy after rapid cooling from 750 - 1000 C. However exposure at 550 C caused embrittlement; this was associated with an age-hardening reaction caused by the formation of Fe-rich precipitates. In contrast, to the Ni-35<span class="hlt">Al</span>-20Fe alloy, exploratory research indicated that compositions in the range of Ni-35<span class="hlt">Al</span>-12Fe retain the ordered B2 structure of Ni<span class="hlt">Al</span>, are ductile, and do not age-harden or embrittle after thermal exposure. Thus, our recent efforts have focused on the behavior of the Ni-35<span class="hlt">Al</span>-12Fe alloy. A second parallel effort initiated in this program was to use an alternate processing technique, mechanical alloying, to improve the properties of Ni<span class="hlt">Al</span>-alloys. Mechanical alloying in the conventional sense requires ductile powder particles which, through a cold welding and fracture process, can be dispersion strengthened by submicron-sized oxide particles. Using both the Ni-35<span class="hlt">Al</span>-Fe alloys to contain approx. 1 v/o Y2O3. Preliminary results indicate that mechanically alloyed and extruded Ni<span class="hlt">Al</span>-Fe + Y2O3 alloys when heat treated to a grain-coarsened condition, exhibit improved creep resistance at 1000 C when compared to Ni<span class="hlt">Al</span>; oxidation resistance comparable to Ni<span class="hlt">Al</span>; and fracture toughness values a factor of three better than Ni<span class="hlt">Al</span>. As a result of the research initiated on this NASA program, a subsequent project with support from Inco Alloys International is underway.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/24472060','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/24472060"><span id="translatedtitle">Opportunities for improving therapy development in <span class="hlt">ALS</span>.</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Bruijn, Lucie; Cudkowicz, Merit</p> <p>2014-06-01</p> <p>In May 2013, The <span class="hlt">ALS</span> Association and The Northeast <span class="hlt">ALS</span> Consortium (NEALS) convened a meeting of stakeholders for a round-table discussion of ways to improve therapy development in <span class="hlt">ALS</span>. The following overview summarizes issues raised and potential new directions discussed at the meeting. We recommend that future phase II clinical trials in <span class="hlt">ALS</span> proceed when the proposed treatment is directed at targets that are likely to be involved in <span class="hlt">ALS</span> pathogenesis in a defined subgroup of patients, and be accompanied by one or more biomarkers to track both clinical progression and pharmacodynamic engagement of the target. Innovations in trial structure and design, and greater involvement of patient advocates, may also improve trials. PMID:24472060</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1984ApPhL..44..310C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1984ApPhL..44..310C"><span id="translatedtitle">Interaction in Cu/<span class="hlt">Al</span> and Pt/Cu/<span class="hlt">Al</span> thin films: Competing oxygen effects and preferential reaction between Pt and Cu<span class="hlt">Al</span> alloy</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Chang, Chin-An</p> <p>1984-02-01</p> <p>The effects of oxygen on the interactions of the Cu-<span class="hlt">Al</span> thin-film system are studied using both Cu/<span class="hlt">Al</span> and Pt/Cu/<span class="hlt">Al</span> structures. For the Cu/<span class="hlt">Al</span> structure, oxygen-enhanced outdiffusion of <span class="hlt">Al</span> and accumulation of <span class="hlt">Al</span> on the Cu surface are observed. Using the Pt/Cu/<span class="hlt">Al</span> structure, however, no surface accumulation of <span class="hlt">Al</span> on Pt is observed; instead, the observed interdiffusion and alloy formation between Cu and <span class="hlt">Al</span> are both suppressed by oxygen. At increasing temperatures, <span class="hlt">Al</span> preferentially outdiffuses from the Cu<span class="hlt">Al</span> alloy to form a Pt <span class="hlt">Al</span> alloy with the top Pt layer. This last process is also suppressed by oxygen, similar to the binary Pt/<span class="hlt">Al</span> system reported previously. The mechanisms for the competing interactions and ambient effects observed are discussed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19980019510','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19980019510"><span id="translatedtitle">Corrosion Studies of 2195 <span class="hlt">Al</span>-Li Alloy and 2219 <span class="hlt">Al</span> Alloy with Differing Surface Treatments</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Danford, M. D.; Mendrek, M. J.</p> <p>1998-01-01</p> <p>Corrosion studies of 2195 <span class="hlt">Al</span>-Li and 2219 <span class="hlt">Al</span> alloys have been conducted using the scanning reference electrode technique (SRET) and the polarization resistance (PR) technique. The SRET was used to study corrosion mechanisms, while corrosion rate measurements were studied with the PR technique. Plates of <span class="hlt">Al</span>203 blasted, soda blasted and conversion coated 2219 <span class="hlt">Al</span> were coated with Deft primer and the corrosion rates studied with the EIS technique. Results from all of these studies are presented.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015ApPhL.107y3502P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015ApPhL.107y3502P"><span id="translatedtitle">Experimental determination of tunneling characteristics and dwell times from temperature dependence of <span class="hlt">Al/Al</span>2O3/<span class="hlt">Al</span> junctions</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Patio, Edgar J.; Kelkar, N. G.</p> <p>2015-12-01</p> <p>Measurements of current-voltage (I-V) characteristics of a high quality <span class="hlt">Al/Al</span>2O3/<span class="hlt">Al</span> junction at temperatures ranging from 3.5 K to 300 K have been used to extract the barrier properties. Fitting results using Simmons's model led to a constant value of barrier width s 20.8 and a continuous increase in the barrier height with decreasing temperature. The latter is used to determine the energy band gap temperature dependence and average phonon frequency ? = 2.05 1013 s-1 in <span class="hlt">Al</span>2O3, which adds confidence to the precision of our measurements. The barrier parameters are used to extract the temperature dependent dwell times in tunneling (?D = 3.6 10-16 s at mid-barrier energies) and locate resonances above the barrier.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/296638','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/296638"><span id="translatedtitle">Effects of hydrogen absorption in TbNi<span class="hlt">Al</span> and UNi<span class="hlt">Al</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Bordallo, H.N.; Nakotte, H.; Schultz, A.; Kolomiets, A.V.; Havela, L.; Andreev, A.V.</p> <p>1998-12-31</p> <p>Although hydrides of intermetallic compounds are used extensively as hydrogen-storage media, little is known about the exact nature of metal-hydrogen interactions. However, this knowledge is of essential importance for the understanding of thermodynamics and other properties. Hydrides (deuterides) of TbNi<span class="hlt">Al</span> and UNi<span class="hlt">Al</span> have been widely studied because of drastic increase of magnetic ordering temperature under hydrogenation. Here the authors report neutron-diffraction results of the three deuterides, TbNi<span class="hlt">Al</span>D{sub 1.28}, TbNi<span class="hlt">Al</span>D{sub 0.8}a nd UNi<span class="hlt">Al</span>D{sub 2.23}.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20020071128','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20020071128"><span id="translatedtitle">Atomistic Modeling of Ru<span class="hlt">Al</span> and (RuNi) <span class="hlt">Al</span> Alloys</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Gargano, Pablo; Mosca, Hugo; Bozzolo, Guillermo; Noebe, Ronald D.; Gray, Hugh R. (Technical Monitor)</p> <p>2002-01-01</p> <p>Atomistic modeling of Ru<span class="hlt">Al</span> and Ru<span class="hlt">Al</span>Ni alloys, using the BFS (Bozzolo-Ferrante-Smith) method for alloys is performed. The lattice parameter and energy of formation of B2 Ru<span class="hlt">Al</span> as a function of stoichiometry and the lattice parameter of (Ru(sub 50-x)Ni(sub x)<span class="hlt">Al</span>(sub 50)) alloys as a function of Ni concentration are computed. BFS based Monte Carlo simulations indicate that compositions close to Ru25Ni25<span class="hlt">Al</span>50 are single phase with no obvious evidence of a miscibility gap and separation of the individual B2 phases.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/5857468','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/5857468"><span id="translatedtitle">Extended <span class="hlt">Al</span>(Mn) solution in a rapidly solidified <span class="hlt">Al</span>-Li-Mn-Zr alloy</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Ruhr, M.; Baram, J.C. ); Lavernia, E.J. )</p> <p>1990-06-01</p> <p>This paper reports the effect of coolingrate on the extension of Mn solid solubility in <span class="hlt">Al</span> and on the relative amount of Mn<span class="hlt">Al</span> (Mn<span class="hlt">Al</span>{sub 6} and Mn<span class="hlt">Al</span>{sub 4}) secondary phases during gas atomization and spray deposition critically examined. An alloy of composition <span class="hlt">Al</span>-6.5Mn-2.3Li-0.65Zr (wt pct) currently being investigated for applications requiring high strength and low density at high temperatures was selected for this study. The material was exposed to various solidification histories by altering gas pressure and powder size during solidification.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/756425','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/756425"><span id="translatedtitle">A new discontinuously reinforced aluminum MMC: <span class="hlt">Al+Al</span>B{sub 2} flakes</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>HALL,AARON C.; ECONOMY,J.</p> <p>2000-06-08</p> <p>Development of a novel metal matrix composite based on the <span class="hlt">Al</span>-B alloy system has been undertaken. Preparation of this discontinuously reinforced material is based on the precipitation of high aspect ratio <span class="hlt">Al</span>B{sub 2} from an <span class="hlt">Al</span>-B alloy. This paper describes a number of efforts forced on preparing high volume fractions (> 30 v%) of <span class="hlt">Al</span>B{sub 2} in aluminum. New insights into the behavior of the <span class="hlt">Al</span>-B alloys system allowed this effort to be successful.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li class="active"><span>18</span></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_18 --> <div id="page_19" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li class="active"><span>19</span></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="361"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19910043314&hterms=1573&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3D%2526%25231573','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19910043314&hterms=1573&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3D%2526%25231573"><span id="translatedtitle">Reaction of Ti and Ti-<span class="hlt">Al</span> alloys with alumina</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Misra, Ajay K.</p> <p>1991-01-01</p> <p>The reaction of single-crystal <span class="hlt">Al</span>2O3 with pure Ti and Ti-<span class="hlt">Al</span> alloys with different <span class="hlt">Al</span> concentrations was examined in the temperature range of 1173 to 1573 K. Significant reaction occurred between <span class="hlt">Al</span>2O3 and the Ti-<span class="hlt">Al</span> alloys with <span class="hlt">Al</span> concentrations lower than that corresponding to the gamma-Ti<span class="hlt">Al</span> phase. The reaction mechanism was determined to be simultaneous diffusion of <span class="hlt">Al</span> and atomic oxygen from <span class="hlt">Al</span>2O3 into Ti and the Ti-<span class="hlt">Al</span> alloys.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/6394628','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/6394628"><span id="translatedtitle">Transition element modifications of <span class="hlt">Al</span>-Li</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Gayle, F.W.; Levoy, N.F.; Vandersande, J.B.</p> <p>1987-05-01</p> <p>The development of aluminum-lithium metallurgy has led to alloys with unsurpassed combinations of density, specific strength, and specific modulus. This paper describes recent advances in the modification of aluminum-lithium binary alloys through additions of the Group IV-A transition metals (titanium, zirconium, and hafnium). These elements lead to a duplex precipitation hardening behavior through the formation of <span class="hlt">Al</span>3Li and <span class="hlt">Al</span>3(TM,Li) (TM = transition element) which act as strengthening precipitates. The influence of the duplex structure on deformation mechanisms and the improvement of mechanical properties in these systems is illustrated by using results for the <span class="hlt">Al</span>-Li-Zr system. 12 references.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/10191071','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/10191071"><span id="translatedtitle">Ni{sub 3}<span class="hlt">Al</span> aluminide alloys</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Liu, C.T.</p> <p>1993-10-01</p> <p>This paper provides a brief review of the recent progress in research and development of Ni{sub 3}<span class="hlt">Al</span> and its alloys. Emphasis has been placed on understanding low ductility and brittle fracture of Ni{sub 3}<span class="hlt">Al</span> alloys at ambient and elevated temperatures. Recent studies have resulted in identifying both intrinsic and extrinsic factors governing the fracture behavior of Ni{sub 3}<span class="hlt">Al</span> alloys. Parallel efforts on alloy design using physical metallurgy principles have led to properties for structural use. Industrial interest in these alloys is high, and examples of industrial involvement in processing and utilization of these alloys are briefly mentioned.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/26613179','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/26613179"><span id="translatedtitle">Arsenate uptake by <span class="hlt">Al</span> nanoclusters and other <span class="hlt">Al</span>-based sorbents during water treatment.</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Mertens, Jasmin; Rose, Jérôme; Wehrli, Bernhard; Furrer, Gerhard</p> <p>2016-01-01</p> <p>In many parts of the world, arsenic from geogenic and anthropogenic sources deteriorates the quality of drinking water resources. Effective methods of arsenic removal include adsorption and coagulation with iron- and aluminum-based materials, of which polyaluminum chloride is widely employed as coagulant in water treatment due to its low cost and high efficiency. We compared the arsenic uptake capacity and the arsenic bonding sites of different <span class="hlt">Al</span>-based sorbents, including <span class="hlt">Al</span> nanoclusters, polyaluminum chloride, polyaluminum granulate, and gibbsite. Extended X-ray absorption fine structure (EXAFS) spectroscopy revealed that As(V) forms bidentate-binuclear complexes in interaction with all <span class="hlt">Al</span>-based removal agents. The octahedral configuration of nanoclusters and the distribution of sorption sites remain the same in all types of removal agents consisting of nano-scale <span class="hlt">Al</span> oxyhydroxide particles. The obtained distances for As(V)-O and As(V)-<span class="hlt">Al</span> agreed with previously published data and were found to be 1.69 ± 0.02 Å and 3.17-3.21 Å, respectively. Our study suggests that As(V) binds to <span class="hlt">Al</span> nanoclusters as strongly as to <span class="hlt">Al</span> oxide surfaces. The As sorption capacity of <span class="hlt">Al</span> nanoclusters was found to be very similar to that of <span class="hlt">Al</span> clusters in a polyaluminum chloride. The most efficient <span class="hlt">Al</span>-based sorbents for arsenic removal were <span class="hlt">Al</span> nanoclusters, followed by polyaluminum granulate. PMID:26613179</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010SCPMA..53...49D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010SCPMA..53...49D"><span id="translatedtitle">Characterization of different-<span class="hlt">Al</span>-content <span class="hlt">Al</span>GaN/GaN heterostructures on sapphire</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Ding, Guojian; Guo, Liwei; Xing, Zhigang; Chen, Yao; Xu, Peiqiang; Jia, Haiqiang; Zhou, Junming; Chen, Hong</p> <p>2010-01-01</p> <p><span class="hlt">Al</span> x Ga1- x N/GaN high-electron-mobility transistor (HEMT) structures with <span class="hlt">Al</span> composition ranging from x = 0.13 to 0.36 are grown on sapphire substrates by low-pressure metalorganic chemical vapor deposition (LP-MOCVD). The effects of <span class="hlt">Al</span> content on crystal quality, surface morphology, optical and electrical characteristics of the <span class="hlt">Al</span>GaN/GaN heterostructures have been analyzed. Although high <span class="hlt">Al</span>-content (36%) heterostructure exhibits a distinguished photoluminescence peak related to recombination between the two-dimensional electron gas and photoexcited holes (2DEG-h), its crystal quality and rough surface morphology are poor. 2DEG mobility increases with the <span class="hlt">Al</span> content up to 26% and then it apparently decreases for high <span class="hlt">Al</span>-content (36%) <span class="hlt">Al</span>GaN/GaN heterostructure. The increase of sheet carrier density with the increase of <span class="hlt">Al</span> content has been observed. A high mobility at room temperature of 2105 cm2/V s with a sheet carrier density of n s = 1.10 1013 cm-2, for a 26% <span class="hlt">Al</span>-content <span class="hlt">Al</span>GaN/GaN heterostructure has been obtained, which is approaching state-of-the-art for HEMT grown on SiC. Sheet resistance as low as 274 ?/? has also been achieved.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013Nanot..24I5203X','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013Nanot..24I5203X"><span id="translatedtitle">High-performance nonvolatile <span class="hlt">Al/Al</span>Ox/CdTe:Sb nanowire memory device</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Xie, Chao; Nie, Biao; Zhu, Long; Zeng, Long-Hui; Yu, Yong-Qiang; Wang, Xian-He; Fang, Qun-Ling; Luo, Lin-Bao; Wu, Yu-Cheng</p> <p>2013-09-01</p> <p>Here we demonstrate a room temperature processed nonvolatile memory device based on an <span class="hlt">Al/Al</span>Ox/CdTe:Sb nanowire (NW) heterojunction. Electrical analysis shows an echelon hysteresis composed of a high-resistance state (HRS) and a low-resistance state (LRS), which can allow it to write and erase data from the device. The conductance ratio is as high as 106, with a retention time of 3 104 s. Moreover, the SET voltages ranged from +6 to +8 V, whilst the RESET voltage ?0 V. In addition, flexible memory nano-devices on PET substrate with comparable switching performance at bending condition were fabricated. XPS analysis of the <span class="hlt">Al/Al</span>Ox/CdTe:Sb NW heterojunction after controlled Ar+ bombardment reveals that this memory behavior is associated with the presence of ultra-thin <span class="hlt">Al</span>Ox film. This <span class="hlt">Al/Al</span>Ox/CdTe:Sb NW heterojunction will open up opportunities for new memory devices with different configurations.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012HTMP...31....3B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012HTMP...31....3B"><span id="translatedtitle">Contribution to Kinetics of Superplastic Deformation of Dispersion Strengthened <span class="hlt">Al-Al</span>4C3 System</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Besterci, Michal; Varchola, Marin; Kov?, Ladislav; Velgosov, Oksana</p> <p>2012-02-01</p> <p>The influence of temperature at constant strain rate has been evaluated with respect to superplastic behavior of dispersion strengthened <span class="hlt">Al-Al</span>4C3 composite with 4 vol.% of <span class="hlt">Al</span>4C3 phase. The dispersion strengthened <span class="hlt">Al-Al</span>4C3 was prepared by powder metallurgy. Material can be characterized by grain size around 1 ?m and dispersed particle <span class="hlt">Al</span>4C3 size around 50 nm. This material showed superplastic behavior for strain rate 10-3 s-1 by test temperature 573 K. The mechanism of superplastic deformation was also investigated. For the presented material with low content of disperse particle slip on grain boundaries is typical. The final fracture is transcrystalline with dimples with their mean size 1.25 ?m. The dimples are initialized by <span class="hlt">Al</span>4C3 particles in size from 40 to 50 nm.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ars.usda.gov/research/publications/Publications.htm?seq_no_115=227818','TEKTRAN'); return false;" href="http://www.ars.usda.gov/research/publications/Publications.htm?seq_no_115=227818"><span id="translatedtitle">Gestion responsable del <span class="hlt">carbono</span> en el suelo</span></a></p> <p><a target="_blank" href="http://www.ars.usda.gov/services/TekTran.htm">Technology Transfer Automated Retrieval System (TEKTRAN)</a></p> <p></p> <p></p> <p>The world's agronomists must broaden their perspective and shift conservation concepts and programs to get away from managing for only yield and erosion control and move to managing soil carbon (C) for crop production sustainability and maintaining environmental quality. This work reviews research o...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015BAAA...57..111M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015BAAA...57..111M"><span id="translatedtitle">Estrellas de <span class="hlt">carbono</span> galcticas en el VVV</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Merlo, D. C.</p> <p>2015-08-01</p> <p>One of the characteristics of carbon stars is their variability, which depends on the evolutionary state and mass. Therefore, the study of this property is relevant to explain the physical processes occurring in their atmospheres. The VVV survey provides an excellent opportunity to carry out this kind of analysis, as it allows to have deep infrared multi-epoch photometry in order to build high-quality light-curves. Here we present an implemented method for identifying galactic carbon stars within the coverage area of VVV and the first results obtained.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/971365','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/971365"><span id="translatedtitle">Interdiffusion in Diffusion Couples: U-Mo v. <span class="hlt">Al</span> and <span class="hlt">Al</span>-Si</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>D. D. Keiser, Jr.; E. Perez; B. Yao; Y. H. Sohn</p> <p>2009-11-01</p> <p>Interdiffusion and microstructural development in the U-Mo-<span class="hlt">Al</span> system was examined using solid-tosolid diffusion couples consisting of U-7wt.%Mo, U-10wt.%Mo and U-12wt.%Mo vs. pure <span class="hlt">Al</span>, annealed at 600C for 24 hours. The influence of Si alloying addition (up to 5 wt.%) in <span class="hlt">Al</span> on the interdiffusion microstructural development was also examined using solid-to-solid diffusion couples consisting of U-7wt.%Mo, U-10wt.%Mo and U-12wt.%Mo vs. pure <span class="hlt">Al</span>, <span class="hlt">Al</span>-2wt.%Si, and <span class="hlt">Al</span>-5wt.%Si annealed at 550C up to 20 hours. Scanning electron microscopy (SEM), transmission electron microscopy (TEM) and electron probe microanalysis (EPMA) were employed to examine the development of a very fine multiphase intermetallic layer. In ternary U-Mo-<span class="hlt">Al</span> diffusion couples annealed at 600C for 24 hours, interdiffusion microstructure varied of finely dispersed UAl3, UAl4, U6Mo4<span class="hlt">Al</span>43, and UMo2<span class="hlt">Al</span>20 phases while the average composition throughout the interdiffusion zone remained constant at approximately 80 at.% <span class="hlt">Al</span>. Interdiffusion microstructure observed by SEM/TEM analyses and diffusion paths drawn from concentration profiles determined by EPMA appear to deviate from the assumption of local thermodynamic equilibrium, and suggest that interdiffusion occurs via supersaturated UAl4 followed by equilibrium transformation into UAl3, U6Mo4<span class="hlt">Al</span>43, UAl4 and UMo2<span class="hlt">Al</span>20 phases. Similar observation was made for U-Mo vs. <span class="hlt">Al</span> diffusion couples annealed at 550C. The addition of Si (up to 5 wt.%) in <span class="hlt">Al</span> significantly reduced the thickness of the intermetallic layer by changing the constituent phases of the interdiffusion zone developed in U-Mo vs. <span class="hlt">Al</span>-Si diffusion couples. Specifically, the formation of (U,Mo)(<span class="hlt">Al</span>,Si)3 with relatively large solubility for Mo and Si, along with UMo2<span class="hlt">Al</span>20 phases was observed along with disappearance of U6Mo4<span class="hlt">Al</span>43 and UAl4 phases. Simplified understanding based on U-<span class="hlt">Al</span>, U-Si, and Mo-Si binary phase diagrams is discussed in the light of the beneficial effect of Si alloying addition.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012JAP...111f3708H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012JAP...111f3708H"><span id="translatedtitle">Electroforming and Ohmic contacts in <span class="hlt">Al-Al</span>2O3-Ag diodes</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Hickmott, T. W.