Sample records for v-cr-ti type alloys

  1. Reactions of oxygen with V?Cr?Ti alloys

    Microsoft Academic Search

    J. R. DiStefano; J. H. DeVan

    1997-01-01

    Fusion reactors have been proposed with a vanadium alloy as the structural\\/containment material. However, vanadium has a significant affinity for interstitial contamination that could deleteriously affect its mechanical properties. The effects of oxygen pick-up in air and low pressure oxygen environments were investigated at 400–500°C for two V?Cr?Ti alloys. As expected the studies showed that the room temperature tensile ductility

  2. An improved procedure for radiochemical processing of activated fusion-reactor-relevant V–Cr–Ti alloy

    Microsoft Academic Search

    S. A. Bartenev; B. N. Kolbasov; E. N. Li; P. V. Romanov; V. N. Romanovskij; N. G. Firsin

    2009-01-01

    The most promising structural material for both demonstration and commercial fusion reactors with liquid metal coolants is vanadium–chromium–titanium (V–Cr–Ti) alloy. Since its base is expensive and scarce vanadium, it is desirable to return this material into fusion power engineering after the reactor decommissioning. This is feasible only after purification of the V–Cr–Ti alloy from activation products. We have developed extraction

  3. Performance of V?Cr?Ti alloys in a hydrogen environment

    NASA Astrophysics Data System (ADS)

    Natesan, K.; Soppet, W. K.

    2000-12-01

    A systematic study is underway at Argonne National Laboratory to evaluate the mechanical properties of several V-Cr-Ti alloys after exposure to environments containing hydrogen at various partial pressures (pH 2). The goal is to correlate the chemistry of the exposure environment with hydrogen uptake by the samples and with the resulting influence on microstructures and tensile properties of the alloys. Other variables examined are specimen cooling rate and synergistic effects, if any, of oxygen and hydrogen on tensile behavior of the alloys. Experiments were conducted to evaluate the effect of pH 2 in the range of 3×10 -6 and 1 Torr on tensile properties of two V-Cr-Ti alloys. Up to pH 2 of 0.05 Torr, negligible effect of H was observed on either maximum engineering stress or uniform and total elongation. However, uniform and total elongation decreased substantially when the alloys were exposed at 500°C to 1.0 Torr of H 2 pressure. Preliminary data from sequential exposures of the materials to low-pO 2 and several low-pH 2 environments did not reveal adverse effects on the maximum engineering stress or on uniform and total elongation when the alloy contained ?2000 wppm O and 16 wppm H. Furthermore, tests in H 2-exposed specimens, initially annealed at various temperatures, showed that grain-size variation by a factor of ?2 had little or no effect on tensile properties. Also, specimen cooling rate had a small effect, if any, on the tensile properties of the alloy.

  4. Subtask 12B1: Welding development for V-Cr-Ti alloys

    SciTech Connect

    King, J.F.; Goodwin, G.M.; Grossbeck, M.L.; Alexander, D.J. [Oak Ridge National Lab., TN (United States)

    1995-03-01

    Development of the metallurgical and technological basis for the welding of thick sections of V-Cr-Ti alloys. The weldability and weldment properties of the V-5Cr-5Ti alloy have been evaluated. Results for the Sigmajig test of the vanadium alloy were similar to the cracking resistance of stainless steels, and indicates hot-cracking is unlikely to be a problem. Subsize Charpy test results for GTA weld metal in the as-welded condition have shown a significant reduction in toughness compared to the base metal. The weld metal toughness properties were restored to approximately that of the base metal after exposure to a PWHT 950{degrees}C. The subsize Charpy toughness results for the EB weld metal from this same heat of vanadium alloy has shown significant improvement in properties compared to the GTA weld metal and the base metal. Further testing and analysis will be conducted to more fully characterize the properties of weld metal for each welding process and develop a basic understanding of the cause of the toughness decrease in the GTA welds. 5 figs., 1 tab.

  5. Effects of oxygen and hydrogen at low pressure on the mechanical properties of V–Cr–Ti alloys

    Microsoft Academic Search

    J. R DiStefano; B. A Pint; J. H DeVan; H. D Röhrig; L. D Chitwood

    2000-01-01

    Exposure of V–Cr–Ti alloys to low oxygen partial pressures at high temperature results in oxygen absorption and internal oxidation. Characterization of a V–4Cr–4Ti alloy after oxidation at 500°C revealed a microstructure with ultrafine oxide precipitates in the matrix and along grain boundaries. Heat treatment at 950°C following oxidation resulted in large TiOx precipitates in the matrix and grain boundaries. Tensile

  6. Feasibility of correlating V-Cr-Ti alloy weld strength with weld chemistry. CRADA final report

    SciTech Connect

    Grossbeck, M.L. [Oak Ridge National Lab., TN (United States); Odom, R.W. [Charles Evans and Associates, Redwood City, CA (United States)

    1998-06-01

    The mechanical properties of refractory metals such as vanadium are determined to a large extent by the interstitial impurities in the alloy. In the case of welding, interstitial impurities are introduced in the welding process from the atmosphere and by dissolution of existing precipitates in the alloy itself. Because of the necessity of having an ultra-pure atmosphere, a vacuum chamber or a glove box is necessary. In the V-Cr-Ti system, the titanium serves as a getter to control the concentration of oxygen and nitrogen in solid solution in the alloy. In this project the secondary ion mass spectrometry (SIMS) technique was used to detect, measure, and map the spacial distribution of impurity elements in welds in the alloy V-4Cr-4Ti. An attempt was then made to correlate the concentrations and distributions of the impurities with mechanical properties of the welds. Mechanical integrity of the welds was determined by Charpy V-notch testing. Welds were prepared by the gas-tungsten-arc (GTA) method. Charpy testing established a correlation between weld impurity concentration and the ductile to brittle transition temperature (DBTT). Higher concentrations of oxygen resulted in a higher DBTT. An exception was noted in the case of a low-oxygen weld which had a high hydrogen concentration resulting in a brittle weld. The concentrations and distributions of the impurities determined by SIMS could not be correlated with the mechanical properties of the welds. This research supports efforts to develop fusion reactor first wall and blanket structural materials.

  7. Effects of neutron irradiation and hydrogen on ductile-brittle transition temperatures of V-Cr-Ti alloys

    SciTech Connect

    Loomis, B.A.; Chung, H.M.; Nowicki, L.J.; Smith, D.L.

    1993-08-01

    The effects of neutron irradiation and hydrogen on the ductile- brittle transition temperatures (DBTTs) of unalloyed vanadium and V-Cr-Ti alloys were determined from Charpy-impact tests on 1/3 ASTM standard size specimens and from impact tests on 3-mm diameter discs. The tests were conducted on specimens containing <30 appm hydrogen and 600-1200 appm hydrogen and on specimens after neutron irradiation to 28-46 dpa at 420, 520, and 600C. The DBTTs were minimum (< {minus}220{degree}C) for V-(105)Ti alloys under for V-4-Cr-4Ti alloy with <30 appm hydrogen. The effect of 600-1200 appm hydrogen in the specimens was to raise the DBTTs by 100--150{degree}C. The DBTTs were minimum (< {minus}220{degree}C) for V-(1-5)Ti alloys and V-4-Cr-4Ti alloys after neutron irradiation.

  8. Effect of time and temperature on grain size of V and V-Cr-Ti alloys

    SciTech Connect

    Natesan, K.; Rink, D.L. [Argonne National Lab., IL (United States)

    1996-10-01

    Grain growth studies were conducted to evaluate the effect of time and temperature on the grain size of pure V, V-4 wt.%Cr-4 wt.%Ti, and V-5 wt.%Cr-5 wt.%Ti alloys. The temperatures used in the study were 500, 650, 800, and 1000{degrees}C, and exposure times ranged between 100 and {approx}5000 h. All three materials exhibited negligible grain growth at 500, 650, and 800{degrees}C, even after {approx}5000 h. At 1000{degrees}C, pure V showed substantial grain growth after only 100 h, and V-4Cr-4Ti showed growth after 2000 h, while V-5Cr-5Ti showed no grain growth after exposure for up to 2000 h.

  9. Revision of the tensile database for V-Ti and V-Cr-Ti alloys tested at ANL.

    SciTech Connect

    Billone, M. C.

    1998-01-13

    The published database for the tensile properties of unirradiated and irradiated vanadium-based alloys tested at Argonne National Laboratory (ANL) has been reviewed. The alloys tested are in the ranges of V-(0-18)wt.%Ti and V-(4-15)wt.%Cr-(3-15)wt.%Ti. A consistent methodology, based on ASTM terminology and standards, has been used to re-analyze the unpublished load vs. displacement curves for 162 unirradiated samples and 91 irradiated samples to determine revised values for yield strength (YS), ultimate tensile strength (UTS), uniform elongation (UE) and total elongation (TE). The revised data set contains lower values for UE ({minus}5{+-}2% strain) and TE ({minus}4{+-}2% strain) than previously reported. Revised values for YS and UTS are consistent with the previously-published values in that they are within the scatter usually associated with these properties.

  10. Effect of Low Temperature Irradiation in ATR On The Mechanical Properties of Ternary V-Cr-Ti Alloys

    SciTech Connect

    Hamilton, Margaret L.; Toloczko, Mychailo B.; Oliver, Brian M.; Garner, Francis A.

    2000-09-01

    Tensile tests and shear punch teats were performed on a variety of vanadium alloys that were irradiated in the Advanced Test Reactor (ATR) at temperatures between 200 and 300 degrees C to doses between 3 and 5 dpa. Tests were performed at room temperature and the irradiation temperature. The results of both the tensile tests and the shear punch tests show that following low temperature irradiation, the yield strength increased by a factor of 3-4 while the ultimate strength increased by a factor of approximately 3.

  11. CaO insulator coatings and self-healing of defects on V-Cr-Ti alloys in liquid lithium

    SciTech Connect

    Park, J.H.; Kassner, T.F.

    1996-02-01

    Electrically insulating and corrosion-resistant coatings are required at the liquid metal/structural interface in fusion first-wall/blanket applications. The electrical resistance of CaO coatings produced on V-5%Cr-5%Ti by exposure of the alloy to liquid Li that contained 0.5--85 wt.% dissolved Ca was measured as a function of time at temperatures between 250 and 600{degrees}C. The solute element, Ca in liquid Li, reacted with the alloy substrate at 400--420{degrees}C to produce a CaO coating. Resistance of the coating layer measured in-situ in liquid Li was {approx}10{sup 6} {Omega} at 400{degrees}C. Thermal cycling between 300 and 700{degrees}C changed the coating layer resistance. which followed insulator behavior. These results suggest that thin homogeneous coatings can be produced on variously shaped surfaces by controlling the exposure time, temperature, and composition of the liquid metal. The technique can be applied to various shapes(e.g., inside/outside of tubes, complex geometrical shapes) because the coating is formed by liquid-phase reaction. Examination of the specimens after cooling to room temperature revealed no spallation, but homogeneous crazing cracks were present in the CaO coating. Additional tests to investigate the in-situ self-healing behavior of the cracks indicated that rapid healing occurred at {ge}360{degrees}C.

  12. Reactions of hydrogen with V–Cr–Ti alloys 1 Research sponsored by the Office of Fusion Energy Sciences, U.S. Department of Energy under contract DE-ACO5-96OR22464 with Lockheed Martin Energy Research Corporation. 1

    Microsoft Academic Search

    J. R DiStefano; J. H De Van; D. H Röhrig; L. D Chitwood

    1999-01-01

    The interest in vanadium alloys for use as a first-wall material in fusion reactor applications has led to a study to determine the effects of hydrogen on the mechanical properties of certain V–Cr–Ti alloys. Hydrogen uptake by the alloys is a function of temperature and pressure. In the absence of increases in oxygen concentration, additions of up to 400 wpm

  13. CaO insulator coatings and self-healing of defects on V-Cr-Ti alloys in liquid lithium system

    SciTech Connect

    Park, J.H.; Kassner, T.F.

    1995-09-01

    Electrically insulating and corrosion-resistant coatings are required at the liquid metal/structural interface in fusion first-wall/blanket applications. Electrical resistance of CaO coatings that were produced on V-5%Cr-5%Ti by exposure of the alloy to liquid Li containing 0.5-85 wt.% dissolved Ca was measured as a function of time at temperatures between 250 and 600{degrees}C. The solute element, Ca in liquid Li, reacted with the alloy substrate at 400-420{degrees}C to produce a CaO coating. Resistance of the coating layer measured in-situ in liquid Li was {approx}10{sup 6} {Omega} at 400{degrees}C. Thermal cycling between 300 and 700{degrees}C changed the coating layer resistance, which followed insulator behavior. These results suggest that thin homogeneous coatings can be produced on variously shaped surfaces by controlling the exposure time, temperature, and composition of the liquid metal. The technique can be applied to various shapes (e.g., inside/outside of tubes, complex geometrical shapes) because the coating is formed by liquid-phase reaction. Examination of the specimens after cooling to room temperature revealed no spallation, but homogeneous crazing cracks were present in the CaO coating. Additional tests to investigate the in-situ self-healing behavior of the cracks indicated that rapid healing occurred at {>=}360{degrees}C.

  14. Reactions of hydrogen with V-Cr-Ti alloys

    SciTech Connect

    DiStefano, J.R.; DeVan, J.H.; Chitwood, L.D. [Oak Ridge National Lab., TN (United States); Roehrig, D.H. [Forschungszentrum Karlsruhe (Germany). Projekleitung Kernfusion

    1998-09-01

    In the absence of increases in oxygen concentration, additions of up to 400 ppm hydrogen to V-4 Cr-4 Ti did not result in significant embrittlement as determined by room temperature tensile tests. However, when hydrogen approached 700 ppm after exposure at 325 C, rapid embrittlement occurred. In this latter case, hydride formation is the presumed embrittlement cause. When oxygen was added during or prior to hydrogen exposure, synergistic effects led to significant embrittlement by 100 ppm hydrogen.

  15. Thermophysical and Mechanical Properties of V-(4-5)%Cr-(4-5)%Ti alloys (3/5/98 draft) S.J. Zinkle

    E-print Network

    California at Los Angeles, University of

    Thermophysical and Mechanical Properties of V-(4-5)%Cr-(4-5)%Ti alloys (3/5/98 draft) S.J. Zinkle Oak Ridge National Laboratory Solid solution V-Cr-Ti alloys exhibit a good combination of high thermal properties for V-(4-5)%Cr-(4-5)%Ti alloys are summarized in the following. Some of these data are available

  16. Effects of neutron irradiation on vanadium-base alloys

    Microsoft Academic Search

    D. L. Smith; B. A. Loomis; H. M. Chung

    1994-01-01

    Vanadium-base alloys of the V-Cr-Ti-Si system are attractive candidates for use as structural materials in fusion reactors. The vanadium-base alloys exhibit relatively low long-term activation, irradiation induced afterheat and neutron-induced helium transmutation rates. Because of favorable physical properties these alloys can accommodate higher surface heat fluxes than the steels. The current focus of the U. S. program is on V-(0–10%)Cr-(0–5%)Ti-(0–1%)Si

  17. [Fatigue properties of dental alloys. 12% Au-Pd-Ag alloy and type III gold alloy].

    PubMed

    Kato, H

    1989-12-01

    Usually the mechanical properties of dental alloys are determined from the values obtained through static tests of their tensile strength, hardness, etc. Generally, high tensile strength and ductility are preferred. However, when small stresses within proportional limits are applied repeatedly (even though not amounting to destructive forces in static tests), they may cause rupture in the alloy or, at least, cause it to lose its original mechanical properties. This phenomenon is called metal fatigue. It is estimated that the intraoral stress loads received by dental restorations during mastication or during insertion and removal of appliances are repeated more than 3 x 10(5) times/year. From this standpoint, it may be more appropriate to estimate the fracture strength of such dental alloys based on the fatigue properties of the restorative materials used for clasps, bars, and fixed bridges. For this reason, it is necessary to obtain data through fatigue tests on the fatigue strength and the fatigue endurance limits of dental alloys, and it is important to find a correlation between these data and the static data on tensile strengths and ductility obtained by tensile tests. Two alloys are used in these experiments. Both wrought specimens and cast specimens of 12% Au-Pd-Ag and Type III gold alloy were prepared for the fatigue tests. The size of the rectangular wrought specimens was 3 x 4 x 110 mm. The 12% Au-Pd-Ag alloy was heated to 800 degrees C for 15 minutes, quenched, and reheated to 400 degrees C for 20 minutes and quenched again according to the manufacturer's instructions for heat treatment. The Type III gold alloy was heated to 700 degrees C for 10 minutes, quenched, and reheated to 350 degrees C for 20 minutes and quenched again. The cylindrical cast specimens were 60 mm long and 2 mm in diameter. They were invested by conventional methods and cast in a centrifugal casting machine, Thermotrol Model 2500. The four point bending test for the wrought specimen was performed with a Universal Fatigue testing machine, Shimazu UF-15 at a stress amplitude rate of 30 Hz. The cylindrical cast specimens were tested in cyclic tension in a Hydraulic IC Servo Machine, Instron Model 8501 at a gauge length of 25 mm and a stress amplitude of 10 Hz. The tensile tests for both wrought and cast specimens were performed with a Universal Testing Machine, Instron Model 1125 and measured at a cross-head speed of 1 mm/min.(ABSTRACT TRUNCATED AT 400 WORDS) PMID:2489466

  18. Control Method for a 3D Form Display with Coil-type Shape Memory Alloy

    E-print Network

    Tachi, Susumu

    Control Method for a 3D Form Display with Coil-type Shape Memory Alloy Masashi Nakatani1 , Hiroyuki.t.u-tokyo.ac.jp Abstract - We previously proposed a new 3D form display actuated by shape memory alloy (SMA), which of the shape memory alloy with a simple matrix drive circuit. This type of drive circuit can dramatically

  19. Formation of F- and P-Type Icosahedral Quasicrystals in the Zn Mg Ho Alloy System

    Microsoft Academic Search

    Takayuki Shimizu; Tsutomu Ishimasa

    1998-01-01

    Two types of icosahedral quasicrystals, F- and P-types, formed at 563°C in the Zn60Mg40-xHox alloy depending on Ho content. In the composition range of 6≦x≦10, F-type icosahedral quasicrystal formed as a major phase in these alloys. The intensity of superlattice reflections which occurred due to F-type ordering became weaker in the alloys with lower Ho content. At x=5, P-type icosahedral

  20. Development and testing ov danadium alloys for fusion applications

    SciTech Connect

    Chung, H.M.; Loomis, B.A.; Smith, D.L.

    1996-10-01

    V base alloys have advantages for fusion reactor first-wall and blanket structure. To screen candidate alloys and optimize a V-base alloy, physical and mechanical properties of V-Ti, V-Cr-Ti, and V-Ti- Si alloys were studied before and after irradiation in Li environment in fast fission reactors. V-4Cr-4Ti containing 500-1000 wppM Si and <1000 wppM O+N+C was investigated as the most promising alloy, and more testing is being done. Major results of the work are presented in this paper. The reference V-4Cr-4Ti had the most attractive combination of the mechanical and physical properties that are prerequisite for first-wall and blanket structures: good thermal creep, good tensile strength/ductility, high impact energy, excellent resistance to swelling, and very low ductile-brittle transition temperature before and after irradiation. The alloy was highly resistant to irradiation-induced embrittlement in Li at 420-600 C, and the effects of dynamically charged He on swelling and mechanical properties were insignificant. However, several important issues remain unresolved: welding, low-temperature irradiation, He effect at high dose and high He concentration, irradiation creep, and irradiation performance in air or He. Initial results of investigation of some of these issues are also given.

  1. The effect of cobalt content in U-700 type alloys on degradation of aluminide coatings

    NASA Technical Reports Server (NTRS)

    Zaplatynsky, I.

    1985-01-01

    The influence of cobalt content in U-700 type alloys on the behavior of aluminide coatings is studied in burner rig cyclic oxidation tests at 1100C. It is determined that aluminide coatings on alloys with higher cobalt offer better oxidation protection than the same coatings on alloys containing less cobalt.

  2. INVITED FEATURE PAPERS Growth and transport properties of p-type GaNBi alloys

    E-print Network

    Wu, Junqiao

    INVITED FEATURE PAPERS Growth and transport properties of p-type GaNBi alloys Alejandro X. Levander 2011) Thin films of GaNBi alloys with up to 12.5 at.% Bi were grown on sapphire using low to the midgap position of GaN, whereas the conduction band edge shifted more gradually. I. INTRODUCTION Alloying

  3. Classification of binary alloys and their phase diagrams by the type of transformations occurring in them

    Microsoft Academic Search

    G. I. Pogodin-Alekseev

    1967-01-01

    1.Binary alloys crystallizing from homogeneous liquid melts can be divided into alloys of the eutectic, peritectic, and megotectic type, depending on the type of the transformations and structures occurring. Each of them can have complete, limited, or no solubility in the solid state, i.e., have a homogeneous solid solution, a mixture of solid solutions with limited solubility, or a mixture

  4. Electrochemical behavior of Alloy 22 and friction type rock bolt

    Microsoft Academic Search

    2006-01-01

    Alloy 22 (Ni-22Cr-13Mo-3Fe-3W) is a candidate alloy for the outer shell of spent nuclear materials storage containers in the Yucca Mountain High Level Nuclear Waste Repository because of its excellent corrosion resistance. The nuclear waste container is cylindrical in shape and the end caps are welded. Typically, Alloy 22 retains the high temperature single phase cubic structure near room temperature,

  5. Electron diffraction identification of structure types of martensite in Cu-Zn-Al alloys.

    PubMed

    Wang, R H; Zhao, Y C; Gui, J A

    1987-12-01

    Electron diffraction technique for identifying structure types of martensite in beta-Hume-Rothery alloys is described. It includes determination of the stacking sequence of the martensite of the basal planes, differentiation of the long-range ordering in martensite inherited from its parent phase (A2 type disordered; B2 type ordered; and D03, or Heusler, type ordered), and distinguishing between normal-type and modified-type martensite. In addition to the 18R1-type martensite, 12R, 6R, and 2H martensites were found in quenched Cu-Zn-Al alloys using this technique. PMID:3505596

  6. ABC6 Type Ordered Structure in Pt-rich Pt-Mn Alloys

    NASA Astrophysics Data System (ADS)

    Takahashi, Miwako; Sembiring, Timbangen; Yashima, Masatomo; Shishido, Toetsu; Ohshima, Ken-ichi

    2002-03-01

    In situ neutron diffraction experiments were performed on single crystals of Pt-12.5 and 14.4 at.% Mn alloys in order to elucidate the ordered structures of Pt-rich Pt-Mn alloys. The observed diffraction patterns at various temperatures up to 1050°C have revealed two ordered phases in these alloys. Below the order-disorder transition temperature, a Cu3Au type ordered structure appears and at low temperature, an ABC6 type ordered structure with a unit cell 2 × 2 × 2 as large as that of the fundamental fcc cell was found to be stable. A secondary ordering in the alloys is discussed in terms of two order parameters in the ABC6 type structure utilizing the method of static concentration waves originally proposed by Khachaturyan [Prog. Mater. Sci. 22 (1978) 24]. The ideal alloy composition for the structure is also discussed with the experimentally estimated order parameters.

  7. Corrosion behavior of dental alloys in various types of electrolyzed water.

    PubMed

    Dong, Hongwei; Nagamatsu, Yuki; Chen, Ker-Kong; Tajima, Kiyoshi; Kakigawa, Hiroshi; Shi, Sizhen; Kozono, Yoshio

    2003-12-01

    The corrosion behavior of dental alloys was examined in electrolyzed strong acid water, weak acid water and neutral water using a 7-day immersion test. The precious metal alloys, gold alloy. Au-Ag-Pd alloy and silver alloy showed the greatest surface color change and dissolution of constituents in the strong acid water and the smallest in the neutral water. The release of Au from gold alloy was especially marked in the strong acid water. Co-Cr alloy showed greater corrosion and tarnish resistance in the strong acid water rather than in the weak acid water and the neutral water. X-ray microanalysis revealed that the corrosion products on the precious metal alloys were silver chloride crystals and the thin brown products on Co-Cr alloy were cobalt and chromium oxides. Ti was sound in all three types of electrolyzed water. The neutral water appeared the least corrosive to metals among the three types showing equivalent bactericidal activity. PMID:15005226

  8. Investigation of new type Cu-Hf-Al bulk glassy alloys

    NASA Astrophysics Data System (ADS)

    Nagy, E.; Rontó, V.; Sólyom, J.; Roósz, A.

    2009-01-01

    In the last years new type Cu-Hf-Al ternary alloys were developed with high glass forming ability and ductility. The addition of Al to Cu-Hf alloys results in improvements in glass formation, thermal stability and mechanical properties of these alloys. We have investigated new Cu-based bulk amorphous alloys in Cu-Hf-Al ternary system. The alloys with Cu49Hf42Al9, Cu46Hf45Al9, Cu50Hf42.5Al7.5 and Cu50Hf45Al5 compositions were prepared by arc melting. The samples were made by centrifugal casting and were investigated by X-ray diffraction method. Thermodynamic properties were examined by differential scanning calorimetry and the structure of the crystallising phases by scanning electron microscopy. The determination of liquidus temperatures of alloys were measured by differential thermal analysis.

  9. Thermal evolution of vacancy-type defects in quenched FeCrNi alloys

    NASA Astrophysics Data System (ADS)

    Zhang, C. X.; Cao, X. Z.; Li, Y. H.; Jin, S. X.; Lu, E. Y.; Tian, H. W.; Zhang, P.; Wang, B. Y.

    2015-06-01

    The effect of isochronal annealing on vacancy-type defects in quenched FeCrNi alloys and SUS316 was investigated via positron annihilation technique. Vacancy-type defects clustered and grew with increasing annealing temperatures of up to 523 K and, in FeCrNi alloys, were gradually annihilated with increasing temperature. The annihilation temperature was relatively insensitive to the addition of Mo and nonmetal elements, and after annealing at 673 K, the vacancy-type defects were annihilated and dislocation-type defects were formed in all of the alloys. In addition, due to the formation of Mo-vacancy complexes, the density of defects in the Mo-diluted FeCrNi model alloy was lower than that in the FeCrNi model alloy. The long lifetime of vacancy-type defects in commercial stainless steel SUS316 was smaller than that in the FeCrNi model alloys due to the nonmetal-element-induced change in mobility of the defects. Moreover, the vacancy-type and dislocation-type defects contributed to the S and W parameters of positron annihilation during the entire annealing treatment.

  10. NDE detectability of fatigue type cracks in high strength alloys

    NASA Technical Reports Server (NTRS)

    Christner, B. K.; Rummel, W. D.

    1983-01-01

    Specimens suitable for investigating the reliability of production nondestructive evaluation (NDE) to detect tightly closed fatigue cracks in high strength alloys representative of those materials used in spacecraft engine/booster construction were produced. Inconel 718 was selected as representative of nickel base alloys and Haynes 188 was selected as representative of cobalt base alloys used in this application. Cleaning procedures were developed to insure the reusability of the test specimens and a flaw detection reliability assessment of the fluorescent penetrant inspection method was performed using the test specimens produced to characterize their use for future reliability assessments and to provide additional NDE flaw detection reliability data for high strength alloys. The statistical analysis of the fluorescent penetrant inspection data was performed to determine the detection reliabilities for each inspection at a 90% probability/95% confidence level.

  11. Effect of irradiation damage and helium on the swelling and structure of vanadium-base alloys

    SciTech Connect

    Chung, H.M.; Loomis, B.A.; Smith, D.L.

    1993-12-01

    Swelling behavior and microstructural evolution of V-Ti, V-Cr-Ti, and V-Ti-Si alloys were investigated after irradiation at 420--600C up to 114 dpa. The alloys exhibited swelling maxima between 30 and 80 dpa and swelling decreased on irradiation to higher dpa. This is in contrast to the monotonically increasing swelling of binary alloys that contain Fe, Ni, Cr, Mo, W, and Si. Precipitation of dense Ti{sub 5}Si{sub 3} promotes good resistance to swelling of the Ti-containing alloys and it was concluded that Ti of >3 wt.% and 400--1000 wppm Si are necessary to effectively suppress swelling. Swelling was minimal in V-4Cr-4Ti, identified as the most promising alloy based on good mechanical properties and superior resistance to irradiation embrittlement. V-20Ti doped with B exhibited somewhat higher swelling because of He generation. Lithium atoms, generated from transmutation of {sup 10}B, formed {gamma}-LiV{sub 2}O{sub 5} precipitates and did not seem to produce undesirable effects on mechanical properties.

  12. The effect of Mg on the structure and properties of Type 319 aluminum casting alloys

    Microsoft Academic Search

    J. Y. Hwang; R. Banerjee; H. W. Doty; M. J. Kaufman

    2009-01-01

    The precipitation hardening behavior of a Type 319 aluminum alloy (Al–6.7wt.% Si–3.75wt.% Cu) with and without 0.45wt.% Mg has been investigated. It is shown that both ? and Q phase exist in the as-cast samples and are dissolved during solution heat treatment. Subsequent artificial aging results in the precipitation of both the metastable ?? phase typical of aged alloy 319

  13. Journal of Statistical Physics, Vol. 38, Nos. 1/2, 1985 Phase Diagram of Cu-Au-Type Alloys ~

    E-print Network

    Lebowitz, Joel

    phase diagram of an binary alloy on a face centered cubic lattice. In Ising spin language the nearest. This paper investigates some aspects of the phase diagram of a binary alloy on a face centered cubic (fccJournal of Statistical Physics, Vol. 38, Nos. 1/2, 1985 Phase Diagram of Cu-Au-Type Alloys ~ Joel L

  14. Distributed type of actuators by shape memory alloy and its application to underwater mobile robotic mechanism

    Microsoft Academic Search

    Toshio Fukuda; Hidemi Hosokai; Isamu Kikuchi

    1990-01-01

    The basic idea of a new type of actuator based on a shape memory alloy (SMA) and its application to underwater mobile robots are presented. The actuator consists of a multimode SMA, so that any shape can be produced as the synthesized sum of excited modes. Thus, the actuator shows the characteristics of distributed-parameter-type actuators with a specified number of

  15. Evaluation of the retentive force of a b-type Ti-6Mo-4Sn alloy wire clasp.

    PubMed

    Yoda, Nobuhiro; Yokoyama, Masayoshi; Adachi, Genki; Takahashi, Masatoshi; Sasaki, Keiichi

    2010-01-01

    The retentive force of a wire clasp composed of a b-type Ti-6Mo-4Sn alloy (b-Ti alloy) with a low Young modulus was evaluated using a piezoelectric transducer to determine the appropriate undercut for removable partial dentures. There were no significant differences in retentive force between a b-Ti alloy wire with a 0.50-mm undercut and a cobalt-chromium alloy (Co-Cr alloy) wire with a 0.25-mm undercut, or between a b-Ti alloy wire with a 0.75-mm undercut and a Co-Cr alloy wire with a 0.50-mm undercut. The b-Ti alloy wire may be applicable for abutment teeth with a large number of undercuts. Int J Prosthodont 2010;23:38-41. PMID:20234890

  16. Strain glass transition in a multifunctional ?-type Ti alloy

    PubMed Central

    Wang, Yu; Gao, Jinghui; Wu, Haijun; Yang, Sen; Ding, Xiangdong; Wang, Dong; Ren, Xiaobing; Wang, Yunzhi; Song, Xiaoping; Gao, Jianrong

    2014-01-01

    Recently, a class of multifunctional Ti alloys called GUM metals attracts tremendous attentions for their superior mechanical behaviors (high strength, high ductility and superelasticity) and novel physical properties (Invar effect, Elinvar effect and low modulus). The Invar and Elinvar effects are known to originate from structural or magnetic transitions, but none of these transitions were found in the GUM metals. This challenges our fundamental understanding of their physical properties. In this study, we show that the typical GUM metal Ti-23Nb-0.7Ta-2Zr-1.2O (at%) alloy undergoes a strain glass transition, where martensitic nano-domains are frozen gradually over a broad temperature range by random point defects. These nano-domains develop strong texture after cold rolling, which causes the lattice elongation in the rolling direction associated with the transition upon cooling and leads to its Invar effect. Moreover, its Elinvar effect and low modulus can also be explained by the nano-domain structure of strain glass. PMID:24500779

  17. Investigation on the primary creep of a nickel based alloy. [Nimonic 75 type alloy

    SciTech Connect

    Kong, Q.P.; Wang, X. (Inst. of Solid State Physics, Hefei (China))

    1993-07-01

    It is widely accepted that dislocation climb is involved in the steady state (i.e. secondary) creep at high temperatures, which is characterized by the formation and evolution of substructures. In current theories of steady state creep, dislocation climb is regarded as the rate controlling process. However, the role of dislocation climb in the primary (i.e. transient) creep at high temperatures is not clear. The present paper is to report the observations by transmission electron microscopy (TEM) on high temperature creep of a nickel based alloy. It will be shown that dislocation climb plays an important role not only in the steady state creep, but also in the primary creep.

  18. Alloy development for first wall materials used in water-cooling type fusion reactors

    NASA Astrophysics Data System (ADS)

    Kiuchi, K.; Ishiyama, T.; Hishinuma, A.

    1991-03-01

    Austenitic stainless steels with high resistance to IASCC were developed for the first wall used in a water cooling type fusion reactor. New alloys with ultra low carbon content were designed to improve all-round properties relevant to the reliability below 450°C, by enhancing the austenite phase stability and purifying the austenite matrix. For this purpose, these were manufactured by means of controlling minor elements, adjusting principal elements and applying SAR thermomechanical treatment. The major characteristics of these alloys were compared with that of Type 316 and JPCA. These alloys showed a good swelling resistance to electron irradiation and high cracking resistance to high heat fluxes of hydrogen beam. The ductility loss and decrease of tensile strength at the objective temperature were also minimized.

  19. Enhanced thermoelectric figure-of-merit in nanostructured p-type silicon germanium bulk alloys.

    PubMed

    Joshi, Giri; Lee, Hohyun; Lan, Yucheng; Wang, Xiaowei; Zhu, Gaohua; Wang, Dezhi; Gould, Ryan W; Cuff, Diana C; Tang, Ming Y; Dresselhaus, Mildred S; Chen, Gang; Ren, Zhifeng

    2008-12-01

    A dimensionless thermoelectric figure-of-merit (ZT) of 0.95 in p-type nanostructured bulk silicon germanium (SiGe) alloys is achieved, which is about 90% higher than what is currently used in space flight missions, and 50% higher than the reported record in p-type SiGe alloys. These nanostructured bulk materials were made by using a direct current-induced hot press of mechanically alloyed nanopowders that were initially synthesized by ball milling of commercial grade Si and Ge chunks with boron powder. The enhancement of ZT is due to a large reduction of thermal conductivity caused by the increased phonon scattering at the grain boundaries of the nanostructures combined with an increased power factor at high temperatures. PMID:19367858

  20. Three defect types in friction stir welding of aluminum die casting alloy

    Microsoft Academic Search

    Y. G. Kim; H. Fujii; T. Tsumura; T. Komazaki; K. Nakata

    2006-01-01

    For different tool plunge downforces, the optimum FSW conditions of aluminum die casting alloy were examined. The higher the tool plunge downforce is, the wider the range of the optimum FSW conditions is. The following three different types of defects are formed, depending on the FSW conditions. (1) A large mass of flash due to the excess heat input; (2)

  1. New type of decagonal quasicrystal with superlattice order in AlNiCo alloy

    Microsoft Academic Search

    K. Edagawa; M. Ichihara; K. Suzuki; S. Takeuchi

    1992-01-01

    A new type of decagonal phase having superlattice order has been found in an AI70Ni15Co15 alloy by means of the electron diffraction technique. Most of the grains in the Al70Ni15Co15 sample heat treated at 600°C for 216h exhibit superlattice order. In contrast, superlattice order has not been seen for the Al65Cu20Co15 decagonal phase. The relation between the structures with and

  2. Phase stability of B1-type carbides in nickel-based alloys

    Microsoft Academic Search

    Yoshinori Murata; Ryuzi Ninomiya; Natsuo Yukawa

    1988-01-01

    In nickel-based superalloys, the B1-type monocarbides contain several kinds of transition elements. At elevated temperatures, the monocarbides transform to other carbides, such as M23C6 and M6C as a result of the reaction with the alloy. The phase stability of monocarbides was investigated by X-ray diffraction techniques. The degree of stability is strongly affected by the composition of the monocarbides and

  3. Surface treatment for inhibition of corrosion and hydrogen penetration of type 718 alloy

    SciTech Connect

    Popov, B.N.; Zheng, G.; White, R.E. (Univ. of South Carolina, Columbia, SC (United States). Dept. of Chemical Engineering)

    1994-08-01

    Polarization and permeation experiments showed that a monolayer coverage of lead (Pb) effectively inhibited the hydrogen (H) evolution reaction and H penetration through type 718 (UNS N07718) alloy. Observed inhibition effects were a result of the kinetic limitations of the H discharge reaction and suppression of H absorption on the deposited monolayer. H evolution reaction and H permeation rates were reduced by [approximately]67% and 70%, respectively.

  4. Mechanical properties of L1{sub 2} type Zn{sub 3}Ti-based alloy

    SciTech Connect

    Hosoda, Hideki; Hanada, Shuji

    1999-07-01

    An alloy composed of L1{sub 2}-type Zn{sub 3}Ti was investigated in terms of phase stability and mechanical properties. Zn and Ti powders were mixed at a composition of Zn-25mol%Ti using a ball mill in Ar, and an ingot was made by melting the powders. Optical microscopy, X-ray diffraction analysis and thermogravimetry--differential thermal analysis were carried out. Mechanical properties were investigated by Vickers hardness tests at room temperature (RT) and compression tests from RT to 703K in Ar. It is found that (1) the alloy is mainly composed of L1{sub 2}Zn{sub 3}Ti, (2) the alloy has weak positive temperature dependence of strength, and (3) normalized strength by melting point is comparable to that of L1{sub 2}Al{sub 3}Ti-Cr alloys. L1{sub 2}Zn{sub 3}Ti has HV178 and is brittle at RT. Reaction temperatures of Zn-rich portion of the Zn-Ti phase diagram were also reinvestigated and a peritectic-reaction temperature between Zn{sub 3}Ti and liquid + Zn{sub 2}Ti is determined to be at 880K.

  5. Elastic softening of ?-type Ti-Nb alloys by indium (In) additions.

    PubMed

    Calin, Mariana; Helth, Arne; Gutierrez Moreno, Julio J; Bönisch, Matthias; Brackmann, Varvara; Giebeler, Lars; Gemming, Thomas; Lekka, Christina E; Gebert, Annett; Schnettler, Reinhard; Eckert, Jürgen

    2014-11-01

    Recent developments showed that ?-type Ti-Nb alloys are good candidates for hard tissue replacement and repair. However, their elastic moduli are still to be further reduced to match Young?s modulus values of human bone, in order to avoid stress shielding. In the present study, the effect of indium (In) additions on the structural characteristics and elastic modulus of Ti-40 Nb was investigated by experimental and theoretical (ab initio) methods. Several ?-type (Ti-40 Nb)-xIn alloys (with x ? 5.2 wt%) were produced by cold-crucible casting and subsequent heat treatments (solid solutioning in the ?-field followed by water quenching). All studied alloys completely retain the ?-phase in the quenched condition. Room temperature mechanical tests revealed ultimate compressive strengths exceeding 770 MPa, large plastic strains (>20%) and a remarkable strain hardening. The addition of up to 5.2 wt% indium leads to a noticeable decrease of the elastic modulus from 69 GPa to 49 GPa, which is closer to that of cortical bone (<30 GPa). Young's modulus is closely related to the bcc lattice stability and bonding characteristics. The presence of In atoms softens the parent bcc crystal lattice, as reflected by a lower elastic modulus and reduced yield strength. Ab initio and XRD data agree that upon In substitution the bcc unit cell volume increases almost linearly. The bonding characteristics of In were studied in detail, focusing on the energies that appeared from the EDOSs significant for possible hybridizations. It came out that minor In additions introduce low energy states with s character that present antibonding features with the Ti first neighboring atoms as well as with the Ti-Nb second neighboring atoms thus weakening the chemical bonds and leading to elastic softening. These results could be of use in the design of low rigidity ?-type Ti-alloys with non-toxic additions, suitable for orthopedic applications. PMID:25128870

  6. Electroplating of thin films of bismuth onto type 4340 steel and alloy 718 to prevent hydrogen embrittlement

    SciTech Connect

    Popov, B.N.; Zheng, G.; White, R.E. [Univ. of South Carolina, Columbia, SC (United States). Dept. of Chemical Engineering

    1995-06-01

    Polarization and permeation experiments showed that a thin layer of electroplated bismuth (1 {mu}m to 2 {mu}m) inhibited the evolution and penetration of hydrogen through nickel-chromium alloy 718 (UNS N07718) and type 4340 (UNS G43400) steel. Inhibition effects were due to the kinetic limitations of the hydrogen discharge reaction and to the suppression of hydrogen adsorption on the deposited layers. The hydrogen evolution reactions on alloy 718 and type 4340 steel were inhibited by 28% and 85%, respectively. The hydrogen permeation rates through these alloys were reduced by 76% and 65%, respectively.