</p> <p>2012-03-01</p> <p>Electroforming of metal-insulator-metal (MIM) diodes is a non-destructive dielectric breakdown process that changes the diode from its initial high resistance state (HRS) to a low resistance state (LRS). After electroforming, resistance switching memories (RSMs) use voltages to switch from HRS to LRS and back. Many MIM combinations are proposed for use in RSMs. In many cases conduction in the LRS is nearly temperature independent at low temperatures; an Ohmic contact with a barrier to electron injection of ˜0 eV results from electroforming. Electroforming of <span class="hlt">Al-Al</span>2O3-Ag diodes with amorphous anodic <span class="hlt">Al</span>2O3 thicknesses between 12 and 41 nm has been studied. Two anodizing electrolytes have been used; 0.1 M ammonium pentaborate (bor-H2O) and a solution of 0.1 M of ammonium pentaborate per liter of ethylene glycol (bor-gly). Polarization of <span class="hlt">Al</span>2O3 and negative charge in <span class="hlt">Al</span>2O3 are much larger when <span class="hlt">Al</span>2O3 is formed in bor-H2O solution than when <span class="hlt">Al</span> is anodized in bor-gly solution. Electroforming of <span class="hlt">Al-Al</span>2O3-Ag diodes results in an Ohmic contact at the <span class="hlt">Al-Al</span>2O3 interface, voltage-controlled negative resistance (VCNR) in the current-voltage (I-V) characteristics, electroluminescence (EL), and electron emission into vacuum (EM) from filamentary conducting channels. Two distinct modes of electroforming occur for <span class="hlt">Al-Al</span>2O3-Ag diodes. α-forming occurs for 2.5 V ≲ VS ≲ 5 V, where VS is the applied voltage. It is characterized by an abrupt current jump with the simultaneous appearance of EL and EM. β-forming occurs for VS ≳ 7 V. I-V curves, EL, and EM develop gradually and are smaller than for α-forming. Electroforming occurs more readily for diodes with <span class="hlt">Al</span>2O3 formed in bor-H2O that have greater defect densities. Fully developed I-V curves have similar VCNR, EL, and EM after α-forming or β-forming. A model is proposed in which excited states of F-centers, oxygen vacancies in amorphous anodic <span class="hlt">Al</span>2O3, form defect conduction bands. Electroforming that results in an Ohmic contact requires injection of positive charge at the <span class="hlt">Al-Al</span>2O3 interface. α-forming is the result of ionization of F-center recombination centers with energies that are close to the <span class="hlt">Al</span> Fermi level. Hole injection by high-field ionization of valence band states of <span class="hlt">Al</span>2O3 causes β-forming.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/792926','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/792926"><span id="translatedtitle">12th Annual <span class="hlt">ALS</span> Users' Association Meeting</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Robinson, Arthur L.</p> <p>1999-12-17</p> <p>Science took the front seat as 219 Advanced Light Source (<span class="hlt">ALS</span>) users and staff gathered on Monday and Tuesday, October 18 and 19 for the twelfth annual users' meeting. The bulk of the meeting was dedicated to reports on science at the <span class="hlt">ALS</span>. Packed into two busy days were 31 invited oral presentations and 80 submitted poster presentations, as well as time to visit 24 vendor booths. The oral sessions were dedicated to environmental science, chemical dynamics, biosciences, magnetic materials, and atomic and molecular science. In addition, there was an <span class="hlt">ALS</span> highlights session that emphasized new results and a session comprising highlights from the young scientists who will carry the <span class="hlt">ALS</span> into the future.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/18625409','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/18625409"><span id="translatedtitle">Glial cells in <span class="hlt">ALS</span>: the missing link?</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Raibon, Elsa; Todd, Lisa Marie; Mller, Thomas</p> <p>2008-08-01</p> <p>Amyotrophic lateral sclerosis (<span class="hlt">ALS</span>) was initially known as Charcot's sclerosis, named after the French neurobiologist and physician Jean-Martin Charcot who first described this type of muscular atrophy in the early nineteenth century. In the United States, <span class="hlt">ALS</span> became widely known as Lou Gehrig's disease after the famous baseball player who succumbed to the disease in the late 1930s. Currently, <span class="hlt">ALS</span> is the most common motor neuron disease, with a worldwide incidence of 8 cases per 100,000 population per year. Familial forms constitute approximately 5% to 10% of all cases. Onset increases with age, with a peak in the seventh decade and a slight preponderance (relative risk, 1.3-1.5) among men compared with women. Rapid progression of motor neuron loss leads to death an average of 3 to 5 years after symptom onset. The cause of <span class="hlt">ALS</span> remains unknown and there is still no curative therapy. PMID:18625409</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/23186722','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/23186722"><span id="translatedtitle">Transplantation of mesenchymal stem cells in <span class="hlt">ALS</span>.</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Mazzini, Letizia; Vercelli, Alessandro; Ferrero, Ivana; Boido, Marina; Cantello, Roberto; Fagioli, Franca</p> <p>2012-01-01</p> <p>Amyotrophic lateral sclerosis (<span class="hlt">ALS</span>) is a devastating incurable, neurodegenerative disease that targets motor neurons (MNs) in the primary motor cortex, brainstem, and spinal cord, leading to muscle atrophy, paralysis, and death due to respiratory failure within 2-5 years. Currently, there is no cure for <span class="hlt">ALS</span>. The development of a therapy that can support or restore MN function and attenuate toxicity in the spinal cord provides the most comprehensive approach for treating <span class="hlt">ALS</span>. Mesenchymal stem cells might be suitable for cell therapy in <span class="hlt">ALS</span> because of their immunomodulatory and protective properties. In this review, the authors discuss the major challenges to the translation of in vitro and animal studies of MSCs therapy in the clinical setting. PMID:23186722</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3866720','PMC'); return false;" href="http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3866720"><span id="translatedtitle"><span class="hlt">ALS</span> and Oxidative Stress: The Neurovascular Scenario</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Thakur, Keshav; Gupta, Pawan Kumar</p> <p>2013-01-01</p> <p>Oxidative stress and angiogenic factors have been placed as the prime focus of scientific investigations after an establishment of link between vascular endothelial growth factor promoter (VEGF), hypoxia, and amyotrophic lateral sclerosis (<span class="hlt">ALS</span>) pathogenesis. Deletion of the hypoxia-response element in the vascular endothelial growth factor promoter and mutant superoxide dismutase 1 (SOD1) which are characterised by atrophy and muscle weakness resulted in phenotype resembling human <span class="hlt">ALS</span> in mice. This results in lower motor neurodegeneration thus establishing an important link between motor neuron degeneration, vasculature, and angiogenic molecules. In this review, we have presented human, animal, and in vitro studies which suggest that molecules like VEGF have a therapeutic, diagnostic, and prognostic potential in <span class="hlt">ALS</span>. Involvement of vascular growth factors and hypoxia response elements also highlights the converging role of oxidative stress and neurovascular network for understanding and treatment of various neurodegenerative disorders like <span class="hlt">ALS</span>. PMID:24367722</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4439492','PMC'); return false;" href="http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4439492"><span id="translatedtitle"><span class="hlt">AL</span> Amyloidosis Complicated by Persistent Oral Bleeding</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Marconcini, Luiz Antonio Liarte; Stewart, Forrest Marc; Sonntag, Lisa; Stevens, Emily; Burwick, Nicholas</p> <p>2015-01-01</p> <p>A case of amyloid light chain (<span class="hlt">AL</span>) amyloidosis is presented here with uncontrolled bleeding after a nonsurgical dental procedure, most likely multifactorial in nature, and consequently treated with a multidisciplinary approach. PMID:26064714</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://eric.ed.gov/?q=Anthropology+AND+epistemology&pg=5&id=EJ310992','ERIC'); return false;" href="http://eric.ed.gov/?q=Anthropology+AND+epistemology&pg=5&id=EJ310992"><span id="translatedtitle">On Dobbert et <span class="hlt">al</span>, 'Cultural Transmission...'</span></a></p> <p><a target="_blank" href="http://www.eric.ed.gov/ERICWebPortal/search/extended.jsp?_pageLabel=advanced">ERIC Educational Resources Information Center</a></p> <p>Gearing, Frederick</p> <p>1984-01-01</p> <p>Criticizes Dobbert et <span class="hlt">al</span>'s model of cultural transmission (presented in earlier article) as being a species of social physics. Suggests improvements to the model, notably that observation and analysis at the emic level be taken into account. (RDN)</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015IJT....36.3037L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015IJT....36.3037L"><span id="translatedtitle">Thermal Conductivity of <span class="hlt">Al</span>-Salt Composites</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Li, Peng; Zhang, Mei; Wang, Lijun; Seetharaman, Seshadri</p> <p>2015-11-01</p> <p>With a view to examine the possibility of estimating the content of entrapped metallic aluminium in the salt cake from aluminium remelting, the thermal diffusivity of reference composites of KCl-NaCl-<span class="hlt">Al</span> was measured as a function of aluminium metal content at room temperature. The thermal conductivity of the reference composites was found to increase with the metallic <span class="hlt">Al</span> content. The lumped parameter model approach was carried out to discuss the influence of different geometry arrangements of each phase, viz. air, salts and metallic aluminium on the thermal conductivity. Application of the present results to industrial samples indicates that factors such as the interfacial condition of metallic <span class="hlt">Al</span> particles have to be considered in order to estimate the amount of entrapped <span class="hlt">Al</span> in the salt cake.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=2650295','PMC'); return false;" href="http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=2650295"><span id="translatedtitle">Substitutional alloy of Ce and <span class="hlt">Al</span></span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Zeng, Qiao-Shi; Ding, Yang; Mao, Wendy L.; Luo, Wei; Blomqvist, Andreas; Ahuja, Rajeev; Yang, Wenge; Shu, Jinfu; Sinogeikin, Stas V.; Meng, Yue; Brewe, Dale L.; Jiang, Jian-Zhong; Mao, Ho-kwang</p> <p>2009-01-01</p> <p>The formation of substitutional alloys has been restricted to elements with similar atomic radii and electronegativity. Using high-pressure at 298 K, we synthesized a face-centered cubic disordered alloy of highly dissimilar elements (large Ce and small <span class="hlt">Al</span> atoms) by compressing the Ce3<span class="hlt">Al</span> intermetallic compound >15 GPa or the Ce3<span class="hlt">Al</span> metallic glass >25 GPa. Synchrotron X-ray diffraction, Ce L3-edge absorption spectroscopy, and ab initio calculations revealed that the pressure-induced Kondo volume collapse and 4f electron delocalization of Ce reduced the differences between Ce and <span class="hlt">Al</span> and brought them within the Hume-Rothery (HR) limit for substitutional alloying. The alloy remained after complete release of pressure, which was also accompanied by the transformation of Ce back to its ambient 4f electron localized state and reversal of the Kondo volume collapse, resulting in a non-HR alloy at ambient conditions. PMID:19188608</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/25802988','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/25802988"><span id="translatedtitle">Continuous germanene layer on <span class="hlt">Al</span>(111).</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Derivaz, Mickael; Dentel, Didier; Stephan, Rgis; Hanf, Marie-Christine; Mehdaoui, Ahmed; Sonnet, Philippe; Pirri, Carmelo</p> <p>2015-04-01</p> <p>Germanene, a 2D honeycomb structure similar to silicene, has been fabricated on <span class="hlt">Al</span>(111). The 2D germanene layer covers uniformly the substrate with a large coherence over the <span class="hlt">Al</span>(111) surface atomic plane. It is characterized by a (3 3) superstructure with respect to the substrate lattice, shown by low energy electron diffraction and scanning tunnelling microscopy. First-principles calculations indicate that the Ge atoms accommodate in a very regular atomic configuration with a buckled conformation. PMID:25802988</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li class="active"><span>19</span></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_19 --> <div id="page_20" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li class="active"><span>20</span></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="381"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3139582','PMC'); return false;" href="http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3139582"><span id="translatedtitle">Analysis of <span class="hlt">al</span>-2 Mutations in Neurospora</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Daz-Snchez, Violeta; Estrada, Alejandro F.; Trautmann, Danika; Limn, M. Carmen; Al-Babili, Salim; Avalos, Javier</p> <p>2011-01-01</p> <p>The orange pigmentation of the fungus Neurospora crassa is due to the accumulation of the xanthophyll neurosporaxanthin and precursor carotenoids. Two key reactions in the synthesis of these pigments, the formation of phytoene from geranylgeranyl pyrophosphate and the introduction of ? cycles in desaturated carotenoid products, are catalyzed by two domains of a bifunctional protein, encoded by the gene <span class="hlt">al</span>-2. We have determined the sequence of nine <span class="hlt">al</span>-2 mutant alleles and analyzed the carotenoid content in the corresponding strains. One of the mutants is reddish and it is mutated in the cyclase domain of the protein, and the remaining eight mutants are albino and harbor different mutations on the phytoene synthase (PS) domain. Some of the mutations are expected to produce truncated polypeptides. A strain lacking most of the PS domain contained trace amounts of a carotenoid-like pigment, tentatively identified as the squalene desaturation product diapolycopene. In support, trace amounts of this compound were also found in a knock-out mutant for gene <span class="hlt">al</span>-2, but not in that for gene <span class="hlt">al</span>-1, coding for the carotene desaturase. The cyclase activity of the <span class="hlt">AL</span>-2 enzyme from two albino mutants was investigated by heterologous expression in an appropriately engineered E. coli strain. One of the <span class="hlt">AL</span>-2 enzymes, predictably with only 20% of the PS domain, showed full cyclase activity, suggesting functional independence of both domains. However, the second mutant showed no cyclase activity, indicating that some alterations in the phytoene synthase segment affect the cyclase domain. Expression experiments showed a diminished photoinduction of <span class="hlt">al</span>-2 transcripts in the <span class="hlt">al</span>-2 mutants compared to the wild type strain, suggesting a synergic effect between reduced expression and impaired enzymatic activities in the generation of their albino phenotypes. PMID:21818281</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/10175632','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/10175632"><span id="translatedtitle">Performance of the <span class="hlt">ALS</span> injection system</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Kim, C.H.</p> <p>1993-05-01</p> <p>The authors started commissioning the Advanced Light Source (<span class="hlt">ALS</span>) storage ring on January 11, 1993. The stored beam reached 60 mA on March 24, 1993 and 407 mA on April 9, 1993. The fast pace of storage ring commissioning can be attributed partially to the robust injection system. In this paper they describe the operating characteristics of the <span class="hlt">ALS</span> injection system.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/25123918','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/25123918"><span id="translatedtitle">Genetic architecture of <span class="hlt">ALS</span> in Sardinia.</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Borghero, Giuseppe; Pugliatti, Maura; Marrosu, Francesco; Marrosu, Maria Giovanna; Murru, Maria Rita; Floris, Gianluca; Cannas, Antonino; Parish, Leslie D; Occhineri, Patrizia; Cau, Tea B; Loi, Daniela; Ticca, Anna; Traccis, Sebastiano; Manera, Umberto; Canosa, Antonio; Moglia, Cristina; Calvo, Andrea; Barberis, Marco; Brunetti, Maura; Pliner, Hannah A; Renton, Alan E; Nalls, Mike A; Traynor, Bryan J; Restagno, Gabriella; Chiò, Adriano</p> <p>2014-12-01</p> <p>Conserved populations, such as Sardinians, displaying elevated rates of familial or sporadic amyotrophic lateral sclerosis (<span class="hlt">ALS</span>) provide unique information on the genetics of the disease. Our aim was to describe the genetic profile of a consecutive series of <span class="hlt">ALS</span> patients of Sardinian ancestry. All <span class="hlt">ALS</span> patients of Sardinian ancestry, identified between 2008 and 2013 through the Italian <span class="hlt">ALS</span> Genetic Consortium, were eligible to be included in the study. Patients and controls underwent the analysis of TARDBP, C9ORF72, SOD1, and FUS genes. Genetic mutations were identified in 155 out of 375 Sardinian <span class="hlt">ALS</span> cases (41.3%), more commonly the p.A382T and p.G295S mutations of TARDBP and the GGGGCC hexanucleotide repeat expansion of C9ORF72. One patient had both p.G295S and p.A382T mutations of TARDBP and 8 carried both the heterozygous p.A382T mutation of TARDBP and a repeat expansion of C9ORF72. Patients carrying the p.A382T and the p.G295S mutations of TARDBP and the C9ORF72 repeat expansion shared distinct haplotypes across these loci. Patients with cooccurrence of C9ORF72 and TARDBP p.A382T missense mutation had a significantly lower age at onset and shorter survival. More than 40% of all cases on the island of Sardinia carry a mutation of an <span class="hlt">ALS</span>-related gene, representing the highest percentage of <span class="hlt">ALS</span> cases genetically explained outside of Scandinavia. Clinical phenotypes associated with different genetic mutations show some distinctive characteristics, but the heterogeneity between and among families carrying the same mutations implies that <span class="hlt">ALS</span> manifestation is influenced by other genetic and nongenetic factors. PMID:25123918</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/862324','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/862324"><span id="translatedtitle">17th Annual <span class="hlt">ALS</span> Users' Association Meeting</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Robinson, Art; Tamura, Lori</p> <p>2004-11-29</p> <p>It's not exactly Russian roulette, but scheduling October events outdoors is not risk-free, even in usually sunny California. An overflow crowd of more than 400 registered users, <span class="hlt">ALS</span> staff, and vendors enjoyed a full indoor program featuring science highlights and workshops spread over two and a half days from October 18 to October 20. However, a major storm, heralding the onset of the San Francisco Bay Area rainy season, posed a few weather challenges for the events on the <span class="hlt">ALS</span> patio.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/6395567','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/6395567"><span id="translatedtitle">Magnetism of <span class="hlt">Al</span>-Mn quasicrystals</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Liu, F.; Khanna, S.N.; Magaud, L.; Jena, P. ); de Coulon, V.; Reuse, F. ); Jaswal, S.S.; He, X. ); Cyrot-Lackman, F. )</p> <p>1993-07-01</p> <p>The effect of symmetry and concentration of Mn on the magnetism of <span class="hlt">Al</span>-Mn quasicrystals has been investigated through self-consistent density-functional calculations using molecular clusters and supercell band-structure schemes. A single Mn atom surrounded by 54 <span class="hlt">Al</span> atoms in an icosahedral or a cuboctahedral structure is found to be nonmagnetic. However, as the Mn concentration is increased, moments develop on Mn sites whose magnitude and coupling depend on their location.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/20406180','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/20406180"><span id="translatedtitle">Clinical trials for neuroprotection in <span class="hlt">ALS</span>.</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Siciliano, G; Carlesi, C; Pasquali, L; Piazza, S; Pietracupa, S; Fornai, F; Ruggieri, S; Murri, L</p> <p>2010-07-01</p> <p>Owing to uncertainty on the pathogenic mechanisms underlying motor neuron degeneration in amyotrophic lateral sclerosis (<span class="hlt">ALS</span>) riluzole remains the only available therapy, with only marginal effects on disease survival. Here we review some of the recent advances in the search for disease-modifying drugs for <span class="hlt">ALS</span> based on their putative neuroprotective effetcs. A number of more or less established agents have recently been investigated also in <span class="hlt">ALS</span> for their potential role in neuroprotection and relying on antiglutamatergic, antioxidant or antiapoptotic strategies. Among them Talampanel, beta-lactam antibiotics, Coenzyme Q10, and minocycline have been investigated. Progress has also been made in exploiting growth factors for the treatment of <span class="hlt">ALS</span>, partly due to advances in developing effective delivery systems to the central nervous system. A number of new therapies have also been identified, including a novel class of compounds, such as heat-shock protein co-inducers, which upregulate cell stress responses, and agents promoting autophagy and mitochondriogenesis, such as lithium and rapamycin. More recently, alterations of mRNA processing were described as a pathogenic mechanism in genetically defined forms of <span class="hlt">ALS</span>, as those related to TDP-43 and FUS-TLS gene mutations. This knowledge is expected to improve our understanding of the pathogenetic mechanism in <span class="hlt">ALS</span> and developing more effective therapies. PMID:20406180</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/26584004','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/26584004"><span id="translatedtitle">Excitotoxicity in <span class="hlt">ALS</span>: Overstimulation, or overreaction?</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>King, Anna E; Woodhouse, Adele; Kirkcaldie, Matthew T K; Vickers, James C</p> <p>2016-01-01</p> <p>Amyotrophic lateral sclerosis (<span class="hlt">ALS</span>) is an adult onset neurodegenerative disease that results in motor dysfunction and death, generally from respiratory failure. 90% of <span class="hlt">ALS</span> cases are sporadic with no known cause. Familial cases have been linked with mutations in several disparate classes of genes, including those involved in DNA/RNA metabolism, protein misfolding, oxidative stress and the cytoskeleton, leading to the proposition that <span class="hlt">ALS</span> could be a multi-factorial disease. However, alterations in excitability have been reported in all types of <span class="hlt">ALS</span> cases, and may be a common disease mechanism predisposing neurons to degeneration. Excitotoxicity has long been suspected as a mediator in the disease process, and may arise from changes in synaptic inputs, or alterations in the excitability of the neurons being stimulated. Although the glutamatergic system is widely recognised as a therapeutic avenue with the potential to extend lifespan and delay disease onset, the causes of altered excitability in <span class="hlt">ALS</span> are currently unclear and warrant further investigation. This article reviews current evidence of alterations to excitatory and inhibitory signalling in the cortex and spinal cord, and in the intrinsic excitability of motor neurons, in <span class="hlt">ALS</span>. PMID:26584004</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/516447','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/516447"><span id="translatedtitle">Modeling of precipitation in <span class="hlt">Al</span> alloys</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Asta, M.; Foiles, S.M.; Wolfer, W.G.</p> <p>1996-10-01</p> <p>Objective was the development of a computational model of precipitation from a supersaturated alloy solid solution. The model is based on the formalism of chemical-reaction-rate theory combined with classical descriptions of precipitate thermodynamic properties and a mean-field treatment of diffusion-limited growht and coarsening. For the case of precipitation of <span class="hlt">Al</span>{sub 3}Sc in supersaturated <span class="hlt">Al</span>-Sc alloys, it is demonstrated how the model can be used to calculate number densities and size distributions of precipitates as a function of aging time and temperature, including effects of continuous cooling and thermally generated point defects. Application of the model to a specific alloy system requires knowledge of diffusion data, point defect energetics, and thermodynamic properties for bulk phases and interphase interfaces. For interfaces and point defects, thermodynamic data can be difficult to measure and reliable values of defect free energies are often unavailable. For this reason, part of the efforts were devoted to applying semiempirical and first-principles atomistic techniques to the calculation of interfacial and point-defect thermodynamic properties. This report discusses applications for interphase interfaces in the <span class="hlt">Al</span>-Ag, <span class="hlt">Al</span>-Sc, and <span class="hlt">Al</span>-Li alloy systems. We also describe atomistic work aimed at understanding the energetics of vacancy clusters in <span class="hlt">Al</span>. These clusters serve as sinks for isolated vacancies during aging and their growth can lead to more complex defects, such as dislocation loops, that act as heterogeneous nucleation sites.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/1185327','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/1185327"><span id="translatedtitle">Metastability in the Mg<span class="hlt">Al</span>2O4-<span class="hlt">Al</span>2O3 System</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Wilkerson, Dr. Kelley R.; Smith, Jeffrey D; Hemrick, James Gordon</p> <p>2014-01-01</p> <p>Aluminum oxide must take a spinel form ( -<span class="hlt">Al</span>2O3) at elevated temperatures in order for extensive solid solution to form between Mg<span class="hlt">Al</span>2O4 and -<span class="hlt">Al</span>2O3. The solvus line between Mg<span class="hlt">Al</span>2O4 and <span class="hlt">Al</span>2O3 has been dened at 79.6 wt% <span class="hlt">Al</span>2O3 at 1500C, 83.0 wt% <span class="hlt">Al</span>2O3 at 1600C, and 86.5 wt% <span class="hlt">Al</span>2O3 at 1700C. A metastable region has been dened at temperatures up to 1700C which could have signicant implications for material processing and properties. Additionally, initial processing could have major implications on nal chemistry. The spinel solid solution region has been extended to form an innite solid solution with <span class="hlt">Al</span>2O3 at elevated temperatures. A minimum in melting at 1975C and a chemistry of 96 wt% <span class="hlt">Al</span>2O3 rather than a eutectic is present, resulting in no eutectic crystal formation during solidication.