  7. Osteoblast cell behavior on the new beta-type Ti-25Ta-25Nb alloy.

    PubMed

    Cimpean, Anisoara; Mitran, Valentina; Ciofrangeanu, Cristina M; Galateanu, Bianca; Bertrand, Emmanuel; Gordin, Doina-Margareta; Iordachescu, Dana; Gloriant, Thierry

    2012-08-01

    Among metallic materials used as bone substitutes, ? titanium alloys gain an increasing importance because of their low modulus, high corrosion resistance and good biocompatibility. In this work, an investigation of the in vitro cytocompatibility of a recently new developed ?-type Ti-25Ta-25Nb alloy was carried out by evaluating the behavior of human osteoblasts. The metallic Ti-6Al-4V biomaterial, which is one of representative ?+? type titanium alloys for biomedical applications, and Tissue Culture Polystyrene (TCPS), were also investigated as reference Ti-based material and control substrate, respectively. Both metallic surfaces were analyzed by X-ray diffraction, atomic force microscopy and X-ray photoelectron spectroscopy. The cellular response was quantified by assessments of viability, cell attachment and spreading, cell morphology, production and extracellular organization of fibronectin and cell proliferation. Polished surfaces from both materials having an equiaxed grain microstructure and nanometre scale surface roughness elicited an essentially identical osteoblast response in terms of all analyzed cellular parameters. Thus, on both surfaces the cells displayed high survival rates, good cell adhesion and spreading, a dense and randomly dispersed fibronectin matrix and increasing cell proliferation rates over the incubation time. Furhermore, the enhanced biological performance of Ti-25Ta-25Nb was highly supported by the results obtained in comparison with TCPS. These findings, together with previously shown superelastic behavior, low Young's modulus and high corrosion resistance, recommend Ti-25Ta-25Nb as good candidate for applications in bone implantology. PMID:24364960

  8. On the Understanding of Aluminum Grain Refinement by Al-Ti-B Type Master Alloys

    NASA Astrophysics Data System (ADS)

    Wang, Xiaoming; Liu, Zhiwei; Dai, Wei; Han, Qingyou

    2014-11-01

    Al-Ti-B type master alloys have been widely used in the grain refinement of aluminum since 1940s. The introduction of Al3Ti and TiB2(AlB2) particles reduces the grain sizes down to about 200 micrometer level and makes aluminum alloys castable. However, the mechanism for the grain refinement is still not clear, though it is believed that TiB2 particles in the presence of Al3Ti nucleate ?-Al grains during solidification. This paper presents our finding on the formation of (Ti,Al)B2 solid solution, which leads to a proposed theory on grain refinement by Al-Ti-B type master alloys that upon addition into aluminum melt stable TiB2 particles react with aluminum slowly and release titanium into the melt. The titanium thus released in combination with titanium in the melt through dissolution of Al3Ti particles maintains a dynamic titanium-rich layer on the surface of (Ti,Al)B2. This layer offers a low crystal mismatch with ?-Al and promotes the nucleation of aluminum grains.

  9. Thermoelectric properties of the Heusler-type Fe2VTaxAl1-x alloys

    NASA Astrophysics Data System (ADS)

    Renard, Krystel; Mori, Arinori; Yamada, Yuichiro; Tanaka, Suguru; Miyazaki, Hidetoshi; Nishino, Yoichi

    2014-01-01

    This study focuses on the thermoelectric properties of the Heusler-type Fe2VTaxAl1-x alloys (0?x?0.12). By means of Rietveld analyses on synchrotron X-ray diffraction patterns, it is shown that the Ta atoms enter sites occupied by V atoms in the stoichiometric Fe2VAl alloy, while the ejected V atoms are transferred to the vacant Al sites. This Ta substitution leads to an improvement of the n-type thermoelectric properties owing to two mechanisms. On the one hand, the atoms position in the structure leads to an off-stoichiometric effect such as already observed in V-rich Fe2V1+yAl1-y compounds: the Seebeck coefficient is increased towards negative absolute values and the electrical resistivity is decreased, with a large shift of their peak temperature towards higher temperature. The maximum power factor is 6.5 × 10-3 W/mK2 for x = 0.05 at 340 K. On the other hand, the heavy element Ta substitution combined with this off-stoichiometric effect leads to a large decrease of the thermal conductivity, owing to an increase of the scattering events. Consequently, the dimensionless figure of merit is seen to reach higher values than for the Fe2V1+yAl1-y alloys, i.e., 0.21-0.22 around 400-500 K for x = 0.05 and 500 K for x = 0.08.

  10. Development of casting investment preventing blackening of noble metal alloys Part 2. Application of developed investment for type 4 gold alloy.

    PubMed

    Nakai, Akira; Kakuta, Kiyoshi; Goto, Shin-ichi; Kato, Katuma; Yara, Atushi; Ogura, Hideo

    2003-09-01

    The objective of this study was to evaluate the efficacy of the developed investment for the prevention of blackening of a cast Type 4 gold and to analyze the oxides on its surface in relation to the blackening of the alloy. The experimental investments were prepared using a gypsum-bonded investment in which boron (B) or aluminum (Al) was added as a reducing agent. A Type 4 gold alloy was cast into the mold made of the prepared investment. The effect of the additives was evaluated from the color difference (deltaE*) between the as-cast surface and the polished surface of the cast specimen. B and Al were effective to prevent the blackening of a Type 4 gold alloy and the color of the as-cast surface approached that of the polished surface with increasing B and Al content. The prevention of the blackening of the gold alloy can be achieved by restraining the formation of CuO. PMID:14620998

  11. Predominant factor determining wear properties of ?-type and (?+?)-type titanium alloys in metal-to-metal contact for biomedical applications.

    PubMed

    Lee, Yoon-Seok; Niinomi, Mitsuo; Nakai, Masaaki; Narita, Kengo; Cho, Ken

    2015-01-01

    The predominant factor determining the wear properties of a new titanium alloy, Ti-29Nb-13Ta-4.6Zr (TNTZ) and a conventional titanium alloy, Ti-6Al-4V extra-low interstitial (Ti64) was investigated for TNTZ and Ti64 combinations in metal-to-metal contacting bio-implant applications. The worn surfaces, wear debris, and subsurface damages were analyzed using a scanning electron microscopy combined with energy-dispersive spectroscopy and electron-back scattered diffraction analysis. The volume loss of TNTZ is found to be larger than that of Ti64, regardless of the mating material. The wear track of TNTZ exhibits the galled regions and severe plastic deformation with large flake-like debris, indicative of delamination wear, which strongly suggests the occurrence of adhesive wear. Whereas, the wear track of Ti64 have a large number of regular grooves and microcuttings with cutting chip-like wear debris and microfragmentation of fine oxide debris, indicative of abrasive wear combined with oxidative wear. This difference in the wear type is caused by severe and mild subsurface deformations of TNTZ and Ti64, respectively. The lower resistance to plastic shearing for TNTZ compared to that of Ti64 induces delamination, resulting in a higher wear rate. PMID:25460417

  12. Thermoelectric properties of Heusler-type off-stoichiometric Fe2V1+xAl1-x alloys

    NASA Astrophysics Data System (ADS)

    Miyazaki, Hidetoshi; Tanaka, Suguru; Ide, Naoki; Soda, Kazuo; Nishino, Yoichi

    2014-03-01

    We report the thermoelectric properties of Heusler-type off-stoichiometric Fe2V1+xAl1-x alloys. Due to the off-stoichiometric effect, which is the substitution of V/Al atoms with Al/V atoms, semiconductor-like electric resistivity behavior in Fe2VAl is changed to metallic behavior in Fe2V1+xAl1-x alloys and both positive and negative absolute Seebeck coefficients are drastically increased. The maximum thermoelectric power factor of Fe2V1+xAl1-x alloys is 4.3 × 10-3 (x = -0.03: p-type) and 6.8 × 10-3 W mK-2 (x = 0.05: n-type) with a peak temperature in the range 300-600 K, exceeding the values of previously reported Fe-based Heusler alloys as well as those of available thermoelectric materials such as Bi-Te semiconductors. Based on x-ray diffraction and photoemission spectroscopy results, it is thought that the maintenance of the Heusler-type (L21) crystal structure and the modification of the electronic structure due to the off-stoichiometry could explain the large thermoelectric power factor and high peak temperature in Fe2V1+xAl1-x alloys.

  13. Effects of the types of overlap on the mechanical properties of FSSW welded AZ series magnesium alloy joints

    NASA Astrophysics Data System (ADS)

    Wang, Dan; Shen, Jun; Wang, Lin-Zhi

    2012-03-01

    The effects of the types of overlap on the mechanical properties of the friction stir spot welding (FSSW) welded AZ series magnesium alloy joints were investigated by microstructural observations, microhardness tests, and tensile tests. The results show that the microstructure of the stir zone adjacent to the periphery of the rotating pin is mainly composed of the upper sheet. The average distance D between the longitudinal segment of the curved interface and the keyhole periphery, the tensile shear force, and the microhardness of the stir zone of the FSSW welded AZ61 alloy joint are the highest in all samples. During FSSW of AZ31 and AZ61 dissimilar magnesium alloys, the irregular deformation of the longitudinal segment of the curved interface appears, while the microhardness of the stir zone is higher when AZ61 alloy is the upper sheet. Moreover, the microhardness of the stir zone increases initially and then decreases sharply in the longitudinal test position.

  14. Microstructure and mechanical properties of thermoelectric nanostructured n-type silicon-germanium alloys synthesized employing spark plasma sintering

    SciTech Connect

    Bathula, Sivaiah [CSIR-Network of Institutes for Solar Energy, CSIR-National Physical Laboratory, Dr. K. S. Krishnan Marg, New Delhi 110012 (India); Department of Applied Physics, Delhi Technological University, Delhi (India); Gahtori, Bhasker; Tripathy, S. K.; Tyagi, Kriti; Srivastava, A. K.; Dhar, Ajay, E-mail: adhar@nplindia.org [CSIR-Network of Institutes for Solar Energy, CSIR-National Physical Laboratory, Dr. K. S. Krishnan Marg, New Delhi 110012 (India); Jayasimhadri, M. [Department of Applied Physics, Delhi Technological University, Delhi (India)

    2014-08-11

    Owing to their high thermoelectric (TE) figure-of-merit, nanostructured Si{sub 80}Ge{sub 20} alloys are evolving as a potential replacement for their bulk counterparts in designing efficient radio-isotope TE generators. However, as the mechanical properties of these alloys are equally important in order to avoid in-service catastrophic failure of their TE modules, we report the strength, hardness, fracture toughness, and thermal shock resistance of nanostructured n-type Si{sub 80}Ge{sub 20} alloys synthesized employing spark plasma sintering of mechanically alloyed nanopowders of its constituent elements. These mechanical properties show a significant enhancement, which has been correlated with the microstructural features at nano-scale, delineated by transmission electron microscopy.

  15. Effects of temperature and environment on fatigue crack growth in ordered (Fe, Ni)3 V-type alloys

    NASA Astrophysics Data System (ADS)

    Kuruvilla, A. K.; Stoloff, N. S.

    1985-05-01

    The effects of long range order, test temperature, and test environment on fatigue crack growth of two (Fe, Ni)3 V-type ordered alloys have been determined. Long range order suppressed crack growth at low and intermediate ?K, but had less effect at high ?K. Crack growth resistance of the ordered alloys decreased at 600 ‡C, but still compared favorably to that of several commercial high temperature alloys. Crack growth resistance of ordered material was decreased in the presence of hydrogen (precharged or gaseous), accompanied by a change in fracture path from transgranular to intergranular. Disordered material was nearly unaffected by hydrogen. The effects of long range order and hydrogen exposure on crack growth rates are discussed in terms of the characteristic superlattice dislocations in ordered alloys.

  16. A new type of Cu-Al-Ta shape memory alloy with high martensitic transformation temperature

    NASA Astrophysics Data System (ADS)

    Wang, C. P.; Su, Y.; Y Yang, S.; Shi, Z.; Liu, X. J.

    2014-02-01

    In this study, a new type of Cu-Al-Ta (Cu86Al12Ta2 wt%) shape memory alloy with high martensitic transformation temperature is explored. The microstructure, reversible martensitic transformation and shape memory properties are investigated by means of optical microscopy, back-scattered electron, electron probe microanalysis, x-ray diffraction, differential scanning calorimetry and tensile tests. It is proposed that Cu86Al12Ta2 alloy consists of a mixture of primarily {\\beta }_{1}^{\\prime} martensite and a little {\\gamma }_{1}^{\\prime} martensite and some different precipitates. The tiny thin-striped Ta2(Al,Cu)3 precipitate is predominant in the as-quenched condition, whereas the particle-shaped Cu(Al, Ta) precipitate is dominant after hot-rolling. Additionally, the dendritic-shaped ?1(Cu9Al4) phase begins to appear after hot-rolling, but it disappears when the sample is re-quenched. All studied samples have reversible martensitic transformation temperatures higher than 450?° C. The results show that two-step martensitic transformation behavior is observed for Cu86Al12Ta2 alloy in all three different conditions due to the transformations between ({\\beta }_{1}^{\\prime}+{\\gamma }_{1}^{\\prime}) martensites and the austenite parent phase. The results further show that the recovery ratios are almost 100% when the pre-strains are ?2.5%, then they gradually decrease with further increase of the pre-strains. The shape memory effects clearly increase as a result of increase of the pre-strains, up to a maximum value of 3.2%.

  17. Origin of thickness dependent spin reorientation transition of B2 type FeCo alloy films

    SciTech Connect

    Kim, Dongyoo [Applied Materials Physics, Department of Materials Science and Engineering, Royal Institute of Technology, SE-10044 Stockholm (Sweden); Hong, Jisang [Department of Physics, Pukyong National University, Busan 608-737 (Korea, Republic of)

    2013-12-07

    We have investigated the origin of thickness dependent spin reorientation transition (SRT) of B2 type FeCo alloy using the full potential linearized augmented plane wave method. It has been reported that FeCo alloy films on various substrates show a SRT from perpendicular to in-plane magnetization at an approximate thickness of 15 monolayers (MLs). The enhanced perpendicular magnetic anisotropy in bulk FeCo is attributed to a tetragonal distortion. However, we have found that the tetragonal distortion tends to suppress the magnetocrystalline anisotropy (MCA) energy at increasing film thickness in two-dimensional structure. In contrast, the magnitude of the shape anisotropy energy increases at increasing FeCo film thickness. Interestingly, the shape anisotropy overcomes the MCA and the SRT, from perpendicular anisotropy to in-plane magnetization, which occurs at a thickness of 15 ML. Consequently, we are able to clearly understand the physical mechanism of the thickness dependent SRT in terms of the competing reactions of these two counteracting contributions.

  18. Thermal Expansion of NANOPERM-type Alloys from In-situ X-ray Diffraction

    SciTech Connect

    Bednarcik, J.; Franz, H. [Deutsches Elektronen Synchrotron, Notkestr. 85, D-22603, Hamburg (Germany); Miglierini, M. [Slovak University of Technology, Ilkovicova 3, 81219 Bratislava (Slovakia); Centre for Nanomaterial Reserach, Palacky University, Svobody 26, 771 46 Olomouc (Czech Republic); Curfs, C. [European Synchrotron Radiation Facility ESRF, BP 220, 38043 Grenoble (France)

    2010-07-13

    NANOPERM-type alloys with nominal compositions of (Fe{sub 1-x}Co{sub x}){sub 76}Mo{sub 8}Cu{sub 1}B{sub 15}(x = 0 and 0.5) were prepared by a single-roller melt-spinning technique. Temperature evolution of the as-quenched ribbons during constant-rate heating (10 degree sign C/min) was continuously followed using a high-energy (88 keV) X-ray diffraction (XRD), performed on the ID11 undulator beamline at the ESRF (Grenoble, France). Moessbauer spectroscopy and XRD confirm an amorphous nature of the melt-spun ribbons. Furthermore, Moessbauer spectroscopy reveals a significant change of magnetic state of the as-quenched precursors when substituting Fe by Co (x 0.5). Analyzing a series of XRD patterns in a reciprocal space yields a thermal expansion of the amorphous alloys providing an insight about the thermally activated effects such as relaxation and crystallization.

  19. Low-temperature electrical transport in Heusler-type Fe2V (AlSi) alloys

    NASA Astrophysics Data System (ADS)

    Vasundhara, M.; Srinivas, V.; Rao, V. V.

    2005-09-01

    The temperature variation of the electrical resistivity ? and the Seebeck coefficient S of Heusler-type Fe2VAl1-xSix (0<=x<=1) alloys has been investigated. We have shown that the transport parameters are very sensitive to doping. For the x = 0 sample, high values of ? and negative temperature coefficient of resistivity (TCR) have been observed. As the Si concentration increases, ? decreases and the TCR changes its sign, while S shows significant changes in magnitude as well as sign when Al is replaced with Si. These changes appear to be reminiscent of a metal to semiconductor transition. It has been shown that the conventional transport theories proposed for intermetallic alloys or semiconductors cannot explain the transport behaviour in the whole temperature range of the present study. Low-temperature resistivity data of x = 0-0.02 samples could be described with a gapless semiconductor model. The strong composition dependence of S and ? is attributed to the sharp variations in electronic density of states at the Fermi energy. It is also shown that by optimum doping one can achieve very large values of power factor (P). The estimated power factor at room temperature is observed to be highest (2.23 × 10-3 W mK-2) for x = 0.06 and comparable to that of conventional thermoelectric material. At lower temperatures P is found to be even higher than that of conventional thermoelectric material.

  20. Corrosion of high Ni-Cr alloys and Type 304L stainless steel in HNO/sub 3/-HF

    SciTech Connect

    Ondrejcin, R.S.; McLaughlin, B.D.

    1980-04-01

    Nineteen alloys were evaluated as possible materials of construction for steam heating coils, the dissolver vessel, and the off-gas system of proposed facilities to process thorium and uranium fuels. Commercially available alloys were found that are satisfactory for all applications. With thorium fuel, which requires HNO/sub 3/-HF for dissolution, the best alloy for service at 130/sup 0/C when complexing agents for fluoride are used is Inconel 690; with no complexing agents at 130/sup 0/C, Inconel 671 is best. At 95/sup 0/C, six other alloys tested would be adequate: Haynes 25, Ferralium, Inconel 625, Type 304L stainless steel, Incoloy 825, and Haynes 20 (in order of decreasing preference); based on composition, six untested alloys would also be adequate. The ions most effective in reducing fluoride corrosion were the complexing agents Zr/sup 4 +/ and Th/sup 4 +/; Al/sup 3 +/ was less effective. With uranium fuel, modestly priced Type 304L stainless steel is adequate. Corrosion will be most severe in HNO/sub 3/-HF used occasionally for flushing and in solutions of HNO/sub 3/ and corrosion products (ferric and dichromate ions). HF corrosion can be minimized by complexing the fluoride ion and by passivation of the steel with strong nitric acid. Corrosion caused by corrosion products can be minimized by operating at lower temperatures.

  1. Environmental Factors in the Stress Corrosion Cracking of Type 316L Stainless Steel and Alloy 825 in Chloride Solutions

    Microsoft Academic Search

    G. Cragnolino; N. Sridhar; D. S. Dunn

    1996-01-01

    This paper describes the experimental studies conducted to date to investigate the stress corrosion cracking (SCC) of candidate container materials for the proposed high-level nuclear waste repository at Yucca Mountain, Nevada. The effects of environmental variables, such as chloride concentration, the addition of thiosulfate, and temperature on the SCC susceptibility of type 316L, stainless steel (SS) and alloy 825 (Ni-29%

  2. Collagen type-I leads to in vivo matrix mineralization and secondary stabilization of Mg-Zr-Ca alloy implants.

    PubMed

    Mushahary, Dolly; Wen, Cuie; Kumar, Jerald Mahesh; Lin, Jixing; Harishankar, Nemani; Hodgson, Peter; Pande, Gopal; Li, Yuncang

    2014-10-01

    Biodegradable magnesium-zirconia-calcium (Mg-Zr-Ca) alloy implants were coated with Collagen type-I (Coll-I) and assessed for their rate and efficacy of bone mineralization and implant stabilization. The phases, microstructure and mechanical properties of these alloys were analyzed using X-ray diffraction (XRD), optical microscopy and compression test, respectively, and the corrosion behavior was established by their hydrogen production rate in simulated body fluid (SBF). Coll-I extracted from rat tail, and characterized using fourier transform infrared (FT-IR) spectroscopy, was used for dip-coating the Mg-based alloys. The coated alloys were implanted into the femur bones of male New Zealand white rabbits. In vivo bone formation around the implants was quantified by measuring the bone mineral content/density (BMC/BMD) using dual-energy X-ray absorptiometry (DXA). Osseointegration of the implant and new bone mineralization was visualized by histological and immunohistochemical analysis. Upon surface coating with Coll-I, these alloys demonstrated high surface energy showing enhanced performance as an implant material that is suitable for rapid and efficient new bone tissue induction with optimal mineral content and cellular properties. The results demonstrate that Coll-I coated Mg-Zr-Ca alloys have a tendency to form superior trabecular bone structure with better osteoinduction around the implants and higher implant secondary stabilization, through the phenomenon of contact osteogenesis, compared to the control and uncoated ones in shorter periods of implantation. Hence, Coll-I surface coating of Mg-Zr-Ca alloys is a promising method for expediting new bone formation in vivo and enhancing osseointegration in load bearing implant applications. PMID:25179112

  3. Short-range order types in binary alloys: A reflection of coherent phase stability

    SciTech Connect

    W. Wolverton; V. Ozolins; Alex Zunger

    1999-11-23

    The short-range order (SRO) present in disordered solid solutions is classified according to three characteristic system-dependent energies: (1) formation enthalpies of ordered compounds, (2) enthalpies of mixing of disordered alloys, and (3) the energy of coherent phase separation, (the composition-weighted energy of the constituents each constrained to maintain a common lattice constant along an A/B interface). These energies are all compared against a common reference, the energy of incoherent phase separation (the composition-weighted energy of the constituents each at their own equilibrium volumes). Unlike long-range order (LRO), short-range order is determined by energetic competition between phases at a fixed composition, and hence only coherent phase-separated states are of relevance for SRO. The authors find five distinct SRO types, and show examples of each of these five types, including Cu-Au, Al-Mg, GaP-InP, Ni-Au, and Cu-Ag. The SRO is calculated from first-principles using the mixed-space cluster expansion approach combined with Monte Carlo simulations. Additionally, they examine the effect of inclusion of coherency strain in the calculation of SRO, and specifically examine the appropriate functional form for accurate SRO calculations.

  4. Dot arrays of L11 type Co-Pt ordered alloy perpendicular films

    NASA Astrophysics Data System (ADS)

    Shimatsu, T.; Sato, H.; Mitsuzuka, K.; Kataoka, H.; Aoi, H.; Okamoto, S.; Kitakami, O.

    2009-04-01

    Magnetic properties of dot arrays of L11 type Co-Pt ordered alloy perpendicular films were studied. L11-Co-Pt films with a large uniaxial magnetic anisotropy Ku of the order of 107 erg/cm3 were fabricated at a substrate temperature of 360 °C using ultrahigh vacuum sputter film deposition. Dot patterns with dot diameters of 70-200 nm were made using high resolution e-beam lithography and reactive ion etching (RIE). The values of Ku were measured by the GST method using the Anomalous Hall Effect; we observed the averaged signals of 6000 dots. The values of Ku for dot arrays of 10-nm-thick L11-Co50Pt50 films deposited on MgO(111) substrates (single crystal films) and glass disks (polycrystalline films) were nearly the same as those of the original films independent of D, indicating no significant etching damage by the RIE process. Magnetic force microscopy images revealed that all dots were single domains in the present D region. The coercivity Hc of the dot arrays was 25.0 kOe [MgO(111) substrate, D =70 nm] and 14.3 kOe (glass disks, D =80 nm). The switching field distribution ? /Hc was relatively small, ? /Hc=0.15, even for dot arrays fabricated on glass disks, indicating the homogeneous formation of a L11 type ordered structure in the Co50Pt50 layers.

  5. Effects of temperature on crack growth rate in sensitized type 304 stainless steel and alloy 600

    SciTech Connect

    Andresen, P.L. (GE Corporate Research and Development Center, Schenectady, NY (United States))

    1993-09-01

    Effects of temperature on stress corrosion crack growth rates were studied on three heats of sensitized type 304 (UNS S30400) stainless steel (SS) and one heat of sensitized alloy 600 (UNS N06600). Data were obtained using reversed direct current (DC) potential drop crack length monitoring on 25-mm compact-type (CT) specimens in 25 C. to 288 C. water, usually containing 200 ppb oxygen (O[sub 2]). Most data were obtained in 0.3 [mu]M sulfuric acid. In one heat, 0.1[mu]M hydrochloric acid, 0.5 [mu]M HCI, and air-saturated water also were evaluated. All heats and materials had similar temperature dependence and showed a peak in crack growth rate at [approximately] 200 C. in these water chemistries, which typically was a factor of 30 to 100 times higher than at 288 C. or 25 C. Growth rates decreased rapidly above 250 C. compared to those between 25 C. and 200 C. In many cases, similar rates were observed at 25 C. and 288 C. Data were compared with the literature on fracture mechanics and slow strain rate specimens. Issues in determining the value and origin of apparent activation energies also were discussed.

  6. Electronic transport in Heusler-type Fe2VAl1-xMx alloys (M=B,In,Si)

    NASA Astrophysics Data System (ADS)

    Vasundhara, M.; Srinivas, V.; Rao, V. V.

    2008-06-01

    The temperature variation of electrical resistivity ?(T) and Seebeck coefficient S(T) of Heusler-type Fe2VAl1-xBx (0?x?1) alloys have been investigated. All the studied alloys were crystallized into a single-phase cubic structure with Fm3m space group. The ?(T) shows a negative temperature coefficient of resistivity (TCR) for the x=0 sample, which turns into a positive TCR for the x=1 sample; while intermediate compositions show a resistivity minimum at low temperatures (Tmin) below 50 K. From the analysis of temperature dependence of the electrical resistivity data, we demonstrate a semiconductorlike to metal transition on B substitution in the Fe2VAl alloy. With a minute substitution of isoelements (B and In) and nonisoelement (Si), S changes drastically in its sign and magnitude accompanied by an appearance of a broad maximum at higher temperatures, which shifts toward high temperatures with increasing concentration of the substituents. These features are indicative of a dramatic modification in the band structures of the Fe2VAl alloy with the substitution of elements. Although similar changes in ? and S values with compositions of B-, In-, and Si-substituted Fe2VAl alloys are observed, the ? decreases rapidly on B substitution and ultimately attains a metallic behavior, suggesting a true semiconductorlike to metal transition. The strong composition dependence of S and ? on elemental substitution is attributed to the size, relative positions of the atomic levels and the number of valence electrons of the substituents.

  7. Precipitation of an intermetallic phase with Pt{sub 2}Mo-type structure in alloy 625

    SciTech Connect

    Sundararaman, M.; Kumar, L.; Prasad, G.E.; Mukhopadhyay, P.; Banerjee, S. [Bhabha Atomic Research Centre, Mumbai (India). Materials Science Div.

    1999-01-01

    The microstructure of Alloy 625, which has undergone prolonged ({approximately}70,000 hours) service at temperatures close to but less than 600 C, has been characterized by transmission electron microscopy. The precipitation of an intermetallic phase Ni{sub 2}(Cr, Mo) with Pt{sub 2}Mo-type structure has been observed in addition to that of the {gamma}{double_prime} phase. Six variants of Ni{sub 2} (Cr, Mo) precipitates have been found to occur in the austenite grains. These particles exhibit a snowflake-like morphology and are uniformly distributed in the matrix. They have been found to dissolve when the alloy is subjected to short heat treatments at 700 C. The occurrence of the Ni{sub 2}(Cr, Mo) phase has been discussed by taking the alloy chemistry into consideration. Apart from the intermetallic phases, the precipitation of a M{sub 6}C-type carbide phase within the matrix and the formation of near continuous films, comprising discrete M{sub 6}C/M{sub 23}C{sub 6} carbide particles, at the austenite grain boundaries have been noticed in the alloy after prolonged service.

  8. Effect of Mg and Sr-modification on the mechanical properties of 319-type aluminum cast alloys subjected to artificial aging

    Microsoft Academic Search

    F. J. Tavitas-Medrano; J. E. Gruzleski; F. H. Samuel; S. Valtierra; H. W. Doty

    2008-01-01

    Aluminum-based 319-type cast alloys are commonly used in the automotive industry to manufacture cylinder heads and engine blocks. These applications require good mechanical properties and in order to achieve them through precipitation hardening, artificial aging treatments are applied to the products. The standard artificial aging treatment for alloy 319, as defined by the T6 heat treatment temper, consists in solution

  9. Magnetic surface anisotropies in NiFe-alloy films: separation of intrinsic Néel-type from strain relaxation contributions

    Microsoft Academic Search

    U. Gradmann; H. J Elmers

    1999-01-01

    Magnetic surface anisotropies (MSA) in NiFe\\/Cu(111) films were investigated experimentally, for varying compositions of the NiFe alloy. By restricting the measurements to the pseudomorphic range, the pure intrinsic Néel-type anisotropy could be isolated without strain relaxation contributions. The intrinsic MSA of the xNi(1?x)Fe\\/Cu(111) interface varies linearly with composition x between easy plane for pure Ni to perpendicular for x=60 and

  10. High Cycle Fatigue of (Fe, Ni, Co)3V type alloys

    NASA Astrophysics Data System (ADS)

    Ashok, S.; Kain, K.; Tartaglia, J. M.; Stoloff, N. S.

    1983-10-01

    High cycle fatigue tests in vacuum have been performed on ordered (Fe, Co, Ni)3V alloys between 25 °C and 850 °C. Heat-to-heat variations in fatigue properties of a Co-16.5 wtpct Fe-25 pct alloy, LRO-1, appeared to be due to differing quantities of grain boundary precipitates. Modification of this alloy with 0.4 pct Ti, to produce an alloy designated LRO-23, reduced the density of grain boundary precipitates and increased ductility, resulting in superior fatigue strength at high temperatures. The fatigue lives of LRO-1 and LRO-23 decreased rapidly above 650 °C, and increased intergranular failure was noted. The fatigue resistance of a cobalt-free alloy, Fe-29 pct Ni-22 pct V-0.4 pct Ti (LRO-37), was examined at 25 °C, 400 °C, and 600 °C; there was little evidence for intergranular fracture at any of these temperatures. Fatigue behavior of the LRO alloys is compared to that of conventional high temperature alloys.

  11. Microstructure and electrochemical properties of Ti-containing AB2 type hydrogen storage electrode alloy

    E-print Network

    Song, Xueyan

    ) analysis. The systematic structural analysis shows that there are two phases in the Ti- substituted alloy; Zr±Ni binaries 1. Introduction The AB2 (A=Zr, Ti; B=V, Cr, Mn) hydrogen sto- rage intermetallic

  12. Wegner estimate and localization for alloy-type models with sign-changing exponentially decaying single-site potentials

    NASA Astrophysics Data System (ADS)

    Leonhardt, Karsten; Peyerimhoff, Norbert; Tautenhahn, Martin; Veseli?, Ivan

    2015-05-01

    We study Schrödinger operators on L2(?d) and ?2(?d) with a random potential of alloy-type. The single-site potential is assumed to be exponentially decaying but not necessarily of fixed sign. In the continuum setting, we require a generalized step-function shape. Wegner estimates are bounds on the average number of eigenvalues in an energy interval of finite box restrictions of these types of operators. In the described situation, a Wegner estimate, which is polynomial in the volume of the box and linear in the size of the energy interval, holds. We apply the established Wegner estimate as an ingredient for a localization proof via multiscale analysis.

  13. Effect of boron additive on the cycle life of low-Co AB 5-type electrode consisting of alloy prepared by cast and rapid quenching

    NASA Astrophysics Data System (ADS)

    Zhang, Yang-huan; Chen, Mei-yan; Wang, Xin-lin; Wang, Guo-qing; Lin, Yu-fang; Qi, Yan

    In order to modify the cycle stability of low-Co AB 5-type alloy, a trace of boron was added in MmNi 3.8Co 0.4Mn 0.6Al 0.2 hydrogen storage alloy. The low-Co AB 5-type alloys MmNi 3.8Co 0.4Mn 0.6Al 0.2B x( x=0, 0.1, 0.2, 0.3, 0.4) were prepared by cast and rapid quenching. The cycle lives and microstructures of the as-cast and quenched alloys were measured and analyzed. The effects of boron additive on the microstructures and cycle lives of as-cast and quenched alloys were investigated comprehensively. The obtained results showed that the addition of boron could dramatically enhance the cycle lives of the as-cast and quenched alloys. When boron content x increases from 0 to 0.4, the cycle lives of the as-cast alloys were increased from 118 to 183 cycles, and for as-quenched alloys with quenching rate of 38 m/s from 310 to 566 cycles.

  14. The role of nanoscale defect features in enhancing the thermoelectric performance of p-type nanostructured SiGe alloys.

    PubMed

    Bathula, Sivaiah; Jayasimhadri, M; Gahtori, Bhasker; Singh, Niraj Kumar; Tyagi, Kriti; Srivastava, A K; Dhar, Ajay

    2015-08-01

    Despite SiGe being one of the most widely studied thermoelectric materials owing to its application in radioisotope thermoelectric generators (RTG), the thermoelectric figure-of merit (ZT) of p-type SiGe is still quite low, resulting in poor device efficiencies. In the present study, we report a substantial enhancement in ZT? 1.2 at 900 °C for p-type nanostructured Si80Ge20 alloys by creating several types of defect features within the Si80Ge20 nanostructured matrix in a spectrum of nano to meso-scale dimensions during its nanostructuring, by employing mechanical alloying followed by spark plasma sintering. This enhancement in ZT, which is ?25% over the existing state-of-the-art value for a p-type nanostructured Si80Ge20 alloy, is primarily due to its ultralow thermal conductivity of ?2.04 W m(-1) K(-1) at 900 °C, resulting from the scattering of low-to-high wavelength heat-carrying phonons by different types of defect features in a range of nano to meso-scale dimensions in the Si80Ge20 nanostructured matrix. These include point defects, dislocations, isolated amorphous regions, nano-scale grain boundaries and more importantly, the nano to meso-scale residual porosity distributed throughout the Si80Ge20 matrix. These nanoscale multi-dimensional defect features have been characterized by employing scanning and transmission electron microscopy and correlated with the electrical and thermal transport properties, based on which the enhancement of ZT has been discussed. PMID:26138852

  15. Microstructural variations induced by gravity level during directional solidification of near-eutectic iron-carbon type alloys

    NASA Astrophysics Data System (ADS)

    Stefanescu, Doru M.; Curreri, Peter A.; Fiske, Michael R.

    1986-07-01

    The effects of gravity on the microstructure of directionally solidified near-eutectic cast irons are studied, using a Bridgman-type automatic directional solidification furnace aboard a NASA KC-135 aircraft which flies parabolic arcs and generates alternating periods of low-g (0.01 to 0.001 g, 30 seconds long) and high-g (1.8 g, 1.5 minutes long). Results show a refinement of the interlamellar spacing of the eutectic during low-g processing of metastable Fe-C eutectic alloys. Low-g processing of stable Fe-C-Si eutectic alloys (lamellar or spheroidal graphite) results in a coarsening of the eutectic grain structure. Secondary dendrite arm spacing of austenite increases in low-g and decreases in high-g. The effectiveness of low-gravity in the removal of buoyancy-driven graphite phase segregation is demonstrated.

  16. Microstructural variations induced by gravity level during directional solidification of near-eutectic iron-carbon type alloys

    NASA Technical Reports Server (NTRS)

    Stefanescu, Doru M.; Fiske, Michael R.; Curreri, Peter A.

    1986-01-01

    The effects of gravity on the microstructure of directionally solidified near-eutectic cast irons are studied, using a Bridgman-type automatic directional solidification furnace aboard a NASA KC-135 aircraft which flies parabolic arcs and generates alternating periods of low-g (0.01 to 0.001 g, 30 seconds long) and high-g (1.8 g, 1.5 minutes long). Results show a refinement of the interlamellar spacing of the eutectic during low-g processing of metastable Fe-C eutectic alloys. Low-g processing of stable Fe-C-Si eutectic alloys (lamellar or spheroidal graphic) results in a coarsening of the eutectic grain structure. Secondary dendrite arm spacing of austenite increases in low-g and decreases in high-g. The effectiveness of low-gravity in the removal of buoyancy-driven graphite phase segregation is demonstrated.

  17. Alloying and coating strategies for improved Pb-Li compatibility in DEMO-type fusion reactors

    NASA Astrophysics Data System (ADS)

    Unocic, K. A.; Pint, B. A.

    2014-12-01

    Two strategies were explored to improve the Pb-16Li compatibility of Fe-base alloys for a fusion energy blanket system. The use of thin (?50 ?m) Al-rich diffusion coatings on Grade 92 (9Cr-2W) substrates significantly reduced the mass loss in static Pb-Li capsule tests for up to 5000 h at 600 °C and 700 °C. However, significant Al loss was observed at 700 °C. Thicker coatings with Fe-Al intermetallic layers partially spalled after exposure at 700 °C, suggesting that coating strategies are limited to lower temperatures. To identify compositions for further alloy development, model FeCrAlY alloys with 10-20 wt.%Cr and 3-5%Al were exposed for 1000 h at 700 °C. There was little effect on mass change of varying the Cr content, however, alloys with <5% Al showed mass losses in these experiments. For both coatings and FeCrAl alloys, the surface reaction product was LiAlO2 after exposure and cleaning.

  18. Characterization of corrosion products of AB{sub 5}-type hydrogen storage alloys for nickel-metal hydride batteries

    SciTech Connect

    Maurel, F.; Knosp, B.; Backhaus-Ricoult, M.

    2000-01-01

    To better understand the decrease in storage capacity of AB{sub 5}-type alloys in rechargeable Ni/MH batteries undergoing repeated charge/discharge cycles, the corrosion of a MnNi{sub 3.55}Co{sub 0.75}Mn{sub 0.4}Al{sub 0.3} alloy in aqueous KOH electrolyte was studied. The crystal structure, chemical composition, and distribution of corrosion products were characterized by X-ray diffraction, scanning electron microscopy, and transmission electron microscopy. Hollow and filed needles of a mixed rare earth hydroxide Mn(OH){sub 3} were found to cover a continuous nanocrystalline corrosion scale composed of metal (Ni, Co) solid solution, oxide (Ni,Co)O solid solution and rare earth hydroxide, and a Mn-depleted alloy subscale. Corrosion kinetics were measured for three different temperatures. Growth kinetics of the continuous corrosion scale and of the Mm(OH){sub 3} needles obeyed linear and parabolic rate laws, respectively. Models for the corrosion mechanism were developed on the basis of diffusional transport of Mn and OH through the hydroxide needles and subsequent diffusion along grain boundaries through the nanocrystalline scale.

  19. Mechanical properties of modified low cobalt powder metallurgy Udimet 700 type alloys

    NASA Technical Reports Server (NTRS)

    Harf, Fredric H.

    1989-01-01

    Eight superalloys derived from Udimet 700 were prepared by powder metallurgy, hot isostatically pressed, heat treated and their tensile and creep rupture properties determined. Several of these alloys displayed properties superior to those of Udimet 700 similarly prepared, in one case exceeding the creep rupture life tenfold. Filter clogging by extracted gamma prime, its measurement and significance are discussed in an appendix.

  20. Influence of product type on stress corrosion cracking of alloy 600

    SciTech Connect

    Gomez-Briceno, D.; Blazquez, F.; Hernandez, F. [Centro de Investigaciones Energeticas Medioambientales y Tecnologicas, Madrid (Spain)

    1999-03-01

    Grain-boundary carbide coverage obtained from metallographic replications has been considered as an estimation of SCC susceptibility of alloy 600 components in pressurized-water reactor (PWR) primary water. Stress corrosion cracking (SCC) initiation tests were carried out on alloy 600 (UNS N06600) in primary water at 325 C and 360 C and in steam with hydrogen at 400 C to gain some insight into the SCC behavior of different alloy 600 products. Forged bars, thick-walled tubes (cold-worked and hot-worked), and steam generator (SG) tubing with different thermomechanical histories were tested. As expected, materials with a high density of intergranular carbide were more resistant to cracking in high-temperature water than materials with few carbides in the grain boundary. However, materials with similar microstructures but different thermomechanical histories presented different SCC susceptibilities. In general, forged bars were more resistant than thick-walled materials with similar grain-boundary carbide coverage. Cold-worked materials (thick-walled tubes and SG tubing) presented similar behaviors. However, appearance of intergranular fractures at high magnification seemed to be related to the SCC behavior of alloy 600 in steam and in primary water. More resistant materials exhibited pseudointergranular fractures.

  1. Heterogeneous nucleation of ?-type precipitates on nanoscale Zr-rich particles in a Mg-6Zn-0.5Cu-0.6Zr alloy

    PubMed Central

    2012-01-01

    Zirconium (Zr) is an important alloying element to Mg-Zn-based alloy system. In this paper, we report the formation of the ?-type precipitates on the nanoscale Zr-rich particles in a Mg-6Zn-0.5Cu-0.6Zr alloy during ageing at 180°C. Scanning transmission electron microscopy examinations revealed that the nanoscale Zr-rich [0001]? rods/laths are dominant in the Zr-rich core regions of the as-quenched sample after a solution treatment at 430°C. More significantly, these Zr-rich particles served as favourable sites for heterogeneous nucleation of the Zn-rich ?-type phase during subsequent isothermal ageing at 180°C. This research provides a potential route to engineer precipitate microstructure for better strengthening effect in the Zr-containing Mg alloys. PMID:22682092

  2. Effect of alloy type and surface conditioning on roughness and bond strength of metal brackets.

    PubMed

    Nergiz, Ibrahim; Schmage, Petra; Herrmann, Wolfram; Ozcan, Mutlu

    2004-01-01

    The effect of 5 different surface conditioning methods on bonding of metal brackets to cast dental alloys was examined. The surface conditioning methods were fine (30-microm) or rough (125-microm) diamond bur, sandblasting (50-microm or 110-microm aluminum oxide [Al2O3]), and silica coating (30-microm silica). Fifty disc-shaped specimens of 5 different alloys (gold-silver, palladium-silver, nickel-chromium, cobalt-chromium, and titanium) were ground with 1200-grit silicone carbide abrasive and polished before being reused for each conditioning method. Polished surfaces were used as negative controls. After measuring surface roughness (RZ), metal brackets were bonded to the conditioned alloys with a self-curing resin composite. Specimens were thermocycled (5000 times, 5 degrees-55 degrees C, 30 seconds), and shear bond tests were performed. Significantly higher (P<.001) surface roughnesses were observed with use of the rough diamond bur (RZ approximately 33 microm), 110-microm Al2O3 (RZ approximately 14 microm), and fine diamond bur (RZ approximately 10 microm), compared with the controls (RZ approximately 1 microm). Silica coating (RZ approximately 4 microm) and 50-microm Al2O3 (RZ approximately 4 microm) demonstrated no significant difference (P>.001) in roughness when compared with the controls. The control group showed no resistance to shear forces (0 MPa). Bond values were greater (19 MPa) when silica coating was used, compared with 50-microm Al2O3 (7 MPa) and 110-microm Al2O3 (8 MPa) for all alloys tested. However, interaction between alloys and conditioning methods exhibited significant differences (P<.0001). PMID:14718878

  3. Applicability of Repassivation Potential for Long-Term Prediction of Localized Corrosion of Alloy 825 and Type 316L Stainless Steel

    Microsoft Academic Search

    N. Sridhar; G. A. Cragnolino

    1993-01-01

    Repassivation potential (E[sub rp]) was investigated for use as a parameter in the long-term prediction of pitting resistance of two Fe-Ni-Cr-Mo alloys that are candidate materials for high-level nuclear waste containers. This potential was found to be independent of the extent of prior pit growth for alloy 825 (UNS N08825) and type 316 L (UNS S31603) stainless steel (SS). Repassivation

  4. Hydrogen embrittlement of ultra-pure alloys of the inconel 600 type: Influence of the additions of elements (C, P, Sn, Sb)

    Microsoft Academic Search

    M. Cornet; C. Bertrand; M. Da Cunha Belo

    1982-01-01

    The mechanical behavior of very high purity nickel base alloys of the Inconel 600 type that were simultaneously charged with\\u000a hydrogen and deformed in tension was investigated. Experimental results show that this procedure decreases markedly the fracture\\u000a strain of the pure 76 pct Ni-16 pct Cr-8 pct Fe alloy; cracks are observed after two to four pct elongation, and the

  5. Status of {ital p}-type SiGe alloys with nanophase inclusions

    SciTech Connect

    Scoville, N.; Bajgar, C.; Rolfe, J. [ThermoTrex Corporation, 74 West Street, Waltham, Massachusetts 02254 (United States); Fleurial, J.; Vandersande, J. [Jet Propulsion Laboratory, 2800 Oak Grove Drive, Pasadena, California 91109 (United States)

    1994-08-10

    Transport models have predicted that the thermal conductivity of SiGe alloys could be appreciably reduced by incorporating discrete 40 A particles within the SiGe grains. These particles would scatter the thermal phonons which transport most of the heat in these alloys. Such a thermal conductivity reduction would lead to substantial improvements in the figure-of-merit and efficiency of thermoelectric materials used in power generation applications. This paper reports on the results of adding 40 A particles to SiGe by using a spark erosion process. Thermal conductivity reductions consistent with the transport models have been achieved, however, the improvement in figure-of-merit has not been as large as predicted. {copyright} {ital 1995} {ital American} {ital Institute} {ital of} {ital Physics}.

  6. Application of p-type microcrystalline silicon to a-Si alloy solar cells

    SciTech Connect

    Sannomiya, H.; Nomoto, K.; Chida, A.; Nakata, Y.; Yamamoto, Y. [Sharp Corp., Nara (Japan). Energy Conversion Labs.

    1994-12-31

    Detailed studies by the RHEED method have clearly indicated that microcrystalline silicon ({micro}c-Si:H) films prepared with a conventional RF p-CVD system can be deposited from the thickness of 10nm even on a-SiC:H, a-SiGe:H alloy films and, furthermore, 25nm-thick films have almost the same crystallinity as the 200 nm-thick {micro}c-Si:H film. Application of this {micro}c-Si:H film to the p-layers of a-SiC:H and a-SiGe:H alloy solar cells have led to increases of 20 {approximately} 40 mV in Voc, compared to typical a-SiC:H p-layer cells. Analysis of the diode saturation currents have shown that these increases of Voc were due to the increases of the built-in potential of the cells.

  7. Direct synthesis of BiCuChO-type oxychalcogenides by mechanical alloying

    SciTech Connect

    Pele, Vincent; Barreteau, Celine [Institut de Chimie Moléculaire et des Matériaux d’Orsay, Univ. Paris-Sud, UMR 8182, Orsay F-91405 (France); CNRS, Orsay F-91405 (France); Berardan, David, E-mail: david.berardan@u-psud.fr [Institut de Chimie Moléculaire et des Matériaux d’Orsay, Univ. Paris-Sud, UMR 8182, Orsay F-91405 (France); CNRS, Orsay F-91405 (France); Zhao, Lidong; Dragoe, Nita [Institut de Chimie Moléculaire et des Matériaux d’Orsay, Univ. Paris-Sud, UMR 8182, Orsay F-91405 (France); CNRS, Orsay F-91405 (France)

    2013-07-15

    We report on the direct synthesis of BiCuChO based materials by mechanical alloying (Ch=Se, Te). We show that contrary to the synthesis paths used in the previous reports dealing with this family of materials, which use costly annealings in closed silica tubes under controlled atmosphere, this new synthesis route enables the synthesis of pure phase materials at room temperature under air, with reasonable milling time. This synthesis procedure is easily scalable for large scale applications. - Highlights: • Phase pure BiCuSeO doped and undoped prepared by mechanical alloying. • Synthesis performed under air at room temperature. • Electrical properties similar to that of samples synthesized by a classical path.

  8. Ion beam synthesis and n-type doping of group III-Nx-V1-x alloys

    NASA Astrophysics Data System (ADS)

    Yu, K. M.

    2002-08-01

    Investigations on the synthesis of group III-Nx-V1-x alloy including GaNxAs1-x, InNxP1-x and AlyGa1-yNxAs1-x using N ion implantation followed by rapid thermal annealing are reviewed. The fundamental band-gap energy for the ion beam synthesized III-Nx-V1-x alloys is found to decrease with increasing N-implantation dose and can be quantitatively described by the anticrossing interaction between the localized N-states and the extended states of the semiconductor matrix. N activation efficiencies in these N ion synthesized alloy films are found to be low, ~10% for GaNxAs1-x and ~20% for InNxP1-x. A preliminary study showed that using pulsed laser melting followed by rapid thermal annealing greatly enhanced the N activation efficiency (~50%) in N-implanted GaAs. The N-induced conduction band modification also results in an enhancement of the maximum free electron concentration in GaNxAs1-x. A maximum free electron concentration as high as 7 × 1019 cm-3 was observed in heavily Se-doped Ga1-3xIn3xNxAs1-x (x = 0.033) films, more than 20 times larger than that observed in GaAs films grown under similar conditions. A similar increase in free electron concentration was also achieved in a S-implanted GaNxAs1-x thin film. Combining the ion synthesis of diluted nitrides and S implantation doping techniques, we realized a large increase in the electrical activation of S co-implanted with N in GaAs within a thin near-surface region (~500 Å), indicating the formation of a heavily doped thin diluted GaNxAs1-x alloy layer with x ~ 0.3%. This result has important practical implications on the fabrication of low-resistance, non-alloyed ohmic contacts to n-type GaAs.

  9. The structural, electronic and dynamic properties of the L12- type Co3Ti alloy

    NASA Astrophysics Data System (ADS)

    Arikan, Nihat; Özduran, Mustafa

    2014-10-01

    The structural, electronic and dynamic properties of the cubic Co3Ti alloy in L12 structure have been investigated using a pseudopotential plane wave (PP-PW) method within the generalized gradient approximation proposed by Perdew-Burke-Ernzerhof (GGA-PBE). The structural properties, including the lattice constant, the bulk modulus and its pressure derivative agree reasonably with the previous results. The density of state (DOS), projected density of state (PDOS) and electronic band structure are also reported. The DOS shows that Co3Ti alloy has a metallic character since the energy bands cross the Fermi level. The density of states at Fermi level mainly comes from the Co-3d states. Phonon dispersion curves and their corresponding total densities of states were obtained using a linear response in the framework of the density functional perturbation theory. All computed phonon frequencies are no imaginer and thus, Co3Ti alloy is dynamically stable. The zone center phonon modes have been founded to be 9.307, 9.626 and 13.891 THz for Co3Ti.

  10. Invar and Elinvar type amorphous Fe-Cr-B alloys with high corrosion resistance

    NASA Technical Reports Server (NTRS)

    Kikuci, M.; Fukamichi, K.; Masumoto, T.

    1987-01-01

    Amorphous (Fe(1-x)Cr(x))85B15 alloys (x = 0 to 0.15) were prepared from the melts by rapid quenching using a single roller techinque, and their Invar and Elinvar characteristics and corrosion resistance were investigated. With an increase in chromium content the Curie temperature and the saturation magnetic moment per iron atom decreased monotonically, while the crystallization temperature incresed gradually. The thermal expansion coefficient alpha around room temperature became slightly larger with increasing chromium content. Nevertheless, these amorphous alloys exhibited excellent Invar characteristics below the Curie temperature. The value of Young's modulus increased remarkably in a relatively low magnetic field and then saturated at a field of about 80 kA/m, showing a large delta E effect. Its value as well as a longitudinal linear magnetostriction became smaller with an increase in chromium content. The temperature coefficient of Young's modulus changed from postive to negative, and the temperature range showing the Elinvar characteristics became narrower with chromium content. The temperature coefficient of delay time determined from the values of alpha and e was very small. The corrosion resistance of these alloys was extremely improved by chromium addition.

  11. Microstructure, elastic deformation behavior and mechanical properties of biomedical ?-type titanium alloy thin-tube used for stents.

    PubMed

    Tian, Yuxing; Yu, Zhentao; Ong, Chun Yee Aaron; Kent, Damon; Wang, Gui

    2015-05-01

    Cold-deformability and mechanical compatibility of the biomedical ?-type titanium alloy are the foremost considerations for their application in stents, because the lower ductility restricts the cold-forming of thin-tube and unsatisfactory mechanical performance causes a failed tissue repair. In this paper, ?-type titanium alloy (Ti-25Nb-3Zr-3Mo-2Sn, wt%) thin-tube fabricated by routine cold rolling is reported for the first time, and its elastic behavior and mechanical properties are discussed for the various microstructures. The as cold-rolled tube exhibits nonlinear elastic behavior with large recoverable strain of 2.3%. After annealing and aging, a nonlinear elasticity, considered as the intermediate stage between "double yielding" and normal linear elasticity, is attributable to a moderate precipitation of ? phase. Quantitive relationships are established between volume fraction of ? phase (V?) and elastic modulus, strength as well as maximal recoverable strain (?max-R), where the ?max-R of above 2.0% corresponds to the V? range of 3-10%. It is considered that the "mechanical" stabilization of the (?+?) microstructure is a possible elastic mechanism for explaining the nonlinear elastic behavior. PMID:25706668

  12. Influence of nitrogen-induced grain refinement on mechanical properties of nitrogen alloyed type 316LN stainless steel

    NASA Astrophysics Data System (ADS)

    Kim, Dae Whan

    2012-01-01

    Tensile, fatigue, and creep tests were conducted to investigate the effect of grain refinement by the addition of nitrogen on mechanical properties of nitrogen alloyed type 316LN stainless steel. Grain size was reduced from 100 ?m to 47 ?m as nitrogen concentration was increased from 0.04% (N04) to 0.10% (N10). When nitrogen concentration was increased, there was a 20% increase in yield stress and a 14% increase in UTS, respectively. Elongation was not significantly changed with increasing nitrogen concentration. As nitrogen concentration was increased, there was a 41% increase in fatigue life and an approximately sixfold increase in the time to rupture. As grain size was reduced from 100 ?m to 47 ?m, there was an 8% increase in yield stress and a 3% increase in UTS, respectively. Elongation was little changed with decreasing grain size. As grain size was reduced from 100 ?m to 47 ?m, there was a 9% increase in fatigue life and a 23% increase in the time to rupture. The grain refinement achieved by the addition of nitrogen improved the high temperature mechanical properties of nitrogen alloyed type 316LN stainless steel but was not the main mechanism for improvement of mechanical properties.

  13. Effect of Sn Doping on the Thermoelectric Properties of n-type Bi2(Te,Se)3 Alloys

    NASA Astrophysics Data System (ADS)

    Lee, Jae-Uk; Lee, Deuk-Hee; Kwon, Beomjin; Hyun, Dow-Bin; Nahm, Sahn; Baek, Seung-Hyub; Kim, Jin-Sang

    2015-06-01

    In the present work, 0.01-0.05wt.% Sn-doped Bi2(Te0.9Se0.1)3 alloys were prepared by mechanical deformation followed by hot pressing, and their thermoelectric properties were studied. We observed that the Sn element is a very effective dopant as an acceptor to control the carrier concentration in the n-type Bi2(Te0.9Se0.1)3 alloys to optimize their thermoelectric property. The n-type carrier concentration can be controlled from 4.2 × 1019/cm3 to 2.4 × 1019/cm3 by 0.05wt.% Sn-doping. While the Seebeck coefficient and the electrical resistivity are both increased with doping, the power factor remains the same. Therefore, we found that the thermoelectric figure-of-merit becomes maximized at 0.75 when the thermal conductivity has a minimum value for the 0.03wt.% Sn-doped sample.

  14. Wegner estimate and localization for alloy-type models with sign-changing exponentially decaying single-site potentials

    E-print Network

    Karsten Leonhardt; Norbert Peyerimhoff; Martin Tautenhahn; Ivan Veselic

    2015-05-20

    We study Schr\\"odinger operators on $L^2 (\\RR^d)$ and $\\ell^2(\\ZZ^d)$ with a random potential of alloy-type. The single-site potential is assumed to be exponentially decaying but not necessarily of fixed sign. In the continuum setting we require a generalized step-function shape. Wegner estimates are bounds on the average number of eigenvalues in an energy interval of finite box restrictions of these types of operators. In the described situation a Wegner estimate which is polynomial in the volume of the box and linear in the size of the energy interval holds. We apply the established Wegner estimate as an ingredient for a localization proof via multiscale analysis.

  15. A model for the high-temperature transport properties of heavily doped n-type silicon-germanium alloys

    NASA Technical Reports Server (NTRS)

    Vining, Cronin B.

    1991-01-01

    A model is presented for the high-temperature transport properties of large-grain-size, heavily doped n-type silicon-germanium alloys. Electron and phonon transport coefficients are calculated using standard Boltzmann equation expressions in the relaxation time approximation. Good agreement with experiment is found by considering acoustic phonon and ionized impurity scattering for electrons, and phonon-phonon, point defect, and electron-phonon scattering for phonons. The parameters describing electron transport in heavily doped and lightly doped materials are significantly different and suggest that most carriers in heavily doped materials are in a band formed largely from impurity states. The maximum dimensionless thermoelectric figure of merit for single-crystal, n-type Si(0.8)Ge(0.2) at 1300 K is estimated at ZT about 1.13 with an optimum carrier concentration of n about 2.9 x 10 to the 20th/cu cm.

  16. Environmental factors in the stress corrosion cracking of type 316L stainless steel and alloy 825 in chloride solutions

    SciTech Connect

    Cragnolino, G.; Dunn, D.S.; Sridhar, N. [Southwest Research Inst., San Antonio, TX (United States). Center for Nuclear Waste Regulatory Analyses

    1996-03-01

    This paper describes the experimental studies conducted to date to investigate the stress corrosion cracking (SCC) of candidate container materials for the proposed high-level nuclear waste repository at Yucca Mountain, Nevada. The effects of environmental variables, such as chloride concentration, the addition of thiosulfate, and temperature on the SCC susceptibility of type 316L, stainless steel (SS) and alloy 825 (Ni-29% Fe-22% Cr-3.0% Mo-2.0% Cu-1.0% Ti) were studied at temperatures from 95 C to 120 C. Results of slow strain rate tests (SSRT) at various potentials were compared to those obtained under constant deflection conditions using U-bend specimens to determine the existence of a critical potential for SCC. While not conclusive, results generated thus far have been consistent with the hypothesis that the repassivation potential for localized corrosion is also the critical potential for SCC in these environments. It was confirmed that alloy 825 was significantly more resistant to SCC than type 316L SS, using both constant deflection tests and SSRT, over a wide range of Cl{sup {minus}} concentrations. In contrast deflection tests, type 316 L SS exhibited cracks above the vapor-solution interface in solutions containing 1,000 ppm Cl{sup {minus}}, indicating that the local environment created as a liquid film on the specimen surface could be more detrimental than the bulk environment. SCC of type 316L SS was observed in SSRT only at Cl{sup {minus}} concentrations > {approximately}6 molal, whereas U-bend tests indicated cracking in 0.03 molal Cl{sup {minus}} solutions.

  17. Environmental factors in the stress corrosion cracking of type 316L stainless steel and alloy 825 in chloride solutions

    SciTech Connect

    Cragnolino, G.; Dunn, D.; Sridhar, N. [Southwest Research Inst., San Antonio, TX (United States). Center for Nuclear Waste Regulatory Analyses

    1995-09-01

    This paper describes the experimental studies conducted to date to investigate the stress corrosion cracking of candidate container materials for the proposed high-level nuclear waste repository at Yucca Mountain. The effects of environmental variables, such as chloride concentration, the addition of thiosulfate, and temperature, on the stress corrosion cracking susceptibility of type 316L stainless steel and alloy 825 (Ni29Fe-22Cr-3.0Mo-2.0Cu-1.0Ti) were studied at temperatures ranging from 95 to 120 C. Results of slow strain rate tests (SSRT) at various potentials were compared to those obtained under constant deflection conditions using U-bend specimens to determine the existence of a critical potential for stress corrosion cracking. Results generated thus far, while not conclusive, are consistent with the hypothesis that the repassivation potential for localized corrosion is also the critical potential for stress corrosion cracking in these environments. It was confirmed that alloy 825 is significantly more resistant to stress corrosion cracking than type 316L stainless steel using both constant deflection tests and SSRT, over a wide range of chloride concentrations. In constant deflection tests, type 316L stainless steel exhibited cracks above the vapor/solution interface in solutions containing 1,000 ppm chloride, indicating that the local environment created as a liquid film on the specimen surface could be more detrimental than the bulk environment. Stress corrosion cracking of type 316L SS was observed in SSRT only at chloride concentrations above about 6 molal, whereas U-bend tests indicated cracking in 0.03 molar chloride solutions.

  18. A new n-type and improved p-type pseudo-ternary (Bi2Te 3)(Sb2Te3)(Sb2Se3 ) alloy for Peltier cooling

    Microsoft Academic Search

    M. H. Ettenberg; W. A. Jesser; F. D. Rosi

    1996-01-01

    The pseudo-ternary alloy of (Bi2Te3)(Sb2Te3)(Sb2 Se3) has been explored for over twenty-five years with little progress in the figure of merit, p-type 3.4×10-3\\/K and n-type 3.2×10-3\\/K. Using multiple dopants, Te and SbI3, higher figure of merit material can be achieved without creating more of the deleterious pure Te commonly found as a second phase in the p-type alloy, (Bi2Te3)25(Sb2Te3 )72(Sb2Se3)3.

  19. Influence of microstructure on the enhancement of soft magnetic character and the induced anisotropy of field annealed HITPERM-type alloys

    NASA Astrophysics Data System (ADS)

    Blázquez, J. S.; Marcin, J.; Varga, M.; Franco, V.; Conde, A.; Skorvanek, I.

    2015-05-01

    Hitperm-type rapidly quenched ribbons were submitted to field annealing, both longitudinal field (LF) and transversal field (TF) to the axis of the ribbon. LF annealing yields a reduction of the magnetic anisotropy and results can be explained in the frame of random anisotropy model. A coercivity of 3 A/m is obtained for Fe39Co39Nb6B15Cu1 alloy. The addition of Cu to these Nb-containing Hitperm-type alloys is a key factor to refine the microstructure in order to reach this very low coercivity value. TF annealing produces samples with sheared hysteresis loops suitable for sensor and high frequency applications.

  20. Irradiation Performance of U-Mo Alloy Based ‘Monolithic’ Plate-Type Fuel – Design Selection

    SciTech Connect

    A. B. Robinson; G. S. Chang; D. D. Keiser, Jr.; D. M. Wachs; D. L. Porter

    2009-08-01

    A down-selection process has been applied to the U-Mo fuel alloy based monolithic plate fuel design, supported by irradiation testing of small fuel plates containing various design parameters. The irradiation testing provided data on fuel performance issues such as swelling, fuel-cladding interaction (interdiffusion), blister formation at elevated temperatures, and fuel/cladding bond quality and effectiveness. U-10Mo (wt%) was selected as the fuel alloy of choice, accepting a somewhat lower uranium density for the benefits of phase stability. U-7Mo could be used, with a barrier, where the trade-off for uranium density is critical to nuclear performance. A zirconium foil barrier between fuel and cladding was chosen to provide a predictable, well-bonded, fuel-cladding interface, allowing little or no fuel-cladding interaction. The fuel plate testing conducted to inform this selection was based on the use of U-10Mo foils fabricated by hot co-rolling with a Zr foil. The foils were subsequently bonded to Al-6061 cladding by hot isostatic pressing or friction stir bonding.

  1. Investigation of early cell-surface interactions of human mesenchymal stem cells on nanopatterned ?-type titanium-niobium alloy surfaces.

    PubMed

    Medda, Rebecca; Helth, Arne; Herre, Patrick; Pohl, Darius; Rellinghaus, Bernd; Perschmann, Nadine; Neubauer, Stefanie; Kessler, Horst; Oswald, Steffen; Eckert, Jürgen; Spatz, Joachim P; Gebert, Annett; Cavalcanti-Adam, Elisabetta A

    2014-02-01

    Multi-potent adult mesenchymal stem cells (MSCs) derived from bone marrow have therapeutic potential for bone diseases and regenerative medicine. However, an intrinsic heterogeneity in their phenotype, which in turn results in various differentiation potentials, makes it difficult to predict the response of these cells. The aim of this study is to investigate initial cell-surface interactions of human MSCs on modified titanium alloys. Gold nanoparticles deposited on ?-type Ti-40Nb alloys by block copolymer micelle nanolithography served as nanotopographical cues as well as specific binding sites for the immobilization of thiolated peptides present in several extracellular matrix proteins. MSC heterogeneity persists on polished and nanopatterned Ti-40Nb samples. However, cell heterogeneity and donor variability decreased upon functionalization of the gold nanoparticles with cyclic RGD peptides. In particular, the number of large cells significantly decreased after 24 h owing to the arrangement of cell anchorage sites, rather than peptide specificity. However, the size and number of integrin-mediated adhesion clusters increased in the presence of the integrin-binding peptide (cRGDfK) compared with the control peptide (cRADfK). These results suggest that the use of integrin ligands in defined patterns could improve MSC-material interactions, not only by regulating cell adhesion locally, but also by reducing population heterogeneity. PMID:24501674

  2. Investigation of early cell–surface interactions of human mesenchymal stem cells on nanopatterned ?-type titanium–niobium alloy surfaces

    PubMed Central

    Medda, Rebecca; Helth, Arne; Herre, Patrick; Pohl, Darius; Rellinghaus, Bernd; Perschmann, Nadine; Neubauer, Stefanie; Kessler, Horst; Oswald, Steffen; Eckert, Jürgen; Spatz, Joachim P.; Gebert, Annett; Cavalcanti-Adam, Elisabetta A.

    2014-01-01

    Multi-potent adult mesenchymal stem cells (MSCs) derived from bone marrow have therapeutic potential for bone diseases and regenerative medicine. However, an intrinsic heterogeneity in their phenotype, which in turn results in various differentiation potentials, makes it difficult to predict the response of these cells. The aim of this study is to investigate initial cell–surface interactions of human MSCs on modified titanium alloys. Gold nanoparticles deposited on ?-type Ti–40Nb alloys by block copolymer micelle nanolithography served as nanotopographical cues as well as specific binding sites for the immobilization of thiolated peptides present in several extracellular matrix proteins. MSC heterogeneity persists on polished and nanopatterned Ti–40Nb samples. However, cell heterogeneity and donor variability decreased upon functionalization of the gold nanoparticles with cyclic RGD peptides. In particular, the number of large cells significantly decreased after 24 h owing to the arrangement of cell anchorage sites, rather than peptide specificity. However, the size and number of integrin-mediated adhesion clusters increased in the presence of the integrin-binding peptide (cRGDfK) compared with the control peptide (cRADfK). These results suggest that the use of integrin ligands in defined patterns could improve MSC-material interactions, not only by regulating cell adhesion locally, but also by reducing population heterogeneity. PMID:24501674

  3. Enhancement of light reflectance and thermal stability in Ag-Cu alloy contacts on p-type GaN

    NASA Astrophysics Data System (ADS)

    Son, Jun Ho; Jung, Gwan Ho; Lee, Jong-Lam

    2008-07-01

    The mechanism for thermally stable Ag-Cu alloy Ohmic contact on p-type GaN was investigated. Ag-Cu contact showed lower contact resistivity as low as 8.6×10-6?cm2, higher reflectance of 84% at 460nm, and better thermal stability than Ag contact after annealing in air ambient. The formation of Ag-Ga solid solution lowered the contact resistivity. Additionally the formation of Cu oxide suppresses the Ag oxidation and increases the work function of the Ag-Cu contact via decreasing the Schottky barrier height for hole injection. Precipitation of Cu oxide at grain boundaries suppresses the Ag agglomeration, leading to enhanced light reflectance as well as thermal stability.

  4. The characterization of shape memory effect for low elastic modulus biomedical {beta}-type titanium alloy

    SciTech Connect

    Wang Liqiang [State Key Laboratory of Metal Matrix Composites, Shanghai Jiao Tong University, Shanghai 200240 (China); Lu Weijie, E-mail: luweijie@sjtu.edu.cn [State Key Laboratory of Metal Matrix Composites, Shanghai Jiao Tong University, Shanghai 200240 (China); Qin Jining; Zhang Fan; Zhang Di [State Key Laboratory of Metal Matrix Composites, Shanghai Jiao Tong University, Shanghai 200240 (China)

    2010-05-15

    This work investigates the textures of biomedical TiNbTaZr alloy rolled by 99% cold reduction ratios in thickness. The relationship between textures and superelasticity of the specimens treated at 873 K and 1223 K for 1.2 ks is studied. The microstructure of tensile specimen is investigated by transmission electron microscopy. Textures of cold-rolled and heat-treated specimens are studied. During unloading, the anisotropy of superelastic strain and pure elastic strain in the heat-treated specimens is observed. Superelastic strain along rolling direction and transverse direction is larger than those along 45 deg. from rolling direction while pure elastic strain shows the highest value along 45 deg. from rolling direction in the specimen treated at 873 K. For the specimen treated at 1223 K, higher pure elastic strain is obtained along rolling direction. The maximum recovered strain around 2.11% is obtained along rolling direction.

  5. Correlation Between Two Types of Surface Stress Mitigation and the Resistance to Corrosion of Alloy 22

    SciTech Connect

    Yilmaz, A; Fix, D V; Estill, J C; Rebak, R B

    2005-02-04

    When metallic plates are welded, residual tensile stresses may develop in the vicinity of the weld seam. Processes such as Low Plasticity Burnishing (LPB) and Laser Shock Peening (LSP) could be applied locally to eliminate the residual stresses produced by welding. In this study, Alloy 22 (N06022) plates were welded and then the above-mentioned surface treatments were applied to eliminate the residual tensile stresses. The aim of the current study was to compare the corrosion behavior of as-welded (ASW) plates with the corrosion behavior of plates with stress mitigated surfaces. Immersion and electrochemical tests were performed. Results show that the corrosion resistance of the mitigated plates was not affected by the surface treatments applied.

  6. The effect of short-term heat treatment on the thermoelectric properties of heavily doped n-type silicon germanium alloys

    Microsoft Academic Search

    V. S. Shukla; D. M. Rowe

    1981-01-01

    Hall effect and electrical resistivity measurements were carried out on samples of heavily doped n-type silicon germanium alloys during high temperature isothermal heat treatment*. The samples were initially annealed at 1300 K, quenched to room temperature and then subjected to short-term heat treatment at temperatures of 630 K, 825 K, 980 K and 1040 K. Dopant precipitates out of solution

  7. Thermoelectric Properties of n-type Polycrystalline BixSb2-xTe3 Alloys N. Gerovac, G. J. Snyder, and T. Caillat

    E-print Network

    be incorporated into advanced thermoelectric unicouples for a variety of power generation applicationsThermoelectric Properties of n-type Polycrystalline BixSb2-xTe3 Alloys N. Gerovac, G. J. Snyder their atomic composition. The thermoelectric properties were measured at room temperature in both directions

  8. Surface alloying of Mg alloys after surface nanocrystallization.

    PubMed

    Zhang, Ming-Xing; Shi, Yi-Nong; Sun, Haiqing; Kelly, Patrick M

    2008-05-01

    Surface nanocrystallization using a surface mechanical attrition treatment effectively activates the surface of magnesium alloys due to the increase in grain boundary diffusion channels. As a result, the temperature of subsequent surface alloying treatment of pure Mg and AZ91 alloy can be reduced from 430 degrees C to 380 degrees C. Thus, it is possible to combine the surface alloying process with the solution treatment for this type of alloy. After surface alloying, the hardness of the alloyed layer is 3 to 4 times higher than that of the substrate and this may significantly improve the wear resistance of magnesium alloys. PMID:18572716

  9. Development of One-Body Type Water- and Air-Cooling Fixed Masks Made of Forged 0.2% Beryllium Copper Alloy

    NASA Astrophysics Data System (ADS)

    Mase, Kazuhiko; Kikuchi, Takashi; Tanaka, Hirokazu; Toyoshima, Akio; Watanabe, Fumio

    One-body type water- and air-cooling fixed masks made of forged 0.2% beryllium copper alloy have been developed, and successfully applied for the front end of a new undulator beamline, BL-13A, at the Photon Factory in Tsukuba, Japan. Advantages of the masks are a simple structure, no welding, low cost, high duration, and an extremely low out-gassing rate. Forged 0.2% beryllium copper alloy is demonstrated to be a valuable material for synchrotron radiation instruments.

  10. Effect of alloy type on the life-time of torsion-preloaded nickel-titanium endodontic instruments.

    PubMed

    Ha, Jung-Hong; Kim, Sung Kyo; Cheung, Gary Shun-Pan; Jeong, Seong Hwa; Bae, Yong Chul; Kim, Hyeon-Cheol

    2015-05-01

    This study was aimed to evaluate the effect of torsional preloads on the cyclic fatigue life of nickel-titanium (NiTi) instruments with different history of heat treatments by manufacturers. WaveOne (Primary) made of M-wire, K3XF (#30/0.06) of R-phase, and ProTaper (F2) of conventional NiTi alloy was used. Each file was preloaded at four conditions (nil, 25, 50, and 75% of their mean ultimate torsional strength) before fatigue testing. The torsional preloads 10-, 30-, or 50-times were applied by securing 5?mm of the file tip, rotating it until the preset torque was attained before returning to the origin. Then, the number of cycles to failure (NCF) was evaluated by rotational bending in a simulated canal. Data were analyzed using multiple linear regression analysis and two-way ANOVA. Fractured instruments were examined under scanning electron microscope (SEM). SEM showed that most WaveOne after 75% preloading, regardless of repetitions, showed some longitudinal cracks parallel to the long axis of the file, which were rare for K3XF. Regression analysis revealed that the brand of instrument was the most critical factor. At up to 75% preloading, ProTaper and K3XF did not show any significant decline in NCF. For 30-repetition groups of WaveOne, the 50 and 25% torsion preloaded groups showed a significantly higher NCF than the 0 and 75% groups. Within the limitations of this study, the alloy type of NiTi instrument have a significant effect on the phenomenon that a certain amount of torsional preload may improve the cyclic fatigue resistance of NiTi rotary instruments. SCANNING 37:172-178, 2015. © 2015 Wiley Periodicals, Inc. PMID:25676195

  11. Thermoelectric generation and related properties of conventional type module based on SiGe alloy

    Microsoft Academic Search

    Masakazu KOBAYASHI; Keiko IKOMA; Kenji FURUYA; Kazuhiko SHINOHARA; Hiroshi TAKAO; Makoto MIYOSHI; Yuichiro IMANISHI; Tetsuo WATANABE

    1996-01-01

    A conventional type thermoelectric module based on Si2Ge has been made for power use. The module consists of 10 pairs of p- and n-type Si2Ge elements in which B and P were doped (~1020 cm-3) respectively. The elements electrically connected in series using Mo electrodes are sandwiched between AIN plates. Each plate is 20 mm×44 mm in area, and the

  12. Low-cycle fatigue of Type 347 stainless steel and Hastelloy alloy X in hydrogen gas and in air at elevated temperatures

    NASA Technical Reports Server (NTRS)

    Jaske, C. E.; Rice, R. C.; Buchheit, R. D.; Roach, D. B.; Porfilio, T. L.

    1976-01-01

    An investigation was conducted to assess the low-cycle fatigue resistance of two alloys, Type 347 stainless steel and Hastelloy Alloy X, that were under consideration for use in nuclear-powered rocket vehicles. Constant-amplitude, strain-controlled fatigue tests were conducted under compressive strain cycling at a constant strain rate of 0.001/sec and at total axial strain ranges of 1.5, 3.0, and 5.0 %, in both laboratory-air and low-pressure hydrogen-gas environments at temperatures from 538 to 871 C. Specimens were obtained from three heats of Type 347 stainless steel bar and two heats of Hastelloy Alloy X. The tensile properties of each heat were determined at 21, 538, 649, and 760 C. The continuous cycling fatigue resistance was determined for each heat at temperatures of 538, 760, and 871 C. The Type 347 stainless steel exhibited equal or superior fatigue resistance to the Hastelloy Alloy X at all conditions of this study.

  13. Fabrication of a maxillary posterior fixed partial denture with a type 4 gold alloy and a dual-polymerizing indirect composite.

    PubMed

    Matsumura, Hideo; Mori, Shuichi; Tanoue, Naomi

    2008-03-01

    The aim of the present study was to design and fabricate a maxillary posterior fixed partial denture (FPD) made of a type 4 gold alloy and an indirect composite. Unlike the conventional framework design of a resin veneered restoration, cut-back was extended approximately 1/4 to 1/3 width in the occlusal table of the buccal cusp. Multiple retentive beads 150-200 mum in diameter were placed on the metal surface to be veneered. The gold alloy was cast in a cristobalite mold using a centrifugal casting machine. The cut surface with the retentive beads was air-abraded with alumina, and a priming agent (Alloy Primer) that contained triazine dithione monomer (VTD) was applied. A tooth-colored veneer was then fabricated with a highly loaded light- and heat-cured composite material (Estenia). This design and procedure can be applied as a standardized laboratory technique for fabrication of maxillary posterior restorations and FPDs. PMID:18403895

  14. Determination of thermal conductivities of Sn-Zn lead-free solder alloys with radial heat flow and Bridgman-type apparatus

    NASA Astrophysics Data System (ADS)

    Meydaneri, Fatma; Saatçi, Buket; Gündüz, Mehmet; Özdemir, Mehmet

    2013-11-01

    The variations of thermal conductivities of solid phases versus temperature for pure Sn, pure Zn and Sn-9 wt.% Zn, Sn-14 wt.% Zn, Sn-50 wt.% Zn, Sn-80 wt.% Zn binary alloys were measured with a radial heat flow apparatus. The thermal conductivity ratios of liquid phase to solid phase for the pure Sn, pure Zn and eutectic Sn-9 wt.% Zn alloy at their melting temperature are found with a Bridgman-type directional solidification apparatus. Thus, the thermal conductivities of liquid phases for pure Sn, pure Zn and eutectic Sn-9 wt.% Zn binary alloy at their melting temperature were evaluated by using the values of solid phase thermal conductivities and the thermal conductivity ratios of liquid phase to solid phase.

  15. Cluster packing geometry for Al-based F-type icosahedral alloys

    E-print Network

    Nobuhisa Fujita; Hikari Takano; Akiji Yamamoto; An-Pang Tsai

    2013-01-29

    This paper presents a new highly stable periodic approximant to the Al-based F-type icosahedral quasicrystals, i-Al-Pd-TM (TM=transition metals). The structure of this intermetallic Al-Pd-Cr-Fe compound is determined ab initio using single-crystal X-ray diffraction, where the space group is identified to be Pa-3 and the lattice constant 40.5 angstrom. The structure is well described as a dense packing of clusters of two kinds, which are known in the literature as the pseudo-Mackay type and the Bergman type clusters. The clusters are centered at the vertices of a canonical cell tiling, in which the parity of each vertex determines the kind of the associated cluster. Adjacent clusters can be markedly interpenetrated, while the structure requires no glue atoms to fill in the gaps between the clusters. It is shown that the crystal can be designated as a 2x2x2 superstructure of the ordinary cubic 3/2 rational approximant. The superlattice ordering is shown to be of a different kind from the P-type superlattice ordering previously reported in i-Al-Pd-Mn. The present results will greatly improve the understanding of atomic structures of F-type icosahedral quasicrystals and their approximants.

  16. Band-gap bowing and p-type doping of (Zn, Mg, Be)O wide-gap semiconductor alloys: a first-principles study

    NASA Astrophysics Data System (ADS)

    Shi, H.-L.; Duan, Y.

    2008-12-01

    Using a first-principles band-structure method and a special quasirandom structure (SQS) approach, we systematically calculate the band gap bowing parameters and p-type doping properties of (Zn, Mg, Be)O related random ternary and quaternary alloys. We show that the bowing parameters for ZnBeO and MgBeO alloys are large and dependent on composition. This is due to the size difference and chemical mismatch between Be and Zn(Mg) atoms. We also demonstrate that adding a small amount of Be into MgO reduces the band gap indicating that the bowing parameter is larger than the band-gap difference. We select an ideal N atom with lower p atomic energy level as dopant to perform p-type doping of ZnBeO and ZnMgBeO alloys. For N doped in ZnBeO alloy, we show that the acceptor transition energies become shallower as the number of the nearest neighbor Be atoms increases. This is thought to be because of the reduction of p- d repulsion. The NO acceptor transition energies are deep in the ZnMgBeO quaternary alloy lattice-matched to GaN substrate due to the lower valence band maximum. These decrease slightly as there are more nearest neighbor Mg atoms surrounding the N dopant. The important natural valence band alignment between ZnO, MgO, BeO, ZnBeO, and ZnMgBeO quaternary alloy is also investigated.

  17. Corrosion of high Ni-Cr alloys and Type 304L stainless steel in HNOâ-HF

    Microsoft Academic Search

    R. S. Ondrejcin; B. D. McLaughlin

    1980-01-01

    Nineteen alloys were evaluated as possible materials of construction for steam heating coils, the dissolver vessel, and the off-gas system of proposed facilities to process thorium and uranium fuels. Commercially available alloys were found that are satisfactory for all applications. With thorium fuel, which requires HNOâ-HF for dissolution, the best alloy for service at 130°C when complexing agents for fluoride

  18. Comparison of different pressing techniques for the preparation of n-type silicon-germanium thermoelectric alloys

    SciTech Connect

    Harringa, J.L.; Cook, B.A.

    1996-06-01

    Improvements to state-of-the-art Si{sub 80}Ge{sub 20} thermoelectric alloys have been observed in laboratory-scale samples by the powder metallurgy techniques of mechanical alloying and hot pressing. Incorporating these improvements in large scale compacts for the production of thermoelectric generator elements is the next step in achieving higher efficiency RTGs. This paper discusses consolidation of large quantities of mechanically alloyed powders into production size compacts. Differences in thermoelectric properties are noted between the compacts prepared by the standard technique of hot uniaxial pressing and hot isostatic pressing. Most significant is the difference in carrier concentration between the alloys prepared by the two consolidation techniques.

  19. Properties of a new type Al/Pb-0.3%Ag alloy composite anode for zinc electrowinning

    NASA Astrophysics Data System (ADS)

    Yang, Hai-tao; Liu, Huan-rong; Zhang, Yong-chun; Chen, Bu-ming; Guo, Zhong-cheng; Xu, Rui-dong

    2013-10-01

    An Al/Pb-0.3%Ag alloy composite anode was produced via composite casting. Its electrocatalytic activity for the oxygen evolution reaction and corrosion resistance was evaluated by anodic polarization curves and accelerated corrosion test, respectively. The microscopic morphologies of the anode section and anodic oxidation layer during accelerated corrosion test were obtained by scanning electron microscopy. It is found that the composite anode (hard anodizing) displays a more compact interfacial combination and a better adhesive strength than plating tin. Compared with industrial Pb-0.3%Ag anodes, the oxygen evolution overpotentials of Al/Pb-0.3%Ag alloy (hard anodizing) and Al/Pb-0.3%Ag alloy (plating tin) at 500 A·m-2 were lower by 57 and 14 mV, respectively. Furthermore, the corrosion rates of Pb-0.3%Ag alloy, Al/Pb-0.3%Ag alloy (hard anodizing), and Al/Pb-0.3%Ag alloy (plating tin) were 13.977, 9.487, and 11.824 g·m-2·h-1, respectively, in accelerated corrosion test for 8 h at 2000 A·m-2. The anodic oxidation layer of Al/Pb-0.3%Ag alloy (hard anodizing) is more compact than Pb-0.3%Ag alloy and Al/Pb-0.3%Ag alloy (plating tin) after the test.