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012AIPC.1426..275Z','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012AIPC.1426..275Z"><span id="translatedtitle">Air blast characteristics of laminated <span class="hlt">al</span> and NI-<span class="hlt">AL</span> casings</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Zhang, Fan; Ripley, Robert; Wilson, William</p> <p>2012-03-01</p> <p>Air blast characteristics of <span class="hlt">Al</span> and Ni-<span class="hlt">Al</span> laminated materials were experimentally investigated in a 23 m3 closed chamber. Ni and <span class="hlt">Al</span> foils, 50 to 100 micrometers in thickness, were rolled and compacted to form a cylindrical casing with a density of 95% TMD through an explosive formation technique. Charges were prepared using 2 kg C4 explosive packed in the laminated casing to a metal-explosive mass ratio of 1.75. The blast pressure history measured on the chamber wall showed a double-shock front structure with a precursor shock followed by the primary blast. The front peak pressure for the Ni-<span class="hlt">Al</span> cased charge reaches 1.5-2 times that of the <span class="hlt">Al</span> cased, consistent with the larger fireball recorded for the Ni-<span class="hlt">Al</span> cased. The long time quasi-static explosion pressure (QSP) from the Ni- <span class="hlt">Al</span> cased charge is 0.8 of that of the <span class="hlt">Al</span> cased, due to half of <span class="hlt">Al</span> mass in the Ni-<span class="hlt">Al</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1986JNuM..141..401T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1986JNuM..141..401T"><span id="translatedtitle">Effects of neutron-irradiation on Mg<span class="hlt">Al</span> 2O 4 and <span class="hlt">Al</span> 20 3</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Tucker, D. S.; Zocco, T.; Kise, C. D.; Kennedy, J. C.</p> <p>1986-11-01</p> <p>Specimens of Mg<span class="hlt">Al</span> 2O 4 and <span class="hlt">Al</span> 20 3 were irradiated to a neutron fluence of approximately 210 26 n/m 2, E > 0.1 MeV at 660 K. Tensile strength was seen to decrease by 25.6% for <span class="hlt">Al</span> 2O 3 and to increase by 24.4% for Mg<span class="hlt">Al</span> 2O 4. Density measurements revealed that <span class="hlt">Al</span> 2O 3 swelled by 3.22% while Mg<span class="hlt">Al</span> 2O 4 densified slightly (0.316%). Both exhibited mixed failure modes in both control and irradiated samples with a shift from intergranular to transgranular for Mg<span class="hlt">Al</span> 2O 4 and vice-versa for <span class="hlt">Al</span> 2O 3 upon irradiation. The Mg<span class="hlt">Al</span> 2O 4 damage microstructure consisted of interstitial dislocation loops and denuded grain boundaries. The microstructure of irradiated <span class="hlt">Al</span> 2O 3 revealed fine areas of damage assumed to be interstitial dislocation loops and voids. Strength and structural changes are correlated with the results and compared with previously obtained results.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/26742954','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/26742954"><span id="translatedtitle">Next-generation sequencing of 28 <span class="hlt">ALS</span>-related genes in a Japanese <span class="hlt">ALS</span> cohort.</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Nakamura, Ryoichi; Sone, Jun; Atsuta, Naoki; Tohnai, Genki; Watanabe, Hazuki; Yokoi, Daichi; Nakatochi, Masahiro; Watanabe, Hirohisa; Ito, Mizuki; Senda, Jo; Katsuno, Masahisa; Tanaka, Fumiaki; Li, Yuanzhe; Izumi, Yuishin; Morita, Mitsuya; Taniguchi, Akira; Kano, Osamu; Oda, Masaya; Kuwabara, Satoshi; Abe, Koji; Aiba, Ikuko; Okamoto, Koichi; Mizoguchi, Kouichi; Hasegawa, Kazuko; Aoki, Masashi; Hattori, Nobutaka; Tsuji, Shoji; Nakashima, Kenji; Kaji, Ryuji; Sobue, Gen</p> <p>2016-03-01</p> <p>We investigated the frequency and contribution of variants of the 28 known amyotrophic lateral sclerosis (<span class="hlt">ALS</span>)-related genes in Japanese <span class="hlt">ALS</span> patients. We designed a multiplex, polymerase chain reaction-based primer panel to amplify the coding regions of the 28 <span class="hlt">ALS</span>-related genes and sequenced DNA samples from 257 Japanese <span class="hlt">ALS</span> patients using an Ion Torrent PGM sequencer. We also performed exome sequencing and identified variants of the 28 genes in an additional 251 <span class="hlt">ALS</span> patients using an Illumina HiSeq 2000 platform. We identified the known <span class="hlt">ALS</span> pathogenic variants and predicted the functional properties of novel nonsynonymous variants in silico. These variants were confirmed by Sanger sequencing. Known pathogenic variants were identified in 19 (48.7%) of the 39 familial <span class="hlt">ALS</span> patients and 14 (3.0%) of the 469 sporadic <span class="hlt">ALS</span> patients. Thirty-two sporadic ALS patients (6.8%) harbored 1 or 2 novel nonsynonymous variants of <span class="hlt">ALS</span>-related genes that might be deleterious. This study reports the first extensive genetic screening of Japanese <span class="hlt">ALS</span> patients. These findings are useful for developing genetic screening and counseling strategies for such patients. PMID:26742954</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013JAP...114w3702H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013JAP...114w3702H"><span id="translatedtitle">Optical microcavities and enhanced electroluminescence from electroformed <span class="hlt">Al-Al</span>2O3-Ag diodes</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Hickmott, T. W.</p> <p>2013-12-01</p> <p>Electroluminescence (EL) and electron emission into vacuum (EM) occur when a non-destructive dielectric breakdown of <span class="hlt">Al-Al</span>2O3-Ag diodes, electroforming, results in the development of a filamentary region in which current-voltage (I-V) characteristics exhibit voltage-controlled negative resistance. The temperature dependence of I-V curves, EM, and, particularly, EL of <span class="hlt">Al-Al</span>2O3-Ag diodes with anodic <span class="hlt">Al</span>2O3 thicknesses between 12 nm and 30 nm, has been studied. Two filters, a long-pass (LP) filter with transmission of photons with energies less than 3.0 eV and a short-pass (SP) filter with photon transmission between 3.0 and 4.0 eV, have been used to characterize EL. The voltage threshold for EL with the LP filter, VLP, is 1.5 V. VLP is nearly independent of <span class="hlt">Al</span>2O3 thickness and of temperature and is 0.3-0.6 V less than the threshold voltage for EL for the SP filter, VSP. EL intensity is primarily between 1.8 and 3.0 eV when the bias voltage, VS ? 7 V. EL in the thinnest diodes is enhanced compared to EL in thicker diodes. For increasing VS, for diodes with the smallest <span class="hlt">Al</span>2O3 thicknesses, there is a maximum EL intensity, LMX, at a voltage, VLMX, followed by a decrease to a plateau. LMX and EL intensity at 4.0 V in the plateau region depend exponentially on <span class="hlt">Al</span>2O3 thickness. The ratio of LMX at 295 K for a diode with 12 nm of <span class="hlt">Al</span>2O3 to LMX for a diode with 25 nm of <span class="hlt">Al</span>2O3 is 140. The ratio of EL intensity with the LP filter to EL intensity with the SP filter, LP/SP, varies between 3 and 35; it depends on <span class="hlt">Al</span>2O3 thickness and VS. Enhanced EL is attributed to the increase of the spontaneous emission rate of a dipole in a non-resonant optical microcavity. EL photons interact with the Ag and <span class="hlt">Al</span> films to create surface plasmon polaritons (SPPs) at the metal-<span class="hlt">Al</span>2O3 interfaces. SPPs generate large electromagnetic fields in the filamentary region of the electroformed <span class="hlt">Al-Al</span>2O3-Ag diode, which then acts as an optical microcavity. A model is proposed for electronic processes in electroformed <span class="hlt">Al-Al</span>2O3-Ag diodes.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/1093153','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/1093153"><span id="translatedtitle">Thermal Properties in the Mg<span class="hlt">Al</span>2O4-<span class="hlt">Al</span>2O3 System</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Wilkerson, Dr. Kelley R.; Smith, Jeffrey D; Hemrick, James Gordon</p> <p>2013-01-01</p> <p>Compositional effects on the thermal diffusivity in the Mg<span class="hlt">Al</span>2O4-<span class="hlt">Al</span>2O3 system were studied. The lowest thermal diffusivity, 0.0258 +/-5% cm/s, was measured between 79.8 and 83.9 wt% <span class="hlt">Al</span>2O3 quenched from various temperatures between 1500 and 1700C. All of the chemistries in this range extend past the solvus, but still form a singe super-saturated spinel solid solution, regardless of quenching tempeature. A super-saturated metastable solid solution region was observed at 1500, 1600, and 1700C extending to 83.9, 85.2, and 87.1 wt% <span class="hlt">Al</span>2O3, respectively. Beyond 83.9% <span class="hlt">Al</span>2O3 a significant increase in thermal diffusivity, 11.7%, was observed and its attributed to precipiation of <span class="hlt">Al</span>2O3 through spinodal decomposition.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013JIEIC..94...93S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013JIEIC..94...93S"><span id="translatedtitle">Process Capability Analysis of Vacuum Moulding for Development of <span class="hlt">Al-Al</span>2O3 MMC</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Singh, R.</p> <p>2013-01-01</p> <p>The purpose of the present study is to investigate process capability of vacuum moulding (VM) for development of <span class="hlt">Al-Al</span>2O3 metal matrix composite (MMC). Starting from the identification of component, prototypes were prepared (with three different input parameters namely: vacuum pressure; component volume and sand grit size to give output in form of dimensional accuracy). Measurements on the coordinate measuring machine helped in calculating the dimensional tolerances of the <span class="hlt">Al-Al</span>2O3 MMC prepared. Some important mechanical properties were also compared to verify the suitability of the components. Final components produced are acceptable as per ISO standard UNI EN 20286-I (1995). The results of study suggest that VM process lies in 4.5 sigma (?) limit as regard to dimensional accuracy of <span class="hlt">Al-Al</span>2O3 MMC is concerned. This process ensures rapid production of pre-series technological prototypes and proof of concept at less production cost and time.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/7023556','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/7023556"><span id="translatedtitle">Tin/<span class="hlt">Al</span> sub 2 O sub 3 /Ti<span class="hlt">Al</span>On composite</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Han, K.</p> <p>1990-04-02</p> <p>The present invention pertains to novel improved density ceramic composites of TiN/<span class="hlt">Al</span>2O3/Ti<span class="hlt">Al</span>ON in which there is no spinel and no <span class="hlt">Al</span>N, but alpha-alumina, titanium nitride, and titanium aluminum oxynitride. In general, the improved density TiN/<span class="hlt">Al</span>2O3/Ti<span class="hlt">Al</span>ON ceramic composites of the invention are prepared by: adding aluminum isobutoxide (<span class="hlt">Al</span>(O-iBu)3) to a refluxing mixture of deionized water and formic acid at elevated temperatures to obtain an aluminum sol; casting the slurry in molds; drying the cast material and calcining it at about 600 C; screening the calcined material to minus 200 mesh; pressing pellets at about 10 KPsi, isostatically pressing them at about 40 KPsi; and sintering the pellets below 1,700 C to obtain sintered bodies having densities greater than about 4.2 g/cc.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015ApPhL.107g2105L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015ApPhL.107g2105L"><span id="translatedtitle">Scattering induced by <span class="hlt">Al</span> segregation in <span class="hlt">Al</span>GaN/GaN heterostructures</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Liu, Xiwen; Ji, Dong; Lu, Yanwu</p> <p>2015-08-01</p> <p>The effect of <span class="hlt">Al</span> segregation near dislocations on the mobility of two-dimensional electron gas in <span class="hlt">Al</span>GaN/GaN heterostructure-based high-electron-mobility transistors was investigated. Exponentially varied composition fluctuation was effective in describing <span class="hlt">Al</span> segregation near dislocations when calculating scattering behavior. Mobility, which was limited by <span class="hlt">Al</span> segregation surrounding dislocation lines, was calculated to be in the order of 103 cm2/Vs to 106 cm2/Vs. Results indicated that the mobility in <span class="hlt">Al</span>GaN/GaN heterojunction was enhanced upon the reduction of dislocation density at low temperature. This study contributes to generating higher electron mobility in <span class="hlt">Al</span>GaN/GaN heterojunctions.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3231464','PMC'); return false;" href="http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3231464"><span id="translatedtitle">Effects of <span class="hlt">Al</span>(III) and Nano-<span class="hlt">Al</span>13 Species on Malate Dehydrogenase Activity</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Yang, Xiaodi; Cai, Ling; Peng, Yu; Li, Huihui; Chen, Rong Fu; Shen, Ren Fang</p> <p>2011-01-01</p> <p>The effects of different aluminum species on malate dehydrogenase (MDH) activity were investigated by monitoring amperometric i-t curves for the oxidation of NADH at low overpotential using a functionalized multi-wall nanotube (MWNT) modified glass carbon electrode (GCE). The results showed that <span class="hlt">Al</span>(III) and <span class="hlt">Al</span>13 can activate the enzymatic activity of MDH, and the activation reaches maximum levels as the <span class="hlt">Al</span>(III) and <span class="hlt">Al</span>13 concentration increase. Our study also found that the effects of <span class="hlt">Al</span>(III) and <span class="hlt">Al</span>13 on the activity of MDH depended on the pH value and aluminum speciation. Electrochemical and circular dichroism spectra methods were applied to study the effects of nano-sized aluminum compounds on biomolecules. PMID:22163924</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2008MMTA...39.1610H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2008MMTA...39.1610H"><span id="translatedtitle">Microscopic Properties of Long-Period Ordering in <span class="hlt">Al</span>-Rich Ti<span class="hlt">Al</span> Alloys</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Hata, S.; Nakano, T.; Kuwano, N.; Itakura, M.; Matsumura, S.; Umakoshi, Y.</p> <p>2008-07-01</p> <p>The ordering mechanism of long-period superstructures (LPSs) in <span class="hlt">Al</span>-rich Ti<span class="hlt">Al</span> alloys has been investigated by high-resolution transmission electron microscopy (HRTEM). The LPSs are classified in terms of arrangements of base clusters with different shapes and compositions formed in Ti-rich (002) layers of L10-Ti<span class="hlt">Al</span> matrix: square Ti4<span class="hlt">Al</span>, fat rhombus Ti3<span class="hlt">Al</span>, and lean rhombus Ti2<span class="hlt">Al</span> type clusters. The HRTEM observations revealed that antiphase boundaries of long-range-ordered LPS domains and short-range-ordered microdomains are constructed by various space-filling arrangements of the base clusters. Such a microscopic property characterized by the base clusters and their arrangements is markedly analogous to that of the {left< {{text{1,1/2,0}}} rightrangle } * special-point ordering alloys such as Ni-Mo.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19890057866&hterms=charles+taylor&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3Dcharles%2Btaylor','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19890057866&hterms=charles+taylor&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3Dcharles%2Btaylor"><span id="translatedtitle">Lowest ionization potentials of <span class="hlt">Al</span>2</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Bauschlicher, Charles W., Jr.; Barnes, Leslie A.; Taylor, Peter R.</p> <p>1989-01-01</p> <p>Potential curves for the lowest two electronic states, X 2Sigma(+)g and A 2Pi(u), of <span class="hlt">Al</span>2(+) were computed using complete active space SCF/multireference CI wave functions and large Gaussian basis sets. The lowest observable vertical ionization potential, to <span class="hlt">Al</span>2(+) X 2Sigma(+)g, of the <span class="hlt">Al</span>2 X 3 Pi(u) ground state is calculated to occur around 6.1 eV, in excellent agreement with the experimental range of 6.0 to 6.42 eV obtained in recent cluster ionization studies by Cox and co-workers. The second vertical ionization potential, to <span class="hlt">Al</span>2(+) A 2Pi(u), occurs near 6.4 eV, also within the experimental range. The adiabatic IP of 5.90 eV is in good agreement with the value of 5.8 to 6.1 eV deduced by Hanley and co-workers from the difference in thresholds between collision induced dissociation processes of <span class="hlt">Al</span>3(+). The computed IP values are somewhat larger than those deduced from branching ratios in cluster fragmentation experiments by Jarrold and co-workers. The observation of an ionization threshold below 6.42 eV is shown to be incompatible with an <span class="hlt">Al</span>2 ground electronic state assignment of 3Sigma(-)g, but the separation between the two lowest states of <span class="hlt">Al</span>2 is so small that it is likely that both are populated in the experiments, so that this does not provide unambiguous support for the recent theoretical assignment of the ground state as 3Pi(u).</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li class="active"><span>20</span></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_20 --> <div id="page_21" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li class="active"><span>21</span></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="401"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19890001234','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19890001234"><span id="translatedtitle">The lowest ionization potentials of <span class="hlt">Al</span>2</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Bauschlicher, Charles W., Jr.; Barnes, Leslie A.; Taylor, Peter R.</p> <p>1988-01-01</p> <p>Potential curves for the lowest two electronic states (X 2 sigma g + and A 2 pi u) of <span class="hlt">Al</span>2(+) were computed using complete active space SCF/multireference CI wave functions and large Gaussian basis sets. The lowest observable vertical ionization potential (to <span class="hlt">Al</span>2(+) X 2 sigma g +) of the <span class="hlt">Al</span>2 X 3 pi u ground state is calculated to occur around 6.1 eV, in excellent agreement with the experimental range of 6.0 to 6.42 eV obtained in recent cluster ionization studies by Cox and co-workers. The second vertical ionization potential (to <span class="hlt">Al</span>2(+) A 2 pi u) occurs near 6.4 eV, also within the experimental range. The adiabatic IP of 5.90 eV is in good agreement with the value of 5.8 to 6.1 eV deduced by Hanley and co-workers from the difference in thresholds between collision induced dissociation processes of <span class="hlt">Al</span>3(+). The computed IP values are somewhat larger than those deduced from branching ratios in cluster fragmentation experiments by Jarrold and co-workers. The observation of an ionization threshold below 6.42 eV is shown to be incompatible with an <span class="hlt">Al</span>2 ground electronic state assignment of 3 sigma g -, but the separation between the two lowest states of <span class="hlt">Al</span>2 is so small that it is likely that both are populated in the experiments, so that this does not provide unambiguous support for the recent theoretical assignment of the ground state as 3 pi u.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016CP....465....9S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016CP....465....9S"><span id="translatedtitle">Quantum chemical study of the reactions of <span class="hlt">Al</span>, <span class="hlt">Al</span>O and <span class="hlt">Al</span>OH with H2O2</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Sharipov, Alexander S.; Starik, Alexander M.</p> <p>2016-02-01</p> <p>Quantum chemical calculations with the use of hybrid density functional with perturbative second-order correlation and dispersion correction are carried out to study the reactions of <span class="hlt">Al</span>, <span class="hlt">Al</span>O and <span class="hlt">Al</span>OH with the H2O2 molecule. The values of energy barriers are estimated by means of extrapolation to the basis set limit. The energetically favorable reaction pathways have been revealed during the examination of the potential energy surfaces. Complex character of the processes under study has been established. It has been found that the initial stages of the considered processes are barrierless. Appropriate rate constants for principal channels of the reactions under study have been estimated by using capture model and canonical variational theory. The Arrhenius approximations for these channels have been proposed for the temperature range T = 300-4000 K.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/919660','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/919660"><span id="translatedtitle">The Stability of <span class="hlt">Al</span> 11Sm3 (<span class="hlt">Al</span>4Sm) Phases in the <span class="hlt">Al</span>-Sm Binary System</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>S.H.Zhou; R.E. Napolitano</p> <p>2007-06-01</p> <p>The relative stability of <span class="hlt">Al</span>{sub 11}Sm{sub 3} (<span class="hlt">Al</span>{sub 4}Sm) intermetallic phases was experimentally investigated through a series of heat treatments followed by microstructural, microchemical, and X-ray diffraction (XRD) analyses. The principal findings are that the high-temperature tetragonal phase is stable from 1655 to 1333 K and that the low-temperature orthorhombic phases, {alpha} and {gamma}, have no range of full stability but are metastable with respect to the crystalline <span class="hlt">Al</span> and Sm reference states down to 0 K. Thermodynamic modeling is used to describe the relative energetics of stable and metastable phases along with the associated two-phase mixtures. Issues regarding transition energetics and kinetics are discussed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19990008594','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19990008594"><span id="translatedtitle">Two-Phase (Ti<span class="hlt">Al+TiCrAl</span>) Coating Alloys for Titanium Aluminides</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Brady, Michael P. (Inventor); Smialek, James L. (Inventor); Brindley, William J. (Inventor)</p> <p>1998-01-01</p> <p>A coating for protecting titanium aluminide alloys, including the Ti<span class="hlt">Al</span> gamma + Ti3<span class="hlt">Al</span> (alpha(sub 2)) class, from oxidative attack and interstitial embrittlement at temperatures up to at least 1000 C. is disclosed. This protective coating consists essentially of titanium, aluminum. and chromium in the following approximate atomic ratio: Ti(41.5-34.5)<span class="hlt">Al</span>(49-53)Cr(9.5-12.5)</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014RJPCA..88..729S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014RJPCA..88..729S"><span id="translatedtitle">Thermodynamic properties of alloys of the <span class="hlt">Al</span>-Co and <span class="hlt">Al</span>-Co-Sc systems</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Shevchenko, M. A.; Berezutskii, V. V.; Ivanov, M. I.; Kudin, V. G.; Sudavtsova, V. S.</p> <p>2014-05-01</p> <p>Enthalpies of mixing for melts of the binary <span class="hlt">Al</span>-Co system at 1870 K in the range 0 < x Co < 0.25, and at 1620 K, 0 < x Co < 0.12, are investigated by means of isoperibolic calorimetry. Enthalpies of mixing for melts of the ternary <span class="hlt">Al</span>-Co-Sc system are investigated at 1870 K for sections <span class="hlt">Al</span>0.75(1 - x)Co0.25(1 - x)Sc x , 0 < x < 0.024, and <span class="hlt">Al</span>0.88(1 - x)Co0.12(1 - x)Sc x , 0 < x < 0.044. Using the literature data on the enthalpies of mixing for liquid and solid alloys, the activities of melt components, and the phase diagram of the <span class="hlt">Al</span>-Co system, the thermodynamic properties of liquid and solid alloys of the <span class="hlt">Al</span>-Co system over a wide range of temperatures and compositions are calculated using a software package of our own design, based on the model of ideal associated solutions (IAS). The enthalpies of mixing and the liquidus surface of the phase diagram of the ternary <span class="hlt">Al</span>-Co-Sc system over the interval of concentrations are estimated by modeling with data on binary boundary subsystems. All of the components of both the binary <span class="hlt">Al</span>-Co and ternary <span class="hlt">Al</span>-Co-Sc systems tend to interact with one another quite strongly: ? H min(<span class="hlt">Al</span>-Co) = -32.5 kJ/mol at x Co = 0.44; ? H min(<span class="hlt">Al</span>-Co-Sc) = -46 kJ/mol for <span class="hlt">Al</span>0.4Co0.3Sc0.3 (estimated).</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4435199','PMC'); return false;" href="http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4435199"><span id="translatedtitle">Remarks on Peinado et <span class="hlt">al.'s</span> Analysis of J3Gen</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Garcia-Alfaro, Joaquin; Herrera-Joancomart, Jordi; Meli-Segu, Joan</p> <p>2015-01-01</p> <p>Peinado et <span class="hlt">al</span>. analyzed the security of the J3Gen pseudorandom number generator proposed by Meli-Segu et <span class="hlt">al</span>., and claimed weaknesses regarding its security properties. They also presented a deterministic attack based on the decimation of the J3Gen output sequences. We show that the assumptions made by Peinado et <span class="hlt">al</span>. are not correct and that the proposed deterministic attack against J3Gen does not hold in practice. PMID:25781510</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/25781510','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/25781510"><span id="translatedtitle">Remarks on Peinado et <span class="hlt">al.'s</span> Analysis of J3Gen.</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Garcia-Alfaro, Joaquin; Herrera-Joancomartí, Jordi; Melià-Seguí, Joan</p> <p>2015-01-01</p> <p>Peinado et <span class="hlt">al</span>. analyzed the security of the J3Gen pseudorandom number generator proposed by Melià-Seguí et <span class="hlt">al</span>., and claimed weaknesses regarding its security properties. They also presented a deterministic attack based on the decimation of the J3Gen output sequences. We show that the assumptions made by Peinado et <span class="hlt">al</span>. are not correct and that the proposed deterministic attack against J3Gen does not hold in practice. PMID:25781510</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2004NIMPB.218..158C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2004NIMPB.218..158C"><span id="translatedtitle">Depolarization currents in <span class="hlt">Al</span> 2O 3 and Mg<span class="hlt">Al</span> 2O 4 oxides</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Carvalhaes, R. P. M.; Rocha, M. S.; de Souza, S. S.; Blak, A. R.