  20. Cluster type grain interaction model including twinning for texture prediction: Application to magnesium alloys

    Microsoft Academic Search

    Sijia Mu; Talal Al-Samman; Volker Mohles; Günter Gottstein

    2011-01-01

    In many materials with low crystal symmetry or low stacking fault energies plastic deformation occurs not only by crystallographic slip, but also by twinning. Several proposals have been made to implement mechanical twinning into texture modeling, for example the predominant twin reorientation (PTR) scheme of Tomé. The grain interaction (GIA) model is one of the most advanced cluster type Taylor

  1. Formation of the properties of antimony matrix alloys for frame-type composite materials

    Microsoft Academic Search

    V. A. Gulevskii; V. I. Antipov; L. V. Vinogradov; A. G. Kolmakov; E. M. Lazarev; A. M. Samarina; Yu. E. Mukhina

    2009-01-01

    A frame-type composite material (CM) produced upon impregnation represents a system consisting of a rigid porous frame and a matrix material filling its voids. When metals are used as a matrix material, they bring up specific problems related to melting of a metal, such as the thermal effect of the metal on the frame and the chemical interaction of the

  2. Improved electrical properties of n-type SiGe alloys

    NASA Technical Reports Server (NTRS)

    Scoville, A. N.; Bajgar, Clara; Vandersande, Jan; Fleurial, Jean-Pierre

    1992-01-01

    The effect of changes in the carrier concentration and mobility for heavily doped n-type SiGe on the electrical power factor has been investigated. It has been shown that power factors of 37-40 microV/cm-K-squared can be achieved with carrier concentrations of 2.0 - 2.5 x 10 exp 20/cu cm and mobilities of 38-40 sq cm/V-sec. Many samples with suitable carrier concentration do not have high mobilities and some rationale for this behavior is presented. Initial results are presented on fabrication of n-type samples from ultrafine powders. The emphasis in this work is to achieve thermal conductivity reductions by adding inert particles to scatter midfrequency phonons.

  3. N-type Doped PbTe and PbSe Alloys for Thermoelectric Applications

    NASA Technical Reports Server (NTRS)

    Snyder, G. Jeffrey (Inventor); LaLonde, Aaron (Inventor); Pei, Yanzhong (Inventor); Wang, Heng (Inventor)

    2014-01-01

    The present invention demonstrates that weak scattering of carriers leads to a high mobility and therefore helps achieve low electric resistivity with high Seebeck coefficient for a thermoelectric material. The inventors demonstrate this effect by obtaining a thermoelectric figure of merit, zT, higher than 1.3 at high temperatures in n-type PbSe, because of the weak scattering of carriers in the conduction band as compared with that in the valence band. The invention further demonstrates favorable thermoelectric transport properties of n-type PbTe.sub.1-xI.sub.x with carrier concentrations ranging from 5.8.times.10.sup.18-1.4.times.10.sup.20 cm.sup.-3.

  4. Formation of the properties of antimony matrix alloys for frame-type composite materials

    Microsoft Academic Search

    V. A. Gulevskii; V. I. Antipov; L. V. Vinogradov; A. G. Kolmakov; E. M. Lazarev; A. M. Samarina; Yu. E. Mukhina

    2009-01-01

    A frame-type composite material (CM) produced upon impregnation represents a system consisting of a rigid porous frame and\\u000a a matrix material filling its voids. When metals are used as a matrix material, they bring up specific problems related to\\u000a melting of a metal, such as the thermal effect of the metal on the frame and the chemical interaction of the

  5. Mechanical properties and cytocompatibility of oxygen-modified ?-type Ti-Cr alloys for spinal fixation devices.

    PubMed

    Liu, Huihong; Niinomi, Mitsuo; Nakai, Masaaki; Cho, Ken; Narita, Kengo; ?en, Mustafa; Shiku, Hitoshi; Matsue, Tomokazu

    2015-01-01

    In this study, various amounts of oxygen were added to Ti-10Cr (mass%) alloys. It is expected that a large changeable Young's modulus, caused by a deformation-induced ?-phase transformation, can be achieved in Ti-10Cr-O alloys by the appropriate oxygen addition. This "changeable Young's modulus" property can satisfy the otherwise conflicting requirements for use in spinal implant rods: high and low moduli are preferred by surgeons and patients, respectively. The influence of oxygen on the microstructures and mechanical properties of the alloys was examined, as well as the bending springback and cytocompatibility of the optimized alloy. Among the Ti-10Cr-O alloys, Ti-10Cr-0.2O (mass%) alloy shows the largest changeable Young's modulus following cold rolling for a constant reduction ratio. This is the result of two competing factors: increased apparent ?-lattice stability and decreased amounts of athermal ? phase, both of which are caused by oxygen addition. The most favorable balance of these factors for the deformation-induced ?-phase transformation occurred at an oxygen concentration of 0.2mass%. Ti-10Cr-0.2O alloy not only exhibits high tensile strength and acceptable elongation, but also possesses a good combination of high bending strength, acceptable bending springback and great cytocompatibility. Therefore, Ti-10Cr-0.2O alloy is a potential material for use in spinal fixture devices. PMID:25449914

  6. In vitro bio-functional performances of the novel superelastic beta-type Ti-23Nb-0.7Ta-2Zr-0.5N alloy.

    PubMed

    Ion, Raluca; Gordin, Doina-Margareta; Mitran, Valentina; Osiceanu, Petre; Dinescu, Sorina; Gloriant, Thierry; Cimpean, Anisoara

    2014-02-01

    The materials used for internal fracture fixations and joint replacements are mainly made of metals which still face problems ranging from higher rigidity than that of natural bone to leaching cytotoxic metallic ions. Beta (?)-type titanium alloys with low elastic modulus made from non-toxic and non-allergenic elements are desirable to reduce stress shielding effect and enhance bone remodeling. In this work, a new ?-type Ti-23Nb-0.7Ta-2Zr-0.5N alloy with a Young's modulus of approximately 50 GPa was designed and characterized. The behavior of MC3T3-E1 pre-osteoblasts on the new alloy, including adhesion, proliferation and differentiation, was evaluated by examining the cytoskeleton, focal adhesion formation, metabolic activity and extracellular matrix mineralization. Results indicated that the pre-osteoblast cells exhibited a similar degree of attachment and growth on Ti-23Nb-0.7Ta-2Zr-0.5N and Ti-6Al-4V. However, the novel alloy proved to be significantly more efficient in sustaining mineralized matrix deposition upon osteogenic induction of the cells than Ti-6Al-4V control. Further, the analysis of RAW 264.7 macrophages cytokine gene and protein expression indicated no significant inflammatory response. Collectively, these findings suggest that the Ti-23Nb-0.7Ta-2Zr-0.5N alloy, which has an increased mechanical biocompatibility with bone, allows a better osteogenic differentiation of osteoblast precursor cells than Ti-6Al-4V and holds great potential for future clinical prosthetic applications. PMID:24411395

  7. Influence of the Front Surface Passivation Quality on Large Area n-Type Silicon Solar Cells with Al-Alloyed Rear Emitter

    Microsoft Academic Search

    T. Wiedenmann; G. Schubert; H. Plagwitz; G. Hahn

    2011-01-01

    Efficiencies of large area n-type silicon solar cells with a screen printed rear side aluminum-alloyed emitter are mainly limited by their front surface recombination velocity. The front surface therefore has to be passivated by an effective passivation layer combined with a front surface field (FSF).In this work we investigate the influence of the front surface passivation quality and the base

  8. Formation and magnetic properties of p-type icosahedral quasicrystals in Zn-Fe-Sc-L (L = Ho, Er, Tm) alloys

    Microsoft Academic Search

    S. Kashimoto; C. Masuda; S. Motomura; S. Matsuo; T. Ishimasa

    2007-01-01

    Icosahedral quasicrystals containing heavy lanthanoids L, namely Ho, Er or Tm, have been discovered in the Zn77Fe7Sc16–xLx alloy systems. The solubility limit of the lanthanoid is approximately half of the Sc atoms. All these quasicrystals belong to p-type and are stable at approximately 973?K. The temperature dependence of the magnetic susceptibility of the Zn77Fe7Sc8Tm8 quasicrystal follows the Curie–Weiss law and

  9. Synthesis of NiCoMnX (X = In, Al) Heusler-type Magnetic Shape Memory Alloy Thin Films 

    E-print Network

    Rios, Steven Eli

    2014-08-13

    found applications in biomedical and aerospace industries, actuator applications are limited to relatively low frequencies compared to piezoelectric materials. The slow response of shape memory alloys is associated with heating or cooling the material...

  10. Subtyping in alloy

    E-print Network

    Torlak, Emina, 1979-

    2004-01-01

    A type system for the Alloy modelling language is described that supports subtypes and allows overloading of relation names. No special syntactic features needed to be added to the language to support the type system; there ...

  11. Applicability of repassivation potential for long-term prediction of localized corrosion of Alloy 825 and type 316L stainless steel

    SciTech Connect

    Sridhar, N.; Cragnolino, G.A. (Southwest Research Inst., San Antonio, TX (United States). Center for Nuclear Waste Regulatory Analyses)

    1993-11-01

    Repassivation potential (E[sub rp]) was investigated for use as a parameter in the long-term prediction of pitting resistance of two Fe-Ni-Cr-Mo alloys that are candidate materials for high-level nuclear waste containers. This potential was found to be independent of the extent of prior pit growth for alloy 825 (UNS N08825) and type 316 L (UNS S31603) stainless steel (SS). Repassivation potential decreased by an increase in backward scan rate after pits were grown under potentiostatic conditions. This was related to the effect of potential on repassivation time. The corrosion potential (E[sup corr]) in simulated pit-crevice solutions increased with a decrease in pH and was independent of chloride (CL[sup [minus

  12. Amorphous metal alloy

    DOEpatents

    Wang, R.; Merz, M.D.

    1980-04-09

    Amorphous metal alloys of the iron-chromium and nickel-chromium type have excellent corrosion resistance and high temperature stability and are suitable for use as a protective coating on less corrosion resistant substrates. The alloys are stabilized in the amorphous state by one or more elements of titanium, zirconium, hafnium, niobium, tantalum, molybdenum, and tungsten. The alloy is preferably prepared by sputter deposition.

  13. Effects of micro- and nano-scale wave-like structures on fatigue strength of a beta-type titanium alloy developed as a biomaterial.

    PubMed

    Narita, Kengo; Niinomi, Mitsuo; Nakai, Masaaki

    2014-01-01

    Some newly developed ?-type titanium alloys for biomedical applications exhibit distinctive heterogeneous structures. The formation mechanisms for these structures have not been completely revealed; however, understanding these mechanisms could lead to improving their properties. In this study, the heterogeneous structures of a Ti-29Nb-13Ta-4.6Zr alloy (TNTZ), which is a candidate for next-generation metallic biomaterials, were analyzed. Furthermore, the effects of such heterogeneous structures on the mechanical strength of this alloy, including fatigue strength, were revealed by comparing its strength to that of homogenous TNTZ. The heterogeneous structures were characterized micro-, submicro- and nano-scale wave-like structures. The formation mechanisms of these wave-like structures are found to be different from each other even though their morphologies are similar. It is revealed that the micro-, submicro- and nano-scale wave-like structures are caused by elemental segregation, crystal distortion related to kink band and phase separation into ? and ?', respectively. However, these structures have no significant effect on both tensile properties and fatigue strength comparison with homogeneous structure in this study. PMID:24184863

  14. Atomic states, potential energies, volumes, stability and brittleness of ordered FCC TiAl 2 type alloys

    Microsoft Academic Search

    Y. Q. Xie; H. J. Tao; H. J. Peng; X. B. Li; X. B. Liu; K. Peng

    2005-01-01

    In this paper, the framework of the systematic science of alloys (SSA) is presented. It has been proved that according to the basic information of sequences of characteristic crystals in the FCC Ti–Al system, not only the states, potential energies and volumes of atoms at various lattice points, and average atomic states, average atomic potential energies, average atomic volumes and

  15. Atomic states, potential energies, volumes, stability and brittleness of ordered FCC TiAl2 type alloys

    Microsoft Academic Search

    Y. Q. Xie; H. J. Tao; H. J. Peng; X. B. Li; X. B. Liu; K. Peng

    2005-01-01

    In this paper, the framework of the systematic science of alloys (SSA) is presented. It has been proved that according to the basic information of sequences of characteristic crystals in the FCC Ti Al system, not only the states, potential energies and volumes of atoms at various lattice points, and average atomic states, average atomic potential energies, average atomic volumes

  16. Structural and dielectric spectroscopy studies of the M-type barium strontium hexaferrite alloys (Ba x Sr 1? x Fe 12 O 19 )

    Microsoft Academic Search

    F. M. M. Pereira; C. A. R. Junior; M. R. P. Santos; R. S. T. M. Sohn; F. N. A. Freire; J. M. Sasaki; J. A. C. de Paiva; A. S. B. Sombra

    2008-01-01

    The M-type barium hexaferrite Ba\\u000a x\\u000a Sr1?x\\u000a Fe12O19 (where 0 x < 1) alloys were prepared by a new ceramic procedure. The samples were studied using X-ray diffraction and Rietveld analysis,\\u000a scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy, infrared and Mössbauer spectroscopy. The X-ray analysis\\u000a indicates that the all the samples present a hexagonal structure. The IR spectra showed three main absorption

  17. Thermoelectric properties of the Heusler-type Fe{sub 2}VTa{sub x}Al{sub 1?x} alloys

    SciTech Connect

    Renard, Krystel, E-mail: renard.krystel@nitech.ac.jp; Mori, Arinori; Yamada, Yuichiro; Tanaka, Suguru; Nishino, Yoichi [Department of Frontier Materials, Nagoya Institute of Technology, Nagoya 466-8555 (Japan); Miyazaki, Hidetoshi [Center for Fostering Young and Innovative Researchers, Nagoya Institute of Technology, Nagoya 466-8555 (Japan)

    2014-01-21

    This study focuses on the thermoelectric properties of the Heusler-type Fe{sub 2}VTa{sub x}Al{sub 1?x} alloys (0?x?0.12). By means of Rietveld analyses on synchrotron X-ray diffraction patterns, it is shown that the Ta atoms enter sites occupied by V atoms in the stoichiometric Fe{sub 2}VAl alloy, while the ejected V atoms are transferred to the vacant Al sites. This Ta substitution leads to an improvement of the n-type thermoelectric properties owing to two mechanisms. On the one hand, the atoms position in the structure leads to an off-stoichiometric effect such as already observed in V-rich Fe{sub 2}V{sub 1+y}Al{sub 1?y} compounds: the Seebeck coefficient is increased towards negative absolute values and the electrical resistivity is decreased, with a large shift of their peak temperature towards higher temperature. The maximum power factor is 6.5?×?10{sup ?3} W/mK{sup 2} for x?=?0.05 at 340?K. On the other hand, the heavy element Ta substitution combined with this off-stoichiometric effect leads to a large decrease of the thermal conductivity, owing to an increase of the scattering events. Consequently, the dimensionless figure of merit is seen to reach higher values than for the Fe{sub 2}V{sub 1+y}Al{sub 1?y} alloys, i.e., 0.21–0.22 around 400–500?K for x?=?0.05 and 500?K for x?=?0.08.

  18. Alloying of aluminum-beryllium alloys

    NASA Astrophysics Data System (ADS)

    Molchanova, L. V.; Ilyushin, V. N.

    2013-01-01

    The existing phase diagrams of Al-Be- X alloys, where X is an alloying element, are analyzed. Element X is noted to poorly dissolve in both aluminum and beryllium. It is shown that the absence of intermetallic compounds in the Al-Be system affects the phase equilibria in an Al-Be- X system. Possible phase equilibria involving phases based on aluminum, beryllium, and intermetallic compounds are proposed, and the types of strengthening of Al-Be alloys by an addition of a third element are classified.

  19. Effect of nickel, copper, and molybdenum content on corrosion resistance of Kh20N40-type alloy in acidic solutions

    Microsoft Academic Search

    E. T. Shapovalov; M. Yu. Ustimenko

    1994-01-01

    The alloys of the Fe-20% Cr-Ni system containing varying amounts of nickel (25-50%), copper (0-3%), and molybdenum (0-7.7%) were tested in 10% HCl, 5 and 50% HâSOâ solutions, in AM (weakly-oxidizing media) and VU (completely passive state) procedure solutions, and in 27%HNOâ + 1 g\\/l Cr{sup 6+} solution. The increase in nickel (to â¼ 40%), copper (to 2%), and molybdenum

  20. Effect of yttrium on the corrosion of AB 5-type alloys for nickel–metal hydride batteries

    Microsoft Academic Search

    F Maurel; P Leblanc; B Knosp; M Backhaus-Ricoult

    2000-01-01

    The influence of Y2O3 powder addition (as well as of rare earth oxides of Gd, Ho, Dy, Nd, Sm or Yb) to the metal hydride electrode on AB5 alloy corrosion rates and on the chemical composition, morphology and density of the corrosion products was studied by X-ray, SEM, TEM and HRTEM. Adding Y2O3 reduces the corrosion rate. This is particularly

  1. The structural, electronic and dynamic properties of the L1{sub 2}- type Co{sub 3}Ti alloy

    SciTech Connect

    Arikan, Nihat [Ahi Evran Üniversitesi E?itim Fakültesi, ?lkö?retim Bölümü, K?r?ehir (Turkey); Özduran, Mustafa [Ahi Evran Üniversitesi, Fen Edebiyat Fakültesi, Fizik Bölümü, K?r?ehir (Turkey)

    2014-10-06

    The structural, electronic and dynamic properties of the cubic Co{sub 3}Ti alloy in L1{sub 2} structure have been investigated using a pseudopotential plane wave (PP-PW) method within the generalized gradient approximation proposed by Perdew–Burke–Ernzerhof (GGA-PBE). The structural properties, including the lattice constant, the bulk modulus and its pressure derivative agree reasonably with the previous results. The density of state (DOS), projected density of state (PDOS) and electronic band structure are also reported. The DOS shows that Co{sub 3}Ti alloy has a metallic character since the energy bands cross the Fermi level. The density of states at Fermi level mainly comes from the Co-3d states. Phonon dispersion curves and their corresponding total densities of states were obtained using a linear response in the framework of the density functional perturbation theory. All computed phonon frequencies are no imaginer and thus, Co{sub 3}Ti alloy is dynamically stable. The zone center phonon modes have been founded to be 9.307, 9.626 and 13.891 THz for Co{sub 3}Ti.

  2. Microstructural studies on Alloy 693

    NASA Astrophysics Data System (ADS)

    Halder, R.; Dutta, R. S.; Sengupta, P.; Samajdar, I.; Dey, G. K.

    2014-10-01

    Superalloy 693, is a newly identified ‘high-temperature corrosion resistant alloy’. Present study focuses on microstructure and mechanical properties of the alloy prepared by double ‘vacuum melting’ route. In general, the alloy contains ordered Ni3Al precipitates distributed within austenitic matrix. M6C primary carbide, M23C6 type secondary carbide and NbC particles are also found to be present. Heat treatment of the alloy at 1373 K for 30 min followed by water quenching (WQ) brings about a microstructure that is free from secondary carbides and Ni3Al type precipitates but contains primary carbides. Tensile property of Alloy 693 materials was measured with as received and solution annealed (1323 K, 60 min, WQ) and (1373 K, 30 min, WQ) conditions. Yield strength, ultimate tensile strength (UTS) and hardness of the alloy are found to drop with annealing. It is noted that in annealed condition, considerable cold working of the alloy can be performed.

  3. Enhanced thermoelectric figure-of-merit in p-type nanostructured bismuth antimony tellurium alloys made from elemental chunks.

    PubMed

    Ma, Yi; Hao, Qing; Poudel, Bed; Lan, Yucheng; Yu, Bo; Wang, Dezhi; Chen, Gang; Ren, Zhifeng

    2008-08-01

    By ball milling alloyed bulk crystalline ingots into nanopowders and hot pressing them, we had demonstrated high figure-of-merit in nanostructured bulk bismuth antimony telluride. In this study, we use the same ball milling and hot press technique, but start with elemental chunks of bismuth, antimony, and tellurium to avoid the ingot formation step. We show that a peak ZT of about 1.3 in the temperature range of 75 and 100 degrees C has been achieved. This process is more economical and environmentally friendly than starting from alloyed bulk crystalline ingots. The ZT improvement is caused mostly by the lower thermal conductivity, similar as the case using ingot. Transmission electron microscopy observations of the microstructures suggest that the lower thermal conductivity is mainly due to the increased phonon scattering from the increased grain boundaries of the nanograins, precipitates, nanodots, and defects. Our material also exhibits a ZT of 0.7 at 250 degrees C, similar to the value obtained when ingot was used. This study demonstrates that high ZT values can be achieved in nanostructured bulk materials with ball milling elemental chunks, suggesting that the approach can be applied to other materials that are hard to be made into ingot, in addition to its advantage of lower manufacturing cost. PMID:18624384

  4. Extrusion die geometry effects on the energy absorbing properties and deformation response of 6063-type Al-Mg-Si aluminum alloy

    NASA Astrophysics Data System (ADS)

    Gbenebor, O. P.; Fayomi, O. S. I.; Popoola, A. P. I.; Inegbenebor, A. O.; Oyawale, F.

    The response of 6063-type Al-Mg-Si alloy to deformation via extrusion was studied using tool steel dies with 15°, 30°, 45°, 60° and 75° entry angles. Compressive loads were subjected to each sample using the AVERY DENISON machine, adapted to supply a compressive load on the punch. The ability of the extrudate to absorb energy before fracture was calculated by integrating numerically the polynomial relationship between the compressive stress and sample strains. Strain rate was calculated for each specimen and the deformation zone length was mathematically derived from the die geometry to decipher its influence on both lateral and axial deformations. Results showed that extruding with a 15° die was the fastest as a result of the low flow stress encountered. Outstanding compressive strength, plastic deformation, strain rate and energy absorbing capacity were observed for the alloy extruded with a 75° die angle. Increase in die angles led to a decrease in deformation zone length and samples deformed more in the axial direction than in the lateral except for the 45o die which showed the opposite; the sample also showed the least ductility.

  5. The fractography of casting alloys

    Microsoft Academic Search

    G POWELL

    1994-01-01

    Several types of casting alloys were fractured using various loading modes (uniaxial tension, bending, impact, and torsion, and cyclic stressing), and the corresponding mechanical properties were determined. The unetched and etched fracture surfaces and the microstructures were examined using conventional techniques. The types of casting alloys that were the subjects f these investigations include gray iron, ductile iron, cast steel,

  6. Alloys for crown and bridgework.

    PubMed

    Brockhurst, P J; Cannon, R W

    1981-10-01

    The requirements of alloys for metal-ceramic crowns and bridgework are examined. The functional requirements and manipulative behaviour and cost of cheaper alternatives to high gold alloys are discussed. All types use--high gold, reduced gold, silver palladium and base metal--appear to function satisfactorily in the mouth. Nickel and beryllium do not appear to be health hazards. Dental laboratory procedures and materials must be chosen to suit the type of alloy employed, although all alloy types appear suitable for crown and bridgework. The cost of alloy must be carefully examined in the context of total cost to the patient, and the use of alternatives to gold alloys in many cases may not warrant the required changes to laboratory procedures, but the saving is real, and can make permanent restorations available to greater proportion of the community. PMID:7036968

  7. Influence of shooting angle of polishing particle on surface roughness of a cobalt-chromium alloy using a centrifugal shooting type polishing machine.

    PubMed

    Ono, Takahiro; Ishikawa, Kaori; Yamaba, Osamu; Nokubi, Takashi

    2004-12-01

    The centrifugal shooting type polishing machine is a recently developed apparatus that seeks to improve the efficiency and environment of polishing removable prostheses. In an attempt to optimize the effectiveness of this apparatus, this study examined the influence of the shooting angle of polishing particle on the surface roughness of cobalt-chromium alloy casting specimens. Polishing was performed for three minutes under five shooting angle conditions: 90 degrees, 60 degrees, 45 degrees, 30 degrees, and 15 degrees. Surface roughness (Ra, Sm) was measured after each polishing stage. There were significant differences (p < 0.01) in Ra between shooting angle of 90 degrees (0.95 microm) and shooting angles of 45 degrees (0.62 microm) or less, and in Sm between 90 degrees (207 microm), 60 degrees (350 microm), and shooting angles of 45 degrees (868 microm) or less. These findings indicated that excellent surface texture was produced when shooting angle was 45 degrees or less. PMID:15688732

  8. High temperature low-cycle fatigue of friction welded joints - type 304-304 stainless steel and alloy 718-718 nickel base superalloy

    SciTech Connect

    Wakai, T. (Power Reactor and Nuclear Fuel Development Corp., Ibaraki (Japan). Oarai Engineering Center); Sakane, M.; Ohnami, M. (Ritsumeikan Univ., Kyoto (Japan). Dept. of Mechanical Engineering); Okita, K. (Hyogo Prefectural Inst. of Industrial Research, Miki (Japan). Technical Center for Machinery and Metals); Fukuchi, Y. (Hyogo Prefectural Inst. of Industrial Research, Kobe (Japan))

    1993-01-01

    This paper assesses the high-temperature low-cycle fatigue of the Type 304 stainless steel and Alloy 718 superalloy friction-welded joints. Strain controlled low-cycle fatigue tests for 304-304 and 718-718 friction-welded specimens were carried out at 923 K in air to obtain the fatigue strength of the joints. These materials were selected as the cyclic hardening and softening materials, respectively. The 304-304 welded specimens showed inferior fatigue strength in comparison with the base metal while the 718-718 specimens exhibited fatigue strength equivalent to that of the base metal. The difference in the fatigue strength between the two materials is discussed from the viewpoint of the cyclic deformation behavior and strain reduction at weld interface.

  9. Instability types at ion-assisted alloy deposition: from two-dimensional to three-dimensional nanopattern growth

    E-print Network

    Abrasonis, Gintautas

    2012-01-01

    Ion irradiation during film growth has a strong impact on structural properties. By means of linear stability analysis we demonstrate that ion irradiation of growing binary alloys leads to the formation of composition-modulated surface patterns. We show that the ion-to-atom arrival ratio $R$ is the pattern control parameter. Close to the instability threshold we identify different regimes of instabilities driven by ion-induced surface roughness processes or roughness-composition feedback interactions. In particular, the synergistic effects of the curvature-dependent displacement coupling to the preferential sputtering or to the diffusivity are found to induce instabilities and pattern formation. Depending on the film growth and ion-irradiation conditions the instabilities show stationary or oscillating behavior. The corresponding phase diagrams are presented in terms of experimentally accessible parameters. This presents opportunities to control surface patterning and to grow three-dimensional laterally or ve...

  10. Design and fabrication of a locomotive mechanism for capsule-type endoscopes using shape memory alloys (SMAs)

    Microsoft Academic Search

    Byungkyu Kim; Sunghak Lee; Jong Heong Park; Jong-Oh Park

    2005-01-01

    Endoscopes are medical devices to diagnose various kinds of diseases throughout the whole gastrointestinal tracks. Generally, they are divided into conventional push-type endoscopes and more recently developed wireless capsule-type endoscopes. The conventional endoscopes cannot reach the small intestines and generate pain and discomfort to patients due to the stiffness of their body. Such disadvantages do not exist in wireless capsule-type

  11. Effect of applied potential on changes in solution chemistry inside crevices on type 304L stainless steel and Alloy 825

    SciTech Connect

    Sridhar, N.; Dunn, D.S. [Southwest Research Inst., San Antonio, TX (United States). Center for Nuclear Waste Regulatory Analyses

    1994-12-31

    The changes in the pH, chloride concentration, and potential inside a rectangular crevice of metal against polymethyl methacrylate (PMMA) are monitored using microelectrodes as a function of time and externally applied potential. It is found that the environment inside the crevice is altered within the experimental time frame only when the external potential is maintained above a certain value. When the external potential exceeds a certain value, there is an incubation period followed by a rapid increase in the current density which is succeeded by a decrease in pH and the potential inside the crevice. The current density also decreases rapidly upon reversal of the external potential, while a significant reversal of pH occurs over a much longer period of time. The kinetics of these changes in the environment is a function of crevice tightness. A decrease in crevice gap results in a greater decrease in pH. The changes in chloride concentration are much more modest, perhaps due to the formation of chloride complexes which can not be detected by the Ag/AgCl microelectrode. Presence of chromium depletion on the surface of alloy 825 in the crevice results in a more rapid decrease in pH even when the surface is rougher. These observations are explained in terms of crevice corrosion nucleation in small zones of narrow gap between the peaks of surface asperities which then propagate laterally to adjoining zones of wider gaps between the peaks and valleys of the asperities.

  12. Effect of applied potential on changes in solution chemistry inside crevices on type 304L stainless steel and alloy 825

    SciTech Connect

    Sridhar, N.; Dunn, D.S. (Southwest Research Inst., San Antonio, TX (United States). Center for Nuclear Waste Regulatory Analyses)

    1994-11-01

    Changes in pH, chloride (Cl) concentration, and potential inside a rectangular crevice of metal against polymethyl methacrylate (PMMA) were monitored using microelectrodes as a function of time and externally applied potential. The environment inside the crevice was altered within the experimental time frame only when the external potential was maintained above a certain value. When the external potential exceeded that value, there was an incubation period followed by a rapid increase in current density. This event was succeeded by a decrease in pH and potential inside the crevice. The current density also decreased rapidly upon reversal of the external potential, while a significant reversal of pH occurred over a much longer time. The kinetics of these changes in environment were functions of crevice tightness. A decrease in crevice gap resulted in a greater decrease in pH. Changes in Cl concentration were much more modest, perhaps because of formation of Cl complexes that could not be detected by the silver-silver chloride microelectrode. Chromium depletion on the surface of alloy 825 (UNS N08825) in the crevice resulted in a more rapid decrease in pH even when the surface was rougher. These observations were explained in terms of crevice corrosion nucleation in narrow gaps between peaks of surface asperities, which then propagated laterally to adjoining wider gaps between the peaks and valleys of the asperities.

  13. Alloys based on nickel aluminides

    Microsoft Academic Search

    V. P. Buntushkin; E. N. Kablov; O. A. Bazyleva; G. I. Morozova

    1999-01-01

    The possibility of replacing commercial high-termperature alloys of the ZhS6U type by alloys based on nickel aluminides is\\u000a considered. A complex study of alloys based on nickel aluminide has been conducted with determination of ways to increase\\u000a their ductility, heat-resistance, and strength in a wide range of operating temperatures.

  14. Amorphous metal alloy and composite

    DOEpatents

    Wang, Rong (Richland, WA); Merz, Martin D. (Richland, WA)

    1985-01-01

    Amorphous metal alloys of the iron-chromium and nickel-chromium type have excellent corrosion resistance and high temperature stability and are suitable for use as a protective coating on less corrosion resistant substrates. The alloys are stabilized in the amorphous state by one or more elements of titanium, zirconium, hafnium, niobium, tantalum, molybdenum, and tungsten. The alloy is preferably prepared by sputter deposition.

  15. Effects of Stoichiometry on Transformation Temperatures and Actuator-Type Performance of NiTiPd and NiTiPdX High-Temperature Shape Memory Alloys

    NASA Technical Reports Server (NTRS)

    Bigelow, Glen S.; Gaydosh, Darrell; Garg, Anita; Padula, Santo A., II; Noebe, Ronald D.

    2007-01-01

    High-temperature shape memory NiTiPd and NiTiPdX (X=Au, Pt, Hf) alloys were produced with titanium equivalent (Ti+Hf) compositions of 50.5, 50.0, 49.5, and 49.0 at.%. Thermo-mechanical testing in compression was used to evaluate the transformation temperatures, transformation strain, work output, and permanent deformation behavior of each alloy to study the effects of quaternary alloying and stoichiometry on high-temperature shape memory alloy behavior. Microstructural evaluation showed the presence of second phases for all alloy compositions. No load transformation temperatures in the stoichiometric alloys were relatively unchanged by Au and Pt substitutions, while the substitution of Hf for Ti causes a drop in transformation temperatures. The NiTiPd, NiTiPdAu and NiTiPdHf alloys exhibited transformation temperatures that were highest in the Ti-rich compositions, slightly lower at stoichiometry, and significantly reduced when the Ti equivalent composition was less than 50 at.%. For the NiTiPdPt alloy, transformation temperatures were highest for the Ti-rich compositions, lowest at stoichiometry, and slightly higher in the Ni-rich composition. When thermally cycled under constant stresses of up to 300 MPa, all of the alloys had transformation strains, and therefore work outputs, which increased with increasing stress. In each series of alloys, the transformation strain and thus work output was highest for stoichiometric or Ti-rich compositions while permanent strain associated with the constant-load thermal cycling was lowest for alloys with Ni-equivalent-rich compositions. Based on these results, basic rules for optimizing the composition of NiTiPd alloys for actuator performance will be discussed.

  16. The response of shape memory alloy composites

    Microsoft Academic Search

    Jacob Aboudi

    1997-01-01

    A microstructural model that couples the local and global effects is employed to analyse the behavior of composite materials with shape memory alloy fibers. Both metallic matrices and resin matrix composites with embedded shape memory alloy fibers are considered. Since shape memory alloys form fibers with large diameter, this model is particularly suitable for the analysis of this type of

  17. Dot arrays of L10-type FePt ordered alloy perpendicular films fabricated using low-temperature sputter film deposition

    NASA Astrophysics Data System (ADS)

    Shimatsu, T.; Inaba, Y.; Kataoka, H.; Sayama, J.; Aoi, H.; Okamoto, S.; Kitakami, O.

    2011-04-01

    Using ultrahigh vacuum sputter film deposition, we fabricated L10-type Fe50Pt50 ordered alloy perpendicular films on MgO(001) single-crystal substrates and 2.5 in. glass disks at low substrate temperatures of 200-350 °C. Then we examined the magnetic properties of the dot arrays made from these films. The uniaxial magnetic anisotropy Ku for L10-type FePt films (10 nm in thickness) deposited with a Pd underlayer on MgO(001) substrates reached about 2 × 107 erg/cm3 at the substrate temperature Ts of 200 °C, and 3 × 107 erg/cm3 at Ts = 250 °C. The order parameter S was about 0.46 at Ts = 300 °C. Moreover, Ku for L10-FePt films fabricated on glass disks using MgO/Cr underlayers shows 3.4 × 107 erg/cm3 at Ts = 300 °C, which was almost equal to that for FePt single-crystal films deposited on Pd/MgO(001). The switching field distribution ?/Hc for dot arrays made from L10-FePt film [5 nm in thickness, on Pd/MgO(001) at Ts = 250 °C] was small; ?/Hc = 0.11 for a dot diameter of 15 nm. This value was smaller than that of hcp-Co75Pt25 dot arrays (?/Hc = 0.18). The difference was mainly attributable to the degree of the easy axis distribution. This result demonstrates the homogeneous formation of a L10-type ordered structure in the FePt layers.

  18. Enhanced Thermoelectric Performance of p-Type Bi-Sb-Te Alloys by Codoping with Ga and Ag

    NASA Astrophysics Data System (ADS)

    Lee, Kyu Hyoung; Choi, Soon-Mok; Roh, Jong Wook; Hwang, Sungwoo; Kim, Sang Il; Shin, Weon Ho; Park, Hee Jung; Lee, Jeong Hoon; Kim, Sung Wng; Yang, Dae Jin

    2015-06-01

    We report an enhancement of the thermoelectric performance in spark-plasma-sintered polycrystalline p-type Bi0.42Sb1.58Te3 by codoping with Ga and Ag at Bi/Sb-site. Through controlled doping of Ga ( n-type) and Ag ( p-type), electronic transport properties including the electrical conductivity (~988 S/cm at 300 K) and power factor (~3.91 mW m-1 K-2 at 300 K) could be maintained at values comparable to those of pristine Bi0.42Sb1.58Te3, while the lattice thermal conductivity was significantly reduced due to point-defect phonon scattering originating from the mass difference between the host atoms (Bi and Sb) and dopants (Ga and Ag). Through these synergetic effects, a peak ZT of 1.15 was obtained in Bi0.42Sb1.5535Ga0.025Ag0.0015Te3 at 360 K, and ZT could be engineered to be over 1.0 for a wide temperature range (300 K to 420 K).

  19. Characterization of Newly Developed Semisolid Stir Joining Method for Cast Cu Base Alloy (Cu-Al-Si-Fe) and Effect of Stirrer Type on Uniformity of Microstructure

    NASA Astrophysics Data System (ADS)

    Ferasat, Keyvan; Aashuri, Hossein; Kokabi, Amir Hossein; Nikzad, Siamak; Shafizadeh, Mahdi

    2015-02-01

    In this research, the semisolid stir joining method was used to overcome the problem of hot cracking in welding aluminum and silicon bronzes. Moreover, the effects of grooved and cylindrical tools on the microstructure and mechanical properties of samples were examined. After welding specimens, mechanical tests were carried out to find differences between the cast and welded samples. Optical microscopy and scanning electron microscopy were used to study microstructure. X-ray diffraction was used to investigate compounds formed during casting and welding. The solidus and liquidus temperatures of the alloy were measured by differential scanning calorimetry. In this study, the temperature of the work pieces was raised to 1203 K (930 °C) that is in the semisolid region, and the weld seams were stirred by two different types of tools at the speed of 1600 rpm. Macro and micro-structural analyses show uniformity in the phase distribution for specimens welded by cylindrical tool. Desirable and uniform mechanical properties obtained when the cylindrical tool was used.

  20. Improvement in Fatigue Strength of Biomedical ?-type Ti-Nb-Ta-Zr Alloy While Maintaining Low Young's Modulus Through Optimizing ?-Phase Precipitation

    NASA Astrophysics Data System (ADS)

    Nakai, Masaaki; Niinomi, Mitsuo; Oneda, Takahiro

    2012-01-01

    The improvement in fatigue strength, with maintenance of a low Young's modulus, in a biomedical ?-type titanium alloy, Ti-29Nb-13Ta-4.6Zr (TNTZ), by thermomechanical treatment was investigated. A short aging time at an ?-phase-forming temperature combined with severe cold rolling was employed. A fine ? phase is observed in TNTZ subjected to this thermomechanical treatment. Because the rolling texture of ? phase is formed by cold rolling, such as the ? phase may be preferentially oriented to a direction that is effective for inhibiting the increase in Young's modulus. The samples aged at 573 K (300 °C) for 3.6 ks and 10.8 ks after cold rolling exhibit a good balance between a high tensile strength and low Young's modulus. In the case of the sample aged for 3.6 ks, the tensile strength is improved, although the fatigue strength is not improved significantly. Both the tensile strength and the fatigue strength of the sample aged for 10.8 ks are improved. This fatigue strength is the highest among the TNTZ samples used in the current and in previous studies with Young's moduli less than 80 GPa.

  1. Enhanced thermoelectric performance in p-type BiSbTe bulk alloy with nanoinclusion of ZnAlO

    NASA Astrophysics Data System (ADS)

    Zhang, Ting; Zhang, Qiushi; Jiang, Jun; Xiong, Zhen; Chen, Jianmin; Zhang, Yulong; Li, Wei; Xu, Gaojie

    2011-01-01

    p-type BiSbTe/x wt % ZnAlO (x =0, 0.25, 0.5, 0.75, and 1.0) composites were prepared by zone melting method. A peak thermoelectric figure of merit (ZT) of 1.33 at 370 K was achieved for the sample with x =0.75, about 34% higher than that of BiSbTe at the same temperature, making these composites more attractive for commercial applications. This enhancement of ZT can be mainly ascribed to a remarkable increase of the electrical conductivity and a simultaneous decrease of the lattice thermal conductivity by the introduction of ZnAlO nanopowder.

  2. Enhanced thermoelectric performance in p-type BiSbTe bulk alloy with nanoinclusion of ZnAlO

    SciTech Connect

    Zhang Ting; Zhang Qiushi; Jiang Jun; Xiong Zhen; Chen Jianmin; Zhang Yulong; Li Wei; Xu Gaojie [Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences, Ningbo 315201 (China)

    2011-01-10

    p-type BiSbTe/x wt % ZnAlO (x=0, 0.25, 0.5, 0.75, and 1.0) composites were prepared by zone melting method. A peak thermoelectric figure of merit (ZT) of 1.33 at 370 K was achieved for the sample with x=0.75, about 34% higher than that of BiSbTe at the same temperature, making these composites more attractive for commercial applications. This enhancement of ZT can be mainly ascribed to a remarkable increase of the electrical conductivity and a simultaneous decrease of the lattice thermal conductivity by the introduction of ZnAlO nanopowder.

  3. Synthesis and structure determination of a new series of hydrogen storage alloys; RMg 2Ni 9 (R=La, Ce, Pr, Nd, Sm and Gd) built from MgNi 2 Laves-type layers alternating with AB 5 layers

    Microsoft Academic Search

    K. Kadir; T. Sakai; I. Uehara

    1997-01-01

    A number of new ternary magnesium based alloys, RMg2Ni9 (where R=La, Ce, Pr, Nd, Sm and Gd), have been synthesized by reacting a mixture of MgNi2 with RNi5 intermetallic compounds or by direct combination of the elements in the atomic ratio R:Mg:Ni=1:2:9. The crystal structure, determined by Guinier-Hägg X-ray powder diffraction, is related to the hexagonal PuNi3 type. All interatomic

  4. Compositional short-range ordering in metallic alloys: Band-filling, charge-transfer, and size effects from a first-principles all-electron Landau-type theory

    NASA Astrophysics Data System (ADS)

    Staunton, J. B.; Johnson, D. D.; Pinski, F. J.

    1994-07-01

    Using a mean-field statistical description, we derive a general formalism to investigate atomic short-range order in alloys based on a density-functional description of the finite-temperature, grand potential of the random alloy. This ``first-principles,'' Landau-type approach attempts to treat several contributions (electronic structure, Fermi surface, electrostatics, magnetism, etc.) to the electronic energy on an equal footing. An important ingredient for the statistical averaging is the replacement of the molecular mean fields (Weiss fields) with Onsager cavity fields, which forces the diagonal part of the fluctuation-dissipation theorem to be obeyed. To show its general applicability and usefulness, we apply the theory to three fcc alloy systems. In Cu0.75Pd0.25, the incommensurate atomic short-range order is driven by a Fermi-surface effect, in agreement with earlier work. In contrast, Pd0.5Rh0.5 exhibits clustering tendencies, with both band-filling and charge-rearrangement effects being important in setting the spinodal temperature at 1150 K, in good agreement with experiment. In the final examples of three nickel-rich NiCr alloys, previously ignored electrostatic effects are found to play a significant role in determining the atomic short-range order.

  5. Compositional short-range ordering in metallic alloys: Band-filling, charge-transfer, and size effects from a first-principles all-electron Landau-type theory

    SciTech Connect

    Staunton, J.B. (Department of Physics, University of Warwick, Coventry CV7 4AL (United Kingdom)); Johnson, D.D. (Computational Materials Science Department, Sandia National Laboratories, Livermore, California 94551-0969 (United States)); Pinski, F.J. (Department of Physics, University of Cincinnati, Cincinnati, Ohio 45221-0011 (United States))

    1994-07-15

    Using a mean-field statistical description, we derive a general formalism to investigate atomic short-range order in alloys based on a density-functional description of the finite-temperature, grand potential of the random alloy. This first-principles,'' Landau-type approach attempts to treat several contributions (electronic structure, Fermi surface, electrostatics, magnetism, etc.) to the electronic energy on an equal footing. An important ingredient for the statistical averaging is the replacement of the molecular mean fields (Weiss fields) with Onsager cavity fields, which forces the diagonal part of the fluctuation-dissipation theorem to be obeyed. To show its general applicability and usefulness, we apply the theory to three fcc alloy systems. In Cu[sub 0.75]Pd[sub 0.25], the incommensurate atomic short-range order is driven by a Fermi-surface effect, in agreement with earlier work. In contrast, Pd[sub 0.5]Rh[sub 0.5] exhibits clustering tendencies, with both band-filling and charge-rearrangement effects being important in setting the spinodal temperature at 1150 K, in good agreement with experiment. In the final examples of three nickel-rich NiCr alloys, previously ignored electrostatic effects are found to play a significant role in determining the atomic short-range order.

  6. Alloy development for cladding and duct applications. [LMFBR

    SciTech Connect

    Straalsund, J.L.; Johnson, G.D.

    1981-02-02

    Three general classes of materials under development for cladding and ducts are listed. Solid solution strengthened, or austenitic, alloys are Type 316 stainless steel and D9. Precipitation hardened (also austenitic) alloys consist of D21, D66 and D68. These alloys are similar to such commercial alloys as M-813, Inconel 706, Inconel 718 and Nimonic PE-16. The third general class of alloys is composed of ferritic alloys, with current emphasis being placed on HT-9, a tempered martensitic alloy, and D67, a delta-ferritic steel. The program is comprised of three parallel paths. The current reference, or first generation alloy, is 20% cold worked Type 316 stainless steel. Second generation alloys for near-term applications include D9 and HT-9. Third generation materials consist of the precipitation strengthened steels and ferritic alloys, and are being considered for implementation at a later time than the first and second generation alloys. The development of second and third generation materials was initiated in 1974 with the selection of 35 alloys. This program has proceeded to today where there are six advanced alloys being evaluated. These alloys are the developmental alloys D9, D21, D57, D66 and D68, together with the commerical alloy, HT-9. The status of development of these alloys is summarized.

  7. Effect of chromium content on stress corrosion cracking susceptibility of shielded metal arc weld metals for 600 type alloy in high-temperature pressurised pure water

    Microsoft Academic Search

    Satoru Nishikawa; Yukihiko Horii; Kenji Ikeuchi

    2012-01-01

    The stress corrosion cracking (SCC) susceptibility of SMAW metals for Inconel alloy 600 to which Cr was added to 14.8–21.4 mass% has been investigated on the basis of a creviced bent beam test in pressurized hot water (corresponding to the service condition of boiling water reactor nuclear power plant), since the TIG weld metal of alloy 82 involving 18–22 mass%

  8. Development of the high performance magnesium based hydrogen storage alloy

    Microsoft Academic Search

    Mustafa Anik; Fatma Karanfil; Nilüfer Küçükdeveci

    Series of MgNi type alloys with Ti, Al, Zr, Pd and Co additive elements were synthesized by mechanical alloying and their electrochemical hydrogen storage characteristics were investigated. Systematical alloy designing indicated that Mg0.80Ti0.15Al0.05Zr0.05Ni0.95 alloy has the best electrode performance. The atomic fractions in this alloy were believed to be optimum to get the reasonable amount of hydrogen storage with the

  9. Mechanical Alloying

    Microsoft Academic Search

    J. S. Benjamin

    1976-01-01

    A new technique of combining metals has been developed which overcomes many of the limitations of conventional alloying. Ball mills that generate higher energies than conventional ball mills are used to tumble a mixture of powders, such as WC and Co, in order to form a composite. Ni-base alloys can be dispersion-hardened in this way with an oxide such as

  10. Stress corrosion of high strength aluminum alloys.

    NASA Technical Reports Server (NTRS)

    Cocks, F. H.; Brummer, S. B.

    1972-01-01

    An investigation has been carried out to examine the relationship of the observed chemical and mechanical properties of Al-Cu and Al-Zn-Mg alloys to the stress corrosion mechanisms which dominate in each case. Two high purity alloys and analogous commercial alloys were selected. Fundamental differences between the behavior of Al-Cu and of Al-Zn-Mg alloys were observed. These differences in the corrosion behavior of the two types of alloys are augmented by substantial differences in their mechanical behavior. The relative cleavage energy of the grain boundaries is of particular importance.

  11. [Composition and morphology of oxides on porcelain fused to Ni-Cr alloys. Be containing alloys].

    PubMed

    Watanabe, T

    1989-06-01

    Bonding strength between porcelain and Ni-Cr alloy for the porcelain fused-to metal crown in which Be is contained in the alloy is known to be higher than those in which Be is not contained. Since, bonding between porcelain and alloy is the reaction of oxides and porcelain, the bonding is thought to be influenced by the quality the oxides film which forms on the alloy surface. The purpose of this study was to determine the composition and morphology of the oxides formed on both Be containing and non-Be contained Ni-Cr alloys. The oxides analysis was done using an EPMA and Auger analysis. Also, the Porcelain/Ni-Cr alloy interface was observed by a scanning electron microscope (SEM). The following results are indicated from this investigation: 1. The oxides from the alloys not containing Be are corundum type Cr2O3 and spinel type NiCr2O4. These oxide layers are uniform, thick and porous and the adhesion to alloy is poor. 2. The oxides from alloy containing Be is BeO only. The BeO is uniform, thin and condensed. The adhesion to the alloy is good. 3. The oxide layer formed when the porcelain is fused to alloy containing Be is thin (1 micron average) and has good adhesion to alloy. 4. Be is selectively oxidized and controlled the form of Cr2O3 and NiO. PMID:2700282

  12. Precipitates in Biomedical Co-Cr Alloys

    NASA Astrophysics Data System (ADS)

    Narushima, Takayuki; Mineta, Shingo; Kurihara, Yuto; Ueda, Kyosuke

    2013-04-01

    Herein, precipitates in biomedical Co-Cr-Mo and Co-Cr-W-Ni alloys are reviewed with a focus on their phase, chemical composition, morphology, and formation/dissolution during heat treatment. The effects of the heat-treatment conditions and the addition of minor alloying elements such as carbon, nitrogen, Si, and Mn on the precipitates are also discussed. Mostly, the precipitates in the alloys are of the ?-phase, M23X6-type phase, ?-phase (M6X-M12X type), ?-phase (M2T3X type), ?-phase, M7X3-type phase, or M2X-type phase (M and T refer to metallic elements, and X refers to carbon and/or nitrogen); the ?- and ?-phases are intermetallic compounds, and the others are carbides, nitrides, and carbonitrides. The dissolution of the precipitates during solution treatment is delayed by the formation of the ?-phase at temperatures where partial melting occurs in the alloys. In addition, the stability of the precipitates depends on the content of minor alloying elements. For example, the addition of carbon enhances the formation of M23X6-type and M7X3-type precipitates. Nitrogen stabilizes the M2X-type, ?-phase, and ?-phase precipitates, and Si stabilizes the ?-phase and ?-phase precipitates. The balance between the minor alloying element abundances also affects the constitution of the precipitates in Co-Cr alloys.

  13. Effect of a microstructure and surface hydrogen alloying of a VT6 alloy on diffusion welding

    NASA Astrophysics Data System (ADS)

    Senkevich, K. S.; Skvortsova, S. V.; Kudelina, I. M.; Knyazev, M. I.; Zasypkin, V. V.

    2014-01-01

    The effect of a structural type (lamellar, fine, gradient) and additional surface alloying with hydrogen on the diffusion bonding of titanium alloy VT6 samples is studied. It is shown that the surface alloying of VT6 alloy parts with hydrogen allows one to decrease the diffusion welding temperature by 50-100°C, to obtain high-quality pore-free bonding, and to remove the "structural" boundary between materials to be welded that usually forms during welding of titanium alloys with a lamellar structure.

  14. Bond Strength of Gold Alloys Laser Welded to Cobalt-Chromium Alloy

    PubMed Central

    Watanabe, Ikuya; Wallace, Cameron

    2008-01-01

    The objective of this study was to investigate the joint properties between cast gold alloys and Co-Cr alloy laser-welded by Nd:YAG laser. Cast plates were fabricated from three types of gold alloys (Type IV, Type II and low-gold) and a Co-Cr alloy. Each gold alloy was laser-welded to Co-Cr using a dental laser-welding machine. Homogeneously-welded and non-welded control specimens were also prepared. Tensile testing was conducted and data were statistically analyzed using ANOVA. The homogeneously-welded groups showed inferior fracture load compared to corresponding control groups, except for Co-Cr. In the specimens welded heterogeneously to Co-Cr, Type IV was the greatest, followed by low-gold and Type II. There was no statistical difference (P<0.05) in fracture load between Type II control and that welded to Co-Cr. Higher elongations were obtained for Type II in all conditions, whereas the lowest elongation occurred for low-gold welded to Co-Cr. This study indicated that, of the three gold alloys tested, the Type IV gold alloy was the most suitable alloy for laser-welding to Co-Cr. PMID:19088892

  15. Near-forward Raman scattering by bulk and surface phonon-polaritons in the model percolation-type ZnBeSe alloy

    NASA Astrophysics Data System (ADS)

    Hajj Hussein, R.; Pagès, O.; Firszt, F.; Paszkowicz, W.; Maillard, A.

    2013-08-01

    We study the bulk and surface phonon-polaritons of the Zn0.67Be0.33Se zincblende alloy by near-forward Raman scattering. The short (Be-Se) bond exhibits a distinct percolation doublet in the conventional backscattering Raman spectra, corresponding to a three-mode behavior in total [1×(Zn-Se), 2×(Be-Se)] for Zn0.67Be0.33Se. This offers an opportunity to achieve a refined understanding of the phonon-polariton modes of a zincblende alloy beyond the current two-mode approximation, corresponding to a [1×(Zn-Se), 1×(Be-Se)] description in the present case. The discussion is supported by contour modeling of the Raman signals of the multi-mode bulk and surface phonon-polaritons within the formalism of the linear dielectric response.

  16. First-principle investigation of electronic structure, magnetism and phase stability of Heusler-type Pt2-xMn1+xGa alloys

    NASA Astrophysics Data System (ADS)

    Feng, L.; Liu, E. K.; Zhang, W. X.; Wang, W. H.; Wu, G. H.

    2015-03-01

    The electronic structure, magnetism and phase stability of Pt2-xMn1+xGa (x=0, 0.25, 0.5, 0.75, 1) alloys are studied by first-principle calculations. The calculations reveal that a potential magnetic martensitic transformation can be expected in all the series. In addition, a large magnetic-field-induced strain is likely to appear in Pt2-xMn1+xGa (x=0, 0.25, 0.75, 1) alloys. The electronic structure calculations indicate that the tetragonal phase is stabilized upon the distortion because of the pseudogap formation at the Fermi Level. The magnetic structure is also investigated and the total magnetic moment of the tetragonal phase is a little larger than that of the cubic austenite phase in all the series.

  17. Comparison of Three Primary Surface Recuperator Alloys

    SciTech Connect

    Matthews, Wendy [Capstone Turbines; More, Karren Leslie [ORNL; Walker, Larry R [ORNL

    2010-01-01

    Extensive work performed by Capstone Turbine Corporation, Oak Ridge National Laboratory, and various others has shown that the traditional primary surface recuperator alloy, type 347 stainless steel, is unsuitable for applications above 650 C ({approx}1200 F). Numerous studies have shown that the presence of water vapor greatly accelerates the oxidation rate of type 347 stainless steel at temperatures above 650 C ({approx}1200 F). Water vapor is present as a product of combustion in the microturbine exhaust, making it necessary to find replacement alloys for type 347 stainless steel that will meet the long life requirements of microturbine primary surface recuperators. It has been well established over the past few years that alloys with higher chromium and nickel contents than type 347 stainless steel have much greater oxidation resistance in the microturbine environment. One such alloy that has replaced type 347 stainless steel in primary surface recuperators is Haynes Alloy HR-120 (Haynes and HR-120 are trademarks of Haynes International, Inc.), a solid-solution-strengthened alloy with nominally 33 wt % Fe, 37 wt % Ni and 25 wt % Cr. Unfortunately, while HR-120 is significantly more oxidation resistant in the microturbine environment, it is also a much more expensive alloy. In the interest of cost reduction, other candidate primary surface recuperator alloys are being investigated as possible alternatives to type 347 stainless steel. An initial rainbow recuperator test has been performed at Capstone to compare the oxidation resistance of type 347 stainless steel, HR-120, and the Allegheny Ludlum austenitic alloy AL 20-25+Nb (AL 20-25+Nb is a trademark of ATI Properties, Inc. and is licensed to Allegheny Ludlum Corporation). Evaluation of surface oxide scale formation and associated alloy depletion and other compositional changes has been carried out at Oak Ridge National Laboratory. The results of this initial rainbow test will be presented and discussed in this paper.

  18. Strength and fracture of aluminum alloys

    Microsoft Academic Search

    T Kobayashi

    2000-01-01

    In aluminum alloys, it is general that dimple type fracture occurs from inclusions or second phases particles. Intergranular, local shear and delamination type fractures are also sometimes observed. On Al–Li alloy (A2091), effect of inclusion particles on fracture behavior is analyzed using HRR singularity and Eshelby type internal stress analysis. Fracture of inclusions of CuAl2 and Al2CuMg is observed (5–8

  19. Welding and brazing of nickel and nickel-base alloys

    NASA Technical Reports Server (NTRS)

    Mortland, J. E.; Evans, R. M.; Monroe, R. E.

    1972-01-01

    The joining of four types of nickel-base materials is described: (1) high-nickel, nonheat-treatable alloys, (2) solid-solution-hardening nickel-base alloys, (3) precipitation-hardening nickel-base alloys, and (4) dispersion-hardening nickel-base alloys. The high-nickel and solid-solution-hardening alloys are widely used in chemical containers and piping. These materials have excellent resistance to corrosion and oxidation, and retain useful strength at elevated temperatures. The precipitation-hardening alloys have good properties at elevated temperature. They are important in many aerospace applications. Dispersion-hardening nickel also is used for elevated-temperature service.

  20. VAl Alloy

    NASA Astrophysics Data System (ADS)

    Mikami, M.; Mizoshiri, M.; Ozaki, K.; Takazawa, H.; Yamamoto, A.; Terazawa, Y.; Takeuchi, T.

    2014-06-01

    Power generation performance of a thermoelectric module consisting of the Heusler Fe2VAl alloy was evaluated. For construction of the module, W-doped Fe2VAl alloys were prepared using powder metallurgy process. Power generation tests of the module consisting of 18 pairs of p- n junctions were conducted on a heat source of 373-673 K in vacuum. The reduction of thermal conductivity and improvement of thermoelectric figure of merit by W-doping enhanced the conversion efficiency and the output power. High output power density of 0.7 W/cm2 was obtained by virtue of the high thermoelectric power factor of the Heusler alloy. The module exhibited good durability, and the relatively high output power was maintained after temperature cycling test in air.

  1. Tritium Production from Palladium Alloys

    SciTech Connect

    Claytor, T.N.; Schwab, M.J.; Thoma, D.J.; Teter, D.F.; Tuggle, D.G.

    1998-04-19

    A number of palladium alloys have been loaded with deuterium or hydrogen under low energy bombardment in a system that allows the continuous measurement of tritium. Long run times (up to 200 h) result in an integration of the tritium and this, coupled with the high intrinsic sensitivity of the system ({approximately}0.1 nCi/l), enables the significance of the tritium measurement to be many sigma (>10). We will show the difference in tritium generation rates between batches of palladium alloys (Rh, Co, Cu, Cr, Ni, Be, B, Li, Hf, Hg and Fe) of various concentrations to illustrate that tritium generation rate is dependent on alloy type as well as within a specific alloy, dependent on concentration.

  2. Imparting passivity to vapor deposited magnesium alloys

    NASA Astrophysics Data System (ADS)

    Wolfe, Ryan C.

    Magnesium has the lowest density of all structural metals. Utilization of low density materials is advantageous from a design standpoint, because lower weight translates into improved performance of engineered products (i.e., notebook computers are more portable, vehicles achieve better gas mileage, and aircraft can carry more payload). Despite their low density and high strength to weight ratio, however, the widespread implementation of magnesium alloys is currently hindered by their relatively poor corrosion resistance. The objective of this research dissertation is to develop a scientific basis for the creation of a corrosion resistant magnesium alloy. The corrosion resistance of magnesium alloys is affected by several interrelated factors. Among these are alloying, microstructure, impurities, galvanic corrosion effects, and service conditions, among others. Alloying and modification of the microstructure are primary approaches to controlling corrosion. Furthermore, nonequilibrium alloying of magnesium via physical vapor deposition allows for the formation of single-phase magnesium alloys with supersaturated concentrations of passivity-enhancing elements. The microstructure and surface morphology is also modifiable during physical vapor deposition through the variation of evaporation power, pressure, temperature, ion bombardment, and the source-to-substrate distance. Aluminum, titanium, yttrium, and zirconium were initially chosen as candidates likely to impart passivity on vapor deposited magnesium alloys. Prior to this research, alloys of this type have never before been produced, much less studied. All of these metals were observed to afford some degree of corrosion resistance to magnesium. Due to the especially promising results from nonequilibrium alloying of magnesium with yttrium and titanium, the ternary magnesium-yttrium-titanium system was investigated in depth. While all of the alloys are lustrous, surface morphology is observed under the scanning electron microscope. The corrosion rate of the nonequilibrium sputtered alloys, as determined by polarization resistance, is significantly reduced compared to the most corrosion resistant commercial magnesium alloys. The open circuit potentials of the sputter deposited alloys are significantly more noble compared to commercial, equilibrium phase magnesium alloys. Galvanic corrosion susceptibility has also been considerably reduced. Nonequilibrium magnesium-yttrium-titanium alloys have been shown to achieve passivity autonomously by alteration of the composition chemistry of the surface oxide/hydroxide layer. Self-healing properties are also evident, as corrosion propagation can be arrested after initial pitting of the material. A clear relationship exists between the corrosion resistance of sputter vapor deposited magnesium alloys and the amount of ion bombardment incurred by the alloy during deposition. Argon pressure, the distance between the source and the substrate, and alloy morphology play important roles in determining the ability of the alloy to develop a passive film. Thermal effects, both during and after alloy deposition, alter the stress state of the alloys, precipitation of second phases, and the mechanical stability of the passive film. An optimal thermal treatment has been developed in order to maximize the corrosion resistance of the magnesium-yttrium-titanium alloys. The significance of the results includes the acquisition of electrochemical data for these novel materials, as well as expanding the utilization of magnesium alloys by the improvement in their corrosion resistance. The magnesium alloys developed in this work are more corrosion resistant than any commercial magnesium alloy. Structural components comprised of these alloys would therefore exhibit unprecedented corrosion performance. Coatings of these alloys on magnesium components would provide a corrosion resistant yet galvanically-compatible coating. The broad impact of these contributions is that these new low-density, corrosion resistant magnesium alloys can be used to produce engine

  3. Alloys of clathrate allotropes for rechargeable batteries

    DOEpatents

    Chan, Candace K; Miller, Michael A; Chan, Kwai S

    2014-12-09

    The present disclosure is directed at an electrode for a battery wherein the electrode comprises clathrate alloys of silicon, germanium or tin. In method form, the present disclosure is directed at methods of forming clathrate alloys of silicon, germanium or tin which methods lead to the formation of empty cage structures suitable for use as electrodes in rechargeable type batteries.

  4. New alloys to conserve critical elements

    NASA Technical Reports Server (NTRS)

    Stephens, J. R.

    1978-01-01

    Based on availability of domestic reserves, chromium is one of the most critical elements within the U.S. metal industry. New alloys having reduced chromium contents which offer potential as substitutes for higher chromium containing alloys currently in use are being investigated. This paper focuses primarily on modified Type 304 stainless steels having one-third less chromium, but maintaining comparable oxidation and corrosion properties to that of type 304 stainless steel, the largest single use of chromium. Substitutes for chromium in these modified Type 304 stainless steel alloys include silicon and aluminum plus molybdenum.

  5. Orthodontic silver brazing alloys.

    PubMed

    Brockhurst, P J; Pham, H L

    1989-10-01

    Orthodontic silver brazing alloys suffer from the presence of cadmium, excessive flow temperatures, and crevice corrosion on stainless steel. Seven alloys were examined. Two alloys contained cadmium. The lowest flow temperature observed was 629 degrees C for a cadmium alloy and 651 degrees C for two cadmium free alloys. Three alloys had corrosion resistance superior to the other solders. Addition of low melting temperature elements gallium and indium reduced flow temperature in some cases but produced brittleness in the brazing alloy. PMID:2576971

  6. The response of shape memory alloy composites

    NASA Astrophysics Data System (ADS)

    Aboudi, Jacob

    1997-02-01

    A microstructural model that couples the local and global effects is employed to analyse the behavior of composite materials with shape memory alloy fibers. Both metallic matrices and resin matrix composites with embedded shape memory alloy fibers are considered. Since shape memory alloys form fibers with large diameter, this model is particularly suitable for the analysis of this type of smart composite material where the coupling between the microstructural details and the macrostructure of the composite must be incorporated. Results are given that exhibit the response of composites with embedded shape memory alloy fibers in various circumstances.

  7. Castability, opaque masking, and porcelain bonding of 17 porcelain-fused-to-metal alloys.

    PubMed

    O'Connor, R P; Mackert, J R; Myers, M L; Parry, E E

    1996-04-01

    Seventeen porcelain-fused-to-metal alloys, which represented a cross section of the various alloy types available, were evaluated for castability, opaque masking, and porcelain bond strength. The base metal alloys generally cast more completely than the noble alloys, with the presence of beryllium as an important factor for greater castability among the base metal alloys. Statistically significant differences were observed in the ability of an opaque porcelain to mask the different alloy substrates but no systematic effect of alloy type was observed. Porcelain bond testing revealed that nickel-chromium-beryllium alloys produced significantly better porcelain-metal bonds than nickel-chromium alloys without beryllium. In addition, it was found that palladium-copper alloys produced significantly better bonds with porcelain than palladium-cobalt alloys. PMID:8642521

  8. Internal oxidation and carburisation of heat-resistant alloys

    Microsoft Academic Search

    M. Hänsel; C. A. Boddington; D. J. Young

    2003-01-01

    The commercial alloys Nicrofer-HT, Alloy 800 and Type 304 stainless steel have been exposed under thermal cycling conditions to CO–CO2 gas mixtures at temperatures of 650–750 °C. Thermal cycling led to repeated scale spallation which accelerated chromium depletion from the alloy subsurface regions. Subsequent dissolution of carbon and oxygen into the alloys led to extensive internal precipitation of carbides and

  9. Advanced cutting conditions for the milling of aeronautical alloys

    Microsoft Academic Search

    L. N López de lacalle; J Pérez; J. I Llorente; J. A Sánchez

    2000-01-01

    This paper deals with possible improvement aspects on the chip cutting milling of two alloys that are used frequently in the aerospace industry, in particular the titanium alpha–beta-based alloy Ti6Al4V and the nickel alloy usually known as type 718. Both alloys are used widely in the manufacture of different turbo-engine parts, considering their excellent mechanic features, and their resistance to

  10. The Development of the Low-Cost Titanium Alloy Containing Cr and Mn Alloying Elements

    NASA Astrophysics Data System (ADS)

    Zhu, Kailiang; Gui, Na; Jiang, Tao; Zhu, Ming; Lu, Xionggang; Zhang, Jieyu; Li, Chonghe

    2014-04-01

    The ? + ?-type Ti-4.5Al-6.9Cr-2.3Mn alloy has been theoretically designed on the basis of assessment of the Ti-Al-Cr-Mn thermodynamic system and the relationship between the molybdenum equivalent and mechanical properties of titanium alloys. The alloy is successfully prepared by the split water-cooled copper crucible, and its microstructures and mechanical properties at room temperature are investigated using the OM, SEM, and the universal testing machine. The results show that the Ti-4.5Al-6.9Cr-2.3Mn alloy is an ? + ?-type alloy which is consistent with the expectation, and its fracture strength, yield strength, and elongation reach 1191.3, 928.4 MPa, and 10.7 pct, respectively. Although there is no strong segregation of alloying elements under the condition of as-cast, the segregation of Cr and Mn is obvious at the grain boundary after thermomechanical treatment.

  11. High-resolution soft x-ray photoelectron study of density of states and thermoelectric properties of the Heusler-type alloys (Fe2/3V1/3)100-yAly

    NASA Astrophysics Data System (ADS)

    Soda, K.; Murayama, H.; Shimba, K.; Yagi, S.; Yuhara, J.; Takeuchi, T.; Mizutani, U.; Sumi, H.; Kato, M.; Kato, H.; Nishino, Y.; Sekiyama, A.; Suga, S.; Matsushita, T.; Saitoh, Y.

    2005-06-01

    The high-resolution soft x-ray photoelectron study of Heusler(L21) -type (Fe2/3V1/3)100-yAly (y=23.8-25.8) alloys directly confirms the correlation between their thermoelectric properties and the electronic structures near the Fermi level. It shows the rigid-band-like shift of the main 3d bands and the increase of the photoelectron intensity at the Fermi edge with the small deviation of the Al content from stoichiometry, i.e., y=25.0 . This implies the existence of the pseudogap across the Fermi level in Fe2VAl . The Seebeck coefficients evaluated from the present spectroscopic data agree well with the experimental ones as well as the values estimated from a theoretical density of states in a rigid-band model, while the shift is much smaller than what is expected in the rigid-band model. The small modification of the electronic structure in the off-stoichiometric (Fe2/3V1/3)100-yAly alloys may be attributed to the lower contribution of Al to the electronic states near EF .

  12. High-resolution electron microscopy analysis of structural defects in a (2/1, 5/3)-type approximant of a decagonal quasicrystal of an Al-Pd-Mn alloy

    SciTech Connect

    Yu, D.P.; Ren, G.; Zhang, Z. [Chinese Academy of Sciences, Beijing (China). Beijing Lab. of Electron Microscopy

    1996-10-01

    Structural defects were analyzed by means of high-resolution electron microscopy (HREM) in a crystalline (2/1, 5/3)-type Fibonacci approximant of an Al-Pd-Mn alloy system. A kind of stacking fault is observed with a projected displacement vector R parallel to the [{minus}3 0 29] direction; its amplitude {vert_bar}R{vert_bar} = 2a sin 18 deg = 1.19 nm, and its habit plane lies in the (1 0 1) plane. Two kinds of domain boundaries have been found and the domains are related by a 180 deg rotation around the c-axis plus a displacement along the [3 0 {minus}29] or the [{minus}3 0 {minus}29] direction in a plane perpendicular to the b-axis. The domain boundary planes are the {l_brace}1 0 1{r_brace} planes.

  13. Anomalous physical properties of Heusler-type Co2Cr (Ga,Si) alloys and thermodynamic study on reentrant martensitic transformation

    NASA Astrophysics Data System (ADS)

    Xu, Xiao; Nagasako, Makoto; Kataoka, Mitsuo; Umetsu, Rie Y.; Omori, Toshihiro; Kanomata, Takeshi; Kainuma, Ryosuke

    2015-03-01

    Electronic, magnetic, and thermodynamic properties of Co2Cr(Ga,Si) -based shape-memory alloys, which exhibit reentrant martensitic transformation (RMT) behavior, were studied experimentally. For electric resistivity (ER), an inverse (semiconductor-like) temperature dependence in the parent phase was found, along with anomalous behavior below its Curie temperature. A pseudobinary phase diagram was determined, which gives a "martensite loop" clearly showing the reentrant behavior. Differential scanning calorimetry and specific-heat measurements were used to derive the entropy change ? S between martensite and parent phases. The temperature dependence of the derived ? S was analyzed thermodynamically to confirm the appearances of both the RMT and normal martensitic transformation. Detailed studies on the specific heat in martensite and parent phases at low temperatures were also conducted.

  14. Superplastic behavior in a commercial 5083 aluminum alloy

    Microsoft Academic Search

    J. S. Vetrano; C. A. Lavender; M. T. Smith; S. M. Bruemmer; C. H. Hamilton

    1994-01-01

    When considering the forming and post-forming properties required of a superplastic material, attractive candidates are commercial Al-Mg-Mn weldable alloys such as AA5083. There have been several investigations of hot deformation of 5083-type alloys in the literature. Only two studies evaluated commercial-purity 5083 and they achieved tensile elongations of 150% and 200%. Alloy modification has produced improved behavior in three 5083-type

  15. Problems of the strength of welded joints in niobium and its alloys

    Microsoft Academic Search

    S. M. Gurevich; M. M. Nerodenko; E. A. Asnis; S. V. Smirnov; M. D. Rabkina

    1973-01-01

    Translated from Probl. Prochnosti; 5: No. 1, 112-114(Jan 1973). The ; static and fatigue strength of welded joints of niobium and its alloys were ; investigated. The experimental materials (sheets 2 mm thick) included technical ; grade niobium, a hardened solidsolution type alloy Nb--W--Mo--Zr (alloy 1), and a ; dispersionhardening alloy Nb--Zr--C (alloy 2). All these materials were used in

  16. Alloyed junction Ge Esaki diodes on Si substrates realised by aspect ratio trapping

    E-print Network

    Rommel, Sean

    Alloyed junction Ge Esaki diodes on Si substrates realised by aspect ratio trapping technique D-type junction and a controlled alloyed reaction of Al and Ge forms the p-type junction. At an alloy temperature trenches with a thickness of 825 nm above the oxide, which exhibits a rough surface. Coalescence defects

  17. The Chloride Corrosion of Low-Gold Casting Alloys

    Microsoft Academic Search

    N. K. Sarkar; R. A. Fuys; J. W. Stanford

    1979-01-01

    Potentiodynamic polarization measurements have indicated that the so-called 'low-gold' casting alloys are characterized by decreased chloride corrosion resistance, when compared with ADA Type III and Type IV gold alloys. This decrease in chloride corrosion resistance results apparently from the presence of Ag-rich microsegregations with a possible minor contribution from Curich segregations or precipitates.

  18. On the Origin of the Heavy-Fermion-Like Behavior of the Heusler-Type Fe3-xVxM (M=Al,Ga) Alloys

    NASA Astrophysics Data System (ADS)

    Deniszczyk, J.

    2001-02-01

    The electronic structure of {Fe3-xVxM} (M=Al, Ga) alloys was investigated by ab initio method. Magnetic and non-magnetic band structure of {Fe3-xVxM} was calculated for concentrations x=0.0-1.0. Calculations have shown that the transition from magnetic to non-magnetic state is accompanied by the qualitative changes in the band structure in the vicinity of the Fermi level ({\\varepsilon F}). For concentrations 0.5? x? 1 the Density Of States (DOS) at {\\varepsilon F} in both magnetic states display a sharp peak composed solely of the 3d states of impurity Fe-AS atom ( Fe atom at nominally V atom position of {Fe2VAl} Heusler compound). In the magnetic state only majority-spin states enter the DOS near {\\varepsilon F}. The quasi-gap around the {\\varepsilon F} found in {Fe2VM} is filled up by 3d states of Fe-AS which produce the sharp structures at {\\varepsilon F}. Transition to the non-magnetic state results in the narrowing and strengthening of the peak of Fe-AS 3d-states DOS at {\\varepsilon F} and the opening of the well-defined gap just above the Fermi level. The changes of the DOS around {\\varepsilon F} connected with the variation of Fe-AS concentration and magnetic transition explain the peculiar behavior of the electrical resistivity observed experimentally.

  19. Metal alloy identifier

    DOEpatents

    Riley, William D. (Avondale, MD); Brown, Jr., Robert D. (Avondale, MD)

    1987-01-01

    To identify the composition of a metal alloy, sparks generated from the alloy are optically observed and spectrographically analyzed. The spectrographic data, in the form of a full-spectrum plot of intensity versus wavelength, provide the "signature" of the metal alloy. This signature can be compared with similar plots for alloys of known composition to establish the unknown composition by a positive match with a known alloy. An alternative method is to form intensity ratios for pairs of predetermined wavelengths within the observed spectrum and to then compare the values of such ratios with similar values for known alloy compositions, thereby to positively identify the unknown alloy composition.

  20. Structural studies of secondary crystallization products of the Fe23B6-type in a nanocrystalline FeCoB-based alloy

    E-print Network

    Laughlin, David E.

    Structural studies of secondary crystallization products of the Fe23B6-type in a nanocrystalline FeCo and 740 °C, respectively. After annealing the sample at 820 °C for 1 h, a Fe23B6-type phase FeCoNb 23B6 consist of nanometer size -FeSi DO3 FineMet ,1 -Fe bcc NANOPERM ,2 and -FeCo B2 HITPERM Ref. 3 grains

  1. Effects of Alloy Disorder on Schottky-Barrier Heights

    E-print Network

    MYLES, CW; REN, SF; Allen, Roland E.; REN, SY.

    1987-01-01

    minus the lowest empty defect level for n-type material, and the highest oc- cupied defect level minus the valence-band edge for p-type material) which results from these calculations is shown (straight thick lines) in Fig. 1 for the alloys Al& Ga... of alloy disorder on Schottky-barrier heights may be large enough to be ob- servable. We predict, for example, relatively large alloy- disorder effects in GaAs& Sb . In the calculations of Allen et al. , the alloy host was treated in the virtual...

  2. Alloy 33 weld overlay extends boiler tube life and saves money

    SciTech Connect

    Paul, L.; Clark, G.; Ossenberg-Engels, A. [ThyssenKrupp VDM (United States)

    2007-09-15

    Low-NOx burners installed in coal-fired utility boilers cause problems with boiler tube cracking. Materials with increased corrosion resistance such as the new Alloy 33 should be more resistant to this type of 'circumferential cracking'. Alloy 33 is cheaper and has lower nickel and molybdenum content than the traditional Alloy 622 and 625. The article describes extensive corrosion testing experiments carried out by ThyssenKrupp VDM on Alloy 33 and Alloy 622. In the lab, in environments representative of coal-fired boilers operating under low-NOx combustion conditions, Alloy 33 was found to be better than Alloy 622. Field tests compared Alloy 33 and Alloy 622 in two supercritical tangentially-fired boilers and one tangentially-fired high pressure drum boiler. After up to 23 months of exposure there was no evidence of cracks and only slight evidence of corrosion in Alloy 33. 1 fig., 2 tabs., 2 photos.

  3. Resistance Butt Welding of Zirconium Alloy Material

    Microsoft Academic Search

    D. S. Setty; Reddy P. Ravinder; A. L. N. Murthy

    2008-01-01

    Zirconium alloy is the main structural material used in the nuclear fuel production. This material has distinct advantages like less thermal neutron absorption cross-section and better chemical and mechanical properties for the reactor-working conditions. This material is widely used in boiling water and heavy water type reactors. Natural Uranium Dioxide (UO2) pellets are loaded into thin wall zirconium alloy tubes

  4. Hydrogen diffusion in Al-Li alloys

    Microsoft Academic Search

    P. N. Anyalebechi

    1990-01-01

    The diffusion coefficients of hydrogen in binary Al-Li alloys containing 1,2, and 3 wt pct Li have been determined from desorption curves of samples saturated with hydrogen at 473 to 873 K. Within this temperature range, the diffusivity of hydrogen in the binary Al-Li alloys investigated has an Arrhenius-type temperature dependence and follows the equation of the general form D

  5. Hydrogen diffusion in Al-Li alloys

    Microsoft Academic Search

    P. N. Anyalebechi

    1990-01-01

    The diffusion coefficients of hydrogen in binary Al-Li alloys containing 1,2, and 3 wt pct Li have been determined from desorption\\u000a curves of samples saturated with hydrogen at 473 to 873 K. Within this temperature range, the diffusivity of hydrogen in the\\u000a binary Al-Li alloys investigated has an Arrhenius-type temperature dependence and follows the equation of the general formD =

  6. Biocompatibility of dental casting alloys.

    PubMed

    Geurtsen, Werner

    2002-01-01

    Most cast dental restorations are made from alloys or commercially pure titanium (cpTi). Many orthodontic appliances are also fabricated from metallic materials. It has been documented in vitro and in vivo that metallic dental devices release metal ions, mainly due to corrosion. Those metallic components may be locally and systemically distributed and could play a role in the etiology of oral and systemic pathological conditions. The quality and quantity of the released cations depend upon the type of alloy and various corrosion parameters. No general correlation has been observed between alloy nobility and corrosion. However, it has been documented that some Ni-based alloys, such as beryllium-containing Ni alloys, exhibit increased corrosion, specifically at low pH. Further, microparticles are abraded from metallic restorations due to wear. In sufficient quantities, released metal ions-particularly Cu, Ni, Be, and abraded microparticles-can also induce inflammation of the adjacent periodontal tissues and the oral mucosa. While there is also some in vitro evidence that the immune response can be altered by various metal ions, the role of these ions in oral inflammatory diseases such as gingivitis and periodontitis is unknown. Allergic reactions due to metallic dental restorations have been documented. Ni has especially been identified as being highly allergenic. Interestingly, from 34% to 65.5% of the patients who are allergic to Ni are also allergic to Pd. Further, Pd allergy always occurrs with Ni sensitivity. In contrast, no study has been published which supports the hypothesis that dental metallic materials are mutagenic/genotoxic or might be a carcinogenic hazard to man. Taken together, very contradictory data have been documented regarding the local and systemic effects of dental casting alloys and metallic ions released from them. Therefore, it is of critical importance to elucidate the release of cations from metallic dental restorations in the oral environment and to determine the biological interactions of released metal components with oral and systemic tissues. PMID:12097239

  7. Electrochemical And Hydrogen Sorption Properties of Ab 5 —Type Alloys Where A — La, Ce; B — Ni, Co, Mn, Fe, Cu, Cr, Al

    Microsoft Academic Search

    T. A. Zotov; I. A. Romanov; S. V. Mitrokhin; V. N. Verbetsky; O. A. Pertii

    Like other accumulator types Ni-MH batteries are unable to keep high characteristics in the temperature range ?30°C to +40°C.\\u000a To solve this problem the negative electrode material — intermetallic compound (IMC) hydride — must have dissociation pressure\\u000a of 0.1–1.5 atm in this temperature interval. The IMC composition was calculated with mathematic model. The model describes\\u000a dependence of IMC hydrides properties

  8. Thermal and transport properties of the Heusler-type Fe2VAl1-xGex(0?x?0.20) alloys: Effect of doping on lattice thermal conductivity, electrical resistivity, and Seebeck coefficient

    NASA Astrophysics Data System (ADS)

    Nishino, Y.; Deguchi, S.; Mizutani, U.

    2006-09-01

    We report on the thermoelectric properties of the Heusler-type Fe2VAl1-xGex alloys with compositions 0?x?0.20 . While Fe2VAl(x=0) exhibits a semiconductorlike behavior in electrical resistivity, a slight substitution of Ge for Al causes a significant decrease in the low-temperature resistivity and a large enhancement in the Seebeck coefficient, reaching -130?V/K for x=0.05 at around room temperature. Comparison with the Fe2VAl1-xSix system demonstrates that the compositional variation of the Seebeck coefficient falls on a universal curve irrespective of the doping elements (Ge and Si), both of which are isoelectronic elements. The net effect of doping is most likely to cause a rigid-bandlike shift of the Fermi level from the central region in the pseudogap. In spite of a similar decrease in the electrical resistivity with composition of Ge and Si, the thermal conductivity decreases more rapidly for the Ge substitution. It is concluded that doping of heavier atoms such as Ge reduces more effectively the lattice thermal conductivity while retaining the low electrical resistivity as well as the large Seebeck coefficient.