</p> <p>2004-06-01</p> <p>In the present work, dipole defects in ?-irradiated and thermally treated samples of <span class="hlt">Al</span> 2O 3 and Mg<span class="hlt">Al</span> 2O 4 oxides are investigated, applying the thermally stimulated depolarisation currents technique (TSDC). The TSDC spectra of Mg<span class="hlt">Al</span> 2O 4 doped with Fe 2+, Fe 3+, Co 2+, Cr 3+ and Mn 2+ show four bands at 130 K, 160 K, 250 K and 320 K, and the spectra of <span class="hlt">Al</span> 2O 3 doped with Mg 2+, Cr 3+ and Fe 3+ show bands between 230 K and 260 K. It has been observed that the bands at 130 K, 160 K and 250 K in Mg<span class="hlt">Al</span> 2O 4 spinel and that the 230 K and 240 K bands in <span class="hlt">Al</span> 2O 3 are related to dipole defects. The other bands are possibly related to different types of charge storage mechanisms (space-charge and interfacial polarisation) or deal with distributions in activation energies and/or in relaxation times. A thermal decrease of the TSDC bands for heat treatments above 1000 K has been observed. In Mg<span class="hlt">Al</span> 2O 4 spinel, the 250 K band could be recovered after ?-irradiation and the two dipole peaks in <span class="hlt">Al</span> 2O 3 were partially recovered. Thermal treatments affect the dipole aggregation processes in both oxides. Optical absorption (AO) results indicate that the presence of bands of water molecules in the infrared region obstructs the appearance of the TSDC bands in both <span class="hlt">Al</span> 2O 3 and Mg<span class="hlt">Al</span> 2O 4. The 250 K peak in Mg<span class="hlt">Al</span> 2O 4 was correlated to V-type centres and the 250 K peak in <span class="hlt">Al</span> 2O 3 to a substitutional Mg 2+ ion near a trapped hole localised on an adjacent oxygen ion.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/26241194','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/26241194"><span id="translatedtitle"><span class="hlt">Al</span>3AuIr: A New Compound in the <span class="hlt">Al</span>-Au-Ir System.</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Kadok, Joris; de Weerd, Marie-Cécile; Boulet, Pascal; Gaudry, Émilie; Grin, Yuri; Fournée, Vincent; Ledieu, Julian</p> <p>2015-08-17</p> <p>A new ternary phase with a composition of <span class="hlt">Al</span>3AuIr has been found in the <span class="hlt">Al</span>-rich area of the <span class="hlt">Al</span>-Au-Ir system. Differential thermal analysis indicates a melting point of 990 °C, and single-crystal X-ray diffraction measurements reveal that this ternary phase adopts a Ni2<span class="hlt">Al</span>3 structure type (space group P3̅m1) with a = 4.2584(5) Å and c = 5.1991(7) Å. This compound is isostructural to the <span class="hlt">Al</span>3Cu1.5Co0.5 phase also found in the <span class="hlt">Al</span>-rich part of the <span class="hlt">Al</span>-Cu-Co ternary diagram. Experimental evidence combined with ab initio calculations point toward an <span class="hlt">Al</span>3AuIr phase stabilized by a Hume-Rothery mechanism. Quantum chemical calculations indicate two-center and multicenter interactions in the <span class="hlt">Al</span>3AuIr phase. Layered distribution of two-center interactions separated by regions with four- and five-center bonds suggests a preferential cleavage of the material at puckered planes perpendicular to the [001] direction. PMID:26241194</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/20001647','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/20001647"><span id="translatedtitle">Microsample testing of single crystalline Ti-52 at% <span class="hlt">Al</span> and Ti-55.5 at% <span class="hlt">Al</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Zupan, M.; Dimiduk, D.M.; Hemker, K.J.</p> <p>1999-07-01</p> <p>Dislocation activity in two-phase commercial Ti<span class="hlt">Al</span> alloys occurs most readily in the {gamma}-Ti<span class="hlt">Al</span> phase, and measurements of the CRSS of single crystalline {gamma}-Ti<span class="hlt">Al</span> provides a solid foundation for understanding the mechanical performance of these alloys. Single crystals of {gamma}-Ti<span class="hlt">Al</span> with greater than 54.5 at% <span class="hlt">Al</span> have been grown using the optical float zone crystal growing technique, but single crystals with lower <span class="hlt">Al</span> content, closer to that of commercial alloys, have not. In the present study, polycrystalline ingots of Ti-52 at% <span class="hlt">Al</span> have been heat treated to form very large grains, and microsample tensile specimens, which have a nominal gage cross-section of 250{micro}m x 300{micro}m, a gage length of 250{micro}m and an overall length of 3 mm, have been machined from within single grains. Microsample high-temperature stress-strain curves for Ti-55.5 at% <span class="hlt">Al</span> single crystals oriented along the [001] and [010] are presented. Tensile test results for Ti-52 at% <span class="hlt">Al</span> tested at 1,073K along the[{bar 2}37], [{bar 1}73] and [{bar 3}44] orientations will also be discussed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19830003032&hterms=coal&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D80%26Ntt%3Dcoal','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19830003032&hterms=coal&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D80%26Ntt%3Dcoal"><span id="translatedtitle">High temperature deformation of Ni<span class="hlt">Al</span> and Co<span class="hlt">Al</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Nix, W. D.</p> <p>1982-01-01</p> <p>The high temperature mechanical properties of the aluminides are reviewed with respect to their potential as high temperature structural materials. It is shown that Ni<span class="hlt">Al</span> and Co<span class="hlt">Al</span> are substantially stronger than the pure metals Ni and Co at high temperatures and approach the strength of some superalloys, particularly when those superalloys are tested in "weak" directions. The factors that limit and control the high temperature strengths of Ni<span class="hlt">Al</span> and Co<span class="hlt">Al</span> are examined to provide a basis for the development of intermetallic alloys of this type.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19920053767&hterms=metal+heat+combustion&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3Dmetal%2Bheat%2Bcombustion','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19920053767&hterms=metal+heat+combustion&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3Dmetal%2Bheat%2Bcombustion"><span id="translatedtitle">Combustion synthesis of TiB2-<span class="hlt">Al</span>2O3-<span class="hlt">Al</span> composite materials</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Feng, H. J.; Moore, J. J.; Wirth, D. G.</p> <p>1991-01-01</p> <p>The oxide-aluminum exothermic reduction reaction is presently used in the combustion-synthesis of ceramic/metal composites. An excess of <span class="hlt">Al</span> is used in the reacting materials, which rapidly generate enough heat to exceed <span class="hlt">Al</span>'s melting point. The molten <span class="hlt">Al</span> thus evolved is allowed to infiltrate the porous ceramic matrix as the exothermic reaction proceeds; this feature of the process turns the disadvantage of high porosity levels in combustion-synthesized materials into an advantage. Attention is given to the system obtained with 3TiO2 + 3B2O3 + (10-x)<span class="hlt">Al</span> starting materials.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/100049','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/100049"><span id="translatedtitle">Solid state reaction of <span class="hlt">Al</span> and Zr in <span class="hlt">Al</span>/Zr multilayers: A calorimetry study</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Blobaum, K.J.; Weihs, T.P.; Barbee, T.W. Jr.; Wall, M.A.</p> <p>1995-04-14</p> <p>The exothermic, solid state reaction of <span class="hlt">Al</span> and Zr has been studied in thick <span class="hlt">Al</span>/Zr multilayers using Differential Scanning Calorimetry and X-ray diffraction. The multilayer samples were magnetron sputter deposited into highly textured alternate layers of <span class="hlt">Al</span> and Zr with nominal composition <span class="hlt">Al</span>{sub 3}Zr. The samples used in this study were 47{mu}m thick with a 427{Angstrom} period. When samples were isochronally scanned from 25 to 725C, a large exotherm at {approximately}350C was followed by one or two smaller exotherms at {approximately}650C. The first exotherm is dominated by a diffusion based reaction of <span class="hlt">Al</span> and Zr that produces two phases in isochronal scans: amorphous <span class="hlt">Al</span>-Zr and cubic <span class="hlt">Al</span>{sub 3}Zr, and two additional phases in isothermal anneals: <span class="hlt">Al</span>{sub 2}Zr and tetragonal <span class="hlt">Al</span>{sub 3}Zr. The exothermic heat from this multi-phase reaction is measured using isochronal scans and isothermal anneals, and the heat flow is analyzed using a 1-D diffusion based model. An average activation energy and a diffusion constant are determined. In the isothermal scans, the total exothermic heat increases linearly with {radical}time, and layer thicknesses vary linearly with heat.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2004APS..MARD33006C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2004APS..MARD33006C"><span id="translatedtitle">Photoemission from <span class="hlt">Al</span> Alloys during Tensile Deformation</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Cai, Mingdong; Langford, Stephen; Levine, Lyle; Dickinson, Thomas</p> <p>2004-03-01</p> <p>We report simultaneous measurements of strain and photoelectron emission intensity from high purity <span class="hlt">Al</span> (1350), <span class="hlt">Al</span>-Mg (5052), <span class="hlt">Al</span>-Mn (3003), <span class="hlt">Al</span>-Cu (2024) and <span class="hlt">Al</span>-Mg-Si (6061) alloys under uniaxial tension due to pulsed excimer laser radiation (248-nm). The photoemission signals are sensitive to deformation-induced changes in surface morphology, including the formation of slip lines and slip bands. In the early stages of deformation (strain ¡ 0.03), the photoemission intensity increases gradually in a nonlinear fashion. Depending on sample composition and heat treatment, the photoemission intensity subsequently grows linearly until the accumulated strain reaches about 0.20. Finally, the photoemission intensity increases parabolically until failure. The onset of strain localization corresponds to the transition from linear to parabolic growth. A constitutional model incorporating microstructure evolution and work-hardening during tensile deformation is proposed to qualitatively interpret the growth of the photoemission signals as a function of strain. The photoemission signals from the tested alloys are interpreted in terms of the effect of surface treatment, work function, microstructure, and composition on the development of dislocation structures during deformation.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/616445','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/616445"><span id="translatedtitle">Long range order and vacancy properties in <span class="hlt">Al</span>-rich Fe{sub 3}<span class="hlt">Al</span> and Fe{sub 3}<span class="hlt">Al</span>(Cr) alloys</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Kim, S.M.; Morris, D.G.</p> <p>1998-05-01</p> <p>Neutron powder diffraction measurements have been carried out in situ from room temperature to about 100 C in Fe28<span class="hlt">Al</span> (28 at.% <span class="hlt">Al</span>), Fe32.5<span class="hlt">Al</span> (32.5 at.% <span class="hlt">Al</span>) and Fe28<span class="hlt">Al</span>15Cr (28 at.% <span class="hlt">Al</span>, 5 at.% Cr) alloys. X-ray diffraction and TEM studies provided supporting information. The data were analyzed to obtain information about the temperature dependence of the DO{sub 3} and B2 long range order parameters, the location of the Cr atoms and their effect on the ordering energies, and on the vacancy formation and migration properties in Fe28<span class="hlt">Al</span> and Fe32.5<span class="hlt">Al</span> alloys. The location of the ternary alloying addition in DO{sub 3} and B2 ordered <span class="hlt">Al</span>-rich Fe{sub 3}<span class="hlt">Al</span> is shown to be consistent with considerations of interatomic bond energies.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014SurSc.624....1L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014SurSc.624....1L"><span id="translatedtitle">First-principle study of adhesion, wetting and bonding on <span class="hlt">Al/Al</span>3V(001) interface</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Li, Jian; Qi, Yuning; Zhang, Ming; Zhou, Yong; Li, Xiao</p> <p>2014-06-01</p> <p>The adhesion, wetting, and bonding on fcc-<span class="hlt">Al</span>(001)/D022-<span class="hlt">Al</span>3V(001) interface were investigated using density functional calculations. Considering different terminations of <span class="hlt">Al</span>3V(001) (<span class="hlt">Al</span>- and <span class="hlt">Al</span> + V-terminated) and stacking sites (center-, hollow- and top-sites), six <span class="hlt">Al/Al</span>3V(001) models were calculated. For the models with same stacking site, <span class="hlt">Al</span> + V-terminated model has larger work of adhesion (Wad) than the <span class="hlt">Al</span>-terminated one. For the models with same termination, the work of adhesion decreases, and the interface energy (γint) increases as the order of top-, bridge- and center-sites. <span class="hlt">Al</span>-terminated-center-sited and <span class="hlt">Al</span> + V-terminated-center-sited models are more stable among six models. After complete structure relaxation, both models have the same epitaxial stacking style. Therefore, the both models can be regarded as of the same and most stable one (noted as CSI model), but separating along <span class="hlt">Al-Al</span> and <span class="hlt">Al-Al</span>+V inter-planes. Based on the perfect wetting and strong adhesion in CSI model, the heterogeneous nucleation of α-<span class="hlt">Al</span> on <span class="hlt">Al</span>3V(001) was interpreted in terms of crystallography and thermodynamics. The interfacial bonding was discussed with analysis of valence electron density distribution and partial density of states (PDOS). The bonding is mainly contributed from <span class="hlt">Al</span>V covalent bonds and <span class="hlt">AlAl</span> metallic interactions.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/26524174','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/26524174"><span id="translatedtitle">The new structure type Gd3Ni7<span class="hlt">Al</span>14.</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Pukas, Svitlana; Gladyshevskii, Roman</p> <p>2015-11-01</p> <p>The crystal structure of Gd3Ni7<span class="hlt">Al</span>14 (trigadolinium heptanickel tetradecaaluminide) belongs to a family of two-layer structures and can be described as an assembly of interpenetrating centred straight prisms. For the Ni atoms, trigonal prisms (<span class="hlt">Al</span>4Gd2 and <span class="hlt">Al</span>6) are observed, the <span class="hlt">Al</span> atoms are inside tetragonal (Ni2<span class="hlt">Al</span>2Gd4, Ni2<span class="hlt">Al</span>4Gd2, <span class="hlt">Al</span>4Gd4, Ni4<span class="hlt">Al</span>4 and <span class="hlt">Al</span>8) and pentagonal (Ni4<span class="hlt">Al</span>6 and <span class="hlt">Al</span>10) prisms, while the Gd atoms are at the centres of pentagonal (Ni4<span class="hlt">Al</span>6) and hexagonal (Ni4<span class="hlt">Al</span>8) prisms. In each case, the true coordination polyhedron is a capped prism, also including atoms from the same layer. The structural features of Gd3Ni7<span class="hlt">Al</span>14 are similar to those of the intermetallides PrNi2<span class="hlt">Al</span>3 and ZrNi<span class="hlt">Al</span>. In all these structures, Ni-centred trigonal prisms form infinite columns via common triangular faces. The columns share prism edges and form a three-dimensional framework with six-membered rings in the (001) plane in the case of the PrNi2<span class="hlt">Al</span>3 and ZrNi<span class="hlt">Al</span> types. In the case of Gd3Ni7<span class="hlt">Al</span>14, six-membered rings are also observed, but only two-thirds of the rings are interconnected via prism edges. PMID:26524174</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/6542417','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/6542417"><span id="translatedtitle">Combustion synthesis of Ti<span class="hlt">Al</span>-matrix composites in the Ti-<span class="hlt">Al</span>-BN system</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Mabuchi, H.; Tsuda, H.; Nakayama, Y. . Dept. of Metallurgy and Materials Science)</p> <p>1995-01-15</p> <p>The intermetallic compound Ti<span class="hlt">Al</span> has attracted much attention for its potential use as a structural high-temperature material. However, its use has been limited because of its negligible low-temperature ductility and fracture toughness and low high-temperature strength and creep. To improve these properties, recently this compound has been made as a composite material containing a secondary phase such as boride, carbide, nitride, or oxide. Recently, combustion synthesis or self-propagating, high-temperature synthesis (SHS) using powder compacts has been developed to produce intermetallics or ceramics. It is also possible to form intermetallic-intermetallic, intermetallic-ceramic, or ceramic-ceramic composites from combustion reactions between corresponding elemental constituents. It has the advantage of an in-situ forming technique compared with conventional artificial composite production approaches. In the previous studies using elemental powders, combustion reaction was carried out to form intermetallic-ceramic composites in the Ti-<span class="hlt">Al</span>-C, or Ti-<span class="hlt">Al</span>-N system. The compacts of Ti and <span class="hlt">Al</span> powders with carbon powder or in gaseous nitrogen reacted exothermically, and formed a mixture product which had a fine distribution of the Ti[sub 2]<span class="hlt">Al</span>C or Ti[sub 2]<span class="hlt">Al</span>N particles in the matrix Ti<span class="hlt">Al</span> with a small amount of Ti[sub 3]<span class="hlt">Al</span>. The processing technique, therefore, is of interest as a combustion reaction synthesis to make in-situ intermetallic-based composite materials. In the present work, to investigate the effect of BN addition on the reaction of Ti And <span class="hlt">Al</span> powder mixtures, combustion synthesis of Ti<span class="hlt">Al</span>-matrix composites has been performed for the Ti-<span class="hlt">Al</span>-BN system.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/19089902','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/19089902"><span id="translatedtitle">Aquaporin-4 overexpression in rat <span class="hlt">ALS</span> model.</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Nicaise, Charles; Soyfoo, Muhammad Shahnawaz; Authelet, Michle; De Decker, Robert; Bataveljic, Danijela; Delporte, Christine; Pochet, Roland</p> <p>2009-02-01</p> <p>Onset of motoneuron death characterizing amyotrophic lateral sclerosis (<span class="hlt">ALS</span>) is closely linked to modified astrocytic and glial environments. Here, we show that in the spinal cord from transgenic rat overexpressing mutated human SOD1, aquaporin-4 mRNA and protein are specifically overexpressed in the gray matter at end stage of disease. Immunohistochemistry and double immunofluorescence allowed to detect, in the spinal cord gray matter of the <span class="hlt">ALS</span> rat, increased aquaporin-4 surrounding both vessel and motoneuron perikarya. The use of pre-embedding immunohistochemistry at electron microscopic level confirmed such localization associated with swollen astrocytic processes surrounding the vessels. The AQP4 immunohistochemical labeling surrounding several motoneuron perikarya was only seen in <span class="hlt">ALS</span> rats. Identification of this AQP4-positive cellular type remains unclear. PMID:19089902</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/676870','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/676870"><span id="translatedtitle">Boron strengthening in Fe<span class="hlt">Al</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Baker, I.; Li, X.; Xiao, H.; Klein, O.; Nelson, C.; Carleton, R.L.; George, E.P.</p> <p>1998-11-01</p> <p>The effect of boron on the strength of B2-structured Fe<span class="hlt">Al</span> is considered as a function of composition, grain size and temperature. Boron does not affect the concentrations of antisite atoms or vacancies present, with the former increasing and the latter decreasing with increasing deviation from the stoichiometric composition. When vacancies are absent, the strength increase per at. % B per unit lattice strain, {Delta}{sigma}/({Delta}c x {epsilon}) increases with increasing aluminum concentration, but when vacancies are present (>45 at. % <span class="hlt">Al</span>), {Delta}{sigma}/({Delta}c x {epsilon}) decreases again. Boron increases grain size strengthening in Fe<span class="hlt">Al</span>. B strengthening is roughly independent of temperature up to the yield strength peak but above the point, when diffusion-assisted deformation occurs, boron strengthening increases dramatically.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li class="active"><span>21</span></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_21 --> <div id="page_22" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li class="active"><span>22</span></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li><a href="#" onclick='return showDiv("page_24");'>24</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="421"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/434994','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/434994"><span id="translatedtitle">The mechanical properties of Fe<span class="hlt">Al</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Baker, I.; George, E.P.</p> <p>1996-12-31</p> <p>Only in the last few years has progress been made in obtaining reproducible mechanical properties data for Fe<span class="hlt">Al</span>. Two sets of observations are the foundation of this progress. The first is that the large vacancy concentrations that exist in Fe<span class="hlt">Al</span> at high temperature are easily retained at low temperature and that these strongly affect the low-temperature mechanical properties. The second is that RT ductility is adversely affected by water vapor. Purpose of this paper is not to present a comprehensive overview of the mechanical properties of Fe<span class="hlt">Al</span> but rather to highlight our understanding of key phenomena and to show how an understanding of the factors which control the yield strength and fracture behavior has followed the discovery of the above two effects. 87 refs, 9 figs.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/11465925','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/11465925"><span id="translatedtitle">Calcium: the Darth Vader of <span class="hlt">ALS</span>.</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Appel, S H; Beers, D; Siklos, L; Engelhardt, J I; Mosier, D R</p> <p>2001-03-01</p> <p>Motor neuron dysfunction and loss in amyotrophic lateral sclerosis (<span class="hlt">ALS</span>) have been attributed to several different mechanisms, including increased intracellular calcium, glutamate excitotoxicity, oxidative stress and free radical damage, mitochondrial dysfunction, and neurofilament aggregation and dysfunction of transport mechanisms. These alterations are not mutually exclusive, and increased calcium could be a common denominator. Furthermore, the selective vulnerability of spinal motor neurons and the relative sparing of eye motor neurons represent striking features of both sporadic and familial <span class="hlt">ALS</span>. Here we review the evidence that calcium homeostasis is altered in <span class="hlt">ALS</span>, and that low levels of the calcium binding proteins parvalbumin and calbindin-D28K contribute to selective vulnerability by decreasing the ability of motor neurons to handle an increased calcium load, with cell injury and death as the consequence. PMID:11465925</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/20406177','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/20406177"><span id="translatedtitle">Repetitive transcranial magnetic stimulation for <span class="hlt">ALS</span>.</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Dileone, M; Profice, P; Pilato, F; Ranieri, F; Capone, F; Musumeci, G; Florio, L; Di Iorio, R; Di Lazzaro, V</p> <p>2010-07-01</p> <p>Amyotrophic lateral sclerosis (<span class="hlt">ALS</span>) is a devastating neurodegenerative disease affecting upper and lower motor neurons characterized by progressive weakness, respiratory failure and death within 3-5 years. It has been proposed that glutamate-related excitotoxicity may promote motor neuron death in <span class="hlt">ALS</span>. Glutamatergic circuits of the human motor cortex can be activated noninvasively using transcranial magnetic stimulation (TMS) of the brain, and repetitive TMS (rTMS) can produce changes in neurotransmission that outlast the period of stimulation. In recent years a remarkable number of papers about the potential effects of rTMS in several neurological disorders including <span class="hlt">ALS</span> has been published. Preliminary studies have shown that rTMS of the motor cortex, at frequencies that decrease cortical excitability, causes a slight slowing in the progression rate of <span class="hlt">ALS</span>, suggesting that these effects might be related to a diminution of glutamate-driven excitotoxicity. RTMS could also interfere with motor neuron death through different mechanisms: rTMS could modulate the production of brain-derived neurotrophic factor (BDNF), a potent survival factor for neurons, that in turn might represent a promoter of motor neuron sparing in <span class="hlt">ALS</span>. Despite some promising preliminary data, recent studies have demonstrated a lack of significant long-term beneficial effects of rTMS on neurological deterioration in <span class="hlt">ALS</span>. However, further studies are warranted to evaluate the potential efficacy of different protocols of motor cortex stimulation (in terms of technique, duration and frequency of stimulation), particularly during the early stages of the disease when the progression rate is more pronounced. PMID:20406177</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/10386051','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/10386051"><span id="translatedtitle">[<span class="hlt">Al</span>-Biruni--a universal scientist].