  9. Influence of chemical composition of zirconium alloy E110 on embrittlement under LOCA conditions – Part 1: Oxidation kinetics and macrocharacteristics of structure and fracture

    Microsoft Academic Search

    S. A. Nikulin; A. B. Rozhnov; V. A. Belov; E. V. Li; V. S. Glazkina

    2011-01-01

    Exploratory investigations of the influence of alloying and impurity content in the E110 alloy cladding tubes on the behavior under conditions of Loss of Coolant Accidents (LOCA) has been performed. Three alloys of E110 type have been tested: E110 alloy of nominal composition Zr–1%Nb (E110), E110 alloy of modified composition Zr–1%Nb–0.12%Fe–0.13%O (E110M), E110 alloy of nominal composition Zr–1%Nb with reduced

  10. Influence of chemical composition of zirconium alloy E110 on embrittlement under LOCA conditions - Part 1: Oxidation kinetics and macrocharacteristics of structure and fracture

    Microsoft Academic Search

    S. A. Nikulin; A. B. Rozhnov; V. A. Belov; E. V. Li; V. S. Glazkina

    2011-01-01

    Exploratory investigations of the influence of alloying and impurity content in the E110 alloy cladding tubes on the behavior under conditions of Loss of Coolant Accidents (LOCA) has been performed. Three alloys of E110 type have been tested: E110 alloy of nominal composition Zr-1%Nb (E110), E110 alloy of modified composition Zr-1%Nb-0.12%Fe-0.13%O (E110M), E110 alloy of nominal composition Zr-1%Nb with reduced

  11. Investigation of crystallization of a mechanically alloyed Sm-Fe alloy

    SciTech Connect

    Lue, M.Q.; Wang, K.Y.; Miao, W.F.; Song, Q.H.; Sun, W.S.; Wei, W.D.; Wang, L.B. (State Key Laboratory of RSA, Institute of Metal Research, Academia Sinica, Shenyang 110015 (China))

    1992-06-15

    The crystallization of a mechanically alloyed Sm-Fe alloy was investigated. The results show that the Sm-Fe alloy prepared by mechanical alloying consists of amorphous Sm-Fe phase and crystalline {alpha}-Fe phase. The composition of the alloy is inhomogeneous, i.e., the surface of the as-milled powder is relatively poor in iron. The crystallization process involves the long-range diffusion of iron atoms and solid state reaction. After proper crystallization, the as-milled powder transforms into a Sm{sub 2}Fe{sub 17} phase completely; no distinguishable crystalline {alpha}-Fe phase can be found. A metastable phase, which may be a Sm{sub 2}Fe{sub 17} phase with the structure of hexagonal Th{sub 2}Ni{sub 17} type, appears during the crystallization process.

  12. Conduction mechanisms in p-type Pb{sub 1-x}Eu{sub x}Te alloys in the insulator regime

    SciTech Connect

    Peres, M. L.; Rubinger, R. M.; Ribeiro, L. H.; Rubinger, C. P. L. [Departamento de Fisica e Quimica, Instituto de Ciencias Exatas, Universidade Federal de Itajuba, Itajuba, PB 50, MG CEP 37500-903 (Brazil); Ribeiro, G. M. [Departamento de Fisica, ICEx, Universidade Federal de Minas Gerais, Belo Horizonte, PB 702, MG CEP 30123-970 (Brazil); Chitta, V. A. [Instituto de Fisica, Universidade de Sao Paulo, Sao Paulo, PB 66318, SP CEP 05315-970 (Brazil); Rappl, P. H. O.; Abramof, E. [Laboratorio Associado de Sensores e Materiais, Instituto Nacional de Pesquisas Espaciais, Sao Jose dos Campos, PB 515, SP CEP 12201-970 (Brazil)

    2012-06-15

    Electrical resistivity measurements were performed on p-type Pb{sub 1-x}Eu{sub x}Te films with Eu content x = 4%, 5%, 6%, 8%, and 9%. The well-known metal-insulator transition that occurs around 5% at room temperature due to the introduction of Eu is observed, and we used the differential activation energy method to study the conduction mechanisms present in these samples. In the insulator regime (x > 6%), we found that band conduction is the dominating conduction mechanism for high temperatures with carriers excitation between the valence band and the 4f levels originated from the Eu atoms. We also verified that mix conduction dominates the low temperatures region. Samples with x = 4% and 5% present a temperature dependent metal insulator transition and we found that this dependence can be related to the relation between the thermal energy k{sub B}T and the activation energy {Delta}{epsilon}{sub a}. The physical description obtained through the activation energy analysis gives a new insight about the conduction mechanisms in insulating p-type Pb{sub 1-x}Eu{sub x}Te films and also shed some light over the influence of the 4f levels on the transport process in the insulator region.

  13. Titanium-alloy enhances bone-pedicle screw fixation: mechanical and histomorphometrical results of titanium-alloy versus stainless steel

    Microsoft Academic Search

    Finn Bjarke Christensen; Michel Dalstra; Flemming Sejling; Søren Overgaard; Cody Bünger

    2000-01-01

    Several types of pedicle screw systems have been utilized to augment lumbar spine fusion. The majority of these systems are\\u000a made of stainless steel (Ss), but titanium-alloy (Ti-alloy) devices have recently been available on the market. Ti-alloy implants\\u000a have several potential advantages over Ss ones. High bioactivity and more flexibility may improve bone ingrowth and mechanical\\u000a fixation, and the material

  14. Magnetic circular dichroism at transition metal L2,3 edges in D03-type (Fe(1-x)Vx)3Al alloys.

    PubMed

    Yoshimoto, O; Kato, M; Soda, K; Nozaki, H; Takeuchi, T; Mizutani, U; Kato, M; Nishino, Y; Imada, S; Suga, S; Matsushita, T; Saitoh, Y

    2001-03-01

    Magnetic circular dichroism (MCD) spectra have been measured at the Fe and V L2,3 edges of DO3-type (Fe(1-x)Vx)3Al in order to investigate their local magnetic moments and electronic structures. Large MCD is observed at the Fe L2,3 edges, while the V L2,3 MCD shows relatively small intensity with complicated features. Signs of these MCD spectra indicate an antiferromagnetic coupling between the magnetic moments on Fe and V. According to the analysis based on the magneto-optical sum rules, the magnetic moment decreases with x, but remains fairly large for Fe2VAl, which might arise from its marginally magnetic nature. PMID:11512813

  15. High figure-of-merit n-type SiGe/GaP alloys. [used in thermoelectric devices for space applications

    NASA Technical Reports Server (NTRS)

    Scoville, A. N.; Bajgar, Clara; Vandersande, Jan; Fleurial, Jean-Pierre

    1991-01-01

    Improvements to the figure-of-merit of n-type SiGe have been achieved via a systematic anneal study aimed at determining the optimal P:Ga ratio. Figures-of-merit of 0.85 to 0.90 x 10-3K-1 have been routinely and reproducibly achieved starting with an initial P:Ga ratio of 3:1. These samples have carrier concentrations in excess of 4.0 x 1020/cu cm, the highest reported for SiGe. This value has been shown to be too high, resulting in unfavorably low Seebeck coefficients. The optimal carrier concentration has been shown to be 1.5-3.0 x 1020/cu cm. Thus, further improvements will be achieved by reductions in the P and Ga concentrations.

  16. Nucleation mechanism of nano-sized NaZn13-type and ?-(Fe,Si) phases in La-Fe-Si alloys during rapid solidification

    NASA Astrophysics Data System (ADS)

    Hou, Xue-Ling; Xue, Yun; Liu, Chun-Yu; Xu, Hui; Han, Ning; Ma, Chun-Wei; Phan, Manh-Huong

    2015-03-01

    The nucleation mechanism involving rapid solidification of undercooled La-Fe-Si melts has been studied experimentally and theoretically. The classical nucleation theory-based simulations show a competitive nucleation process between the ?-(Fe,Si) phase (size approximately 10 to 30 nm) and the cubic NaZn13-type phase (hereinafter 1:13 phase, size approximately 200 to 400 nm) during rapid solidification, and that the undercooled temperature change ? T plays an important factor in this process. The simulated results about the nucleation rates of the ?-(Fe,Si) and 1:13 phases in La-Fe-Si ribbons fabricated by a melt-spinner using a copper wheel with a surface speed of 35 m/s agree well with the XRD, SEM, and TEM studies of the phase structure and microstructure of the ribbons. Our study paves the way for designing novel La-Fe-Si materials for a wide range of technological applications.

  17. Weldability of intermetallic alloys

    SciTech Connect

    David, S.A. (Oak Ridge National Lab., TN (United States))

    1990-01-01

    Ordered intermetallic alloys are a unique class of material that have potential for structural applications at elevated temperatures. The paper describes the welding and weldability of these alloys. The alloys studied were nickel aluminide (Ni[sub 3]Al), titanium aluminide (Ti[sub 3]Al), and iron aluminide.

  18. Alloy phase diagrams

    Microsoft Academic Search

    L. H. Bennett; B. C. Giessen; T. B. Massalski

    1984-01-01

    These proceedings collect papers presented at a symposium on alloy phase diagrams. Topics include: Crystal phase transformations; order-disorder transformations; crystal lattices; metallic glasses; metastable states; solubility; binary alloy systems; and alloys of iron, tantalum, silicon, aluminum, germanium, palladium, copper, and nickel.

  19. Alloys for aerospace

    Microsoft Academic Search

    S. Tuominen; C. Wojcik

    1995-01-01

    Aerospace industries require special allows with many properties tailored to meet specific needs. Prerequisites include clean melting techniques to maintain low impurity levels, tight control of alloy chemistry, and the analytical capability to characterize the product. Teledyne Wah Chang (TWC) produces specially refractory metals, including zirconium, hafnium, titanium, niobium and vanadium, which are essential components of many aerospace alloys. Alloys

  20. Development of a carburizing stainless steel alloy

    SciTech Connect

    Wert, D.E. (Carpenter Technology Corp., Reading, PA (United States))

    1994-06-01

    A new carburizing stainless steel alloy that resists corrosion, heat, and fatigue has been developed for bearing and gear applications. Pyrowear 675 Stainless alloy is vacuum induction melted and vacuum arc remelted (VIM/VAR) for aircraft-quality cleanliness. Test results show that it has corrosion resistance similar to that of AISI Type 440-C stainless, and its rolling fatigue resistance is superior to that of AISI M50 (UNS K88165). In contrast to alloy gear steels and Type 440C, Pyrowear 675 maintains case hardness of HRC 60 at operating temperatures up to 200 C (400 F). Impact and fracture toughness are superior to that of other stainless bearing steels, which typically are relatively brittle and can break under severe service. Toughness is also comparable or superior to conventional noncorrosion-resistant carburizing bearing steels, such as SAE Types 8620 and 9310.

  1. Production and welding technology of some high-temperature nickel alloys in relation to their properties

    SciTech Connect

    Bassford, T.H.; Hosier, J.C.

    1984-07-01

    The most effective matching of alloys to the needs of advanced high-temperature gas-cooled reactors requires not only a knowledge of material properties, but also some understanding of the inherent general characteristics of this type of alloy. Some of the characteristic features of high-temperature nickel-based alloys are explored and general guidelines offered for their most effective use. Examples are drawn from three commercial materials: Inconel alloy 617, Incoloy alloy 800H, and Nimonic alloy 86. Such items as hot and cold working, heat treating, welding, and mechanical properties are considered.

  2. In vitro corrosion of dental Au-based casting alloys in polyvinylpyrrolidone-iodine solution.

    PubMed

    Takasusuki, Norio; Ida, Yusuke; Hirose, Yukito; Ochi, Morio; Endo, Kazuhiko

    2013-01-01

    The corrosion and tarnish behaviors of two Au-based casting alloys (ISO type 1 and type 4 Au alloys) and their constituent pure metals, Au, Ag, Cu, Pt, and Pd in a polyvinylpyrrolidone-iodine solution were examined. The two Au alloys actively corroded, and the main anodic reaction for both was dissolution of Au as AuI?(-). The amount of Au released from the ISO type 1 Au alloy was significantly larger than that from the ISO type 4 Au alloy (P<0.05). Visible light spectrophotometry revealed that the type 1 alloy exhibited higher susceptibility to tarnishing than the type 4 alloy. The corrosion forms of the two Au alloys were found to be completely different, i.e., the type 1 alloy exhibited the corrosion attack over the entire exposed surface with a little irregularity whereas the type 4 alloy exhibited typical intergranular corrosion, which was caused by local cells produced by segregation of Pd and Pt. PMID:23718998

  3. Environmental embrittlement in ordered intermetallic alloys

    SciTech Connect

    Liu, C.T. [Oak Ridge National Lab., TN (United States); Stoloff, N.S. [Rensselaer Polytechnic Inst., Troy, NY (United States). Dept. of Materials Engineering

    1992-12-31

    Ordered intermetallics based on aluminides and silicides possess many promising properties for elevated-temperature applications; however, poor fracture resistance and limited fabricability restrict their use as engineering material. Recent studies have shown that environmental embrittlement is a major cause of low ductility and brittle fracture in many ordered intermetallic alloys. There are two types of environmental embrittlement observed in intermetallic alloys. One is hydrogen-induced embrittlement occurring at ambient temperatures in air. The other is oxygen-induced embrittlement in oxidizing atmospheres at elevated temperatures. In most cases, the embrittlements are due to a dynamic effect involving generation and penetration of embrittling agents (i.e., hydrogen or oxygen ) during testing. Diffusion of embrittling agents plays a dominant role in fracture of these intermetallic alloys. This chapter summarizes recent progress in understanding and reducing environmental embrittlement in these alloys.

  4. Alloy 33 weld overlay extends boiler tube life and saves money

    Microsoft Academic Search

    L. Paul; G. Clark; A. Ossenberg-Engels

    2007-01-01

    Low-NOx burners installed in coal-fired utility boilers cause problems with boiler tube cracking. Materials with increased corrosion resistance such as the new Alloy 33 should be more resistant to this type of 'circumferential cracking'. Alloy 33 is cheaper and has lower nickel and molybdenum content than the traditional Alloy 622 and 625. The article describes extensive corrosion testing experiments carried

  5. Effect of matrix and atmosphere on the creep deformation of aluminum alloy matrix composites

    Microsoft Academic Search

    Norio Matsuda; Hideki Tazawa; Satoshi Ishikawa; Mitsuru Saitoh

    2001-01-01

    Creep behavior of two types of aluminum alloy matrix composites, which were reinforced with alumina particles and have different matrix alloy, have been investigated at temperatures from 573 to 773 K. Matrices of the composites were 6061 and 2014 Al alloys. The composites contained about 10 or 20 vol.% of alumina particles, the size of which is about 10–30 ?m.

  6. The effect of penultimate grain size on rolling texture in cu-Sn alloys

    Microsoft Academic Search

    Y. C. Liu; G. A. Alers

    1973-01-01

    The effect of penultimate grain size on the texture of Cu-Sn alloys has been investigated using the modulus method. It was observed that in alloys which exhibited the brass-type texture, the large grained specimens yielded a smaller proportion of textured material than those which were fine grained. In alloys which exhibited transition textures, however, the larger grain size specimens exhibited

  7. High temperature mechanical properties of a zirconium-modified, precipitation- strengthened nickel, 30 percent copper alloy

    NASA Technical Reports Server (NTRS)

    Whittenberger, J. D.

    1974-01-01

    A precipitation-strengthened Monel-type alloy has been developed through minor alloying additions of zirconium to a base Ni-30Cu alloy. The results of this exploratory study indicate that thermomechanical processing of a solution-treated Ni-30Cu-0.2Zr alloy produced a dispersion of precipitates. The precipitates have been tentatively identified as a Ni5Zr compound. A comparison of the mechanical properties, as determined by testing in air, of the zirconium-modified alloy to those of a Ni-30Cu alloy reveals that the precipitation-strengthened alloy has improved tensile properties to 1200 K and improved stress-rupture properties to 1100 K. The oxidation characteristics of the modified alloy appeared to be equivalent to those of the base Ni-30Cu alloy.

  8. Superplastic forming of bellows expansion joints made of titanium alloys

    Microsoft Academic Search

    G. Wang; K. F. Zhang; D. Z. Wu; J. Z. Wang; Y. D. Yu

    2006-01-01

    A new forming technology was developed for bellows expansion joints. This technology uses superplastic forming (SPF) method of applying gas pressure and compressive axial load. It is developed and can be used to manufacture large diameter “U” type bellows expansion joints made of titanium alloys. The forming technology for bellows expansion joints made of titanium alloys is presented to make

  9. Giant magnetoelectric effect in mechanically clamped heterostructures of magnetostrictive alloy and piezoelectric crystal-alloy cymbal

    Microsoft Academic Search

    Yaojin Wang; Siu Wing; Helen Lai Wa Chan; Xiangyong Zhao; Haosu Luo

    2008-01-01

    We experimentally and theoretically report a giant magnetoelectric (ME) effect in a heterostructure made by clamping a bar-shaped magnetostrictive Tb0.3Dy0.7Fe1.92 (Terfenol-D) alloy actuator and a cymbal-type piezoelectric 0.7Pb(Mg1\\/3Nb2\\/3)O3-0.3PbTiO3(PMN-PT) (PMN-PT) single crystal-brass alloy transducer in a brass alloy frame. The reported ME effect originates from the stress-mediated product of the magnetostrictive effect in the Terfenol-D bar actuator and the mechanically transformed\\/amplified

  10. The effect of weldability of alloy JBK-75 with various filler metal wire additions

    SciTech Connect

    Taylor, C.L.

    1991-04-01

    The purpose of this study was to investigate the compositional factors that affect the weldability of alloy JBK-75. This study was accomplished by using a variety of different commercial filler materials to systematically evaluate the weldability in the compositional range surrounding alloy JBK-75. The experimental design included varestraint testing, scanning electron microscopy, and phase diagram analysis. The varestraint testing demonstrated that the weldability of alloy JBK-75 could be improved with the use of other commercially available filler metals. The best improvement to weldability of alloy JBK-75 was with type 308L stainless steel and Hastelloy W filler metals. Adequate improvement to the weldability of alloy JBK-75 was obtained when utilizing types 309L and 310 stainless steel filler metals. Alloy 320LR, alloy 650 (NiCrFe-1), Incoloy 901, and Inconel 92 (NiCrFe-6) filler metals only marginally improved the weldability of alloy JBK-75. 59 refs., 27 figs., 24 tabs.

  11. High strength alloys

    DOEpatents

    Maziasz, Phillip James [Oak Ridge, TN; Shingledecker, John Paul [Knoxville, TN; Santella, Michael Leonard [Knoxville, TN; Schneibel, Joachim Hugo [Knoxville, TN; Sikka, Vinod Kumar [Oak Ridge, TN; Vinegar, Harold J [Bellaire, TX; John, Randy Carl [Houston, TX; Kim, Dong Sub [Sugar Land, TX

    2010-08-31

    High strength metal alloys are described herein. At least one composition of a metal alloy includes chromium, nickel, copper, manganese, silicon, niobium, tungsten and iron. System, methods, and heaters that include the high strength metal alloys are described herein. At least one heater system may include a canister at least partially made from material containing at least one of the metal alloys. At least one system for heating a subterranean formation may include a tubular that is at least partially made from a material containing at least one of the metal alloys.

  12. Creep crack growth behavior of several structural alloys

    NASA Astrophysics Data System (ADS)

    Sadananda, K.; Shahinian, P.

    1983-07-01

    Creep crack growth behavior of several high temperature alloys, Inconel 600, Inconel 625, Inconel X-750, Hastelloy X, Nimonic PE-16, Incoloy 800, and Haynes 25 (HS-25) was examined at 540, 650, 760, and 870 °C. Crack growth rates were analyzed in terms of both linear elastic stress intensity factor and J*-integral parameter. Among the alloys Inconel 600 and Hastelloy X did not show any observable crack growth. Instead, they deformed at a rapid rate resulting in severe blunting of the crack tip. The other alloys, Inconel 625, Inconel X-750, Incoloy 800, HS-25, and PE-16 showed crack growth at one or two temperatures and deformed continuously at other temperatures. Crack growth rates of the above alloys in terms ofJ* parameter were compared with the growth rates of other alloys published in the literature. Alloys such as Inconel X-750, Alloy 718, and IN-100 show very high growth rates as a result of their sensitivity to an air environment. Based on detailed fracture surface analysis, it is proposed that creep crack growth occurs by the nucleation and growth of wedge-type cracks at triple point junctions due to grain boundary sliding or by the formation and growth of cavities at the boundaries. Crack growth in the above alloys occurs only in some critical range of strain rates or temperatures. Since the service conditions for these alloys usually fall within this critical range, knowledge and understanding of creep crack growth behavior of the structural alloys are important.

  13. Photoelectron spectroscopic study on the electronic structures of the dental gold alloys and their interaction with L-cysteine

    SciTech Connect

    Ogawa, Koji; Takahashi, Kazutoshi; Azuma, Junpei; Kamada, Masao [Synchrotron Light Application Center, Saga University, 1 Honjo, Saga, Saga 840-8502 (Japan); Tsujibayashi, Toru; Ichimiya, Masayoshi [Department of Physics, Osaka Dental University, 8-1 Kuzuha-hanazono, Hirakata, Osaka 573-1121 (Japan); Fujimoto, Hitoshi [Graduate School of Science and Technology, Kumamoto University, 2-39-1 Kurokami, Kumamoto, Kumamoto 860-8555 (Japan); Sumimoto, Michinori [Graduate School of Science and Engineering, Yamaguchi University, 2-16-1 Tokiwadai, Ube, Yamaguchi 755-8611 (Japan)

    2011-11-15

    The valence electronic structures of the dental gold alloys, type 1, type 3, and K14, and their interaction with L-cysteine have been studied by ultraviolet photoelectron spectroscopy with synchrotron radiation. It was found that the electronic structures of the type-1 and type-3 dental alloys are similar to that of polycrystalline Au, while that of the K14 dental alloy is much affected by Cu. The peak shift and the change in shape due to alloying are observed in all the dental alloys. It is suggested that the new peak observed around 2 eV for the L-cysteine thin films on all the dental alloys may be due to the bonding of S 3sp orbitals with the dental alloy surfaces, and the Cu-S bond, as well as the Au-S and Au-O bonds, may cause the change in the electronic structure of the L-cysteine on the alloys.

  14. Superplastic behavior in a commercial 5083 aluminum alloy

    SciTech Connect

    Vetrano, J.S.; Lavender, C.A.; Smith, M.T.; Bruemmer, S.M. (Pacific Northwest Lab., Richland, WA (United States)); Hamilton, C.H. (Washington State Univ., Pullman, WA (United States). Dept. of Mechanical and Materials Engineering)

    1994-03-01

    When considering the forming and post-forming properties required of a superplastic material, attractive candidates are commercial Al-Mg-Mn weldable alloys such as AA5083. There have been several investigations of hot deformation of 5083-type alloys in the literature. Only two studies evaluated commercial-purity 5083 and they achieved tensile elongations of 150% and 200%. Alloy modification has produced improved behavior in three 5083-type alloys developed specifically for SPF. Two were deemed high-purity 5083 (low Fe and Si) and achieved elongations of 450% and 630%. Engineering strains up to 700% were measured by Watanabe et al. in a 5083-based alloy with the addition of 0.6% Cu as a grain refiner. These results suggest that alloy modifications such as reduced Fe and Si contents or Cu additions may be required to improve superplastic response. Unfortunately, specific SPF-grade 5083 alloys are substantially more expensive than the commercial grade, and the addition of Cu decreases the corrosion resistance of the base material. The purpose of this work is to examine the effect of prior degrees of cold work on the SPF behavior of a standard-grade 5083 alloy. Superplastic behavior of this material at 510[degree]C is assessed and compared to published results for the SPF-grade alloys.

  15. Creep and tensile properties of several oxide dispersion strengthened nickel base alloys

    NASA Technical Reports Server (NTRS)

    Whittenberger, J. D.

    1977-01-01

    The creep properties at 1365 K of several oxide dispersion strengthened (ODS) alloys were studied, where the creep exposures involved low strains, on the order of 1% or less, after nominally 100 hours of testing. It was found that ODS alloys possess threshold stresses for creep. Creep in polycrystalline ODS alloys is an inhomogeneous process. The threshold stresses in large grain size ODS Ni-20Cr and Ni-16Cr-4/5Al type alloys are dependent on the grain aspect ratio.

  16. Mg sheet metal forming: Lessons learned from deep drawing Li and Y solid-solution alloys

    Microsoft Academic Search

    Sean R. Agnew; Jeremy W. Senn; Joseph A. Horton

    2006-01-01

    The sheet formability of current magnesium alloys at ambient temperatures is poor; however, the formability at moderately\\u000a elevated temperatures can be excellent. Cylindrical cup drawing tests are used to compare the warm forming characteristics\\u000a of conventional alloy AZ31B with alloys containing lithium oryttrium solid solutions. While both types of experimental alloy\\u000a can have better room-temperature ductility (?f?25–30%) than AZ31B, only

  17. Mg sheet metal forming: Lessons learned from deep drawing Li and Y solid-solution alloys

    Microsoft Academic Search

    Sean R. Agnew; Jeremy W. Senn; Joseph A. Horton

    2006-01-01

    The sheet formability of current magnesium alloys at ambient temperatures is poor; however, the formability at moderately elevated temperatures can be excellent. Cylindrical cup drawing tests are used to compare the warm forming characteristics of conventional alloy AZ31B with alloys containing lithium oryttrium solid solutions. While both types of experimental alloy can have better room-temperature ductility (?f˜25-30%) than AZ31B, only

  18. Corrosion Embrittlement of Duralumin II Accelerated Corrosion Tests and the Behavior of High-Strength Aluminum Alloys of Different Compositions

    NASA Technical Reports Server (NTRS)

    Rawdon, Henry S

    1928-01-01

    The permanence, with respect to corrosion, of light aluminum alloy sheets of the duralumin type, that is, heat-treatable alloys containing Cu, Mg, Mn, and Si is discussed. Alloys of this type are subject to surface corrosion and corrosion of the interior by intercrystalline paths. Results are given of accelerated corrosion tests, tensile tests, the effect on corrosion of various alloying elements and heat treatments, electrical resistance measurements, and X-ray examinations.

  19. The Mg impurity in nitride alloys

    NASA Astrophysics Data System (ADS)

    Zvanut, M. E.; Willoughby, W. R.; Sunay, U. R.; Koleske, D. D.; Allerman, A. A.; Wang, Ke; Araki, Tsutomu; Nanishi, Yasushi

    2014-02-01

    Although several magnetic resonance studies address the Mg acceptor in GaN, there are few reports on Mg doping in the alloys, where hole production depends strongly on the Al or In content. Our electron paramagnetic resonance (EPR) measurements of the p-type alloys suggest that the Mg impurity retains the axial symmetry, characteristic of a p-type dopant in both alloys; however, In and Al produce additional, different characteristics of the acceptor. In InGaN, the behavior is consistent with a lowering of the acceptor level and increasing hole density as In concentration increases. For AlGaN, the amount of neutral Mg decreases with increasing Al content, which is attributed to different kinetics of hydrogen diffusion thought to occur in samples with higher Al mole fraction.

  20. The Mg impurity in nitride alloys

    SciTech Connect

    Zvanut, M. E.; Willoughby, W. R.; Sunay, U. R. [Department of Physics, University of Alabama at Birmingham, Birmingham AL (United States); Koleske, D. D.; Allerman, A. A. [Sandia National Laboratory, Albuquerque NM (United States); Wang, Ke; Araki, Tsutomu [Department of Photonics, Ritsumeikan University, Kusatsu, Shiga (Japan); Nanishi, Yasushi [Department of Photonics, Ritsumeikan University, Kusatsu, Shiga, Japan and WCU Program, Department of Materials Science and Engineering, Seoul National University, Seoul (Korea, Republic of)

    2014-02-21

    Although several magnetic resonance studies address the Mg acceptor in GaN, there are few reports on Mg doping in the alloys, where hole production depends strongly on the Al or In content. Our electron paramagnetic resonance (EPR) measurements of the p-type alloys suggest that the Mg impurity retains the axial symmetry, characteristic of a p-type dopant in both alloys; however, In and Al produce additional, different characteristics of the acceptor. In InGaN, the behavior is consistent with a lowering of the acceptor level and increasing hole density as In concentration increases. For AlGaN, the amount of neutral Mg decreases with increasing Al content, which is attributed to different kinetics of hydrogen diffusion thought to occur in samples with higher Al mole fraction.

  1. Development of titanium alloys by the method of complex alloying

    Microsoft Academic Search

    A. I. Khorev

    2006-01-01

    We study the effect of alloying on the mechanical properties of welded joints and base metal of titanium alloys of the system\\u000a Ti-Al-Mo-V-Cr-Fe. We also formulate the theoretical aspects and principles of complex alloying of titanium alloys and the\\u000a theory of alloying of additive materials for the welding of ?-, (? + ?), and ?-alloys. It has been shown that

  2. Uranium-titanium-niobium alloy

    Microsoft Academic Search

    Ludtka

    1990-01-01

    This patent describes a uranium alloy having small additions of Ti and Nb. It shows improved strength and ductility in cross-section of greater than one inch over prior uranium alloy having only Ti as an alloy element.

  3. Catalyst Alloys Processing

    NASA Astrophysics Data System (ADS)

    Tan, Xincai

    2014-10-01

    Catalysts are one of the key materials used for diamond formation at high pressures. Several such catalyst products have been developed and applied in China and around the world. The catalyst alloy most widely used in China is Ni70Mn25Co5 developed at Changsha Research Institute of Mining and Metallurgy. In this article, detailed techniques for manufacturing such a typical catalyst alloy will be reviewed. The characteristics of the alloy will be described. Detailed processing of the alloy will be presented, including remelting and casting, hot rolling, annealing, surface treatment, cold rolling, blanking, finishing, packaging, and waste treatment. An example use of the catalyst alloy will also be given. Industrial experience shows that for the catalyst alloy products, a vacuum induction remelt furnace can be used for remelting, a metal mold can be used for casting, hot and cold rolling can be used for forming, and acid pickling can be used for metal surface cleaning.

  4. Evaluation of austenitic alloys 304L and 316L and alloy 825 under tuff-repository conditions

    Microsoft Academic Search

    Kass

    1989-01-01

    Primary concerns over use of types 304L and 316L are for chloride- induced stress-corrosion cracking (SCC) and weld microstructure stability. Possibly alloy 825 will be a more suitable candidate. (DLC)

  5. Evaluation of austenitic alloys 304L and 316L and alloy 825 under tuff-repository conditions

    SciTech Connect

    Kass, J.

    1989-05-01

    Primary concerns over use of types 304L and 316L are for chloride- induced stress-corrosion cracking (SCC) and weld microstructure stability. Possibly alloy 825 will be a more suitable candidate. (DLC)

  6. Semiconductor alloy theory

    Microsoft Academic Search

    A. B. Chen

    1986-01-01

    This grant supported our work on semiconductor alloy theory. Many useful results have been obtained, including: (1) generalization of Brooks' formula for alloy-scattering limited electron mobility to including multiple bands and indirect gaps, (2) calculation of SiGe alloys band structure, electron-mobility and core-exciton binding energy and linewidth, (3) comprehensive calculation of bond energy, bond length and mixing enthalpy for all

  7. Low activation ferritic alloys

    DOEpatents

    Gelles, David S. (West Richland, WA); Ghoniem, Nasr M. (Granada Hills, CA); Powell, Roger W. (Pasco, WA)

    1986-01-01

    Low activation ferritic alloys, specifically bainitic and martensitic stainless steels, are described for use in the production of structural components for nuclear fusion reactors. They are designed specifically to achieve low activation characteristics suitable for efficient waste disposal. The alloys essentially exclude molybdenum, nickel, nitrogen and niobium. Strength is achieved by substituting vanadium, tungsten, and/or tantalum in place of the usual molybdenum content in such alloys.

  8. Electrical characterization of germanium-silicon alloy 

    E-print Network

    Kishore, Kumar P.

    1994-01-01

    Samples of strained germanium-silicon (Ge-Si) alloy were electrically characterized using resistivity and Hall-mobility measurements. The samples were obtained from a n-type Ge-Si strained epi-layer which was grown on a ...

  9. Vanadium alloys with improved resistance to helium embrittlement

    SciTech Connect

    Braski, D.N.

    1990-01-01

    A series of experimental vanadium alloys have been designed with small MC-type carbides in their microstructures to trap helium produced during neutron irradiation, thereby reducing helium embrittlement. The tensile properties and fabricability of the alloys were strongly influenced by the amounts of MC-forming-elements, especially carbon. Alloys with 0.05 and 0.10 wt % carbon exhibited slightly lower yield strengths at 420 to 600{degree}C than vanadium alloys such as V-5Cr-5Ti, Vanstar-7, V-3Ti-1Si, and V-15Cr-5Ti. However, this characteristic may actually be an asset from the standpoint of resistance to irradiation hardening. After implantation with 300 appm {sup 3}He, both the V-Ti-C and V-Ti-Zr-C alloys exhibited less ductility losses at 600{degree}C than the other vanadium alloys tested under comparable conditions. Examination of the experimental alloy microstructures by AEM showed that the small MC-type carbides did, in fact, trap helium and that they were responsible for the increased resistance to helium embrittlement of these alloys. 16 refs., 12 figs., 2 tabs.

  10. The effect of selected alloying element additions on properties of Mg-based alloy as bioimplants: A literature review

    NASA Astrophysics Data System (ADS)

    Zhang, Li-Nan; Hou, Zeng-Tao; Ye, Xin; Xu, Zhao-Bin; Bai, Xue-Ling; Shang, Peng

    2013-09-01

    This review investigates the current application limitations of Mg and Mg alloys. The key issues hindering the application of biodegradable Mg alloys as implants are their fast degradation rate and biological consideration. We have discussed the effect of some selected alloying element additions on the properties of the Mg-based alloy, especially the nutrient elements in human (Zn, Mn, Ca, Sr). Different grain sizes, phase constituents and distributions consequently influence the mechanical properties of the Mg alloys. Solution strengthening and precipitation strengthening are enhanced by the addition of alloying elements, generally improving the mechanical properties. Besides, the hot working process can also improve the mechanical properties. Combination of different processing steps is suggested to be adopted in the fabrication of Mg-based alloys. Corrosion properties of these Mg-based alloys have been measured in vitro and in vivo. The degradation mechanism is also discussed in terms of corrosion types, rates, byproducts and response of the surrounding tissues. Moreover, the clinical response and requirements of degradable implants are presented, especially for the nutrient elements (Ca, Mn, Zn, Sr). This review provides information related to different Mg alloying elements and presents the promising candidates for an ideal implant.

  11. Physical and welding metallurgy of Gd-enriched austenitic alloys for spent nuclear fuel applications. Part II, nickel base alloys.

    SciTech Connect

    Mizia, Ronald E. (Idaho National Engineering and Environmental Laboratory, Idaho Falls, ID); Michael, Joseph Richard; Williams, David Brian (Lehigh University, Bethlehem, PA); Dupont, John Neuman (Lehigh University, Bethlehem, PA); Robino, Charles Victor

    2004-06-01

    The physical and welding a metallurgy of gadolinium- (Gd-) enriched Ni-based alloys has been examined using a combination of differential thermal analysis, hot ductility testing. Varestraint testing, and various microstructural characterization techniques. Three different matrix compositions were chosen that were similar to commercial Ni-Cr-Mo base alloys (UNS N06455, N06022, and N06059). A ternary Ni-Cr-Gd alloy was also examined. The Gd level of each alloy was {approx}2 wt-%. All the alloys initiated solidification by formation of primary austenite and terminated solidification by a Liquid {gamma} + Ni{sub 5}Gd eutectic-type reaction at {approx}1270 C. The solidification temperature ranges of the alloys varied from {approx}100 to 130 C (depending on alloy composition). This is a substantial reduction compared to the solidification temperature range to Gd-enriched stainless steels (360 to 400 C) that terminate solidification by a peritectic reaction at {approx}1060 C. The higher-temperature eutectic reaction that occurs in the Ni-based alloys is accompanied by significant improvements in hot ductility and solidification cracking resistance. The results of this research demonstrate that Gd-enriched Ni-based alloys are excellent candidate materials for nuclear criticality control in spent nuclear fuel storage applications that require production and fabrication of large amounts of material through conventional ingot metallurgy and fusion welding techniques.

  12. Equiatomic transition metal alloys of manganese

    Microsoft Academic Search

    A. Kjekshus; R. Møllerud; A. F. Andresen; W. B. Pearson

    1967-01-01

    The structural and magnetic properties of well characterized alloys have been studied in the range from 40 to 66 at. % Pd. The CsCl type, cubic PdMn phase is stable only at high temperatures, homogeneous between ?40 and?50 at. % Pd at 685°c, and paramagnetic with 2SMn = 5·0 ± 0·5 ('spin only’ approximation). The CuAul type, tetragonal PdMn phase

  13. Radiation effects on corrosion of zirconium alloys

    SciTech Connect

    Johnson, A.B. Jr.

    1989-06-01

    From the wide use of zirconium alloys as components in nuclear reactors, has come clear evidence that reactor radiation is a major corrosion parameter. The evidence emerges from comparisons of zirconium alloy corrosion behavior in different reactor types, for example, BWRs versus PWRs and in corresponding reactor loop chemistries; also, oxidation rates differ with location along components such as fuel rods and reactor pressure tubes. In most respects, oxidation effects on power reactor components are paralleled by oxidation behavior on specimens exposed to radiation in reactor loops.

  14. Copper-tantalum alloy

    DOEpatents

    Schmidt, Frederick A. (Ames, IA); Verhoeven, John D. (Ames, IA); Gibson, Edwin D. (Ames, IA)

    1986-07-15

    A tantalum-copper alloy can be made by preparing a consumable electrode consisting of an elongated copper billet containing at least two spaced apart tantalum rods extending longitudinally the length of the billet. The electrode is placed in a dc arc furnace and melted under conditions which co-melt the copper and tantalum to form the alloy.

  15. Ductile transplutonium metal alloys

    DOEpatents

    Conner, W.V.

    1981-10-09

    Alloys of Ce with transplutonium metals such as Am, Cm, Bk and Cf have properties making them highly suitable as souces of the transplutonium element, e.g., for use in radiation detector technology or as radiation sources. The alloys are ductile, homogeneous, easy to prepare and have a fairly high density.

  16. ZIRCONIUM ALLOYS FOR REACTORS

    Microsoft Academic Search

    Nishihara

    1960-01-01

    The general characteristics of the reactor-grade Zr alloys are revewed, ; including the physical properties of pure Zr and of the pertinent alloys, ; manufacturing processes of Zr sponge and of Zircaloy, electric arc welding ; methods for the pure metal and the ingot, hot and cold working, annealing and ; welding. The high temperatare behavior of Zircaloy, Ozhennite and

  17. Shape Memory Alloys

    Microsoft Academic Search

    Abhijit Bhattacharyya; Dimitris C Lagoudas

    2007-01-01

    This special issue on shape memory alloys (SMA) is an encore to a special issue on the same topic edited by us six years ago (Smart Mater. Struct.9 (5) October 2000). A total of 19 papers is offered in this issue, organized into the three broad categories of modeling, characterization and applications. In addition to thermally activated shape memory alloys,

  18. Rhenium alloys in electronics

    Microsoft Academic Search

    E. M. Savitskii; M. A. Tylkina; A. M. Levin

    1980-01-01

    The book presents information on the utilization of rhenium and its alloys in electronics for electronic vacuum devices such as preheaters, cathodes, and screens, and also in the thin-film microelectronic designs. Data on physical and chemical interaction of rhenium with other elements are generalized, and basic theoretical premises in the development of rhenium alloys with specified properties are summarized. The

  19. Cesium iodide alloys

    DOEpatents

    Kim, H.E.; Moorhead, A.J.

    1992-12-15

    A transparent, strong CsI alloy is described having additions of monovalent iodides. Although the preferred iodide is AgI, RbI and CuI additions also contribute to an improved polycrystalline CsI alloy with outstanding multispectral infrared transmittance properties. 6 figs.

  20. Ductile transplutonium metal alloys

    DOEpatents

    Conner, William V. (Boulder, CO)

    1983-01-01

    Alloys of Ce with transplutonium metals such as Am, Cm, Bk and Cf have properties making them highly suitable as sources of the transplutonium element, e.g., for use in radiation detector technology or as radiation sources. The alloys are ductile, homogeneous, easy to prepare and have a fairly high density.

  1. JOURNAL DE PHYSIQUE Colloque C 1, supplement au n 2-3, Tome 32, Fevrier-Mars 1971, page C I -865 MAGNETIC PROPERTIES OF Au4X TYPE ORDERED ALLOYS

    E-print Network

    Paris-Sud XI, Université de

    (Fe, Mn and Cr) obey this prediction, whereas the elements at the left do not. For example, for Au4V, the magnetic properties change from ferromagnetic for Au4Mn (Te ~ 360 °K), antiferromagnetic for Au4Cr (r such sensitive changes [1]. On the other hand, the structural study of Au rich, ordered Au-Mn alloys [2

  2. Mechanically alloyed, ferritic oxide dispersion strengthened alloys: structure and properties

    Microsoft Academic Search

    A. Czyrska-Filemonowicz; B. Dubiel

    1997-01-01

    The paper presents information concerning the production of oxide dispersion strengthened (ODS) alloys by mechanical alloying process. The macro- and microstructures of the ferritic ODS alloys, INCOLOY MA 956 and PM2000 are discussed in detail. The basic engineering properties of these alloys, namely oxidation resistance and mechanical properties, especially tensile, compression and high temperature creep, are outlined.

  3. Alloying aluminum alloys with scandium and zirconium additives

    Microsoft Academic Search

    V. G. Davydov; V. I. Elagin; V. V. Zakharov; D. Rostoval

    1996-01-01

    In recent years Russian specialists have developed industrial weldable aluminum alloys alloyed with a small amount of scandium. Scandium added to existing weldable aluminum alloys improves considerably the set of their operational properties. In addition, the presence of scandium makes it possible to create new materials superior to traditional aluminum alloys. The present paper is devoted to problems of simultaneous

  4. Thermoelectric properties of Cu-doped n-type (Bi{sub 2}Te{sub 3}){sub 0.9}-(Bi{sub 2-x}Cu{sub x}Se{sub 3}){sub 0.1}(x=0-0.2) alloys

    SciTech Connect

    Cui, J.L. [School of Mechanical Engineering, Ningbo University of Technology, Ningbo 315016 (China)], E-mail: cuijl@nbip.net; Mao, L.D. [College of Chemical Engineering and Materials Science, Zhejiang University of Technology, Hangzhou 310014 (China); School of Mechanical Engineering, Ningbo University of Technology, Ningbo 315016 (China); Yang, W.; Xu, X.B. [School of Mechanical Engineering, Ningbo University of Technology, Ningbo 315016 (China); Chen, D.Y.; Xiu, W.J. [School of Materials Science and Engineering, China University of Mining and Technology, Xuzhou 221008 (China); School of Mechanical Engineering, Ningbo University of Technology, Ningbo 315016 (China)

    2007-12-15

    n-Type (Bi{sub 2}Te{sub 3}){sub 0.9}-(Bi{sub 2-x}Cu{sub x}Se{sub 3}){sub 0.1} (x=0-0.2) alloys with Cu substitution for Bi were prepared by spark plasma-sintering technique and their structural and thermoelectric properties were evaluated. Rietveld analysis reveals that approximate 9.0% of Bi atomic sites are occupied by Cu atoms and less than 4.0 wt% second phase Cu{sub 2.86}Te{sub 2} precipitated in the Cu-doped parent alloys. Measurements show that an introduction of a small amount of Cu (x{<=}0.1) can reduce the lattice thermal conductivity ({kappa}{sub L}), and improve the electrical conductivity and Seebeck coefficient. An optimal dimensionless figure of merit (ZT) value of 0.98 is obtained for x=0.1 at 417 K, which is obviously higher than those of Cu-free Bi{sub 2}Se{sub 0.3}Te{sub 2.7} (ZT=0.66) and Ag-doped alloys (ZT=0.86) prepared by the same technologies. - Graphical abstract: After Cu-doping with x=0.1, the highest ZT value of 0.98 is obtained at 417 K, which is about 0.32 and 0.12 higher than those of Cu-free Bi{sub 2}Se{sub 0.3}Te{sub 2.7} and the Ag-doped alloys (Bi{sub 2}Te{sub 3}){sub 0.9}-(Bi{sub 2-x}Ag{sub x}Se{sub 3}){sub 0.1} (x=0.4), respectively.

  5. Alloys for aerospace

    SciTech Connect

    Tuominen, S.; Wojcik, C. [Teledyne Wah Chang, Albany, OR (United States)

    1995-04-01

    Aerospace industries require special allows with many properties tailored to meet specific needs. Prerequisites include clean melting techniques to maintain low impurity levels, tight control of alloy chemistry, and the analytical capability to characterize the product. Teledyne Wah Chang (TWC) produces specially refractory metals, including zirconium, hafnium, titanium, niobium and vanadium, which are essential components of many aerospace alloys. Alloys are prepared by vacuum-arc-remelting (VAR) or electron beam (EB) melting, and ingots are processed to products ranging from bar and tube stock to wire and foil. Chemical, mechanical, and microstructural tests are all conducted at TWC`s in-house laboratory facilities. Of the alloys described here, Ti-3Al-2.5V, Tiadyne 3515 (Alloy C), NiTiFe, and C-103 are produced commercially, while orthorhombic titanium aluminides are promising candidates for future light-weight composite matrices.

  6. Alloys in energy development

    SciTech Connect

    Frost, B.R.T.

    1984-02-01

    The development of new and advanced energy systems often requires the tailoring of new alloys or alloy combinations to meet the novel and often stringent requirements of those systems. Longer life at higher temperatures and stresses in aggressive environments is the most common goal. Alloy theory helps in achieving this goal by suggesting uses of multiphase systems and intermediate phases, where solid solutions were traditionally used. However, the use of materials under non-equilibrium conditions is now quite common - as with rapidly solidified metals - and the application of alloy theory must be modified accordingly. Under certain conditions, as in a reactor core, the rate of approach to equilibrium will be modified; sometimes a quasi-equilibrium is established. Thus an alloy may exhibit enhanced general diffusion at the same time as precipitate particles are being dispersed and solute atoms are being carried to vacancy sinks. We are approaching an understanding of these processes and can begin to model these complex systems.

  7. Relationship of wear properties to basal-plane texture of worn surface of Mg alloys

    Microsoft Academic Search

    Takaomi Itoi; Kaname Gonda; Mitsuji Hirohashi

    2011-01-01

    The wear properties of pure-Mg, AZ31 extruded alloy, AZ91 cast alloy, and Mg90.5Cu3.25Y6.25 (at.%) cast alloy consisting of Mg and long-period-ordered (LPO) phases were investigated by pin-on-disk-type wear tests under dry sliding. The wear loss of the Mg90.5Cu3.25Y6.25 cast alloy at high-applied loads over 147N was less than those of AZ Mg alloys, and about two-thirds of the AZ31 extruded

  8. Hydrogen pickup mechanism of zirconium alloys

    NASA Astrophysics Data System (ADS)

    Couet, Adrien

    Although the optimization of zirconium based alloys has led to significant improvements in hydrogen pickup and corrosion resistance, the mechanisms by which such alloy improvements occur are still not well understood. In an effort to understand such mechanisms, a systematic study of the alloy effect on hydrogen pickup is conducted, using advanced characterization techniques to rationalize precise measurements of hydrogen pickup. The hydrogen pick-up fraction is accurately measured for a specially designed set of commercial and model alloys to investigate the effects of alloying elements, microstructure and corrosion kinetics on hydrogen uptake. Two different techniques to measure hydrogen concentrations were used: a destructive technique, Vacuum Hot Extraction, and a non-destructive one, Cold Neutron Prompt Gamma Activation Analysis. The results indicate that hydrogen pickup varies not only from alloy to alloy but also during the corrosion process for a given alloy. For instance Zircaloy type alloys show high hydrogen pickup fraction and sub-parabolic oxidation kinetics whereas ZrNb alloys show lower hydrogen pickup fraction and close to parabolic oxidation kinetics. Hypothesis is made that hydrogen pickup result from the need to balance charge during the corrosion reaction, such that the pickup of hydrogen is directly related to (and indivisible of) the corrosion mechanism and decreases when the rate of electron transport or oxide electronic conductivity sigmao xe through the protective oxide increases. According to this hypothesis, alloying elements (either in solid solution or in precipitates) embedded in the oxide as well as space charge variations in the oxide would impact the hydrogen pick-up fraction by modifying sigmaox e, which drives oxidation and hydriding kinetics. Dedicated experiments and modelling were performed to assess and validate these hypotheses. In-situ electrochemical impedance spectroscopy (EIS) experiments were performed on Zircaloy-4 tubes to directly measure the evolution of sigma oxe as function of exposure time. The results show that sigmao xe decreases as function of exposure time and that its variations are directly correlated to the instantaneous hydrogen pickup fraction variations. The electron transport through the oxide layer is thus altered as the oxide grows, reasons for which are yet to be exactly determined. Preliminary results also show that sigma oxe of ZrNb alloys would be much higher compared with Zircaloy-4. Thus, it is confirmed that sigmaox e is a key parameter in the hydrogen and oxidation mechanism. Because the mechanism whereby alloying elements are incorporated into the oxide layer is critical to changing sigmao xe, the evolution of the oxidation state of two common alloying elements, Fe and Nb, when incorporated into the growing oxide layers is investigated using X-Ray Absorption Near-Edge Spectroscopy (XANES) using micro-beam synchrotron radiation on cross sectional oxide samples. The results show that the oxidation of both Fe and Nb is delayed in the oxide layer compared to that of Zr, and that this oxidation delay is related to the variations of the instantaneous hydrogen pick-up fraction with exposure time. The evolution of Nb oxidation as function of oxide depth is also compatible with space charge compensation in the oxide and with an increase in sigmaox e of ZrNb alloys compared to Zircaloys. Finally, various successively complex models from the well-known Wagner oxidation theory to the more complex effect of space charge on oxidation kinetics have been developed. The general purpose of the modeling effort is to provide a rationale for the sub-parabolic oxidation kinetics and demonstrate the correlation with hydrogen pickup fraction. It is directly demonstrated that parabolic oxidation kinetics is associated with high sigmao xe and low space charges in the oxide whereas sub-parabolic oxidation kinetics is associated with lower sigmaox e and higher space charge in the oxide. All these observations helped us to propose a general corrosion mechanism of zirconium allo

  9. Fusion boundary microstructure evolution in aluminum alloys

    NASA Astrophysics Data System (ADS)

    Kostrivas, Anastasios Dimitrios

    2000-10-01

    A melting technique was developed to simulate the fusion boundary of aluminum alloys using the GleebleRTM thermal simulator. Using a steel sleeve to contain the aluminum, samples were heated to incremental temperatures above the solidus temperature of a number of alloys. In alloy 2195, a 4wt%Cu-1wt%Li alloy, an equiaxed non-dendritic zone (EQZ) could be formed by heating in the temperature range from approximately 630 to 640°C. At temperatures above 640°C, solidification occurred by the normal epitaxial nucleation and growth mechanism. Fusion boundary behavior was also studied in alloys 5454-H34, 6061-T6, and 2219-T8. Additionally, experimental alloy compositions were produced by making bead on plate welds using an alloy 5454-H32 base metal and 5025 or 5087 filler metals. These filler metals contain zirconium and scandium additions, respectively, and were expected to influence nucleation and growth behavior. Both as-welded and welded/heat treated (540°C and 300°C) substrates were tested by melting simulation, resulting in dendritic and EQZ structures depending on composition and substrate condition. Orientation imaging microscopy (OIM(TM)) was employed to study the crystallographic character of the microstructures produced and to verify the mechanism responsible for EQZ formation. OIM(TM) proved that grains within the EQZ have random orientation. In all other cases, where the simulated microstructures were dendritic in nature, it was shown that epitaxy was the dominant mode of nucleation. The lack of any preferred crystallographic orientation relationship in the EQZ supports a theory proposed by Lippold et al that the EQZ is the result of heterogeneous nucleation within the weld unmixed zone. EDS analysis of the 2195 on STEM revealed particles with ternary composition consisted of Zr, Cu and Al and a tetragonal type crystallographic lattice. Microdiffraction line scans on EQZ grains in the alloy 2195 showed very good agreement between the measured Cu composition within the interior of the non-dendritic grains and the corresponding value the Scheil equation predicts for the first solid to form upon solidification for a binary Al-Cu alloy with identical Cu composition. In the context of the alloys, compositions and substrate conditions examined a mechanistic model for EQZ zone formation is proposed, helpful in adjusting base metal compositions and/or substrate conditions to control fusion boundary microstructure.

  10. Cluster model studies on the electronic and magnetic properties of LaCo13 and La(Fe,Al, ,,),,.alloys

    E-print Network

    Gong, Xingao

    (Fe,Al, ,,),,.alloys G. W. Zhang, X. G. Gong,aj and Q. Q. Zheng,a)sb) Institute of Solid State Physics, Academia Sinica(FeXAl,-xjls is discussed. The cubic NaZn,,-type alloys havelong beenthe subject of much research.Recently, the successfulfabrication of LaCo,,, La(Fe,Al,& alloys haveenrichedthis family and attractedmuch experimentaland

  11. An investigation on the microstructure and tensile properties of direct squeeze cast and gravity die cast 2024 wrought Al alloy

    Microsoft Academic Search

    E. Hajjari; M. Divandari

    2008-01-01

    2024 aluminum alloy, conventionally is used for wrought products. If this alloy is subjected to cast process, a large number of shrinkage porosities will be produced within its microstructure due to its long solidification range. Therefore, in order to see the effect of pressure on the microstructure and reduction of shrinkage porosities of this type of alloy, the effect of

  12. Amorphous powders of Al-Hf prepared by mechanical alloying

    SciTech Connect

    Schwarz, R.B.; Hannigan, J.W.; Sheinberg, H.; Tiainen, T.

    1988-01-01

    We synthesized amorphous Al/sub 50/Hf/sub 50/ alloy powder by mechanically alloying an equimolar mixture of crystalline powders of Al and Hf using hexane as a dispersant. We characterized the powder as a function of mechanical-alloying time by scanning electron microscopy, x-ray diffraction, and differential scanning calorimetry. Amorphous Al/sub 50/Hf/sub 50/ powder heated at 10 K s/sup /minus/1/ crystallizes polymorphously at 1003 K into orthorhombic AlHf (CrB-type structure). During mechanical alloying, some hexane decomposes and hydrogen and carbon are incorporated into the amorphous alloy powder. The hydrogen can be removed by annealing the powder by hot pressing at a temperature approximately 30 K below the crystallization temperature. The amorphous compacts have a diamond pyramidal hardness of 1025 DPH. 24 refs., 7 figs., 1 tab.

  13. Technology status of tantalum alloys for space nuclear power applications

    NASA Technical Reports Server (NTRS)

    Hoffman, E. E.

    1985-01-01

    Tantalum alloys have a variety of properties which make them attractive candidates for application in nuclear power systems required to operate in space at elevated temperatures (1200 to 1600 K) for extended time periods. Most of the technology development on this class of alloys which is pertinent to space system application occurred during the 1960 to 1972 time period under NASA sponsorship. The most extensive data bases resulting from this earlier work were obtained on the alloys T-111 (Ta-8W-2Hf) and ASTAR 811C (Ta-8W-1Re-0.7Hf-0.025C). Emphasis in this paper is directed at the following technical factors: producibility, creep strength, weldability and compatibility. These factors are considered to be the most important elements in the selection of alloys for this application. Review of the available information indicates that alloys of this type are appropriate for application in many systems, particularly those utilizing alkali metals as the working fluid.

  14. The time and temperature dependence of the thermoelectric properties of silicon-germanium alloy

    NASA Technical Reports Server (NTRS)

    Raag, V.

    1975-01-01

    Experimental data on the electrical resistivity and Seebeck coefficient of n-type and p-type silicon-germanium alloys are analyzed in terms of a solid-state dopant precipitation model proposed by Lifshitz and Slyozov (1961). Experimental findings on the time and temperature dependence of the thermal conductivity of these two types of alloy indicate that the thermal conductivity of silicon-germanium alloys changes with time, contrary to previous hypothesis. A preliminary model is presented which stipulates that the observed thermal conductivity decrease in silicon-germanium alloys is due partly to dopant precipitation underlying the electrical property changes and partly to enhanced alloying of the material. It is significant that all three properties asymptotically approach equilibrium values with time. Total characterization of these properties will enable the time change to be fully compensated in the design of a thermoelectric device employing silicon-germanium alloys.

  15. Pitting, galvanic, and long-term corrosion studies on candidate container alloys for the Tuff Repository

    SciTech Connect

    Beavers, J.A.; Thompson, N.G.; Durr, C.L. (Cortest Columbus Technologies, OH (United States))

    1992-01-01

    Contest Columbus Technologies, Inc. (CC Technologies) investigated the long-term performance of container materials for high-level radioactive waste packages as part of the information needed by the Nuclear Regulatory Commission to assess the Department of Energy's application to construct a geologic repository for the high-level radioactive waste. The scope of work focused on the Tuff Repository and employed short-term techniques, such as electrochemical and mechanical techniques to examine a wide range of possible failure modes. Two classes of alloys were evaluated for use as container materials for the Tuff Repository; Fe-Cr-Ni alloys and copper-base alloys. The candidate Fe-Cr-Ni alloys were Type 304L Stainless Steel (Alloy 304L) and Incoloy Alloy 825 (Alloy 825). The candidate copper-base alloys were CDA 102 Copper (Alloy CDA 102) and CDA 715 Copper-3D Nickel (Alloy CDA 715). The corrosion testing was performed in a simulated J-13 well water and in solutions selected from an experimental matrix from Task 2 of the program. This report summarizes the results of Task 4 (Pitting Studies), Task 6 (Other Failure Modes) and Task 7 (Long-Term Exposures) of the program. Pit-initiation studies, performed in Task 4, focused on anomalous Cyclic Potentiodynamic Polarization (CPP) behavior of the copper-base alloys reported in Task 2 of the program. Pit propagation studies were performed on Alloy CDA 102 in Task A of the program. Two types of galvanic corrosion studies were performed in Task 6 of the program; thermogalvanic couples and borehole linear-container interactions. In the thermogalvanic couples tests, the effect of temperature variation on the surface of the container on acceleration of corrosion was evaluated for two alloys; Alloy CDA 102 and Alloy 304L. Long-term immersion tests were conducted in Task 7 of the program.

  16. Pitting, galvanic, and long-term corrosion studies on candidate container alloys for the Tuff Repository

    SciTech Connect

    Beavers, J.A.; Thompson, N.G.; Durr, C.L. [Cortest Columbus Technologies, OH (United States)

    1992-01-01

    Contest Columbus Technologies, Inc. (CC Technologies) investigated the long-term performance of container materials for high-level radioactive waste packages as part of the information needed by the Nuclear Regulatory Commission to assess the Department of Energy`s application to construct a geologic repository for the high-level radioactive waste. The scope of work focused on the Tuff Repository and employed short-term techniques, such as electrochemical and mechanical techniques to examine a wide range of possible failure modes. Two classes of alloys were evaluated for use as container materials for the Tuff Repository; Fe-Cr-Ni alloys and copper-base alloys. The candidate Fe-Cr-Ni alloys were Type 304L Stainless Steel (Alloy 304L) and Incoloy Alloy 825 (Alloy 825). The candidate copper-base alloys were CDA 102 Copper (Alloy CDA 102) and CDA 715 Copper-3D Nickel (Alloy CDA 715). The corrosion testing was performed in a simulated J-13 well water and in solutions selected from an experimental matrix from Task 2 of the program. This report summarizes the results of Task 4 (Pitting Studies), Task 6 (Other Failure Modes) and Task 7 (Long-Term Exposures) of the program. Pit-initiation studies, performed in Task 4, focused on anomalous Cyclic Potentiodynamic Polarization (CPP) behavior of the copper-base alloys reported in Task 2 of the program. Pit propagation studies were performed on Alloy CDA 102 in Task A of the program. Two types of galvanic corrosion studies were performed in Task 6 of the program; thermogalvanic couples and borehole linear-container interactions. In the thermogalvanic couples tests, the effect of temperature variation on the surface of the container on acceleration of corrosion was evaluated for two alloys; Alloy CDA 102 and Alloy 304L. Long-term immersion tests were conducted in Task 7 of the program.

  17. Mechanical and corrosion resistance of a new nanostructured Ti-Zr-Ta-Nb alloy.

    PubMed

    Raducanu, D; Vasilescu, E; Cojocaru, V D; Cinca, I; Drob, P; Vasilescu, C; Drob, S I

    2011-10-01

    In this work, a multi-elementary Ti-10Zr-5Nb-5Ta alloy, with non-toxic alloying elements, was used to develop an accumulative roll bonding, ARB-type procedure in order to improve its structural and mechanical properties. The alloy was obtained by cold crucible semi-levitation melting technique and then was ARB deformed following a special route. After three ARB cycles, the total deformation degree per layer is about 86%; the calculated medium layer thickness is about 13 ?m. The ARB processed alloy has a low Young's modulus of 46 GPa, a value very close to the value of the natural cortical bone (about 20 GPa). Data concerning ultimate tensile strength obtained for ARB processed alloy is rather high, suitable to be used as a material for bone substitute. Hardness of the ARB processed alloy is higher than that of the as-cast alloy, ensuring a better behaviour as a implant material. The tensile curve for the as-cast alloy shows an elastoplastic behaviour with a quite linear elastic behaviour and the tensile curve for the ARB processed alloy is quite similar with a strain-hardening elastoplastic body. Corrosion behaviour of the studied alloy revealed the improvement of the main electrochemical parameters, as a result of the positive influence of ARB processing. Lower corrosion and ion release rates for the ARB processed alloy than for the as-cast alloy, due to the favourable effect of ARB thermo-mechanical processing were obtained. PMID:21783152

  18. Tensile and impact properties of iron-aluminum alloys

    SciTech Connect

    Alexander, D.J.; Sikka, V.K.

    1993-12-31

    Tensile and impact tests have been conducted on specimens from a series of five heats of iron-aluminum alloys. These results have been compared to data for the iron aluminide alloy FA-129. The transition temperatures of all of the Fe{sub 3}Al-based alloys were similar, but the simple ternary alloy had a much higher upper-shelf energy. The reduced aluminum alloys [based on Fe-8Al (wt %)] had lower transition temperatures and higher upper-shelf energy levels than the Fe{sub 3}Al-type alloys. The reduced aluminum alloy with yttrium showed excellent tensile properties, with a room temperature total elongation of 40%, and a very high upper-shelf energy level. Despite the high tensile ductility at room temperature, the transition temperature of the yttrium-containing alloy was still about 150 C, compared to approximately 300 C for FA-129. In general, the microstructures were coarse and anisotropic. The fracture processes were dominated by second-phase particles.

  19. Alloy optimization for PWR steam generator heat-transfer tubing

    NASA Astrophysics Data System (ADS)

    Harrod, D. L.; Gold, R. E.; Jacko, R. J.

    2001-07-01

    Several materials have been used for heat-transfer tubing in light water reactor steam generators, including Type 316 stainless steel (a few early units in the late 1960s), Alloy 600MA (mill annealed), Alloy 600TT (thermally treated), Alloy 800Mod, and the current preference, Alloy 690TT. The susceptibility of Alloy 600MA (Ni-16Cr-9Fe) to stress-corrosion cracking led to extensive corrosion studies to select and qualify a new material. Alloy 690TT (Ni-30Cr-10Fe) was chosen in the mid-1980s as the best heat-transfer tubing material, although Alloy 800Mod (Fe-33Ni-22Cr) remains an alternate choice. The basis for selecting Alloy 690TT is briefly summarized, along with a description of efforts to optimize tube manufacturing practices for corrosion resistance. Efforts at further optimization are described, including preconditioning of the tubing by some form of inner-diameter surface passivation in order to minimize corrosion product release rates upon initial service.

  20. On the role of matrix creep in the high temperature deformation of short fiber reinforced aluminum alloys

    Microsoft Academic Search

    G. Kausträter; B. Skrotzki; G. Eggeler

    2001-01-01

    The present study investigates creep of short fiber reinforced metal matrix composites (MMCs) which were produced by squeeze casting. Two types of aluminum alloys were used as matrix materials with class I (alloy type) and class II (metal type) creep behavior. The creep behavior of the resulting MMCs is similar both in terms of the shape of the individual creep

  1. The half-metallicity of LiMgPdSn-type quaternary Heusler alloys FeMnScZ (Z=Al, Ga, In): A first-principle study

    NASA Astrophysics Data System (ADS)

    Gao, Y. C.; Gao, X.

    2015-05-01

    Based on the first-principles calculations, quaternary Heusler alloys FeMnScZ (Z=Al, Ga, In) including its phase stability, band gap, the electronic structures and magnetic properties has been studied systematically. We have found that, in terms of the equilibrium lattice constants, FeMnScZ (Z=Al, Ga, In) are half-metallic ferrimagnets, which can sustain the high spin polarization under a very large amount of lattice distortions. The half-metallic band gap in FeMnScZ (Z=Al, Ga, In) alloys originates from the t1u-t2g splitting instead of the eu-t1u splitting. The total magnetic moments are 3?B per unit cell for FeMnScZ (Z=Al, Ga, In) alloys following the Slater-Pauling rule with the total number of valence electrons minus 18 rather than 24. According to the study, the conclusion can be drawn that all of these compounds which have a negative formation energy are possible to be synthesized experimentally.

  2. CRC Handbook of Electrical Resistivitives of Binary Metallic Alloys

    SciTech Connect

    Schroder, K.

    1983-01-01

    Material design engineers often require a tabulation of physical properties in order to select the appropriate material for use, while developmental engineers need to be aware of basic principles and systemic trends that can be utilized as a guide for developing future materials and alloys. The trade-off in conductivity that results when metals are replaced by alloys for strength and stability purposes becomes an important consideration for both types of engineers. This handbook presents an extensive, updated and comprehensive compilation of the electrical resistivities of metallic alloys.

  3. New icosahedral quasicrystals formed in Cu-based ternary alloys

    Microsoft Academic Search

    T. Honma; T. Ishimasa

    2007-01-01

    New Cu-based P-type icosahedral quasicrystals have been observed in the ternary Cu–(Ga or Al)–Sc alloy systems. The Cu–Ga–Sc quasicrystal forms almost exclusively in a rapidly quenched Cu48Ga34Sc18 alloy, and has a six-dimensional lattice parameter a6D?=?0.6930?nm. The as-cast alloy with the same composition contains no quasicrystal but has a 1\\/1 bcc approximant as its main phase. The Cu–Al–Sc quasicrystal forms at

  4. Radiation induced segregation in candidate fusion reactor alloys

    NASA Astrophysics Data System (ADS)

    Brimhall, J. L.; Baer, D. R.; Jones, R. H.

    The effect of radiation on surface segregation of minor and impurity elements has been studied in four candidate fusion reactor alloys. Radiation induced surface segregation of phosphorus was found in both 316 type stainless steel and in Nimonic PE-16. Segregation and depletion of the other alloying elements in 316 stainless steel agreed with that reported by other investigators. Segregation of nitrogen in ferritic HT-9 was enhanced by radiation but no phosphorus segregation was detected. No significant radiation enhanced or induced segregation was observed in a Ti-6Al-4V alloy. The results indicate that radiation enhanced grain boundary segregation could contribute to the embrittlement of 316 SS and PE-16.

  5. Radiation-induced segregation in candidate fusion-reactor alloys

    SciTech Connect

    Brimhall, J.L.; Baer, D.R.; Jones, R.H.

    1981-07-01

    The effect of radiation on surface segregation of minor and impurity elements has been studied in four candidate fusion reactor alloys. Radiation induced surface segregation of phosphorus was found in both 316 type stainless steel and in Nimonic PE-16. Segregation and depletion of the other alloying elements in 316 stainless steel agreed with that reported by other investigators. Segregation of nitrogen in ferritic HT-9 was enhanced by radiation but no phosphorus segregation was detected. No significant radiation enhanced or induced segregation was observed in a Ti-6Al-4V alloy. The results indicate that radiaton enhanced grain boundary segregation could contribute to the embrittlement of 316 SS and PE-16.

  6. Brazing dissimilar aluminum alloys

    NASA Technical Reports Server (NTRS)

    Dalalian, H.

    1979-01-01

    Dip-brazing process joins aluminum castings to aluminum sheet made from different aluminum alloy. Process includes careful cleaning, surface preparation, and temperature control. It causes minimum distortion of parts.

  7. High temperature niobium alloys

    Microsoft Academic Search

    J. J. Stephens; I. Ahmad

    1991-01-01

    This book covers the following areas regarding high temperature niobium alloys: atomic mass transport of interstitial solutes in niobium; electroplastic effect; dispersion strengthening; dispersion hardening by carbides; tensile behavior of tungsten\\/niobium composites; phase stability; mechanical properties; oxidation.

  8. Ductile ordered intermetallic alloys.

    PubMed

    Liu, C T; Stiegler, J O

    1984-11-01

    Many ordered intermetallic alloys have attractive high-temperature properties; however, low ductility and brittle fracture limit their use for structural applications. The embrittlement in these alloys is mainly caused by an insufficient number of slip systems (bulk brittleness) and poor grain-boundary cohesion. Recent studies have shown that the ductility and fabricability of ordered intermetallics can be substantially improved by alloying processes and control of microstructural features through rapid solidification and thermomechanical treatments. These results demonstrate that the brittleness problem associated with ordered intermetallics can be overcome by using physical metallurgical principles. Application of these principles will be illustrated by results on Ni(3)Al and Ni(3)V-Co(3)V-Fe(3)V. The potential for developing these alloys as a new class of high-temperature structural materials is discussed. PMID:17774926

  9. Nanostructures from directionally solidified NiAl–W eutectic alloys

    Microsoft Academic Search

    Achim Walter Hassel; Andrew Jonathan Smith; Srdjan Milenkovic

    2006-01-01

    A directionally solidified eutectic NiAl–W alloy was employed as a source for NiAl nanopore arrays, W-nanowire arrays and W-nanowires. The NiAl–W eutectic alloy containing 1.5at.% W. A growth rate of 30mmh?1 was used at a temperature gradient of 40Kcm?1 in a Bridgman-type directional solidification furnace. A combined stability diagram was derived from the Pourbaix diagrams of the three elements involved

  10. Size and Shape Effects for Gamma Prime in Alloy 738

    Microsoft Academic Search

    Charles Hays

    2008-01-01

    Cast IN-738 and wrought Inconel 738 are generic applications for most metallurgical designers of gas turbine blades in the\\u000a Power Generation Industry on a worldwide basis... Particularly, where first stage buckets are concerned. This is the case\\u000a because both alloy types exhibit outstanding creep and stress rupture properties to provide an extended service period in\\u000a a harsh environment. Typically, Alloy

  11. Surface segregation in MCrAlY alloys

    Microsoft Academic Search

    C. L. Briant; K. L. Luthra

    1988-01-01

    This paper presents a study of surface segregation in NiCrAlY and FeCrAlY type alloys. The segre-gation was measured using Auger electron spectroscopy. Samples were heated in the spectrometer to temperatures between 800 and 1100 °C, and segregation was measured at temperature as a function of time. The results show that when yttrium and sulfur were present in the alloy, they

  12. Surface segregation in MCrAlY alloys

    Microsoft Academic Search

    C. L. Briant; K. L. Luthra

    1988-01-01

    This paper presents a study of surface segregation in NiCrAlY and FeCrAlY type alloys. The segre-gation was measured using\\u000a Auger electron spectroscopy. Samples were heated in the spectrometer to temperatures between 800 and 1100 C, and segregation\\u000a was measured at temperature as a function of time. The results show that when yttrium and sulfur were present in the alloy,\\u000a they

  13. Thermoelectric properties of alloys based on gadolinium selenides

    Microsoft Academic Search

    Yu. M. Goryachev; V. A. Obolonchik; T. M. Mikhlina; T. M. Yarmola

    1982-01-01

    The gadolinium selenide GdSe1.3 and its alloys are strongly degenerate semimetals of the n-type. These systems can provide a basis for the development of potentially useful thermoelectric materials. Electrotransport in the alloys investigated is effected by electrons in at least two subzones, a strongly degenerate and a weekly degenerate one. Substitution of tantalum and rhenium for gadolinium changes both the

  14. Mechanisms for the hot corrosion of nickel-base alloys

    Microsoft Academic Search

    J. A. Goebel; F. S. Pettit; G. W. Goward

    1973-01-01

    The Na2SO4-induced accelerated oxidation of nickel-base alloys containing elements such as Cr, Al, Mo, W, and V has been studied in\\u000a 1.0 atm O2 in the temperature range of 650? to 1000?C. It has been found that the hot corrosion behavior of these alloys can usually\\u000a be characterized according to one of two types of attack: 1) Na2SO4-induced accelerated oxidation;

  15. Anodic film formation on high strength aluminium alloy FVS0812

    Microsoft Academic Search

    J. SYKES; G. E Thompson; D Mayo; P Skeldon

    1997-01-01

    Barrier-type film growth on the high strength aluminium alloy FVS0812 has been studied by a combination of transmission electron\\u000a microscopy and Rutherford backscattering spectroscopy. The film is composed mainly of amorphous anodic alumina, but is contaminated\\u000a with iron species incorporated into the film from the alloy. The film may also be contaminated with silicon and vanadium species\\u000a at levels below

  16. Injection molding of TiAl alloyed powder

    Microsoft Academic Search

    Kiyotaka Kato; Yoshihiko Nozaki

    1991-01-01

    To realize manufacturing process of near net shape, titanium aluminide powder injection molding was applied to TiAl alloyed powder. TiAl alloyed powder was mixed with the binder consisting of wax and acrylic resin at the content of 45 vol pct. Flow characteristics of this compound was evaluated by extrusion-type flow meter. Then it was injection-molded to the shape of a

  17. Mechanical alloying and milling

    Microsoft Academic Search

    C. Suryanarayana

    2001-01-01

    Mechanical alloying (MA) is a solid-state powder processng technique involving repeated welding, fracturing, and rewelding of powder particles in a high-energy ball mill. Originally developed to produce oxide-dispersion strengthened (ODS) nickel- and iron-base superalloys for applications in the aerospace industry, MA has now been shown to be capable of synthesizing a variety of equilibrium and non-equilibrium alloy phases starting from

  18. Thixoforming 7075 aluminium alloys

    Microsoft Academic Search

    S. Chayong; H. V. Atkinson; P. Kapranos

    2005-01-01

    Commercially extruded 7075 alloy (extrusion ratio of 16:1) has been used as a feedstock for thixoforming in order to investigate thixoformability of a high performance aluminium alloy. The microstructure in the semi-solid state consists of fine spheroidal solid grains surrounded by liquid. The results of thixoforming with one step, two-step and three-step induction heating regimes are presented. Typical defects in

  19. Structure-property relationship of cast Ti-Nb alloys.

    PubMed

    Lee, C M; Ju, C P; Chern Lin, J H

    2002-04-01

    The present work is a study of the microstructure, mechanical properties and corrosion behaviour of a series of binary Ti-Nb alloys with Nb contents up to 35 wt%, with emphasis placed on the structure-property relationship of the alloys. The results indicate that crystal structure and morphology of the Ti-Nb alloys are sensitive to the Nb content. The cast c.p. Ti has a hexagonal alpha phase with a lath type morphology. The alloys containing 15 wt% or less Nb are dominated by a hexagonal alpha' phase with an acicular, martensitic structure. When containing 17.5-25 wt% Nb, the alloys are primarily comprised of an orthorhombic alpha" phase. With 27.5 wt% Nb, metastable beta phase starts to be retained. With Nb contents higher than 30 wt%, the equi-axed beta phase is almost entirely retained. Small amounts of omega phase are detected in alloys containing 27.5 and 30 wt% Nb. Among all present alloys, Ti-10Nb and Ti-27.5Nb exhibit the highest strengths, while the alpha"-dominated (17.5 and 20Nb) and beta-dominated (> 30Nb) alloys have the lowest moduli. All Ti-Nb alloys show excellent corrosion resistance in Hank's solution at 37 degrees C. From the present data, the microhardness, bending strength and modulus of the various phases in Ti-Nb alloys are compared and tentatively summarized as follows: Microhardness: omega > alpha' > alpha" > beta > alpha (c.p. Ti) Bending strength: omega > alpha' > alpha" > beta > alpha (c.p. Ti) Bending modulus: omega > alpha (c.p. Ti) > alpha' > alpha" > beta PMID:11966963

  20. EXAMINATION AND PROPERTIES OF URANIUM ALLOYS

    Microsoft Academic Search

    H. A. Saller; F. A. Rough

    1953-01-01

    The heat treatment, microstructure, hardness, and density data for a ; series of uranium alloys are described. These are alloys which were studied ; because of their potential interest for high-temperature water-corrosion ; resistance. The alloys studied include uranium--zirconium biiiary alloys, ; uranium-- zirconium-base ternary alloys, and uranium --molybdenum alloys. ; (auth);

  1. Corrosion Properties of Lightweight and High-strength 2195 Al-Li Alloy

    Microsoft Academic Search

    Yue XU; Xiaojing WANG; Zhaotong YAN; Jiaxue LI

    2011-01-01

    The intergranular corrosion and exfoliation corrosion of 2195 Al-Li alloy treated by multi-step heating-rate controlled aging (MSRC) are studied. The corrosion features of 2195 Al-Li alloys which are respectively treated by high-temperature nucleation MSRC (H-M) and low-temperature nucleation MSRC (L-M) are contrasted. And the corrosion mechanism of 2195 Al-Li alloy is also discussed from the viewpoint of microstructure (types, distribution,

  2. Electrochemical properties of a SOFC cathode in contact with a chromium-containing alloy separator

    Microsoft Academic Search

    Yoshio Matsuzaki; Isamu Yasuda

    2000-01-01

    Substrate-type solid oxide fuel cells (SOFCs) can reduce the operating temperature of SOFCs to enable alloys to be used as separators. When chromium-forming alloys are used as the separators, however, the performance of SOFC cathodes degrades rapidly. The degradation of a porous La0.6Sr0.4MnO3+? (LSM)\\/YSZ electrode in contact with the alloy current-collector has been investigated using the frequency dispersion diagram of

  3. Hydrogenation effect on magnetic properties of rareearth–Fe\\/Co amorphous alloys

    Microsoft Academic Search

    A andreenko; V Nizhankovski; T Mydlarz; A Salamova; Yu Skourski; N Tristan; V Verbetsky

    1999-01-01

    The effect of hydrogenation on the magnetic properties of rareearth–Fe\\/Co alloys was investigated by means of measuring the magnetization and hysteresisloops. Hydrogenation leads to an increase of positive exchange interactions in 3D-transition metalmagnetic subsystem and magnetization of the alloys. Hydrogenation effect on coercivity isdetermined by a type of the magnetization processes in a particular alloy. Various mechanisms ofphenomena were observed.

  4. Icosahedral quasicrystals in Zn-T-Sc (T = Mn, Fe, Co or Ni) alloys

    Microsoft Academic Search

    Ryo Maezawa; Shiro Kashimoto; Tsutomu Ishimasa

    2004-01-01

    Starting from the Zn17Sc3 cubic approximant, new quasicrystal alloys were sought by replacement of Zn with transition elements T. In the cases when T = Mn, Fe, Co and Ni, new icosahedral quasicrystals are formed in as-cast alloys as major phases at alloy compositions of Zn75T10Sc15. All these quasicrystals belong to a primitive type and have six-dimensional lattice parameters a6D

  5. The effect of penultimate grain size on rolling texture in cu-Sn alloys

    Microsoft Academic Search

    Y. C. Liu; G. A. Alers

    1973-01-01

    The effect of penultimate grain size on the texture of Cu-Sn alloys has been investigated using the modulus method. It was\\u000a observed that in alloys which exhibited the brass-type texture, the large grained specimens yielded a smaller proportion of\\u000a textured material than those which were fine grained. In alloys which exhibited transition textures, however, the larger grain\\u000a size specimens exhibited

  6. Improved tolerance of Pd\\/Cu-treated metal hydride alloys towards air impurities

    Microsoft Academic Search

    Jianwei Ren; Mario Williams; Mykhaylo Lototskyy; Wafeeq Davids; Øystein Ulleberg

    2010-01-01

    Electroless copper plating and colloidal Pd nanoparticle impregnation were shown to greatly improve the tolerance of a multi-component AB5-type alloy towards air impurities. Treated alloys demonstrated improved hydrogen absorption and desorption rates and tolerance towards air impurities when exposed to 0.5 MPa initial hydrogen pressure at room temperature. In addition, the readily-activated response was retained after the treated alloys had been

  7. Adsorption of BTSE and ?-GPS organosilanes on different microstructural regions of 7075-T6 aluminum alloy

    Microsoft Academic Search

    J. Kim; P. C. Wong; K. C. Wong; R. N. S. Sodhi; K. A. R. Mitchell

    2007-01-01

    The adsorption of bis-1,2-(triethoxysilyl)ethane (BTSE) and ?-glycidoxypropyltrimethoxysilane (?-GPS) on mirror-polished 7075-T6 aluminum alloy was studied with an emphasis on the different microstructural regions of the alloy surface, specifically the alloy matrix and the two main types of second-phase particles, as well as how the adsorption was affected by a heating pre-treatment and by changes in the pH of the ?-GPS

  8. Some features of the transgranular embrittlement of ?-titanium alloys under the influence of the environment

    Microsoft Academic Search

    A. I. Igolkin

    1995-01-01

    Some common features of the transgranular embrittlement of a-titanium alloys in chloride solutions, hot salts, liquid metals, and air are established. These types of brittle fracture are typical symptoms of trans-granular embrittlement along the basal (near-basal) cleavage planes of metals (alloys) with hcp crystal lattices with various values of the ratioc\\/a. In this connection, the role of alloying elements and

  9. Stability and elastic properties of Ti-alloys for biomedical application designed with electronic parameters

    Microsoft Academic Search

    W. Elmay; P. Laheurte; A. Eberhardt; B. Bolle; T. Gloriant; E. Patoor; F. Prima; D. Laille; P. Castany; M. Wary

    2010-01-01

    Titanium alloys are receiving a big attention for biomedical applications. Recently, b type titanium alloys composed of non-toxic elements are being developed for these applications. The aim of this paper is to study mechanical properties and deformation mechanisms of three beta titanium alloys designed with similar values of Bo-Md and e\\/a ratio. The contribution of electronic approach to predict beta

  10. The effect of plastic deformation on structure and properties of chosen 6000 series aluminium alloys

    Microsoft Academic Search

    J. Dutkiewicz; L. Litynska

    2002-01-01

    In order to determine the effect of increased copper addition on the strengthening behaviour during deformation and subsequent ageing, two types of Al alloys were continuously cast and extruded: 6013 containing 1.15% Mg, 1.08% Si, 0.7% Mn, 0.3% Fe and 1.1% Cu, and 6XXX alloy containing 1.09% Mg, 0.9% Si, 0.1% Fe and 1.6%Cu (in wt.%). The 6XXX alloy aged

  11. Data mining for structure type prediction

    E-print Network

    Tibbetts, Kevin (Kevin Joseph)

    2004-01-01

    Determining the stable structure types of an alloy is critical to determining many properties of that material. This can be done through experiment or computation. Both methods can be expensive and time consuming. Computational ...