</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Kujundzić, E; Masić, I</p> <p>1999-01-01</p> <p><span class="hlt">Al</span>-Biruni's was of Persian descent. He was born in Horesmiya and had studied mathematics, history and medicine. Acquiring knowledge from these sciences, he wrote an outstanding work on chronology of several nations and devoted it to Ziyarit ruler Kabus. He made a chronological overview of calendars from many nations, including Persians, Greeks, Egyptians, Jews, Melkitian and Nestorian Christians, Sabeyaans as well as the old Arabs. Data presented in the work, according to the later authors, were taken from very reliable sources. He was contemporary of Ibn-Sina, and thanks to their friendship, they have discussed very much miscellaneous topics. He belonged to the group of scholars, taken by Gaznevian Soultan Mahmud to a long journey to India. Afterwards <span class="hlt">Al</span>-Biruni wrote and published detailed work "Description of India"--a work on cultural history of India. Due to excellent abilities of <span class="hlt">Al</span>-Biruni as a philosopher and scholar, there are still significant and reliable notes about buddhistic philosophy, structure of castes and Brahmans' life style. In this <span class="hlt">Al</span>-Biruni's masterpiece, there are many comparative analysis of Suffism and certain Indian philosophical methods. <span class="hlt">Al</span>-Biruni's most important work is "Pharmacopoeia"--"Kitab <span class="hlt">al</span>-saydala", which brilliantly describes all medicaments. This work has been published in many languages. He also wrote few works on astronomy and astrology. In those works he has explained some astrological events through scientific approach in a such peculiar way that nobody has ever explained before. He was also interested in sciences like geology, mineralology, geography, mathematics, psychology and many others. PMID:10386051</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2011mave.book..105G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2011mave.book..105G"><span id="translatedtitle">Mathematik <span class="hlt">als</span> Geisteswissenschaft Der Mathematikschdigung dialogisch vorbeugen</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Gallin, Peter</p> <p></p> <p>Ursprnglich wollte ich Architekt werden getreu den Vorbildern von Vater und Grovater. Darum zeichnete ich bereits <span class="hlt">als</span> neunjhriges Kind Plne von Husern in der Art, wie ich sie oft zu sehen bekam. Ein ausgemustertes Holzdreieck mit einem rechten und zwei halben rechten Winkeln war das einzige Konstruktionswerkzeug, das ich damals besa und mit dem ich mich ans Werk machte. Zuerst einmal war da natrlich ein Rechteck <span class="hlt">als</span> Grundriss des Hauses zu zeichnen: Eine Seite, ein rechter Winkel, die zweite Seite, wieder ein rechterWinkel, die dritte Seite in gleicher Lnge wie die erste und dann der dritte rechte Winkel, dessen letzter Schenkel die vierte Seite gab.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19850044007&hterms=ductility&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3Dductility','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19850044007&hterms=ductility&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3Dductility"><span id="translatedtitle">Ductility in rapidly solidified Ni<span class="hlt">Al</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Gaydosh, D. J.; Jech, R. W.; Titran, R. H.</p> <p>1985-01-01</p> <p>An attempt is made to refine the grain structure of equiatomic Ni<span class="hlt">Al</span> by means of rapid solidification processing, and to examine the effect of small grain size on room temperature ductility. Free melt spinning was used to produce the rapidly solidified material. Room temperature bend testing of both as-spun and heat-treated Ni<span class="hlt">Al</span> ribbon was conducted by free bending the ribbon around a mandrel of successively smaller diameter until failure occurred. Room-temperature plastic deformation was exhibited both before and after a 1-h heat treatment at 1000 C. Heat treatment increased the observed ductility.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4712627','PMC'); return false;" href="http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4712627"><span id="translatedtitle">Complementary and Alternative Therapies in <span class="hlt">ALS</span></span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Bedlack, Richard S.; Joyce, Nanette; Carter, Gregory T.; Pagononi, Sabrina; Karam, Chafic</p> <p>2015-01-01</p> <p>Synopsis Given the severity of their illness and lack of effective disease modifying agents, it is not surprising that most patients with <span class="hlt">ALS</span> consider trying complementary and alternative therapies. Some of the most commonly considered alternative therapies include special diets, nutritional supplements, cannabis, acupuncture, chelation and energy healing. This chapter reviews these in detail. We also describe 3 models by which physicians may frame discussions about alternative therapies: paternalism, autonomy and shared decision making. Finally, we review a program called ALSUntangled which using shared shared decision making to review alternative therapies for <span class="hlt">ALS</span>. PMID:26515629</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19980028484','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19980028484"><span id="translatedtitle">Directional Solidification and Mechanical Properties of Ni<span class="hlt">Al-NiAl</span>Ta Alloys</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Johnson, D. R.; Chen, X. F.; Oliver, B. F.; Noebe, R. D.; Whittenberger, J. D.</p> <p>1995-01-01</p> <p>Directional solidification of eutectic alloys is a promising technique for producing in-situ composite materials exhibiting a balance of properties. Consequently, the microstructure, creep strength and fracture toughness of directionally solidified Ni<span class="hlt">Al-NiAl</span>Ta alloys were investigated. Directional solidification was performed by containerless processing techniques to minimize alloy contamination. The eutectic composition was found to be Ni<span class="hlt">Al</span>-15.5 at% Ta and well-aligned microstructures were produced at this composition. A near-eutectic alloy of Ni<span class="hlt">Al</span>-14.5Ta was also investigated. Directional solidification of the near-eutectic composition resulted in microstructures consisting of Ni<span class="hlt">Al</span> dendrites surrounded by aligned eutectic regions. The off-eutectic alloy exhibited promising compressive creep strengths compared to other Ni<span class="hlt">Al</span>-based intermetallics, while preliminary testing indicated that the eutectic alloy was competitive with Ni-base single crystal superalloys. The room temperature toughness of these two-phase alloys was similar to that of polycrystalline Ni<span class="hlt">Al</span> even with the presence of the brittle Laves phase Ni<span class="hlt">Al</span>Ta.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://eric.ed.gov/?q=Replication&pg=4&id=EJ821622','ERIC'); return false;" href="http://eric.ed.gov/?q=Replication&pg=4&id=EJ821622"><span id="translatedtitle">Replication and Extension of Little et <span class="hlt">al.'s</span> (2003) Forms and Functions of Aggression Measure</span></a></p> <p><a target="_blank" href="http://www.eric.ed.gov/ERICWebPortal/search/extended.jsp?_pageLabel=advanced">ERIC Educational Resources Information Center</a></p> <p>Fite, Paula J.; Stauffacher, Kirstin; Ostrov, Jamie M.; Colder, Craig R.</p> <p>2008-01-01</p> <p>The goal of the current study was to replicate the confirmatory factor analysis of Little et <span class="hlt">al.'s</span> (2003) aggression measure in an American sample of 69 children (mean age = 12.93 years; SD = 1.27). Although an exact replication of the original model could not be estimated given the small sample, a modified model representing a conceptual</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014JOM....66i1785S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014JOM....66i1785S"><span id="translatedtitle">Melting, Processing, and Properties of Disordered Fe-<span class="hlt">Al</span> and Fe-<span class="hlt">Al</span>-C Based Alloys</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Satya Prasad, V. V.; Khaple, Shivkumar; Baligidad, R. G.</p> <p>2014-09-01</p> <p>This article presents a part of the research work conducted in our laboratory to develop lightweight steels based on Fe-<span class="hlt">Al</span> alloys containing 7 wt.% and 9 wt.% aluminum for construction of advanced lightweight ground transportation systems, such as automotive vehicles and heavy-haul truck, and for civil engineering construction, such as bridges, tunnels, and buildings. The melting and casting of sound, porosity-free ingots of Fe-<span class="hlt">Al</span>-based alloys was accomplished by a newly developed cost-effective technique. The technique consists of using a special flux cover and proprietary charging schedule during air induction melting. These alloys were also produced using a vacuum induction melting (VIM) process for comparison purposes. The effect of aluminum (7 wt.% and 9 wt.%) on melting, processing, and properties of disordered solid solution Fe-<span class="hlt">Al</span> alloys has been studied in detail. Fe-7 wt.% <span class="hlt">Al</span> alloy could be produced using air induction melting with a flux cover with the properties comparable to the alloy produced through the VIM route. This material could be further processed through hot and cold working to produce sheets and thin foils. The cold-rolled and annealed sheet exhibited excellent room-temperature ductility. The role of carbon in Fe-7 wt.% <span class="hlt">Al</span> alloys has also been examined. The results indicate that Fe-<span class="hlt">Al</span> and Fe-<span class="hlt">Al</span>-C alloys containing about 7 wt.% <span class="hlt">Al</span> are potential lightweight steels.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/872577','DOE-PATENT-XML'); return false;" href="http://www.osti.gov/scitech/servlets/purl/872577"><span id="translatedtitle">Electronic circuits having Ni<span class="hlt">Al</span> and Ni.sub.3 <span class="hlt">Al</span> substrates</span></a></p> <p><a target="_blank" href="http://www.osti.gov/doepatents">DOEpatents</a></p> <p>Deevi, Seetharama C.; Sikka, Vinod K.</p> <p>1999-01-01</p> <p>An electronic circuit component having improved mechanical properties and thermal conductivity comprises Ni<span class="hlt">Al</span> and/or Ni.sub.3 <span class="hlt">Al</span>, upon which an alumina layer is formed prior to applying the conductive elements. Additional layers of copper-aluminum alloy or copper further improve mechanical strength and thermal conductivity.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2009MMTA...40.1541Q','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2009MMTA...40.1541Q"><span id="translatedtitle">Combustion Synthesis Reactions in Cold-Rolled Ni/<span class="hlt">Al</span> and Ti/<span class="hlt">Al</span> Multilayers</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Qiu, Xiaotun; Liu, Ranran; Guo, Shengmin; Graeter, Jesse Harris; Kecskes, Laszlo; Wang, Jiaping</p> <p>2009-07-01</p> <p>In this article, a cold rolling method was developed to fabricate Ni/<span class="hlt">Al</span> and Ti/<span class="hlt">Al</span> multilayer foils, and the combustion synthesis reactions in the cold-rolled foils were investigated. Combustion synthesis reactions were initiated by heating one end of the cold-rolled foil in a flame for several seconds. The Ni/<span class="hlt">Al</span> foils went through three reaction stages. The first reaction stage was a displacement of reaction zone with <span class="hlt">Al</span>3Ni as the reaction product. During the second stage, the part of the foil in the flame underwent thermal explosion. In the last stage, the heat released by thermal explosion triggered a self-propagating high-temperature synthesis (SHS) reaction across the foil that resulted in the formation of <span class="hlt">Al</span>Ni. In contrast, the Ti/<span class="hlt">Al</span> foils experienced only two reaction stages. First, a displacement of the reaction zone propagated across the foil with formation of <span class="hlt">Al</span>3Ti at the Ti/<span class="hlt">Al</span> interface. Then a thermal explosion reaction occurred in the part of foil that was heated in the flame, resulting in many different phases in the reacted foil.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2009SPIE.7518E..13M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2009SPIE.7518E..13M"><span id="translatedtitle">The evaluation and measurement of <span class="hlt">Al</span>GaN epitaxial layer with high <span class="hlt">Al</span> mole fraction</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Meng, Zhao; Yu, Libo; Li, Xiao; Liu, Qibin; Duan, Huiqiang; Yu, Chenhui; Chen, Changqing</p> <p>2009-08-01</p> <p>The epitaxial layer quality of AlxGa1-xN (x>0.6) on sapphire substrate grown by metal organic chemical vapor deposition (MOCVD) needs to be further improved. In this paper, we evaluated the properties of defects, lattice mismatch between epitaxial layer and substrate, crystal quality and conductivity for these high <span class="hlt">Al</span> mole fraction materials from the viewpoint of fabricating high performance solar blind detectors by comprehensive utilizing various undamaged measurements. The measurement of transmission spectrum was used to evaluate the absorption edge, band gap, mole fraction of <span class="hlt">Al</span> content, hetero-epitaxial interface, and transmissivity in the ultraviolet spectral range. X-ray diffraction (XRD) was used to measure the component of the <span class="hlt">Al</span>GaN material, uniformity of the material and crystal quality. The conductivity of the surface layer of the <span class="hlt">Al</span>GaN film material was obtained by using high precision current-voltage curve measurement. In short, the material quality, optical and electrical properties, and uniformity for high <span class="hlt">Al</span> mole fraction <span class="hlt">Al</span>GaN epitaxial layers were qualitatively or quantitatively measured and analyzed. These works lay the foundation for manufacturing high performance solar blind ultraviolet detectors based on high <span class="hlt">Al</span> mole fraction <span class="hlt">Al</span>GaN epitaxial materials on sapphire substrate.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/22150063','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/22150063"><span id="translatedtitle">Synthesis of nanostructured <span class="hlt">Al</span>N by solid state reaction of <span class="hlt">Al</span> and diaminomaleonitrile</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Rounaghi, S.A.; Eshghi, H.; Kiani Rashid, A.R.; Vahdati Khaki, J.; Samadi Khoshkhoo, M.; Scudino, S.; Eckert, J.; TU Dresden, Institut fuer Werkstoffwissenschaft, Dresden D-01062 </p> <p>2013-02-15</p> <p>The solid state reaction of diaminomaleonitrile (DAMN) with aluminum via both mechanochemical and thermal treatment routes was studied by X-ray diffraction and Fourier transform infrared spectroscopy. During the milling process, the reaction starts with the deammoniation of the DAMN molecules, followed by the formation of nanostructured <span class="hlt">Al</span>N powder as the main solid product after milling for 7 h. The reactivity of the mixed powder was also investigated during the conventional thermal treatment process using differential scanning calorimetry, derivative thermogravimetry and thermogravimetric analysis. The results reveal that DAMN starts to polymerize at 192 Degree-Sign C by the elimination of the amine groups. Furthermore, increasing the annealing temperature leads to the formation of a nitrogen-containing carbonaceous material with the structure similar to non-crystalline carbon. However, no evidence for the formation of <span class="hlt">Al</span>N was observed in the annealed samples even at temperatures as high as the <span class="hlt">Al</span> melting point. - Graphical abstract: <span class="hlt">Al</span>N nanoparticles obtained after milling of <span class="hlt">Al</span> and diaminomaleonitrile (DAMN) for 12 h. Highlights: Black-Right-Pointing-Pointer Solid state reaction of diaminomaleonitrile (DAMN) with <span class="hlt">Al</span> was studied via mechanochemical and thermal treatment routs. Black-Right-Pointing-Pointer Nanocrystalline <span class="hlt">Al</span>N was successfully synthesized by the mechanochemical process. Black-Right-Pointing-Pointer The C/N material was formed by polymerization of DAMN during the thermal treatment process. Black-Right-Pointing-Pointer No reaction between DAMN and <span class="hlt">Al</span> was detected during the thermal treatment method.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/6137079','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/6137079"><span id="translatedtitle">Stress-strain behavior of fine-grained <span class="hlt">Al/Al</span>[sub 3]Ti alloys</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Wang, S.H.; Kao, P.W.; Chang, C.P. )</p> <p>1993-08-01</p> <p>It has been recognized that dispersion strengthening with hard, stable, high melting point phases offers an effective technique for improving the stiffness of aluminum alloys over a wider temperature range compared to precipitation strengthening. Recent research indicates that mechanically alloyed (MA) <span class="hlt">Al</span>-Ti alloys have good ambient and elevated temperature properties. The MA <span class="hlt">Al</span>-Ti alloys are characterized by the presence of large volume fractions of submicron sized <span class="hlt">Al</span>[sub 3]Ti dispersoids within a fine grain aluminum matrix. In addition, such alloys contain a significant amount of ultrafine <span class="hlt">Al</span>[sub 4]C[sub 3] and <span class="hlt">Al</span>[sub 2]O[sub 3] dispersoids incorporated during the MA process. The carbide and oxide dispersoids reside mainly along grain boundaries and can stabilize a fine-grain structure even after long term exposure at elevated temperature. The high temperature strength of these MA aluminum alloys is strongly controlled by carbide and oxide dispersoids. The Young's modulus of <span class="hlt">Al</span>[sub 3]Ti phase was determined to be about 220 GPa. Hence, the presence of the <span class="hlt">Al</span>[sub 3]Ti phase is very effective in increasing the stiffness of the MA aluminum alloys is strongly controlled by carbide and oxide dispersoids. The Young's modulus of <span class="hlt">Al</span>[sub 3]Ti phase was determined to be about 220 GPa. Hence, the presence of the <span class="hlt">Al</span>[sub 3]Ti phase is very effective in increasing the stiffness of the MA aluminum alloys. The strength of such alloys increases with increasing <span class="hlt">Al</span>[sub 3]Ti content; however, the strengthening effect of <span class="hlt">Al</span>[sub 3]Ti dispersoids diminishes at temperatures above about 400C. On the other hand, such dispersoids also appear responsible for improving the high temperature ductility of the MA <span class="hlt">Al</span>-Ti alloys. A better understanding of the strengthening mechanisms is desirable. This paper presents the room temperature stress-strain behavior of two <span class="hlt">Al-Al</span>[sub 3]Ti alloys made by mechanical alloying and hot-pressing.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19980210984','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19980210984"><span id="translatedtitle">CVD Fiber Coatings for <span class="hlt">Al</span>2O3/Ni<span class="hlt">Al</span> Composites</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Boss, Daniel E.</p> <p>1995-01-01</p> <p>While sapphire-fiber-reinforced nickel aluminide (<span class="hlt">Al</span>2O3/Ni<span class="hlt">Al</span>) composites are an attractive candidate for high-temperature structures, the significant difference in the coefficient of thermal expansion between the Ni<span class="hlt">Al</span> matrix and the sapphire fiber creates substantial residual stresses in the composite. This study seeks to produce two fiber-coating systems with the potential to reduce the residual stresses in the sapphire/Ni<span class="hlt">Al</span> composite system. Chemical vapor deposition (CVD) was used to produce both the compensating and compliant-fiber coatings for use in sapphire/Ni<span class="hlt">Al</span> composites. A special reactor was designed and built to produce the FGM and to handle the toxic nickel precursors. This process was successfully used to produce 500-foot lengths of fiber with coating thicknesses of approximately 3 microns, 5 microns, and 10 microns.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010ApPhL..97m3104S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010ApPhL..97m3104S"><span id="translatedtitle">In situ microscopy of rapidly heated nano-<span class="hlt">Al</span> and nano-<span class="hlt">Al</span>/WO3 thermites</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Sullivan, Kyle T.; Chiou, Wen-An; Fiore, Richard; Zachariah, Michael R.</p> <p>2010-09-01</p> <p>The initiation and reaction mechanism of nano-<span class="hlt">Al</span> and nano-<span class="hlt">Al</span> thermites in rapid heating environments is investigated in this work. A semiconductor-based grid/stage was used, capable of in situ heating of a sample from room temperature to 1473 K, and at a rate of 106 K/s, inside an electron microscope. Nano-<span class="hlt">Al</span> was rapidly heated in a transmission electron microscope, and before and after images indicate that the aluminum migrates through the shell, consistent with a diffusion-based mechanism. A nano-<span class="hlt">Al</span>/WO3 composite was then heated in a scanning electron microscope. The results indicate that a reactive sintering mechanism is occurring for the nano-<span class="hlt">Al</span>/WO3 thermite, as the products are found to be in surface contact and significantly deformed after the heating pulse.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19910034051&hterms=stuttgart&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D70%26Ntt%3Dstuttgart','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19910034051&hterms=stuttgart&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D70%26Ntt%3Dstuttgart"><span id="translatedtitle">1300 K compressive properties of a reaction milled Ni<span class="hlt">Al-Al</span>N composites</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Whittenberger, J. Daniel; Arzt, Eduard; Luton, Michael J.</p> <p>1990-01-01</p> <p>When B2 crystal-structure nickel aluminide is subjected to high-intensity mechanical ball milling in a liquid nitrogen bath, or 'cryomilling', an Ni<span class="hlt">Al</span> composite is obtained which contains about 10 vol pct <span class="hlt">Al</span>N particles. This composition arises from the incorporation of N during cryomilling; during subsequent thermomechanical processing, the N reacts with <span class="hlt">Al</span>. While compressive testing of extruded or isostatically pressed specimens at 1300 K indicated that strength at relatively fast strain rates is slightly dependent on consolidation method, slower strain rates indicate no clear dependency on densification technique: four different consolidation methods were found to yield similar creep strengths. The creep properties of Ni<span class="hlt">Al-Al</span>N are similar to those of the single-crystal Ni-base superalloy NASAIR 100.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/5188197','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/5188197"><span id="translatedtitle"><span class="hlt">Al</span>/sub 2/O/sub 3/ adherence on CoCr<span class="hlt">Al</span> alloys</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Kingsley, L.M.</p> <p>1980-04-01</p> <p>Adherence of protective oxides on NiCr<span class="hlt">Al</span> and CoCr<span class="hlt">Al</span> superalloys has been promoted by a dispersion of a highly oxygen reactive element or its oxide being produced within the protection system. Two aspects of this subject are investigated here: the use of <span class="hlt">Al</span>/sub 2/O/sub 3/ as both the dispersion and protective oxide; and the production of an HfO/sub 2/ dispersion while simultaneously aluminizing the alloy. It was found that an <span class="hlt">Al</span>/sub 2/O/sub 3/ dispersion will act to promote the adherence of an external scale of <span class="hlt">Al</span>/sub 2/O/sub 3/ to a degree comparable to previously tested dispersions and an HfO/sub 2/ dispersion comparable to that produced by a Rhines pack treatment is produced during aluminization.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/6118818','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/6118818"><span id="translatedtitle">Calculation of the optical spectra of. beta. prime -Ni<span class="hlt">Al</span> and Co<span class="hlt">Al</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Kim, K.J.; Harmon, B.N.; Lynch, D.W. )</p> <p>1991-01-15</p> <p>Band structures of {beta}{prime}-Ni<span class="hlt">Al</span> and Co<span class="hlt">Al</span> have been calculated to interpret the experimental optical spectra. The optical transitions of both compounds are calculated as direct interband transitions including electric-dipole matrix elements between the eigenstates of the ground state of the system. All of the structures found in the optical spectra of both compounds involve states with some Ni or Co {ital d} character in both the initial and the final states. The overall agreement is good between the calculated spectrum and the optical data for {beta}{prime}-Ni<span class="hlt">Al</span>. For {beta}{prime}-Co<span class="hlt">Al</span> there is qualitative agreement but some discrepancy for the energy positions and the intensities of the structures. A self-energy correction for the excitation spectrum has been used for {beta}{prime}-Co<span class="hlt">Al</span> to improve the agreement.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li class="active"><span>22</span></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li><a href="#" onclick='return showDiv("page_24");'>24</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_22 --> <div id="page_23" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li class="active"><span>23</span></li> <li><a href="#" onclick='return showDiv("page_24");'>24</a></li> <li><a href="#" onclick='return showDiv("page_25");'>25</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="441"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2011MS%26E...23a2040D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2011MS%26E...23a2040D"><span id="translatedtitle">An impedance study of complex <span class="hlt">Al/Cu-Al</span>2O3 electrode</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Denisova, J.; Katkevics, J.; Erts, D.; Viksna, A.</p> <p>2011-06-01</p> <p>Electrochemical impedance spectroscopy (EIS) was used to investigate different Cu deposition regimes on <span class="hlt">Al</span> surface obtained by internal electrolysis and to characterize properties of fabricated electrodes. EIS experimental data confirmed that Cu deposition by internal electrolysis is realized and the complex electrode system is obtained. The main difficulty in preparation of <span class="hlt">Al</span>/Cu electrodes is to prevent aluminium oxidation before and during electrochemical deposition of Cu particles. In this work NaCl, CH3COONa, K2SO4, mono- and diammonium citrate electrolytes were examined to determine their suitability for impedance measurements. <span class="hlt">Al/Cu-Al</span>2O3 electrode composition was approved by equivalent circuit analysis, optical and scanning electron microscope methods. The most optimal Cu deposition mode using internal electrolysis was determined. The obtained results are promising for future electrochemical fabrication of nanostructures directly on <span class="hlt">Al</span> surfaces by internal electrolysis.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015MS%26E...75a2034P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015MS%26E...75a2034P"><span id="translatedtitle">Wear characteristics of <span class="hlt">Al-Al</span>N composites produced in-situ by nitrogenation</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Pradhan, S.; Jena, S. K.; Patnaik, S. C.; Swain, P. K.; Majhi, J.</p> <p>2015-02-01</p> <p>In the present scenario most of the parts used in automobile and aerospace industries are made of composites. Aluminium metal has a very high strength to weight ratio. <span class="hlt">Al-Al</span>N metal matrix composites have excellent mechanical properties like good wear resistance, high hardness and high strength to weight ratio which are obtained from low density of aluminium and high hardness and wear resistance of <span class="hlt">Al</span>N. Therefore, use of <span class="hlt">Al-Al</span>N MMC leads to advantages in automobile industries as it reduces fuel consumption and gives better structural strength. The composites can be produced ex-situ by introducing <span class="hlt">Al</span>N as reinforcement into the metal matrix and in- situ by nitrogenation process. In the present process <span class="hlt">Al-Al</span>N composites were fabricated by treating molten aluminium with a mixture of CaO and NH4Cl and held at temperature range at 750-930C and then cast into a metal mould. Addition of CaO to NH4Cl is found to have a more pronounced effect as a nitrogenation agent in comparison with NH4Cl in the molten aluminium in the temperature range of 700- 1000C. Castings of aluminium and <span class="hlt">Al-Al</span>N composites were prepared by mixing different ratios of aluminium and NH4Cl, at different casting temperatures and holding time. Wear resistance and hardness of the samples were determined, and microstructure studies were carried out. The composite formed using higher amount of NH4Cl had higher hardness and wear resistance.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010JaJAP..49c5701H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010JaJAP..49c5701H"><span id="translatedtitle">Effects of the <span class="hlt">Al</span>N Interlayer on the Distribution and Mobility of Two-Dimensional Electron Gas in <span class="hlt">AlGaN/Al</span>N/GaN Heterojunctions</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Hu, Weiguo; Ma, Bei; Li, Dabing; Miyagawa, Reina; Miyake, Hideto; Hiramatsu, Kazumasa</p> <p>2010-03-01</p> <p><span class="hlt">Al</span>0.25Ga0.75N/<span class="hlt">Al</span>N/GaN heterojunctions with <span class="hlt">Al</span>N interlayers of various thicknesses were grown on c-plane sapphire by metalorganic vapor phase epitaxy (MOVPE). We have revealed that the <span class="hlt">Al</span>N interlayer hardly affects morphologies and crystal qualities; however, it prominently enhances the two-dimensional electron gas (2DEG) mobility. The optimum thickness of the <span class="hlt">Al</span>N interlayer is 1 nm, and the corresponding room temperature Hall mobility and the sheet carrier density are 1700 cm2 V-1 s-1 and 1.27 1013 cm-2, respectively. Self-consistent calculation results indicates that with increasing <span class="hlt">Al</span>N thickness, i) the conduction-band discontinuity between <span class="hlt">Al</span>GaN and GaN linearly increases; ii) the percentage of the total carriers in the <span class="hlt">Al</span>GaN layer exponentially decreases, and content in the <span class="hlt">Al</span>N layer exponentially increases.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010JaJAP..49c5701W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010JaJAP..49c5701W"><span id="translatedtitle">Effects of the <span class="hlt">Al</span>N Interlayer on the Distribution and Mobility of Two-Dimensional Electron Gas in <span class="hlt">AlGaN/Al</span>N/GaN Heterojunctions</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Weiguo Hu,; Bei Ma,; Dabing Li,; Reina Miyagawa,; Hideto Miyake,; Kazumasa Hiramatsu,</p> <p>2010-03-01</p> <p><span class="hlt">Al</span>0.25Ga0.75N/<span class="hlt">Al</span>N/GaN heterojunctions with <span class="hlt">Al</span>N interlayers of various thicknesses were grown on c-plane sapphire by metalorganic vapor phase epitaxy (MOVPE). We have revealed that the <span class="hlt">Al</span>N interlayer hardly affects morphologies and crystal qualities; however, it prominently enhances the two-dimensional electron gas (2DEG) mobility. The optimum thickness of the <span class="hlt">Al</span>N interlayer is 1 nm, and the corresponding room temperature Hall mobility and the sheet carrier density are 1700 cm2 V-1 s-1 and 1.27 1013 cm-2, respectively. Self-consistent calculation results indicates that with increasing <span class="hlt">Al</span>N thickness, i) the conduction-band discontinuity between <span class="hlt">Al</span>GaN and GaN linearly increases; ii) the percentage of the total carriers in the <span class="hlt">Al</span>GaN layer exponentially decreases, and content in the <span class="hlt">Al</span>N layer exponentially increases.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20080047352','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20080047352"><span id="translatedtitle">Formation of gamma(sup prime)-Ni3<span class="hlt">Al</span> via the Peritectoid Reaction: gamma + beta (+ <span class="hlt">Al</span>2O3)=gamma(sup prime)(+ <span class="hlt">Al</span>2O3)</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Copeland, Evan</p> <p>2008-01-01</p> <p>The activities of <span class="hlt">Al</span> and Ni were measured using multi-cell Knudsen effusion-cell mass spectrometry (multi-cell KEMS), over the composition range 8-32 at.%<span class="hlt">Al</span> and temperature range T=1400-1750 K in the Ni-<span class="hlt">Al</span>-O system. These measurements establish that equilibrium solidification of gamma(sup prime)-Ni3<span class="hlt">Al</span>-containing alloys occurs by the eutectic reaction, L (+ <span class="hlt">Al</span>2O3)=gamma + Beta(+ <span class="hlt">Al</span>2O3), at 1640 +/- 1 K and a liquid composition of 24.8 +/- 0.2 at.%<span class="hlt">al</span> (at an unknown oxygen content). The {gamma + Beta (+<span class="hlt">Al</span>2O3} phase field is stable over the temperature range 1633-1640 K, and gamma(sup prime)-Ni3<span class="hlt">Al</span> forms via the peritectoid, gamma + Beta (+ <span class="hlt">Al</span>2O3)=gamma(sup prime) (+ <span class="hlt">Al</span>2O3), at 1633 +/- 1 K. This behavior is consistent with the current Ni-<span class="hlt">Al</span> phase diagram and a new diagram is proposed. This new Ni-<span class="hlt">Al</span> phase diagram explains a number of unusual steady-state solidification structures reported previously and provides a much simpler reaction scheme in the vicinity of the gamma(sup prime)-Ni2<span class="hlt">Al</span> phase field.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20100042390','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20100042390"><span id="translatedtitle">Formation of gamma'-Ni3<span class="hlt">Al</span> via the Peritectoid Reaction: gamma plus beta (+<span class="hlt">Al</span>2O3) equals gamma'(+<span class="hlt">Al</span>2O3)</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Copland, Evan</p> <p>2008-01-01</p> <p>The activities of <span class="hlt">Al</span> and Ni were measured using multi-cell Knudsen effusion-cell mass spectrometry (multi-cell KEMS), over the composition range 8 - 32 at.%<span class="hlt">Al</span> and temperature range T = 1400 - 1750 K in the Ni-<span class="hlt">Al</span>-O system. These measurements establish that equilibrium solidification of gamma'-Ni3<span class="hlt">Al</span>-containing alloys occurs by the eutectic reaction, L (+ <span class="hlt">Al</span>2O3) = gamma + beta (+ <span class="hlt">Al</span>2O3), at 1640 plus or minus 1 K and a liquid composition of 24.8 plus or minus 0.2 at.%<span class="hlt">Al</span> (at an unknown oxygen content). The {gamma + beta + <span class="hlt">Al</span>2O3} phase field is stable over the temperature range 1633 - 1640 K, and gamma'-Ni3<span class="hlt">Al</span> forms via the peritectiod, gamma + beta (+ <span class="hlt">Al</span>2O3) = gamma'(+ <span class="hlt">Al</span>2O3), at 1633 plus or minus 1 K. This behavior is inconsistent with the current Ni-<span class="hlt">Al</span> phase diagram and a new diagram is proposed. This new Ni-<span class="hlt">Al</span> phase diagram explains a number of unusual steady state solidification structures reported previously and provides a much simpler reaction scheme in the vicinity of the gamma'-Ni3<span class="hlt">Al</span> phase field.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/doepatents/biblio/87741','DOE-PATENT-XML'); return false;" href="http://www.osti.gov/doepatents/biblio/87741"><span id="translatedtitle">Ternary Dy-Er-<span class="hlt">Al</span> magnetic refrigerants</span></a></p> <p><a target="_blank" href="http://www.osti.gov/doepatents">DOEpatents</a></p> <p>Gschneidner, K.A. Jr.; Takeya, Hiroyuki</p> <p>1995-07-25</p> <p>A ternary magnetic refrigerant material comprising (Dy{sub 1{minus}x}Er{sub x})<span class="hlt">Al</span>{sub 2} for a magnetic refrigerator using the Joule-Brayton thermodynamic cycle spanning a temperature range from about 60K to about 10K, which can be adjusted by changing the Dy to Er ratio of the refrigerant. 29 figs.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/doepatents/biblio/869994','DOE-PATENT-XML'); return false;" href="http://www.osti.gov/doepatents/biblio/869994"><span id="translatedtitle">Ternary Dy-Er-<span class="hlt">Al</span> magnetic refrigerants</span></a></p> <p><a target="_blank" href="http://www.osti.gov/doepatents">DOEpatents</a></p> <p>Gschneidner, Jr., Karl A. (Ames, IA); Takeya, Hiroyuki (Ibaraki, JP)</p> <p>1995-07-25</p> <p>A ternary magnetic refrigerant material comprising (Dy.sub.1-x Er.sub.x)<span class="hlt">Al</span>.sub.2 for a magnetic refrigerator using the Joule-Brayton thermodynamic cycle spanning a temperature range from about 60K to about 10K, which can be adjusted by changing the Dy to Er ratio of the refrigerant.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/791807','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/791807"><span id="translatedtitle">Joint SSRTNet/<span class="hlt">ALS</span>-MES Workshop report</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Shuh, David; Van Hove, Michel</p> <p>2001-11-30</p> <p>This joint workshop brought together experimentalists and theorists interested in synchrotron radiation and highlighted subjects relevant to molecular environmental science (MES). The strong mutual interest between the participants resulted in joint sessions on the first day, followed by more specialized parallel sessions on the second day. Held in conjunction with the Advanced Light Source (<span class="hlt">ALS</span>) Users' Association Annual Meeting at the Lawrence Berkeley National Laboratory (Berkeley Lab), the Synchrotron Radiation Research Theory Network (SRRTNet) workshop was co-organized by Michel Van Hove (Berkeley Lab and University of California, Davis) and Andrew Canning (Berkeley Lab), while David Shuh (Berkeley Lab) organized the <span class="hlt">ALS</span>-MES workshop. SRRTNet is a global network that promotes the interaction of theory and experiment (http://www.cse.clrc.ac.uk/Activity/SRRTnet). The <span class="hlt">ALS</span>-MES project is constructing Beamline 11.0.2.1-2, a new soft x-ray beamline for MES investigations at photon energies from 75 eV to 2 keV, to provide photons for wet spectroscopy end stations and an upgraded scanning transmission x-ray microscope (STXM). The <span class="hlt">ALS</span>-MES beamline and end stations will be available for users in the late fall of 2002.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/23856645','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/23856645"><span id="translatedtitle">Sirtuins as therapeutic targets of <span class="hlt">ALS</span>.</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Pasinetti, Giulio Maria; Bilski, Amanda E; Zhao, Wei</p> <p>2013-09-01</p> <p>Sirtuins have received a lot of attention in biological functions associated with metabolism, survival development, and most recently, neurodegeneration. The versatile role of sirtuins can be readily redirected for drug discovery studies for novel treatment in amyotrophic lateral sclerosis (<span class="hlt">ALS</span>), as presented in this highlight, by sirtuin-mediated ketogenic responses influencing mitochondrial function. PMID:23856645</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/FR-2010-01-25/pdf/2010-1338.pdf','FEDREG'); return false;" href="https://www.gpo.gov/fdsys/pkg/FR-2010-01-25/pdf/2010-1338.pdf"><span id="translatedtitle">75 FR 3895 - Yale University, et <span class="hlt">al</span>.;</span></a></p> <p><a target="_blank" href="http://www.gpo.gov/fdsys/browse/collection.action?collectionCode=FR">Federal Register 2010, 2011, 2012, 2013, 2014</a></p> <p></p> <p>2010-01-25</p> <p>... notice at 74 FR 67851, December 21, 2009. Docket Number: 09-065. Applicant: U.S. Department of Homeland..., Quanta 200 FEG. Manufacturer: FEI Company, Czech Republic. Intended Use: See notice at 74 FR 67851... International Trade Administration Yale University, et <span class="hlt">al</span>.; Notice of Consolidated Decision on Applications...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/FR-2013-01-23/pdf/2013-01210.pdf','FEDREG'); return false;" href="https://www.gpo.gov/fdsys/pkg/FR-2013-01-23/pdf/2013-01210.pdf"><span id="translatedtitle">78 FR 4967 - Alabama Disaster #<span class="hlt">AL</span>-00046</span></a></p> <p><a target="_blank" href="http://www.gpo.gov/fdsys/browse/collection.action?collectionCode=FR">Federal Register 2010, 2011, 2012, 2013, 2014</a></p> <p></p> <p>2013-01-23</p> <p>... ADMINISTRATION Alabama Disaster <span class="hlt">AL</span>-00046 AGENCY: U.S. Small Business Administration. ACTION: Notice. SUMMARY: This is a notice of an Administrative declaration of a disaster for the State of ALABAMA dated 01/10... INFORMATION CONTACT: A. Escobar, Office of Disaster Assistance, U.S. Small Business Administration, 409...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://eric.ed.gov/?q=Psychoactive+AND+drugs&pg=4&id=EJ492979','ERIC'); return false;" href="http://eric.ed.gov/?q=Psychoactive+AND+drugs&pg=4&id=EJ492979"><span id="translatedtitle">Synopsis of "Reply to Levitas et <span class="hlt">al</span>."</span></a></p> <p><a target="_blank" href="http://www.eric.ed.gov/ERICWebPortal/search/extended.jsp?_pageLabel=advanced">ERIC Educational Resources Information Center</a></p> <p>O'Brien, John</p> <p>1994-01-01</p> <p>This synopsis of a reply by Wolf Wolfensberger to a critique by Levitas et <span class="hlt">al</span>. (EC 609 743) notes extensive documentation supporting Wolfensberger's assertion that prescription psychoactive drugs are health destroying and life destroying. Issues of truth and of epistemology are identified as they apply to the treatment of these socially devalued</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19720000526','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19720000526"><span id="translatedtitle"><span class="hlt">Al</span>/Cl2 molten salt battery</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Giner, J.</p> <p>1972-01-01</p> <p>Molten salt battery has been developed with theoretical energy density of 5.2 j/kg (650 W-h/lb). Battery, which operates at 150 C, can be used in primary mode or as rechargeable battery. Battery has aluminum anode and chlorine cathode. Electrolyte is mixture of <span class="hlt">Al</span>Cl3, NaCl, and some alkali metal halide such as KCl.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://eric.ed.gov/?q=lips&pg=2&id=EJ869605','ERIC'); return false;" href="http://eric.ed.gov/?q=lips&pg=2&id=EJ869605"><span id="translatedtitle">Kinematics of Disease Progression in Bulbar <span class="hlt">ALS</span></span></a></p> <p><a target="_blank" href="http://www.eric.ed.gov/ERICWebPortal/search/extended.jsp?_pageLabel=advanced">ERIC Educational Resources Information Center</a></p> <p>Yunusova, Yana; Green, Jordan R.; Lindstrom, Mary J.; Ball, Laura J.; Pattee, Gary L.; Zinman, Lorne</p> <p>2010-01-01</p> <p>The goal of this study was to investigate the deterioration of lip and jaw movements during speech longitudinally in three individuals diagnosed with bulbar amyotrophic lateral sclerosis (<span class="hlt">ALS</span>). The study was motivated by the need to understand the relationship between physiologic changes in speech movements and clinical measures of speech</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://eric.ed.gov/?q=pattern+AND+recognition+AND+letters+AND+pattern+AND+recognition+AND+letters&pg=5&id=EJ734728','ERIC'); return false;" href="http://eric.ed.gov/?q=pattern+AND+recognition+AND+letters+AND+pattern+AND+recognition+AND+letters&pg=5&id=EJ734728"><span id="translatedtitle">Correction to Rothermund et <span class="hlt">al</span>. (2005)</span></a></p> <p><a target="_blank" href="http://www.eric.ed.gov/ERICWebPortal/search/extended.jsp?_pageLabel=advanced">ERIC Educational Resources Information Center</a></p> <p>Rothermund, Klaus; Wentura, Dirk; De Houwer, Jan</p> <p>2005-01-01</p> <p>This article reports an error in the article "Retrieval of Incidental Stimulus-Response Associations as a Source of Negative Priming" by Rothermund et <span class="hlt">al</span>. ("Journal of Experimental Psychology: Learning, Memory, and Cognition," Vol 31(3) May 2005, 482-495). Table 1 (p. 484) was incorrectly typeset. The correct layout is provided. (The following</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/FR-2011-10-07/pdf/2011-25927.pdf','FEDREG'); return false;" href="https://www.gpo.gov/fdsys/pkg/FR-2011-10-07/pdf/2011-25927.pdf"><span id="translatedtitle">76 FR 62481 - Incapital LLC, et <span class="hlt">al</span>.</span></a></p> <p><a target="_blank" href="http://www.gpo.gov/fdsys/browse/collection.action?collectionCode=FR">Federal Register 2010, 2011, 2012, 2013, 2014</a></p> <p></p> <p>2011-10-07</p> <p>... From the Federal Register Online via the Government Publishing Office SECURITIES AND EXCHANGE COMMISSION Incapital LLC, et <span class="hlt">al</span>.; Notice of Application September 30, 2011. AGENCY: Securities and Exchange Commission (``Commission''). ACTION: Notice of application for an order under section 12(d)(1)(J) of...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://eric.ed.gov/?q=Green+AND+movement&pg=5&id=EJ869605','ERIC'); return false;" href="http://eric.ed.gov/?q=Green+AND+movement&pg=5&id=EJ869605"><span id="translatedtitle">Kinematics of Disease Progression in Bulbar <span class="hlt">ALS</span></span></a></p> <p><a target="_blank" href="http://www.eric.ed.gov/ERICWebPortal/search/extended.jsp?_pageLabel=advanced">ERIC Educational Resources Information Center</a></p> <p>Yunusova, Yana; Green, Jordan R.; Lindstrom, Mary J.; Ball, Laura J.; Pattee, Gary L.; Zinman, Lorne</p> <p>2010-01-01</p> <p>The goal of this study was to investigate the deterioration of lip and jaw movements during speech longitudinally in three individuals diagnosed with bulbar amyotrophic lateral sclerosis (<span class="hlt">ALS</span>). The study was motivated by the need to understand the relationship between physiologic changes in speech movements and clinical measures of speech…</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://files.eric.ed.gov/fulltext/ED542783.pdf','ERIC'); return false;" href="http://files.eric.ed.gov/fulltext/ED542783.pdf"><span id="translatedtitle">U-<span class="hlt">ALS</span>: A Ubiquitous Learning Environment</span></a></p> <p><a target="_blank" href="http://www.eric.ed.gov/ERICWebPortal/search/extended.jsp?_pageLabel=advanced">ERIC Educational Resources Information Center</a></p> <p>Piovesan, Sandra Dutra; Passerino, Liliana Maria; Medina, Roseclea Duarte</p> <p>2012-01-01</p> <p>The diffusion of the use of the learning virtual environments presents a great potential for the development of an application which meet the necessities in the education area. In view of the importance of a more dynamic application and that can adapt itself continuously to the students' necessities, the "U-<span class="hlt">ALS</span>" (Ubiquitous Adapted Learning…</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/5649223','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/5649223"><span id="translatedtitle">Low cost, reliable <span class="hlt">ALS</span> turbopump concept</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Csomor, A.</p> <p>1989-01-01</p> <p>An empirical perspective is presented on the cost structure of past and current turbomachinery for liquid rocket engine turbopumps. The issues which must be addressed in the development of turbopumps for the Advanced Launch System (<span class="hlt">ALS</span>) at an order of magnitude lower recurring cost than for present hardware are discussed. An approach proposed to attain reliability and cost objectives is outlined.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li class="active"><span>23</span></li> <li><a href="#" onclick='return showDiv("page_24");'>24</a></li> <li><a href="#" onclick='return showDiv("page_25");'>25</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_23 --> <div id="page_24" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li class="active"><span>24</span></li> <li><a href="#" onclick='return showDiv("page_25");'>25</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="461"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/503734','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/503734"><span id="translatedtitle">Bierman {ital et <span class="hlt">al</span>.}Reply:</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Bierman, J.D.; Chan, P.; Liang, J.F.; Kelly, M.P.; Sonzogni, A.A.; Vandenbosch, R.</p> <p>1997-05-01</p> <p>reply to the Comment by C.H.Dasso et <span class="hlt">al</span>., Phys. Rev. Lett. 78,XXX(1997). A Reply to the Comment by C.H. Dasso and J. Fern{acute a}ndez-Niello. {copyright} {ital 1997} {ital The American Physical Society}</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4293318','PMC'); return false;" href="http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4293318"><span id="translatedtitle"><span class="hlt">ALS</span> onset is influenced by the burden of rare variants in known <span class="hlt">ALS</span> genes</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Cady, Janet; Allred, Peggy; Bali, Taha; Pestronk, Alan; Goate, Alison; Miller, Timothy M.; Mitra, Rob; Ravits, John; Harms, Matthew B.; Baloh, Robert H.</p> <p>2014-01-01</p> <p>Objective To define the genetic landscape of amyotrophic lateral sclerosis (<span class="hlt">ALS</span>) and assess the contribution of possible oligogenic inheritance, we aimed to comprehensively sequence 17 known <span class="hlt">ALS</span> genes in 391 <span class="hlt">ALS</span> patients from the United States. Methods Targeted pooled-sample sequencing was used to identify variants in 17 <span class="hlt">ALS</span> genes. Fragment size analysis was used to define ATXN2 and C9ORF72 expansion sizes. Genotype-phenotype correlations were made with individual variants and total burden of variants. Rare variant associations for risk of <span class="hlt">ALS</span> were investigated at both the single variant and gene level. Results 64.3% of familial and 27.8% of sporadic subjects carried potentially pathogenic novel or rare coding variants identified by sequencing or an expanded repeat in C9ORF72 or ATXN2. 3.8% of subjects had variants in more than one <span class="hlt">ALS</span> gene, and these individuals had disease onset ten years earlier (p=0.0046) than subjects with variants in a single gene. The number of potentially pathogenic coding variants did not influence disease duration or site of onset. Interpretation Rare and potentially pathogenic variants in known <span class="hlt">ALS</span> genes are present in over 25% of apparently sporadic and 64% of familial patients, significantly higher than previous reports using less comprehensive sequencing approaches. A significant number of subjects carried variants in more than one gene, which influenced the age of symptom onset and supports oligogenic inheritance as relevant to disease pathogenesis. PMID:25382069</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2011SuMi...49..654H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2011SuMi...49..654H"><span id="translatedtitle">Nanocrystalline Fe<span class="hlt">Al</span> intermetallics obtained in mechanically alloyed Fe 50<span class="hlt">Al</span> 40Ni 10 powder</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Hadef, F.; Otmani, A.; Djekoun, A.; Grenche, J. M.</p> <p>2011-06-01</p> <p>B2-Fe 47<span class="hlt">Al</span> 53 intermetallics has been produced by mechanical alloying in a planetary ball mill, using elemental Fe, <span class="hlt">Al</span> and Ni powder mixture. The microstructural and magnetic properties of the mechanically alloyed Fe 50<span class="hlt">Al</span> 40Ni 10 powdered samples were investigated by X-ray diffraction and 57Fe Mssbauer spectrometry at 300 and 77 K. As resulted from the X-ray diffraction studies, the ordered B2 structure was formed in the Fe 50<span class="hlt">Al</span> 40Ni 10 powder, together with the bcc ? i-Fe(<span class="hlt">Al</span>, Ni) ( i = 1, 2) solid solutions. Further milling led to a partial disordering of B2-Fe 47<span class="hlt">Al</span> 53; it has undergone an order-disorder transition which is characterized by an expansion of the volume ? a0 (lattice disorder) and a magnetic transition from the paramagnetic to ferromagnetic state which is characterized by strong ferromagnetic interactions in the alloy. The nanocrystalline bcc ? i-Fe(<span class="hlt">Al</span>, Ni) solid solution was ferromagnetic with a mean crystallite size of 6 nm.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19790025135','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19790025135"><span id="translatedtitle">Some TEM observations of <span class="hlt">Al</span>2O3 scales formed on NiCr<span class="hlt">Al</span> alloys</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Smialek, J.; Gibala, R.</p> <p>1979-01-01</p> <p>The microstructural development of <span class="hlt">Al</span>2O3 scales on NiCr<span class="hlt">Al</span> alloys has been examined by transmission electron microscopy. Voids were observed within grains in scales formed on a pure NiCr<span class="hlt">Al</span> alloy. Both voids and oxide grains grew measurably with oxidation time at 1100 C. The size and amount of porosity decreased towards the oxide-metal growth interface. The voids resulted from an excess number of oxygen vacancies near the oxidemetal interface. Short-circuit diffusion paths were discussed in reference to current growth stress models for oxide scales. Transient oxidation of pure, Y-doped, and Zr-doped NiCr<span class="hlt">Al</span> was also examined. Oriented alpha-(<span class="hlt">Al</span>, Cr)2O3 and Ni(<span class="hlt">Al</span>, Cr)2O4 scales often coexisted in layered structures on all three alloys. Close-packed oxygen planes and directions in the corundum and spinel layers were parallel. The close relationship between oxide layers provided a gradual transition from initial transient scales to steady state <span class="hlt">Al</span>2O3 growth.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19800028901&hterms=corundum&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3Dcorundum','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19800028901&hterms=corundum&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3Dcorundum"><span id="translatedtitle">Some TEM observations of <span class="hlt">Al</span>2O3 scales formed on NiCr<span class="hlt">Al</span> alloys</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Smialek, J.; Gibala, R.</p> <p>1979-01-01</p> <p>The microstructural development of <span class="hlt">Al</span>2O3 scales on NiCr<span class="hlt">Al</span> alloys has been examined by transmission electron microscopy. Voids have been observed within grains in scales formed on a pure NiCr<span class="hlt">Al</span> alloy. Both voids and oxide grains grew measurably with oxidation time at 1100 C. The size and amount of porosity decreased towards the oxide-metal growth interface. It was postulated that the voids resulted from an excess number of oxygen vacancies near the oxide-metal interface. Short-circuit diffusion paths were discussed in reference to current growth stress models for oxide scales. Transient oxidations of pure, Y-doped, and Zr-doped NiCr<span class="hlt">Al</span> was also examined. Oriented alpha-(<span class="hlt">Al</span>,Cr)2O3 and Ni(<span class="hlt">Al</span>,Cr)2O4 scales often coexisted in layered structures on all three alloys. Close-packed oxygen planes and directions in the corundum and spinel layers were parallel. The close relationships between oxide layers provided a gradual transition from initial transient scales to steady state <span class="hlt">Al</span>2O3 growth.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/21175660','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/21175660"><span id="translatedtitle">Electron irradiation of <span class="hlt">Al</span>GaN/GaN and <span class="hlt">Al</span>N/GaN heterojunctions</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Polyakov, A. Y.; Smirnov, N. B.; Govorkov, A. V.; Markov, A. V.; Pearton, S. J.; Dabiran, A. M.; Wowchak, A. M.; Cui, B.; Osinsky, A. V.; Chow, P. P.; Kolin, N. G.; Boiko, V. M.; Merkurisov, D. I.</p> <p>2008-10-13</p> <p>The effects of 10 MeV electron irradiation on <span class="hlt">Al</span>GaN/GaN and <span class="hlt">Al</span>N/GaN heterojunctions grown by molecular beam epitaxy are reported. The irradiation increases the resistivity of the GaN buffer due to compensation by radiation defects with levels near E{sub c}-1 eV and decreases the mobility of the two-dimensional electron gas (2DEG) near the <span class="hlt">Al</span>GaN/GaN (or <span class="hlt">Al</span>N/GaN) interface. The bulk carrier removal rate in the GaN buffer is the same for both types of structures and similar to carrier removal rates for undoped n-GaN films. In structures with a density of residual donors of {approx}10{sup 15} cm{sup -3}, irradiation with electron doses of {approx}5x10{sup 15} cm{sup -2} renders the buffer semi-insulating. The 50% degradation of the 2DEG conductivity happens at several times higher doses (close to 3x10{sup 16} cm{sup -2} versus 6.5x10{sup 15} cm{sup -2}) for <span class="hlt">Al</span>N/GaN than for <span class="hlt">Al</span>GaN/GaN structures, most likely because of the lower thickness of the <span class="hlt">Al</span>N barrier.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2001JNET...26..125F','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2001JNET...26..125F"><span id="translatedtitle">Thermoelectric Powers of Cells With NaF-<span class="hlt">Al</span>F3-<span class="hlt">Al</span>2O3 Melts</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Flem, Belinda E.; Xu, Qian; Kjelstrup, Signe; Sterten, Åsmund</p> <p>2001-07-01</p> <p>A thermodynamic description of the Peltier heat at the aluminum and the oxygen electrode in the system NaF-<span class="hlt">Al</span>F3-<span class="hlt">Al</span>2O3 is given. The thermoelectric power in melts with molar ratios <italic>n</italic> NaF/<italic>n</italic> <span class="hlt">Al</span>F3 from 3.0 to 1.0, saturated with alumina are measured. Seebeck coefficients for molten fluoride electrolytes saturated with alumina, electrolytes that are relevant for aluminum electrowinning electrolysis cells, are reported. The results allow determinations of Peltier heats of aluminum, oxygen and carbon electrodes in NaF-<span class="hlt">Al</span>F3 electrolytes saturated with alumina. For molar ratios of <italic>n</italic> NaF/<italic>n</italic> <span class="hlt">Al</span>F3 between 2.6 and 1.2, there is a Peltier heating of the aluminum cathode. This heating is in the same order of magnitude as the electrolyte Joule heat, when the current density is 0.7 A cm-2. For molar ratio <italic>n</italic> NaF/<italic>n</italic> <span class="hlt">Al</span>F3 equal to 1.0 the Peltier effect at the aluminum electrode approaches zero. From theoretical considerations we expect a drop also for molar ratio 3.0. For the anode we report a Peltier cooling that is larger than the heat produced by the anodic overvoltage, in melts with NaF/<span class="hlt">Al</span>F3 molar ratio between 2.6 and 1.2 saturated with alumina.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016JaJAP..55aAG03W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016JaJAP..55aAG03W"><span id="translatedtitle">Aluminum matrix texture in <span class="hlt">AlAl</span>3Ti functionally graded materials analyzed by electron back-scattering diffraction</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Watanabe, Yoshimi; Sequeira, Paulo D.; Sato, Hisashi; Inamura, Tomonari; Hosoda, Hideki</p> <p>2016-01-01</p> <p><span class="hlt">Al</span> matrix functionally graded materials (FGMs) with oriented <span class="hlt">Al</span>3Ti platelets were fabricated by a centrifugal solid-particle method. The applied centrifugal forces were 30, 60, and 120G (units of gravity). The orientation and volume fraction gradients of the <span class="hlt">Al</span>3Ti platelets within the samples were measured. Since a good lattice correspondence was reported for the close-packed directions and the close-packed planes between <span class="hlt">Al</span> and <span class="hlt">Al</span>3Ti, the <span class="hlt">Al</span> matrix in the <span class="hlt">AlAl</span>3Ti FGMs fabricated by the centrifugal solid-particle method should have some texture. <span class="hlt">Al</span> matrix texture was, therefore, analyzed by electron back-scattering diffraction (EBSD). Analysis of the resulting pole figures indicates a preferred orientation along the (200) plane for the <span class="hlt">Al</span> matrix crystals. Furthermore, increasing the applied centrifugal force enhances the orientation effect. A correlation appears to exist between platelet orientation and the preferred texture of the <span class="hlt">Al</span> matrix.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012AcSpA..97..885M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012AcSpA..97..885M"><span id="translatedtitle">Investigation and comparison of bovine hemoglobin binding to <span class="hlt">Al</span>13 and <span class="hlt">Al</span>(III): Evidences from spectroscopic studies</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Ma, Fei; Sun, Chong; Zhou, Wenshu; Xu, Chongzheng; Zhou, Jiahong; Wang, Guoxiang; Yang, Xiaodi</p> <p>2012-11-01</p> <p>The UV-vis, steady state/time resolved fluorescence spectroscopy and circular dichroism spectroscopy are employed to investigate the interaction mechanisms of <span class="hlt">Al</span>13-Hb and <span class="hlt">Al</span>(III)-Hb, respectively. The UV-vis studies represent that <span class="hlt">Al</span>13 and <span class="hlt">Al</span>(III) could directly disturb the structure of Hb and induce the heme group exposed to the aqueous medium. Steady state/time resolved and synchronous fluorescence spectroscopy reveal that <span class="hlt">Al</span>13 and <span class="hlt">Al</span>(III) can change the polarity around the fluorophore molecule of Hb. <span class="hlt">Al</span>13 makes the protein unfolding and <span class="hlt">Al</span>(III) induces the protein buried inside the structure. The interaction processes are static quenching mechanisms and the main forces are electrostatic interactions. Moreover, circular dichroism spectra display <span class="hlt">Al</span>13 makes greater effect than <span class="hlt">Al</span>(III), which is reflected on the degrees of ?-helix of Hb. The comparison results suggest that <span class="hlt">Al</span>13 displays stronger toxicity.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3587753','PMC'); return false;" href="http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3587753"><span id="translatedtitle">An Epidemiological Study of Cutaneous Leishmaniasis in <span class="hlt">Al</span>-Jabal <span class="hlt">Al</span>-Gharbi, Libya</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Abdellatif, Manal Z. M.; El-Mabrouk, Khamis</p> <p>2013-01-01</p> <p>Cutaneous leishmaniasis (CL) is an endemic parasitic infection in the Mediterranean region, including Libya and its <span class="hlt">Al</span>-jabal <span class="hlt">Al</span>-gharbi province. We aimed at studying the occupational relevance as well as other epidemiological aspects of CL. We investigated 140 CL cases who attended at Gharyan outpatient polyclinic during a period of 6 months in 2009. CL infection was clinically diagnosed and confirmed by demonstration of Leishmania parasites on smears from lesions. Our findings showed that males were more affected than females (P=0.04), and people above 10-years were more affected than younger ones (P=0.0001). A significant percent of CL cases belonged to <span class="hlt">Al</span>-Kawasem subprovince (P=0.0001). Farm-related activities were the most frequent occupations among CL cases (P=0.04). In addition to farm workers, housewives and students are at risk groups since they are engaged at farm activities. Moreover, those who have occupations that require staying outdoors for a part of night, e.g., policemen, are also at risk. Compared to children, adult CL patients had multiple lesions (P=0.001) that were more prevalent in their upper and lower extremities than the face (P=0.0001). We conclude that CL is a major health problem in <span class="hlt">Al</span>-jabal <span class="hlt">Al</span>-gharbi province of Libya. The presence of rodents and sandflies makes it a suitable environment for Leishmania to spread in an endemic epidemiological pattern. Being engaged in farming activities or outdoor occupations increases the risk of infection. Various clinical patterns of CL suggest the presence of more than 1 species of Leishmania at <span class="hlt">Al</span>-jabal <span class="hlt">Al</span>-gharbi province. We propose that the 2 species responsible for CL in this area are L. major and L. tropica. Further investigations to identify the leishmanial species responsible for CL at <span class="hlt">Al</span>-jabal <span class="hlt">Al</span>-gharbi together with adoption of preventive and control programs are needed. PMID:23467624</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/605671','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/605671"><span id="translatedtitle">Growth temperature measurements and solidification microstructure selection of primary <span class="hlt">Al</span>{sub 3}Ni and eutectic in the {alpha}<span class="hlt">Al-Al</span>{sub 3}Ni system</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Juarez-Hernandez, A.; Jones, H.</p> <p>1998-02-03</p> <p>Competition between growth of contending primary phases and their eutectics is a key consideration in determining the solidification microstructure of a material that results from particular conditions. Application of the principle that solidification is led by the constituent which grows at the highest temperature under the prevailing conditions gives predictions that are in good accord with experimental fact. The necessary growth temperatures and their dependence on materials composition and solidification conditions have been measured, however, for rather few constituents in relatively few systems as yet. The present purpose is to extend to primary <span class="hlt">Al</span>{sub 3}Ni and the <span class="hlt">Al-Al</span>{sub 3}Ni eutectic in the <span class="hlt">Al</span>-Ni system the measurements made earlier during Bridgman growth, for primary <span class="hlt">Al</span>{sub 3}Fe(<span class="hlt">Al</span>{sub 13}Fe{sub 4}) and for the <span class="hlt">Al-Al</span>{sub 3}Fe and <span class="hlt">Al-Al</span>{sub 6}Fe eutectics in the <span class="hlt">Al</span>-Fe system. These measurements will be compared with predictions of dendrite and eutectic growth theory and related to the relevant boundary of the reported <span class="hlt">Al-Al</span>{sub 3}Ni solidification microstructure selection diagram. Some preliminary results together with other findings were reported earlier in a cited reference.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/1000697','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/1000697"><span id="translatedtitle">Structure of vapor-phase deposited <span class="hlt">Al</span>-Ge thin films and <span class="hlt">Al</span>-Ge intermediate layer bonding of <span class="hlt">Al</span>-based microchannel structures.</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Mei, F. H.; Meng, W. J.; Hiller, J.; Miller, D. J.; Materials Science Division; Louisana State Univ.</p> <p>2009-02-01</p> <p><span class="hlt">Al</span>-based high-aspect-ratio microscale structures (HARMS) are basic building blocks for all-<span class="hlt">Al</span> microdevices. Bonding of <span class="hlt">Al</span>-based HARMS is essential for device assembly. In this paper, bonding of <span class="hlt">Al</span>-based HARMS to flat <span class="hlt">Al</span> plates using <span class="hlt">Al</span>-Ge thin film intermediate layers is investigated. The structure of sputter codeposited <span class="hlt">Al</span>-Ge thin films was studied by high-resolution transmission electron microscopy as a function of the average film composition. The structure of the interface region between <span class="hlt">Al</span>-based HARMS bonded to flat <span class="hlt">Al</span> plates is studied by combining focused ion beam sectioning and scanning electron microscopy. An extended bonding interface region, {approx}100 {micro}m in width, is observed and suggested to result from liquidus/solidus reactions as well as diffusion of Ge in solid <span class="hlt">Al</span> at the bonding temperature of 500 C. The extended interface region is suggested to be beneficial to <span class="hlt">Al-Al</span> bonding via <span class="hlt">Al</span>-Ge intermediate layers.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2006JaJAP..45.3176N','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2006JaJAP..45.3176N"><span id="translatedtitle">Non-volatile <span class="hlt">Al</span>2O3 Memory using Nanoscale <span class="hlt">Al</span>-rich <span class="hlt">Al</span>2O3 Thin Film as a Charge Storage Layer</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Nakata, Shunji; Saito, Kunio; Shimada, Masaru</p> <p>2006-04-01</p> <p>This article describes the fabrication process and capacitance-voltage (C-V) characteristics of a new non-volatile <span class="hlt">Al</span>2O3 memory with nanoscale thin film deposited by electron-cyclotron-resonance sputtering. <span class="hlt">Al</span>-rich <span class="hlt">Al</span>2O3 shows characteristics somewhere between <span class="hlt">Al</span> and <span class="hlt">Al</span>2O3 in the refractive index and wet etching rate. C-V characteristics of <span class="hlt">Al</span>-rich <span class="hlt">Al</span>2O3 memory show a large hysteresis window due to the <span class="hlt">Al</span>-rich structure, while there is no hysteresis window in the case of stoichiometric <span class="hlt">Al</span>2O3. This memory is expected to stay non-volatile for several years or more because the capacitance value after writing and erasing operation remained almost unchanged after 4 h at T=85 C. Also, another new memory structure comprising SiO2/<span class="hlt">Al</span>2O3 and the <span class="hlt">Al</span>-rich <span class="hlt">Al</span>2O3 structure is proposed, which features increased mobility due to the reduction of electron scattering at the Si/<span class="hlt">Al</span>2O3 interface.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015JMMM..387...72M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015JMMM..387...72M"><span id="translatedtitle">Ferromagnetic ordering in Np<span class="hlt">Al</span>2: Magnetic susceptibility and 27<span class="hlt">Al</span> nuclear magnetic resonance</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Martel, L.; Griveau, J.-C.; Eloirdi, R.; Selfslag, C.; Colineau, E.; Caciuffo, R.</p> <p>2015-08-01</p> <p>We report on the magnetic properties of the neptunium based ferromagnetic compound Np<span class="hlt">Al</span>2. We used magnetization measurements and 27<span class="hlt">Al</span> NMR spectroscopy to access magnetic features related to the paramagnetic and ordered states (TC=56 K). While very precise DC SQUID magnetization measurements confirm ferromagnetic ordering, they show a relatively small hysteresis loop at 5 K reduced with a coercive field HCo~3000 Oe. The variable offset cumulative spectra (VOCS) acquired in the paramagnetic state show a high sensitivity of the 27<span class="hlt">Al</span> nuclei spectral parameters (Knight shifts and line broadening) to the ferromagnetic ordering, even at room temperature.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2011IJTP...50.2790H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2011IJTP...50.2790H"><span id="translatedtitle">Revisiting Deng et <span class="hlt">al.'s</span> Multiparty Quantum Secret Sharing Protocol</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Hwang, Tzonelih; Hwang, Cheng-Chieh; Yang, Chun-Wei; Li, Chuan-Ming</p> <p>2011-09-01</p> <p>The multiparty quantum secret sharing protocol [Deng et <span class="hlt">al</span>. in Chin. Phys. Lett. 23: 1084-1087, 2006] is revisited in this study. It is found that the performance of Deng et <span class="hlt">al.'s</span> protocol can be much improved by using the techniques of block-transmission and decoy single photons. As a result, the qubit efficiency is improved 2.4 times and only one classical communication, a public discussion, and two quantum communications between each agent and the secret holder are needed rather than n classical communications, n public discussions, and 3n/2 quantum communications required in the original scheme.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015JPhCS.653a2039S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015JPhCS.653a2039S"><span id="translatedtitle">Superconductivity of <span class="hlt">Al/Al</span>2O3 interface formed under shock-wave conditions</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Shakhray, D. V.; Avdonin, V. V.; Palnichenko, A. V.; Vyaselev, O. M.</p> <p>2015-11-01</p> <p>A mixture of powdered <span class="hlt">Al</span> and <span class="hlt">Al</span>2O3 has been subjected to a shock-wave pressure of ? 170 kbar, followed by vacuum-encapsulating and quenching of the product to liquid nitrogen. The ac magnetic susceptibility measurements of the samples have revealed metastable superconductivity with Tc ? 37 K, characterized by glassy dynamics of the shielding currents below Tc. Comparison of the ac susceptibility and the dc magnetization measurements infers that the superconductivity arises within the interfacial granular layer formed between metallic <span class="hlt">Al</span> and its oxide due to the shock-wave treatment.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1992GeCoA..56.3831F','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1992GeCoA..56.3831F"><span id="translatedtitle">The formation of polynuclear <span class="hlt">Al</span> 13 under simulated natural conditions</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Furrer, Gerhard; Trusch, Bernhard; Mller, Christian</p> <p>1992-10-01</p> <p>Polynuclear aluminum species can be formed in nature by the dissolution of <span class="hlt">Al</span>-containing minerals, as a consequence of soil and surface water acidification, followed by neutralization processes. Under simulated natural conditions in the laboratory, i.e., by allowing acidic <span class="hlt">Al</span>(III) solutions to flow over granulated marble at flow velocities of 3-4 mm/min, large fractions of monomeric <span class="hlt">Al</span>(III) were transformed to the <span class="hlt">Al</span> 13O 4(OH) 24(H 2O) 127+ polymer (thereafter referred to as <span class="hlt">Al</span> 13 or <span class="hlt">Al</span> 137+), which was measured by 27<span class="hlt">Al</span>-NMR spectroscopy. Over two-thirds of the monomeric <span class="hlt">Al</span>(III) was converted to polynuclear <span class="hlt">Al</span> 13 even when gibbsite particles were mixed with the marble granules. The <span class="hlt">Al</span> 13 polymer was also formed in stirred batch experiments containing marble granules and dissolved phthalate or salicylate. The results suggest that <span class="hlt">Al</span> 13formation is easily possible in nature if the total <span class="hlt">Al</span>(III) concentration is high enough. In these experiments, <span class="hlt">Al</span> 13 was detected when the total dissolved <span class="hlt">Al</span>(III) was 1.9 10 -4 mol/L. The minimum total <span class="hlt">Al</span>(III) concentration required to produce <span class="hlt">Al</span> 13, which can be predicted from available thermodynamic data, is on the order of 10 -5mol/L.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1997SPIE.2921..131Z','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1997SPIE.2921..131Z"><span id="translatedtitle">Structural evolution of Ti-<span class="hlt">Al</span> via mechanical alloying</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Zhang, F.; Lu, Li; Lai, Man O.; Wong, H. Y.</p> <p>1997-03-01</p> <p>Ti<span class="hlt">Al</span> intermetallic compound with composition of Ti-58at.%<span class="hlt">Al</span> was synthesized from elemental Ti and <span class="hlt">Al</span> powder mixture. X-ray measurement showed the presence of both face-centered- tetragonal Ti<span class="hlt">Al</span> phase and face-centered-cubic TiN phase. The formation of Ti<span class="hlt">Al</span> can be divided into three stages: (1) solid solution, (2) partial amorphization, and (3) formation of Ti<span class="hlt">Al</span> phase. The process of formation of Ti<span class="hlt">Al</span> phase via mechanical alloying took about 40 to approximately 50 hours.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015MMTB...46..485V','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015MMTB...46..485V"><span id="translatedtitle">Density of Low-Temperature KF-<span class="hlt">Al</span>F3 Aluminum Baths with <span class="hlt">Al</span>2O3 and <span class="hlt">Al</span>PO4 Additives</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Vasková, Zuzana; Kontrík, Martin; Mlynáriková, Jarmila; Boča, Miroslav</p> <p>2015-02-01</p> <p>The density of the KF-<span class="hlt">Al</span>F3 melts of various KF and <span class="hlt">Al</span>F3 ratio with <span class="hlt">Al</span>2O3 and <span class="hlt">Al</span>PO4 addition has been measured using the Archimedean method. On the basis of the obtained density data the molar volumes of the melts were calculated. These molar volumes decrease with concentration of <span class="hlt">Al</span>2O3 or <span class="hlt">Al</span>PO4. In the system containing <span class="hlt">Al</span>PO4, the relation between cryolite ratios (CRs) vs slopes of molar volume trend lines was identified with excellent correlation factor of R 2 = 0.9844, while in the system containing <span class="hlt">Al</span>2O3 a discontinuity at CR = 2.5 can be observed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/10178202','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/10178202"><span id="translatedtitle">On the crack growth resistance and strength of the B2 iron aluminides Fe-40<span class="hlt">Al</span>, Fe-45<span class="hlt">Al</span>, and Fe-10Ni-40<span class="hlt">Al</span> (at. %)</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Schneibel, J.H.; Maziasz, P.J.</p> <p>1994-09-01</p> <p>The crack growth resistance and yield strength of the B2 iron aluminides Fe-40<span class="hlt">Al</span>, Fe-45<span class="hlt">Al</span>, are Fe-10Ni-40<span class="hlt">Al</span> (at. %) have been investigated at room temperature laboratory air. After fast cooling from 1273 K, Fe-45<span class="hlt">Al</span> and Fe-10Ni-40<span class="hlt">Al</span> are much stronger than Fe-40<span class="hlt">Al</span>, and exhibit considerably lower crack growth resistance. The crack growth resistance decreases with decreasing crack propagation velocity. Low crack propagation velocities favor intergranular fracture, whereas high velocities can lead to significant contributions from transgranular fracture. Boron additions to Fe-40<span class="hlt">Al</span> and Fe-10Ni-40<span class="hlt">Al</span> improve the crack growth resistance, reduce its dependence on the crack propagation velocity, and cause the path to be predominantly transgranular. In a plot of fracture toughness versus yield strength, the properties of the iron aluminides are similar to those of typical aluminum alloys.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li class="active"><span>24</span></li> <li><a href="#" onclick='return showDiv("page_25");'>25</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_24 --> <div id="page_25" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li><a href="#" onclick='return showDiv("page_24");'>24</a></li> <li class="active"><span>25</span></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="481"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1985PhRvB..32.5525K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1985PhRvB..32.5525K"><span id="translatedtitle">Core-excitonic lines at the <span class="hlt">Al</span> 2p surface optical-absorption threshold of <span class="hlt">Al</span>As and <span class="hlt">Al</span>P</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kelly, M. K.; Niles, D. W.; Perfetti, P.; Colavita, E.; Savoia, A.; Margaritondo, G.; Henzler, M.</p> <p>1985-10-01</p> <p>The optical-absorption spectra of <span class="hlt">Al</span>As and <span class="hlt">Al</span>P exhibit unusual features-strong <span class="hlt">Al</span> 2p core-excitonic lines. The data were obtained with synchrotron-radiation photoemission in the partial-yield mode. The analysis was based on the approach proposed by Johnson, Fock, Ley, and Cardona for <span class="hlt">Al</span>Sb and on Onodera and Toyozawa's exciton theory.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/16523990','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/16523990"><span id="translatedtitle">[Symptomatic management in amyotrophic lateral sclerosis (<span class="hlt">ALS</span>)].</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Czaplinski, A; Schweikert, K; Strobel, W; Steck, A J; Weber, M</p> <p>2006-02-22</p> <p>Although disease-specific treatment of amyotrophic lateral sclerosis is still unsatisfactory, a number of advances have been made in the symptomatic therapy of <span class="hlt">ALS</span> patients within the last decade. Current data suggest that active and aggressive multidisciplinary management of <span class="hlt">ALS</span> patients improve their quality of life and prolong their survival. Patient and caregiver communications and decisions are increasingly recognized to be a relevant part of this management. A wide range of supportive and palliative measures, in particular the widely use of symptomatic drugs for pseudobulbar affect, sialorrhea, and sleep disorders is available to relieve patients symptomatology. In addition, patients quality of life has been profoundly improved by the introduction of enteral nutrition and non-invasive ventilation. PMID:16523990</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/24292005','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/24292005"><span id="translatedtitle">[Communication with <span class="hlt">ALS</span> patients: neurosurgical approach].</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Yoshimine, Toshiki; Yanagisawa, Takufumi; Sawada, Jin-Ichi; Hazama, Takanori; Mochizuki, Hideki; Hirata, Masayuki</p> <p>2013-01-01</p> <p>By progression of the disease, motor neurons degenerate in patients with amyotrophic lateral sclerosis (<span class="hlt">ALS</span>) eventually lose nearly all voluntary muscles in the body. They are awake and aware but cannot move or communicate (locked-in state). Since the function of the brain is preserved, one possible measure to support their communication is to interpret their motor intention by decoding (deciphering) brain signals and present it with external devices. This technology called "brain-machine interface (BMI)" is now close to clinical use in Japan and USA.In our system, we record electrocorticogram (ECoG) obtained with subudural electrodes during their motor imagery, decode it and determine the movement they intended. So far, one patient of <span class="hlt">ALS</span> with severe paralysis, implanted with this electrodes, successfully operated the PC communication tool only by thinking. PMID:24292005</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/20001590','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/20001590"><span id="translatedtitle">The mechanical properties of Fe<span class="hlt">Al</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Baker, I.; George, E.P.</p> <p>1999-07-01</p> <p>In the last few years, considerable progress has been made in obtaining reproducible mechanical properties data for binary Fe<span class="hlt">Al</span> alloys. Two sets of observations are the foundation of this progress. The first is that the large equilibrium vacancy concentrations that exist in Fe<span class="hlt">Al</span> at high temperature are easily retained during cooling, and that these strongly affect the low-temperature mechanical properties. The second is that room-temperature ductility is adversely affected by water vapor. The purpose of this paper is to highlight their understanding of key phenomena and to show how an understanding of the factors which control the yield strength and fracture behavior has followed from the discovery of the above two effects. 94 refs., 8 figs.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19790025087','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19790025087"><span id="translatedtitle">Development of Si<span class="hlt">Al</span>ON materials</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Layden, G. K.</p> <p>1979-01-01</p> <p>Cold pressing and sintering techniques were used to produce ceramic test specimens in which the major phase was either Si3N4 or a solid solution having the beta Si3N4 structure. Additional components were incorporated to promote liquid phase sintering. Glass and/or crystalline phase were consequently retained in boundaries between Si3N4 grains which largely determined the physical properties of the bodies. Systems investigated most extensively included R-Si-<span class="hlt">Al</span>-O-N (R = rare earth element) Zr-Si-<span class="hlt">Al</span>-O-N, Y-Si-Be-O-N, and R1-R2-Si-O-N. Room temperature and 1370 C modulus of ruptured, 1370 C creep, and oxidation behavior are discussed in terms of phase relationships in a parent quinery, and relavent oxide systems.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/7375','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/7375"><span id="translatedtitle">Impact of superbends at the <span class="hlt">ALS</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Nishimura, H.; Robin, D.</p> <p>1999-03-19</p> <p>To satisfy a demand for high energy, high brightness x-ray sources at the Advanced Light Source (<span class="hlt">ALS</span>), a plan is in place to replace three 1.3 Tesla normal conducting bending magnets with three 5 Tesla superconducting magnets (superbends) in the year 2001. In this paper they discuss the impact of the superbends on the <span class="hlt">ALS</span> beam parameters and particle dynamics. In particular they show the effect on the emittance, energy spread, and lifetime. They find that by adjusting the dispersion to be positive in the straight section they are able to largely restore the horizontal emittance. The vertical emittance can be adjusted independently to control the lifetime. The particle dynamics are investigated through particle tracking with a frequency analysis postprocessor. They find that by placing the three superbends symmetrically around the ring there is ample dynamic aperture for injection and lifetime.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/792924','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/792924"><span id="translatedtitle">Berkeley Lab's <span class="hlt">ALS</span> generates Femtosecond Synchrotron Radiation</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Robinson, Arthur L.</p> <p>2000-05-23</p> <p>A Lawrence Berkeley National Laboratory (Berkeley Lab) team drawing its members from the Materials Sciences Division (MSD), the Center for Beam Physics in the Accelerator and Fusion Research Division, and the Advanced Light Source (<span class="hlt">ALS</span>) has succeeded in generating 300-femtosecond pulses of synchrotron radiation at the <span class="hlt">ALS</span> synchrotron radiation machine. Though this ''proof-of-principle'' experiment made use of visible light on a borrowed beamline, the laser ''time-slicing'' technique at the heart of the demonstration will soon be applied in a new bend-magnet beamline designed explicitly for the production of femtosecond pulses of X-rays to study long-range and local order in condensed matter with ultrafast time resolution. An undulator beamline based on the same technique has been proposed that will dramatically increase the flux and brightness.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1995AdSpR..15R.123D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1995AdSpR..15R.123D"><span id="translatedtitle"><span class="hlt">Al</span>-26 imaging details from COMPTEL</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Diehl, R.; Knodlseder, J.; Bennett, K.; Bloemen, H.; Dupraz, C.; Hermsen, W.; Lichti, G. G.; Morris, D.; Oberlack, U.; Ryan, J.</p> <p>1995-05-01</p> <p>The Compton Telescope (COMPTEL) map of 1.809 MeV emission from Galactic <span class="hlt">Al</span>-26 is now based on 2 1/2 years of data. Different imaging analysis approaches are discussed: Likelihood maps from point source scans are utilized for searches of emission regions; astrophysical source models are fitted to the measurement with the maximum likelihood method; deconvolved images are produced with the maximum entropy algorithm. Simulations and statistical analysis with the bootstrap method demonstrate that the intensity irregularity and asymmetry along the Galactic plane is significant, although weaker individual features are insignificant by themselves. The comparison of classical <span class="hlt">Al</span>-26 source tracer distributions shows that none of these models represents the COMPTEL data well. The measured 1.809 MeV feature from the Vela region, positionally consistent with the Vela supernova remnant, shows an indication for extended emission.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/960677','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/960677"><span id="translatedtitle">Observable Proxies For 26 <span class="hlt">Al</span> Enhancement</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Fryer, Christopher L; Young, Patrick A; Ellinger, Carola I; Arnett, William D</p> <p>2008-01-01</p> <p>We consider the cospatial production of elements in supernova explosions to find observationally detectable proxies for enhancement of {sup 26}<span class="hlt">Al</span> in supernova ejecta and stellar systems. Using four progenitors we explore a range of 1D explosions at different energies and an asymmetric 3D explosion. We find that the most reliable indicator of the presence of {sup 26}<span class="hlt">Al</span> in unmixed ejecta is a very low S/Si ratio ({approx} 0.05). Production of N in O/S/Si-rich regions is also indicative. The biologically important element P is produced at its highest abundance in the same regions. Proxies should be detectable in supernova ejecta with high spatial resolution multi wavelength observations, but the small absolute abundance of material injected into a proto-planetary disk makes detection unlikely in existing or forming stellar/planetary systems.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014MS%26E...61a2005A','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014MS%26E...61a2005A"><span id="translatedtitle">Stress evolution during ultrasonic <span class="hlt">Al</span> ribbon bonding</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Ando, Masaya; Takashima, Kazumasa; Maeda, Masakatsu; Takahashi, Yasuo</p> <p>2014-08-01</p> <p>The present study reveals the stress distribution in the substrate during ultrasonic bonding. The deformations of the Si substrate, <span class="hlt">Al</span> ribbon, and <span class="hlt">Al</span> pad were numerically analyzed using a finite element method. Experimental observation of the interface using a highspeed video camera was also conducted to determine the actual interfacial slip amplitude. This amplitude becomes smaller than that of tool-tip with bonding time. It was suggested from the numerical simulations that frictional adhesion enhanced the friction force, resulting in an increase in the equivalent stress in the ribbon and pad. As a result, very large stresses occur in the substrate during ultrasonic bonding. These stresses evolve with the progress of ultrasonic bonding, i.e., frictional adhesion.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1983JAP....54.3172R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1983JAP....54.3172R"><span id="translatedtitle">Interdiffusion in ? phase Cu-<span class="hlt">Al</span> alloys</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Romig, A. D., Jr.</p> <p>1983-06-01</p> <p>The diffusion behavior of ? phase Cu-<span class="hlt">Al</span> has been studied at 800, 850, and 950 C using the experimental approach and analysis scheme of Kirkendall and Darken. Diffusion couples were made using the window frame technique and concentration profiles were determined by electron probe microanalysis. The chemical diffusion coefficient, D was found to be D=0.65 exp(-42200/RT) cm2/s. The diffusivity was observed to be independent of composition over the range 11-13 wt. % <span class="hlt">Al</span>. The self-diffusion coefficients DCu and DAl were determined to be DAl =0.13 exp(-38900/RT) cm2/s and DCu =2.2 exp(-43400/RT) cm2/s. All activation energies are in calories/mole.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19930070119&hterms=fgm&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3Dfgm','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19930070119&hterms=fgm&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3Dfgm"><span id="translatedtitle">Fabrication and properties of functionally graded Ni<span class="hlt">Al/Al</span>2O3 composites</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Miller, D. P.; Lannutti, J. J.; Noebe, R. D.</p> <p>1993-01-01</p> <p>A modified sedimentation process was used in the production of a functionally gradient material (FGM), Ni<span class="hlt">Al/Al</span>2O3. A simple finite element model was used to guide our design and fabrication efforts by estimating residual stress states as a function of composite structure. This approach could lead to tailored designs that enhance or avoid specific residual stress states. Thermal cycling tests were factored into the model to predict time dependent or steady-state internal temperature and stress profiles. Four-point bend tests were conducted to establish the mechanical load-displacement behavior of a single interlayer FGM at room temperature, 800 and 1000 K. Room temperature bend strength of the FGM was 3-4 times that of the base Ni<span class="hlt">Al</span>. At elevated temperatures, composite fracture occurred in a gradual, noncatastrophic mode involving Ni<span class="hlt">Al</span> retardation of a succession of cracks originating in the alumina face.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/1007835','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/1007835"><span id="translatedtitle">Interdiffusion in the Mg-<span class="hlt">Al</span> system and Intrinsic Diffusion in (<span class="hlt">Al</span>3Mg2) Phase</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Brennan, Sarah; Bermudez, Katrina; Kulkarni, Nagraj S; Sohn, Yong Ho</p> <p>2011-01-01</p> <p>Increasing use and development of lightweight Mg-alloys have led to the desire for more fundamental research in and understanding of Mg-based systems. As a strengthening component, <span class="hlt">Al</span> is one of the most important and common alloying elements for Mg-alloys. In this study, solid-to-solid diffusion couple techniques were employed to examine the interdiffusion between pure Mg and <span class="hlt">Al</span>. Diffusion anneals were carried out at 300 , 350 , and 400 C for 720, 360, and 240 hours, respectively. Optical and scanning electron microscopies (SEM) were employed to observe the formation of the intermetallics -<span class="hlt">Al</span>12Mg17 and -<span class="hlt">Al</span>3Mg2, but not -phase. Concentration profiles were determined using X-ray energy dispersive spectroscopy (XEDS). The growth constants and activation energies were determined for each intermetallic phase.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/20863724','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/20863724"><span id="translatedtitle">Nonstatistical fluctuations for deep inelastic processes in {sup 27}<span class="hlt">Al</span>+{sup 27}<span class="hlt">Al</span> collisions</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Berceanu, I.; Duma, M.; Moisa, D.; Petrovici, M.; Pop, A.; Simion, V.; Zoppo, A. Del; D'Erasmo, G.; Imme, G.; Lanzano, G.; Pagano, A.; Pantaleo, A.; Raciti, G.</p> <p>2006-08-15</p> <p>The excitation functions (EFs) for different fragments produced in the {sup 27}<span class="hlt">Al</span>+{sup 27}<span class="hlt">Al</span> dissipative collisions have been measured in steps of 250 keV in the incident energy range 122-132 MeV. Deep inelastic processes have been selected by integrating events on a total kinetic energy loss window of 12 MeV between 20 and 32 MeV. Large fluctuations are observed in all the studied EFs. Large-channel cross-correlation coefficients confirm the nonstatistical origin of these fluctuations. The energy autocorrelation function (EAF) shows damped oscillation structure as expected when a dinuclear system with a lifetime [{tau}=(5.1{+-}2.1){center_dot}10{sup -21}s], similar with its revolution period (T=4.9{center_dot}10{sup -21}sec), is formed. From the periodicity of the EAF oscillations, information on the deformation of the {sup 27}<span class="hlt">Al</span>+{sup 27}<span class="hlt">Al</span> dinucleus is inferred.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19720050230&hterms=flow+battery&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3Dflow%2Bbattery','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19720050230&hterms=flow+battery&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3Dflow%2Bbattery"><span id="translatedtitle">Rechargeable <span class="hlt">Al</span>/Cl2 battery with molten <span class="hlt">Al</span>Cl4/-/ electrolyte.</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Holleck, G. L.; Giner, J.; Burrows, B.</p> <p>1972-01-01</p> <p>A molten salt system based on <span class="hlt">Al</span>- and Cl2 carbon electrodes, with an <span class="hlt">Al</span>Cl3 alkali chloride eutectic as electrolyte, offers promise as a rechargeable, high energy density battery which can operate at a relatively low temperature. Electrode kinetic studies showed that the electrode reactions at the <span class="hlt">Al</span> anode were rapid and that the observed passivation phenomena were due to the formation at the electrode surface of a solid salt layer resulting from concentration changes on anodic or cathodic current flow. It was established that carbon electrodes were intrinsically active for chlorine reduction in <span class="hlt">Al</span>Cl3-alkali chloride melts. By means of a rotating vitreous carbon disk electrode, the kinetic parameters were determined.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/21054813','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/21054813"><span id="translatedtitle">Fusion cross sections for the 6,7Li+27<span class="hlt">Al</span>, 9Be+27<span class="hlt">Al</span> systems</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Barbara, E. de; Marti, G. V.; Arazi, A.; Capurro, O. A.; Fernandez Niello, J. O.; Figueira, J. M.; Pacheco, A. J.; Ramirez, M.; Rodriguez, M. D.; Testoni, J. E.; Verruno, M.; Padron, I.; Gomes, P. R. S.</p> <p>2007-02-12</p> <p>We present the results of total fusion cross sections measurements for the 6,7Li + 27<span class="hlt">Al</span>, 9Be + 27<span class="hlt">Al</span>, systems at energies above and below the Coulomb barrier (0.8Vb {<=} E {<=} 2.0Vb). The experimental evidence at the measured energy regime show that the total fusion cross sections of 6Li and 9Be with a light mass target are not affected by the break-up process. The elastic break up cross sections for the 6Li + 27<span class="hlt">Al</span> system were also measured and the results are being presented in this issue. The data for the 7Li + 27<span class="hlt">Al</span> system are still being analyzed and therefore these results should be considered preliminary.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ars.usda.gov/research/publications/Publications.htm?seq_no_115=193650','TEKTRAN'); return false;" href="http://www.ars.usda.gov/research/publications/Publications.htm?seq_no_115=193650"><span id="translatedtitle">TRANSCRIPTIONAL ANALYSIS BETWEEN TWO WHEAT NEAR-ISOGENIC LINES CONTRASTING IN ALUMINUM (<span class="hlt">AL</span>) TOLERANCE UNDER <span class="hlt">AL</span> STRESS</span></a></p> <p><a target="_blank" href="http://www.ars.usda.gov/services/TekTran.htm">Technology Transfer Automated Retrieval System (TEKTRAN)</a></p> <p></p> <p></p> <p>To understand the mechanisms of aluminum (<span class="hlt">Al</span>) tolerance and identify genes responsible for <span class="hlt">Al</span> tolerance in wheat (Triticum aestivum L.), suppression subtractive hybridization (SSH) libraries were constructed from <span class="hlt">Al</span>-stressed roots for two wheat near- isogenic lines (NILs), Chisholm-T (<span class="hlt">Al</span>-tolerant) a...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2009bime.book..197B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2009bime.book..197B"><span id="translatedtitle">Tumor-Wachstumsmodellierung <span class="hlt">als</span> parametrisches Bildregistrierproblem</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Becker, Stefan; Jungmann, Jan Ole; Mang, Andreas; Buzug, Thorsten M.</p> <p></p> <p>In der vorliegenden Arbeit stellen wir ein neues Modell zur Kopplung des Tumormasseeffektes an die, der Wachstumsmodellierung unterliegende, anisotrope Reaktionsdiffusionsgleichung vor. Die Gleichung wird auf einem hochaufgelsten Voxelgitter diskretisiert. Eine Modellierung der Anisotropie des Diffusionsprozesses ermglicht die Integration von Diffusions-Tensor-Bildgebungsdaten. Die raumfordernde Wirkung des Tumors wird <span class="hlt">als</span> parametrisches Bildregistrierproblem aufgefasst. Hierbei wird die resultierende Verteilung der Tumorzellkonzentration in die zu optimierende Zielfunktion integriert. Erste qualitative Ergebnisse zeigen, dass eine Minimierung der aufgestellten Zielfunktion zu einer plausiblen Modellierung des Masseeffektes fhrt.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=retrieve&db=pubmed&list_uids=23345638&dopt=AbstractPlus','TOXNETTOXLINE'); return false;" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=retrieve&db=pubmed&list_uids=23345638&dopt=AbstractPlus"><span id="translatedtitle"><span class="hlt">ALS</span> dysphagia pathophysiology: differential botulinum toxin response.</span></a></p> <p><a target="_blank" href="http://toxnet.nlm.nih.gov/cgi-bin/sis/htmlgen?TOXLINE">TOXLINE Toxicology Bibliographic Information</a></p> <p>Restivo DA; Casabona A; Nicotra A; Zappia M; Elia M; Romano MC; Alfonsi E; Marchese-Ragona R</p> <p>2013-02-12</p> <p>OBJECTIVES: This study looked at the effect of botulinum toxin type A (BoTox-A) in patients with amyotrophic lateral sclerosis (<span class="hlt">ALS</span>) with dysphagia due to isolated upper motor neuron (UMN) involvement or combined UMN/lower motor neuron (LMN) impairment associated with oral phase or oropharyngeal muscles involvement. Establishing whether different pathophysiologic mechanisms underlie different responses to BoTox-A treatment may have important implications for patient management.PATIENTS AND METHODS: We screened 35 patients with sporadic <span class="hlt">ALS</span> with dysphagia and included in the study 20 out of 35 with upper esophageal sphincter (UES) hyperactivity. We divided these 20 patients into 2 groups, based on the presence or absence of LMN impairment. Irrespective of the groups, we treated all 20 patients with BoTox-A injected into the UES. The study outcome was dysphagia severity scored using the Penetration/Aspiration Scale (PAS), measured before and 2, 4, and 20 weeks after injection.RESULTS: Significant mean PAS reduction was noted at weeks 2 and 4. The botulinum-dependent PAS reduction was entirely associated with the variability shown by the group of patients with no sign of LMN impairment (group 2) and was not observed in group 1.CONCLUSIONS: The significant improvement observed in patients with isolated UES dysfunction suggests that a different pathophysiology of <span class="hlt">ALS</span> dysphagia predisposes patients to a different response to treatment with BoTox-A. This treatment may represent an alternative treatment to percutaneous endoscopic gastrostomy (PEG) or prolong PEG-free time.CLASSIFICATION OF EVIDENCE: This study provides Class III evidence that botulinum is more effective at 2 and 4 weeks in improving dysphagia in patients with <span class="hlt">ALS</span> with UES hyperactivity without LMN involvement (vs those with LMN involvement).</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4568392','PMC'); return false;" href="http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4568392"><span id="translatedtitle">Psychosocial adjustment to <span class="hlt">ALS</span>: a longitudinal study</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Matuz, Tamara; Birbaumer, Niels; Hautzinger, Martin; Kübler, Andrea</p> <p>2015-01-01</p> <p>For the current study the Lazarian stress-coping theory and the appendant model of psychosocial adjustment to chronic illness and disabilities (Pakenham, 1999) has shaped the foundation for identifying determinants of adjustment to <span class="hlt">ALS</span>. We aimed to investigate the evolution of psychosocial adjustment to <span class="hlt">ALS</span> and to determine its long-term predictors. A longitudinal study design with four measurement time points was therefore, used to assess patients' quality of life, depression, and stress-coping model related aspects, such as illness characteristics, social support, cognitive appraisals, and coping strategies during a period of 2 years. Regression analyses revealed that 55% of the variance of severity of depressive symptoms and 47% of the variance in quality of life at T2 was accounted for by all the T1 predictor variables taken together. On the level of individual contributions, protective buffering, and appraisal of own coping potential accounted for a significant percentage in the variance in severity of depressive symptoms, whereas problem management coping strategies explained variance in quality of life scores. Illness characteristics at T2 did not explain any variance of both adjustment outcomes. Overall, the pattern of the longitudinal results indicated stable depressive symptoms and quality of life indices reflecting a successful adjustment to the disease across four measurement time points during a period of about two years. Empirical evidence is provided for the predictive value of social support, cognitive appraisals, and coping strategies, but not illness parameters such as severity and duration for adaptation to <span class="hlt">ALS</span>. The current study contributes to a better conceptualization of adjustment, allowing us to provide evidence-based support beyond medical and physical intervention for people with <span class="hlt">ALS</span>. PMID:26441696</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li><a href="#" onclick='return showDiv("page_24");'>24</a></li> <li class="active"><span>25</span></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_25 --> <center> <div class="footer-extlink text-muted"><small>Some links on this page may take you to non-federal websites. 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