  12. Fretting-wear of zirconium alloys

    Microsoft Academic Search

    Nigel J Fisher; Murray K Weckwerth; Dwight A. E Grandison; Brian M Cotnam

    2002-01-01

    Fretting tests of Zircaloy fuel sheath bearing pads in contact with zirconium alloy (Zr–2.5Nb) pressure tube specimens were conducted at temperatures varying from 25 to 315°C. The effects of motion type and amplitude, water chemistry, fuel sheath manufacturer and pressure tube surface finish were also investigated. The effect of temperature is the most significant. The pressure tube wear coefficient in

  13. Superconducting silver brazing alloy (silver solder).

    PubMed

    Thompson, J R; Thomson, J O

    1978-10-01

    A superconducting transition has been observed in a type BAg-3 silver brazing alloy (silver solder) with T(c)=96.(6) mK and H(c)=4.7 Oe. The associated diamagnetism indicates that approximately 1/3 of the sample volume displays the Meissner effect. This property dictates caution in its use at very low temperatures, particularly near sensitive magnetic devices such as ac and SQUID magnetometers. PMID:18698980

  14. Quenching Alloys in Containerless Processing

    NASA Technical Reports Server (NTRS)

    Oran, W. A.

    1984-01-01

    Magnetic levitation and gas quenching combined in proposed method to melt and rapidly solidify alloys without contacting container walls. Method used to develop new carbides for drill bits, high-ductility structured steel and new high-strength superplastic alloys.

  15. Finding the Alloy Genome

    NASA Astrophysics Data System (ADS)

    Hart, Gus L. W.; Nelson, Lance J.; Zhou, Fei; Ozolins, Vidvuds

    2012-10-01

    First-principles codes can nowadays provide hundreds of high-fidelity enthalpies on thousands of alloy systems with a modest investment of a few tens of millions of CPU hours. But a mere database of enthalpies provides only the starting point for uncovering the ``alloy genome.'' What one needs to fundamentally change alloy discovery and design are complete searches over candidate structures (not just hundreds of known experimental phases) and models that can be used to simulate both kinetics and thermodynamics. Despite more than a decade of effort by many groups, developing robust models for these simulations is still a human-time-intensive endeavor. Compressive sensing solves this problem in dramatic fashion by automatically extracting the ``sparse model'' of an alloy in only minutes. This new paradigm to model building has enabled a new framework that will uncover, automatically and in a general way across the periodic table, the important components of such models and reveal the underlying ``genome'' of alloy physics.

  16. Utilization of titanium alloy equipment

    Microsoft Academic Search

    N. M. Shmakov; V. S. Mikheev

    1974-01-01

    Alloys AT-3 and AT-6 have wide application in practice in contrast to many series containing titanium alloyed with cheap obtainable elements such as aluminum, chromium, iron, silicon, and boron. Alloys AT-3 and AT-6 are processable. Extruded electrodes consisting of magnesio-thermic titanium and added alloying elements were fused twice in a vacuum arc furnace in an argon atmosphere. After machining to

  17. Reduction in Defect Content in ODS Alloys

    SciTech Connect

    Ritherdon, J.; Jones, A.R.

    2000-02-01

    The work detailed within this report is a continuation of earlier work that was carried out under contract number IDX-SY382V. The earlier work comprised a literature review of the sources and types of defects found principally in Fe-based ODS alloys together with a series of experiments designed to identify defects in ODS Fe{sub 3}Al material and recommend methods of defect reduction. Defects found in the Mechanically Alloyed (MA) ODS Fe{sub 3}Al included regions of incomplete MA, porosity, intrusions and fine-grained stringers. Some defects tended to be found in association with one another e.g. intrusions and fine-grained stringers. Preliminary powder separation experiments were also performed. The scope and objectives of the present work were laid out in the technical proposal ``Reduction in Defect Content in ODS Alloys--II'' which formed the basis of amendment 3 of the current contract. The current studies were devised in the context of the preceding work with a view to extending and concluding certain experiments while exploring new avenues of investigation of defect control and reduction where appropriate. All work proposed was within the context of achieving an ODS Fe{sub 3}Al alloy of improved overall quality and potential creep performance (particularly) in the consolidated, release condition. The interim outturn of the experimental work performed is also reported.

  18. Cobalt-base ferromagnetic shape memory alloys

    NASA Astrophysics Data System (ADS)

    Craciunescu, Corneliu M.; Kishi, Yoichi; De Graef, Marc; Lograsso, Thomas A.; Wuttig, Manfred R.

    2002-07-01

    Single crystalline and polycrystalline CoxNiyGa100-(x+y), 41 < xCo< 62 and 19.3 < yNi < 32.7, Ferromagnetic Shape Memory Alloys have been produced in the range of the Heusler-type composition. Elasto-mechanical properties have been analyzed for the annealed and quenched states, respectively. The mechanical spectroscopy data show the occurrence of martensitic phase transformation with the transition range and characteristics depending on the state and the composition of the alloys. For XCo approximately equals 49 +/- 1 at percent, the Ni/Ga ratio was shown to be in direct relationship with the transition temperature range, from an Ms of -100 degrees C for Ni/Ga approximately equals (21/29) to a +150 degrees C for a Ni/Ga ratio of about (26/25). For Ga approximately equals 27 +/- 0.4 at percent, the Co/Ni ratio is in indirect relationship with the transition temperature, with an Ms of -125 degrees C for a (53/19) ratio to a +175 degrees C for a ratio of about (49/26). Optical and electron microscopy shows that a typical thermoelastic martensitic transformation occurs. The L21 Structurbericht parent phase transforms into monoclinic or orthohombic martensitic upon cooling. The formation of a Co-rich phase has been observed for alloys with lower Ga content and is considered to be one of the reasons for the difference in the transformation range for annealed and quenched alloys.

  19. Solidification of an alloy 625 weld overlay

    SciTech Connect

    DuPont, J.N. [Lehigh Univ., Bethlehem, PA (United States). Energy Research Center

    1996-11-01

    The solidification behavior (microsegregation, secondary phase formation, and solidification temperature range) of an Alloy 625 weld overlay deposited on 2.25Cr-1Mo steel by gas metal arc welding was investigated by light and electron optical microscopy, electron microprobe, and differential thermal analysis techniques. The overlay deposit was found to terminate solidification at {approx}1,216 C by a {gamma}/Laves eutectic-type reaction. The Laves phase was highly enriched in Nb, Mo, and Si. The solidification reaction and microsegregation potential of major alloying elements in the overlay deposit are compared to other Nb-bearing Ni base alloys and found to be very similar to those for Alloy 718. Solidification cracks observed in the overlay were attributed to the wide solidification temperature range ({approx}170 C) and formation of interdendritic ({gamma} + Laves) constituent. Reasonable agreement is obtained between the calculated and measured volume percent ({gamma} + Laves) constituent with the Scheil equation by treating the overlay system as a simple {gamma}-Nb binary and using an experimentally determined k{sub Nb} value from electron microprobe data.

  20. Phase transformations in Cu-Sn alloys containing Ni, Al, Ge, and In

    Microsoft Academic Search

    M. I. Zakharova; G. N. Dudchenko

    1981-01-01

    After quenching from 700‡C and aging, Cu-Sn alloys containing Ni and Al were found to have a precipitation of?-solid solution, with a DO3 type of ordering, of metastable a',O, and d' phases. It was established that theO phase has an O4 type of ordering while the a' phase has the Cu3Ti type. Observations revealed that Cu-Sn-Al alloys contained two phases,

  1. TERNARY ALLOY-CONTAINING PLUTONIUM

    Microsoft Academic Search

    Waber

    1960-01-01

    Ternary alloys of uranium and plutonium containing as the third element ; either molybdenum or zirconium are reported. Such alloys are particularly useful ; as reactor fuels in fast breeder reactors. The alloy contains from 2 to 25 at.% ; of molybdenum or zirconium, the balance being a combination of uranium and ; plutonium in the ratio of from 1

  2. ELECTROLESS-PLATED BRAZING ALLOYS

    Microsoft Academic Search

    P. Patriarca; G. M. Slaughter; W. D. Manly

    1957-01-01

    The electroless-plating process deposits an Ni-P brazing alloy that ; exhibits excellent wetability and flowability in conjunction with each high-; temperature alloys as austenitic stainless steels or Inconel when heated above ; the eutectic temperature in a dry hydrogen atmosphere. Complex tubeto-fin heat ; exchanger assemblies can be fabricated by preplating with electroless Ni-P alloy ; and then brazing at

  3. De-alloyed platinum nanoparticles

    DOEpatents

    Strasser, Peter (Houston, TX); Koh, Shirlaine (Houston, TX); Mani, Prasanna (Houston, TX); Ratndeep, Srivastava (Houston, TX)

    2011-08-09

    A method of producing de-alloyed nanoparticles. In an embodiment, the method comprises admixing metal precursors, freeze-drying, annealing, and de-alloying the nanoparticles in situ. Further, in an embodiment de-alloyed nanoparticle formed by the method, wherein the nanoparticle further comprises a core-shell arrangement. The nanoparticle is suitable for electrocatalytic processes and devices.

  4. PLUTONIUM-URANIUM-TITANIUM ALLOYS

    Microsoft Academic Search

    Coffinberry

    1959-01-01

    A plutonium-uranium alloy suitable for use as the fuel element in a fast ; breeder reactor is described. The alloy contains from 15 to 60 at.% titanium ; with the remainder uranium and plutonium in a specific ratio, thereby limiting ; the undesirable zeta phase and rendering the alloy relatively resistant to ; corrosion and giving it the essential characteristic

  5. Ageing of zirconium alloy components

    NASA Astrophysics Data System (ADS)

    Chatterjee, S.; Shah, Priti Kotak; Dubey, J. S.

    2008-12-01

    India has two types (pressurized heavy water reactors (PHWRs) and boiling water reactors (BWRs)) of commercial nuclear reactors in operation, in addition to research reactors. Many of the life limiting critical components in these reactors are fabricated from zirconium alloys. The progressive degradation of these components caused by the cumulative exposure of high energy neutron irradiation with increasing period of reactor operation was monitored to assess the degree of ageing. The components/specimens examined included fuel element claddings removed from BWRs, pressure tubes and garter springs removed from PHWRs and calandria tube specimens used in PHWRs. The tests included tension test (for cladding, garter spring), fracture toughness test (for pressure tube), crush test (for garter spring), and measurement of irradiation induced growth (for calandria tube). Results of various tests conducted are presented and applications of the test results are elaborated for residual life estimation/life extension of the components.

  6. Atomistic Method Applied to Computational Modeling of Surface Alloys

    NASA Technical Reports Server (NTRS)

    Bozzolo, Guillermo H.; Abel, Phillip B.

    2000-01-01

    The formation of surface alloys is a growing research field that, in terms of the surface structure of multicomponent systems, defines the frontier both for experimental and theoretical techniques. Because of the impact that the formation of surface alloys has on surface properties, researchers need reliable methods to predict new surface alloys and to help interpret unknown structures. The structure of surface alloys and when, and even if, they form are largely unpredictable from the known properties of the participating elements. No unified theory or model to date can infer surface alloy structures from the constituents properties or their bulk alloy characteristics. In spite of these severe limitations, a growing catalogue of such systems has been developed during the last decade, and only recently are global theories being advanced to fully understand the phenomenon. None of the methods used in other areas of surface science can properly model even the already known cases. Aware of these limitations, the Computational Materials Group at the NASA Glenn Research Center at Lewis Field has developed a useful, computationally economical, and physically sound methodology to enable the systematic study of surface alloy formation in metals. This tool has been tested successfully on several known systems for which hard experimental evidence exists and has been used to predict ternary surface alloy formation (results to be published: Garces, J.E.; Bozzolo, G.; and Mosca, H.: Atomistic Modeling of Pd/Cu(100) Surface Alloy Formation. Surf. Sci., 2000 (in press); Mosca, H.; Garces J.E.; and Bozzolo, G.: Surface Ternary Alloys of (Cu,Au)/Ni(110). (Accepted for publication in Surf. Sci., 2000.); and Garces, J.E.; Bozzolo, G.; Mosca, H.; and Abel, P.: A New Approach for Atomistic Modeling of Pd/Cu(110) Surface Alloy Formation. (Submitted to Appl. Surf. Sci.)). Ternary alloy formation is a field yet to be fully explored experimentally. The computational tool, which is based on the BFS (Bozzolo, Ferrante, and Smith) method for the calculation of the energetics, consists of a small number of simple PCbased computer codes that deal with the different aspects of surface alloy formation. Two analysis modes are available within this package. The first mode provides an atom-by-atom description of real and virtual stages 1. during the process of surface alloying, based on the construction of catalogues of configurations where each configuration describes one possible atomic distribution. BFS analysis of this catalogue provides information on accessible states, possible ordering patterns, and details of island formation or film growth. More importantly, it provides insight into the evolution of the system. Software developed by the Computational Materials Group allows for the study of an arbitrary number of elements forming surface alloys, including an arbitrary number of surface atomic layers. The second mode involves large-scale temperature-dependent computer 2. simulations that use the BFS method for the energetics and provide information on the dynamic processes during surface alloying. These simulations require the implementation of Monte-Carlo-based codes with high efficiency within current workstation environments. This methodology capitalizes on the advantages of the BFS method: there are no restrictions on the number or type of elements or on the type of crystallographic structure considered. This removes any restrictions in the definition of the configuration catalogues used in the analytical calculations, thus allowing for the study of arbitrary ordering patterns, ultimately leading to the actual surface alloy structure. Moreover, the Monte Carlo numerical technique used for the large-scale simulations allows for a detailed visualization of the simulated process, the main advantage of this type of analysis being the ability to understand the underlying features that drive these processes. Because of the simplicity of the BFS method for e energetics used in these calculations, a detailed atom-by-atom analysis can be performed at any

  7. Study of corrosion between a titanium implant and dental alloys.

    PubMed

    Reclaru, L; Meyer, J M

    1994-06-01

    The infiltration of saliva into the multi-metallic structures on titanium implants brings different types of alloys into temporary or permanent contact. In this way a galvanic cell is established as a result of their potential difference. The galvanic cell phenomenon is compounded by another type of corrosion resulting from the geometry of the assembly: localized crevice corrosion. Fifteen galvanic couples (Ti/gold-based alloys, Ti/palladium-based alloy and Ti/non-precious alloys) were studied. Various electrochemical parameters (Ecorr, Ecommon, Ecouple corr, Ecrevice, icorr, icouple corr and Tafel slopes) were analysed. The galvanic currents measured are of the same order of magnitude (except Ti/stainless steel). They remain low. Application of the mixed-potential theory shows that titanium in coupling with the alloys studied will be under either cathodic or anodic control. According to the results obtained, an alloy that is potentially usable for superstructures in a galvanic coupling with titanium must fulfil a certain number of parameters: in a coupling, titanium must have a weak anodic polarization; the current generated by the galvanic cell must also be weak; the crevice potential must be markedly higher than the common potential. PMID:8027459

  8. Boron addition to alloys

    SciTech Connect

    Coad, B. C.

    1985-08-20

    A process for addition of boron to an alloy which involves forming a melt of the alloy and a reactive metal, selected from the group consisting of aluminum, titanium, zirconium and mixtures thereof to the melt, maintaining the resulting reactive mixture in the molten state and reacting the boric oxide with the reactive metal to convert at least a portion of the boric oxide to boron which dissolves in the resulting melt, and to convert at least portion of the reactive metal to the reactive metal oxide, which oxide remains with the resulting melt, and pouring the resulting melt into a gas stream to form a first atomized powder which is subsequently remelted with further addition of boric oxide, re-atomized, and thus reprocessed to convert essentially all the reactive metal to metal oxide to produce a powdered alloy containing specified amounts of boron.

  9. Magnesium and magnesium alloys

    SciTech Connect

    Avedesian, M.; Baker, H. [eds.

    1998-12-31

    This new handbook is the most comprehensive publication of engineering information on commercial magnesium alloys under one cover in the last sixty years. Prepared with the cooperation of the International Magnesium Association, it presents the industrial practices currently used throughout the world, as well as the properties of the products critical to their proper application. Contents include: general characteristics; physical metallurgy; melting, refining, alloying, recycling, and powder production; casting; heat treatment; forging, rolling, and extrusion; semisolid processing; forming; joining; cleaning and finishing; selection, application, and properties of grades and alloys; design considerations; mechanical behavior and wear resistance; fatigue and fracture-mechanics; high-temperature strength and creep; corrosion and stress-corrosion cracking; specification.

  10. Noble alloys in dentistry.

    PubMed

    Gettleman, L

    1991-04-01

    Noble metals used for dental castings continue to consist of alloys of gold, palladium, and silver (not a noble metal), with smaller amounts of iridium, ruthenium, and platinum. The majority are used as a backing for ceramic baking, with the rest used as inlays, onlays, and unveneered crowns. Base metal alloys, principally made of nickel, chromium, and beryllium have gained widespread usage, especially in the United States, due to their lower cost and higher mechanical properties. The current literature, for the most part, cites the use of noble alloys as controls for trials of alternative materials. Direct gold (gold foil) still retains a following and a number of new patents were founded. PMID:1777669

  11. Aluminum alloys for satellite boxes : engineering guidelines for obtaining adequate strength while minimizing residual stresses and machining distortion.

    SciTech Connect

    Younger, Mandy S.; Eckelmeyer, Kenneth Hall

    2007-11-01

    This report provides strategies for minimizing machining distortion in future designs of aluminum alloy satellite boxes, based in part on key findings from this investigation. The report outlines types of aluminum alloys and how they are heat treated, how residual stresses develop during heat treatment of age hardening alloys, ways residual stresses can be minimized, and the design of machining approaches to minimize distortion in parts that contain residual stresses. Specific recommendations are made regarding alloy selection, heat treatment, stress relieving, and machining procedures for boxes requiring various strength levels with emphasis on 6061 and 7075 aluminum alloys.

  12. Iron aluminide alloys with improved properties for high temperature applications

    DOEpatents

    McKamey, Claudette G. (Knoxville, TN); Liu, Chain T. (Oak Ridge, TN)

    1990-01-01

    An improved iron aluminide alloy of the DO.sub.3 type that has increased room temperature ductility and improved high elevated temperature strength. The alloy system further is resistant to corrosive attack in the environments of advanced energy corrosion systems such as those using fossil fuels. The resultant alloy is relatively inexpensive as contrasted to nickel based and high nickel steels currently utilized for structural components. The alloy system consists essentially of 26-30 at. % aluminum, 0.5-10 at. % chromium, 0.02-0.3 at. % boron plus carbon, up to 2 at. % molybdenum, up to 1 at. % niobium, up to 0.5 at. % zirconium, up to 0.1 at. % yttrium, up to 0.5 at. % vanadium and the balance iron.

  13. Iron aluminide alloys with improved properties for high temperature applications

    DOEpatents

    McKamey, C.G.; Liu, C.T.

    1990-10-09

    An improved iron aluminide alloy of the DO[sub 3] type is described that has increased room temperature ductility and improved high elevated temperature strength. The alloy system further is resistant to corrosive attack in the environments of advanced energy conversion systems such as those using fossil fuels. The resultant alloy is relatively inexpensive as contrasted to nickel based and high nickel steels currently utilized for structural components. The alloy system consists essentially of 26--30 at. % aluminum, 0.5--10 at. % chromium, 0.02--0.3 at. % boron plus carbon, up to 2 at. % molybdenum, up to 1 at. % niobium, up to 0.5 at. % zirconium, up to 0.1 at. % yttrium, up to 0.5 at. % vanadium and the balance iron. 3 figs.

  14. Porphyromonas gingivalis lipopolysaccharide affinity for two casting alloys.

    PubMed

    Knoernschild, K L; Tompkins, G R; Lefebvre, C A; Schuster, G S

    1995-07-01

    With the exception of plaque, the affinity of biologically active bacterial products for restorative materials and the influence of that affinity on periodontal health has not been detailed. This study recognized that Porphyromonas gingivalis endotoxin, which is cell envelope lipopolysaccharide (LPS) produced by a bacterium that is common to the crevicular microbial flora, has an affinity for dental casting alloys. Regardless of surface finish, no difference in LPS initial adherence or elution was recorded between a type III gold or nickel-chromium-beryllium alloy (p > 0.05), but LPS readily adhered and remained attached to both alloys. LPS affinity could contribute to periodontal inflammation in tissues that approximate restorations fabricated from either alloy. PMID:7674187

  15. Effect of Zr addition on the aging behavior of A319 aluminum cast alloy

    Microsoft Academic Search

    P. Sepehrband; R. Mahmudi; F. Khomamizadeh

    2005-01-01

    The structure, age hardening response, precipitate type and hardness of A319 cast aluminum alloy without and with zirconium addition were investigated. The as-solutionized and artificially-aged hardness values were higher for the Zr-containing alloy. This is believed to be a consequence of the precipitation of Al3Zr particles produced during sufficiently long solutionizing treatments.

  16. Effect of fetal calf serum on the corrosion behaviour of magnesium alloys

    Microsoft Academic Search

    H. Hornberger; F. Witte; N. Hort; W.-D. Mueller

    2011-01-01

    The corrosion behaviour of WE43 magnesium alloys using the mini cell system was studied. Voltammetry and impedance spectroscopy were applied to study on the one hand the effect of microstructure of the working electrode and on the other hand the effect of proteins in the electrolyte. Two types of alloy samples were produced (i) by permanent mould casting and (ii)

  17. Electric-spark alloying of steel with tungsten-free hard metals

    Microsoft Academic Search

    A. D. Verkhoturov; V. K. Vitryanyuk; F. F. Egorov; E. A. Zaitsev

    1982-01-01

    A study was made of the ESA of steel with tungsten and tungsten-free TN type hard metals in different units and under different conditions, with and without anode dressing. It has been established that in alloying under “finishing” conditions the erosion of a dressed TN-20 alloy anode is greater than that of an undressed one; this is due to the

  18. Cutting Forces Modeling in Finish Turning of Inconel 718 Alloy with Round Inserts

    E-print Network

    Boyer, Edmond

    Cutting Forces Modeling in Finish Turning of Inconel 718 Alloy with Round Inserts S Matrices, Scaling Effect, Inconel 718 Abstract. In turning, the applied forces have to be known with a straight edge. This study deals with finishing operations of Inconel 718 alloy with one type of round

  19. The electrical resistivity and super-conductivity of some uranium alloys and compounds

    Microsoft Academic Search

    B. S. Chandrasekhar; J. K. Hulm

    1958-01-01

    The electrical resistivity and superconductivity of a series of alpha ; (orthorhombic) and quenched (bodycentered cubic) binary alloys of uranium ; with niobium and molybdenum were investigated at temperatures down to 1 K. ; Anomalous resistivity behavior occurs in both types of structure. The ; alloys are particularly unusual in possessing a negative temperature coefficient ; from room temperature down

  20. Effect of titanium additions on the microstructure of DC-cast aluminium alloys

    Microsoft Academic Search

    Majed Jaradeh; Torbjörn Carlberg

    2005-01-01

    The effect of the Ti content on the solidification structures of aluminum alloys of AA3003 type was investigated. Some improved corrosion properties can be obtained from increasing the Ti contents in aluminium alloys to a level above the normal practice for grain refinement. However, increasing the Ti content above the peritectic point, 0.15%, can influence the grain refinement and cause

  1. Modeling of Substitutional Site Preference in Ordered Intermetallic Alloys

    NASA Technical Reports Server (NTRS)

    Bozzolo, Guillermo; Noebe, Ronald D.; Honecy, Frank

    1998-01-01

    We investigate the site substitution scheme of specific alloying elements in ordered compounds and the dependence of site occupancy on compound stoichiometry, alloy concentration. This basic knowledge, and the interactions with other alloying additions are necessary in order to predict and understand the effect of various alloying schemes on the physical properties of a material, its response to various temperature treatments, and the resulting mechanical properties. Many theoretical methods can provide useful but limited insight in this area, since most techniques suffer from constraints in the type of elements and the crystallographic structures that can be modeled. With this in mind, the Bozzolo-Ferrante-Smith (BFS) method for alloys was designed to overcome these limitations, with the intent of providing an useful tool for the theoretical prediction of fundamental properties and structure of complex systems. After a brief description of the BFS method, its use for the determination of site substitution schemes for individual as well as collective alloying additions to intermetallic systems is described, including results for the concentration dependence of the lattice parameter. Focusing on B2 NiAl, FeAl and CoAl alloys, the energetics of Si, Ti, V, Cr, Fe, Co, Ni, Cu, Zr, Nb, Mo, Ru, Hf, Ta and W alloying additions are surveyed. The effect of single additions as well as the result of two simultaneous additions, discussing the interaction between additions and their influence on site preference schemes is considered. Finally, the BFS analysis is extended to ternary L1(sub 2) (Heusler phase) alloys. A comparison between experimental and theoretical results for the limited number of cases for which experimental data is available is also included.

  2. Surface modification of high temperature iron alloys

    DOEpatents

    Park, J.H.

    1995-06-06

    A method and article of manufacture of a coated iron based alloy are disclosed. The method includes providing an iron based alloy substrate, depositing a silicon containing layer on the alloy surface while maintaining the alloy at a temperature of about 700--1200 C to diffuse silicon into the alloy surface and exposing the alloy surface to an ammonia atmosphere to form a silicon/oxygen/nitrogen containing protective layer on the iron based alloy. 13 figs.

  3. Positron-annihilation 2D-ACAR studies of disordered and defected alloys

    SciTech Connect

    Bansil, A.; Prasad, R.; Smedskjaer, L.C.; Benedek, R.; Mijnarends, P.E.

    1987-09-01

    Theoretical and experimental progess in connection with 2D-ACAR positron annihilation studies of ordered, disordered, and defected alloys is discussed. We present, in particular, some of the recent developments concerning the electronic structure of disordered alloys, and the work in the area of annihilation from positrons trapped at vacancy-type defects in metals and alloys. The electronic structure and properties of a number of compounds are also discussed briefly; we comment specifically on high T/sub c/ ceramic superconductors, Heusler alloys, and transition-metal aluminides. 58 refs., 116 figs.

  4. The shape memory capability and life of Cu-Al-Be-X alloys

    SciTech Connect

    Dong, Y.Y.; Dar, K.Z. (Gansu Mechanical Engineering Academy, Lanzhou (China)); Wang, T.M. (Lanzhou Univ. (China)); Zin, S.J. (Lanzhou High Pressure Valve Co. (China))

    1994-09-01

    The shape memory capacity and the shape memory life of three alloys of the Cu-11.6Al-0.4Be-X type have been investigated using the strain angle restoration method and compared with the alloy Cu-25Zn-4Al. The alloys were subjected to various normalizing and normalizing plus aging treatments, and all were found to possess excellent shape memory properties. The alloy Cu-11.6Al-0.4Be-0.2Cr demonstrated the best shape memory capacity and life.

  5. Thermal coatings for titanium-aluminum alloys

    SciTech Connect

    Cunnington, G.R.; Clark, R.K.; Robinson, J.C.

    1993-04-01

    Titanium aluminides and titanium alloys are candidate materials for use in hot structure and heat-shield components of hypersonic vehicles because of their good strength-to-weight characteristics at elevated temperature. However, in order to utilize their maximum temperature capability, they must be coated to resist oxidation and to have a high total remittance. Also, surface catalysis for recombination of dissociated species in the aerodynamic boundary layer must be minimized. Very thin chemical vapor deposition (CVD) coatings are attractive candidates for this application because of durability and very light weight. To demonstrate this concept, coatings of boron-silicon and aluminum-boron-silicon compositions were applied to the titanium-aluminides alpha2 (Ti-14Al-21Nb), super-alpha2 (Ti-14Al-23-Nb-2V), and gamma (Ti-33Al-6Nb-1Ta) and to the titanium alloy beta-21S (Ti-15Mo-3Al-3Nb-0.2Si). Coated specimens of each alloy were subjected to a set of simulated hypersonic vehicle environmental tests to determine their properties of oxidation resistance, surface catalysis, radiative emittance, and thermal shock resistance. Surface catalysis results should be viewed as relative performance only of the several coating-alloy combinations tested under the specific environmental conditions of the LaRC Hypersonic Materials Environmental Test System (HYMETS) arc-plasma-heated hypersonic wind tunnel. Tests were also conducted to evaluate the hydrogen transport properties of the coatings and any effects of the coating processing itself on fatigue life of the base alloys. Results are presented for three types of coatings, which are as follows: (1) a single layer boron silicon coating, (2) a single layer aluminum-boron-silicon coating, and (3) a multilayer coating consisting of an aluminum-boron-silicon sublayer with a boron-silicon outer layer.

  6. Thermal coatings for titanium-aluminum alloys

    NASA Technical Reports Server (NTRS)

    Cunnington, George R.; Clark, Ronald K.; Robinson, John C.

    1993-01-01

    Titanium aluminides and titanium alloys are candidate materials for use in hot structure and heat-shield components of hypersonic vehicles because of their good strength-to-weight characteristics at elevated temperature. However, in order to utilize their maximum temperature capability, they must be coated to resist oxidation and to have a high total remittance. Also, surface catalysis for recombination of dissociated species in the aerodynamic boundary layer must be minimized. Very thin chemical vapor deposition (CVD) coatings are attractive candidates for this application because of durability and very light weight. To demonstrate this concept, coatings of boron-silicon and aluminum-boron-silicon compositions were applied to the titanium-aluminides alpha2 (Ti-14Al-21Nb), super-alpha2 (Ti-14Al-23-Nb-2V), and gamma (Ti-33Al-6Nb-1Ta) and to the titanium alloy beta-21S (Ti-15Mo-3Al-3Nb-0.2Si). Coated specimens of each alloy were subjected to a set of simulated hypersonic vehicle environmental tests to determine their properties of oxidation resistance, surface catalysis, radiative emittance, and thermal shock resistance. Surface catalysis results should be viewed as relative performance only of the several coating-alloy combinations tested under the specific environmental conditions of the LaRC Hypersonic Materials Environmental Test System (HYMETS) arc-plasma-heated hypersonic wind tunnel. Tests were also conducted to evaluate the hydrogen transport properties of the coatings and any effects of the coating processing itself on fatigue life of the base alloys. Results are presented for three types of coatings, which are as follows: (1) a single layer boron silicon coating, (2) a single layer aluminum-boron-silicon coating, and (3) a multilayer coating consisting of an aluminum-boron-silicon sublayer with a boron-silicon outer layer.

  7. Environmentally Assisted Cracking of Nickel Alloys

    SciTech Connect

    Rebak, R B

    2004-02-06

    Environmentally Assisted Cracking (EAC) is a general term that includes phenomena such as stress corrosion cracking (SCC), hydrogen embrittlement (HE), sulfide stress cracking (SSC), liquid metal embrittlement (LME), etc. EAC refers to a phenomenon by which a normally ductile metal looses its toughness (e.g. elongation to rupture) when it is subjected to mechanical stresses in presence of a specific corroding environment. For EAC to occur, three affecting factors must be present simultaneously. These include: (1) Mechanical tensile stresses, (2) A susceptible metal microstructure and (3) A specific aggressive environment. If any of these three factors is removed, EAC will not occur. That is, to mitigate the occurrence of EAC, engineers may for example eliminate residual stresses in a component or limit its application to certain chemicals (environment). The term environment not only includes chemical composition of the solution in contact with the component but also other variables such as temperature and applied potential. Nickel alloys are in general more resistant than stainless steels to EAC. For example, austenitic stainless steels (such as S30400) suffer SCC in presence of hot aqueous solutions containing chloride ions. Since chloride ions are ubiquitous in most industrial applications, the use of stressed stainless steels parts is seriously limited. On the other hand, nickel alloys (such as N10276) are practically immune to SCC in presence of hot chloride solutions and therefore an excellent alternative to replace the troubled stainless steels. Nonetheless, nickel alloys are not immune to other types of EAC. There are several environments (such as hot caustic and hot hydrofluoric acid) that may produce embrittlement in nickel alloys (Crum et al, 2000) (Table 1). The conditions where nickel alloys suffer EAC are highly specific and therefore avoidable by the proper design of the industrial components.

  8. Tensile bond strength of a composite resin cement for bonded prosthesis to various dental alloys.

    PubMed

    Rubo, J H; Pegoraro, L F

    1995-09-01

    The development of composite resin cements that chemically bond to dental alloys has improved the construction of resin-bonded prostheses. Composite resins can be selected for various situations, but specific clinical situations may require different alloys. This study evaluated the ability of a composite resin cement to bond to various dental alloys of different compositions. Ten pairs of disks for each alloy (two NiCr, two NiCrBe, one CuAl, one gold type IV, and one gold for metal ceramic) were bonded to a composite resin cement after air abrasion was performed with aluminum oxide. The disks were then rinsed in tap water and were ultrasonically cleaned in distilled water for 2 minutes. The tensile tests exhibited greater values for alloys ultrasonically cleaned, and the best results were recorded by NiCr and NiCrBe alloys. PMID:7473275

  9. Environmental protection to 922K (1200 F) for titanium alloys

    NASA Technical Reports Server (NTRS)

    Groves, M. T.

    1973-01-01

    Evaluations are presented of potential coating systems for protection of titanium alloys from hot-salt stress-corrosion up to temperatures of 755 K (900 F) and from oxidation embrittlement up to temperature of 922 K (1200 F). Diffusion type coatings containing Si, Al, Cr, Ni or Fe as single coating elements or in various combinations were evaluated for oxidation protection, hot-salt stress-corrosion (HSSC) resistance, effects on tensile properties, fatigue properties, erosion resistance and ballistic impact resistance on an alpha and beta phase titanium alloy (Ti-6Al-2Sn-4Zr-2Mo). All of the coatings investigated demonstrated excellent oxidation protectiveness, but none of the coatings provided protection from hot-salt stress-corrosion. Experimental results indicated that both the aluminide and silicide types of coatings actually decreased the HSSC resistance of the substrate alloy. The types of coatings which have typically been used for oxidation protection of refractory metals and nickel base superalloys are not suitable for titanium alloys because they increase the susceptibility to hot-salt stress-corrosion, and that entirely new coating concepts must be developed for titanium alloy protection in advanced turbine engines.

  10. Interfacial oxidations of pure titanium and titanium alloys with investments.

    PubMed

    Ban, S; Watanabe, T; Mizutani, N; Fukui, H; Hasegawa, J; Nakamura, H

    2000-12-01

    External oxides of a commercially pure titanium (cpTi), Ti6Al4V alloy, and an experimental beta-type titanium alloy (Ti 53.4 wt%, Nb 29 wt%, Ta 13 wt%, and Zr 4.6 wt%) were characterized after heating to 600, 900, 1150, and 1400 degrees C in contact with three types of investments (alumina cement, magnesia cement, and phosphate-bonded) in air. XRD studies demonstrated that MgO, Li2TiO3 and/or Li2Ti3O7 were formed through reactions with the metal and the constituents in the magnesia cement-investment after heating to 900, 1150, and 1400 degrees C. Except for these conditions, TiO2 (rutile) was only formed on cpTi. For titanium alloys, the other components apart from Ti also formed simple and complex oxides such as Al2O3 and Al2TiO5 on Ti6Al4V, and Zr0.25Ti0.75Nb2O7 on the beta-type titanium alloy. However, no oxides containing V or Ta were formed. These results suggest that the constituents of titanium alloys reacted with the investment oxides and atmospheric oxygen to form external oxides due to the free energy of oxide formation and the concentration of each element on the metal surface. PMID:11816365

  11. METALLOGRAPHY OF TITANIUM ALLOYS

    Microsoft Academic Search

    H. R. Ogden; F. C. Holden

    1958-01-01

    Because of the importance of mnetalography to the technolagy of titanium ; and because of the current interest in titanium technology, it is essential that ; the metallurgists working with titanium understand its metallography. In this ; report emphasis is placed on the microstructures of titanium and its alloys. The ; report contains both a general description of titanium metallegraphy

  12. Shape Memory Alloy Actuator

    NASA Technical Reports Server (NTRS)

    Baumbick, Robert J. (Inventor)

    2002-01-01

    The present invention discloses and teaches a unique, remote optically controlled micro actuator particularly suitable for aerospace vehicle applications wherein hot gas, or in the alternative optical energy, is employed as the medium by which shape memory alloy elements are activated. In gas turbine powered aircraft the source of the hot gas may be the turbine engine compressor or turbine sections.

  13. Shape Memory Alloy Actuator

    NASA Technical Reports Server (NTRS)

    Baumbick, Robert J. (Inventor)

    2000-01-01

    The present invention discloses and teaches a unique, remote optically controlled micro actuator particularly suitable for aerospace vehicle applications wherein hot gas, or in the alternative optical energy, is employed as the medium by which shape memory alloy elements are activated. In gas turbine powered aircraft the source of the hot gas may be the turbine engine compressor or turbine sections.

  14. Quinary metallic glass alloys

    DOEpatents

    Lin, Xianghong (Pasadena, CA); Johnson, William L. (Pasadena, CA)

    1998-01-01

    At least quinary alloys form metallic glass upon cooling below the glass transition temperature at a rate less than 10.sup.3 K/s. Such alloys comprise zirconium and/or hafnium in the range of 45 to 65 atomic percent, titanium and/or niobium in the range of 4 to 7.5 atomic percent, and aluminum and/or zinc in the range of 5 to 15 atomic percent. The balance of the alloy compositions comprise copper, iron, and cobalt and/or nickel. The composition is constrained such that the atomic percentage of iron is less than 10 percent. Further, the ratio of copper to nickel and/or cobalt is in the range of from 1:2 to 2:1. The alloy composition formula is: (Zr,Hf).sub.a (Al,Zn).sub.b (Ti,Nb).sub.c (Cu.sub.x Fe.sub.y (Ni,Co).sub.z).sub.d wherein the constraints upon the formula are: a ranges from 45 to 65 atomic percent, b ranges from 5 to 15 atomic percent, c ranges from 4 to 7.5 atomic percent, d comprises the balance, d.multidot.y is less than 10 atomic percent, and x/z ranges from 0.5 to 2.

  15. Quinary metallic glass alloys

    DOEpatents

    Lin, X.; Johnson, W.L.

    1998-04-07

    At least quinary alloys form metallic glass upon cooling below the glass transition temperature at a rate less than 10{sup 3}K/s. Such alloys comprise zirconium and/or hafnium in the range of 45 to 65 atomic percent, titanium and/or niobium in the range of 4 to 7.5 atomic percent, and aluminum and/or zinc in the range of 5 to 15 atomic percent. The balance of the alloy compositions comprise copper, iron, and cobalt and/or nickel. The composition is constrained such that the atomic percentage of iron is less than 10 percent. Further, the ratio of copper to nickel and/or cobalt is in the range of from 1:2 to 2:1. The alloy composition formula is: (Zr,Hf){sub a}(Al,Zn){sub b}(Ti,Nb){sub c}(Cu{sub x}Fe{sub y}(Ni,Co){sub z}){sub d} wherein the constraints upon the formula are: a ranges from 45 to 65 atomic percent, b ranges from 5 to 15 atomic percent, c ranges from 4 to 7.5 atomic percent, d comprises the balance, d{hor_ellipsis}y is less than 10 atomic percent, and x/z ranges from 0.5 to 2.

  16. Corrosion resistant austenitic alloy

    Microsoft Academic Search

    T. A. DeBold; D. G. Frick; J. S. Kutzamanis

    1984-01-01

    An austenitic stainless corrosion resistant alloy and articles made therefrom having good resistance to pitting and crevice corrosion in oxidizing chloride-bearing media combined with resistance to general corrosion and to intergranular corrosion in oxidizing media containing C, Mn, Si, P, S, Cr, Ni, Mo, Cu, N, B, Ce, La, Nb, Ti and the balance iron. The amount of nitrogen is

  17. Alloys for hydrogen storage in nickel/hydrogen and nickel/metal hydride batteries

    NASA Technical Reports Server (NTRS)

    Anani, Anaba; Visintin, Arnaldo; Petrov, Konstantin; Srinivasan, Supramaniam; Reilly, James J.; Johnson, John R.; Schwarz, Ricardo B.; Desch, Paul B.

    1993-01-01

    Since 1990, there has been an ongoing collaboration among the authors in the three laboratories to (1) prepare alloys of the AB(sub 5) and AB(sub 2) types, using arc-melting/annealing and mechanical alloying/annealing techniques; (2) examine their physico-chemical characteristics (morphology, composition); (3) determine the hydrogen absorption/desorption behavior (pressure-composition isotherms as a function of temperature); and (4) evaluate their performance characteristics as hydride electrodes (charge/discharge, capacity retention, cycle life, high rate capability). The work carried out on representative AB(sub 5) and AB(sub 2) type modified alloys (by partial substitution or with small additives of other elements) is presented. The purpose of the modification was to optimize the thermodynamics and kinetics of the hydriding/dehydriding reactions and enhance the stabilities of the alloys for the desired battery applications. The results of our collaboration, to date, demonstrate that (1) alloys prepared by arc melting/annealing and mechanical alloying/annealing techniques exhibit similar morphology, composition and hydriding/dehydriding characteristics; (2) alloys with the appropriate small amounts of substituent or additive elements: (1) retain the single phase structure, (2) improve the hydriding/dehydriding reactions for the battery applications, and (3) enhance the stability in the battery environment; and (3) the AB(sub 2) type alloys exhibit higher energy densities than the AB(sub 5) type alloys but the state-of-the-art, commercialized batteries are predominantly manufactured using Ab(sub 5) type alloys.

  18. Casting Characteristics of Aluminum Die Casting Alloys

    Microsoft Academic Search

    Makhlouf M. Makhlouf; Diran Apelian

    2002-01-01

    The research program investigates the casting characteristics of selected aluminum die casting alloys. Specifically, the alloys' tendencies towards die soldering and sludge formation, and the alloys' fluidity and machinability are evaluated. It was found that: When the Fe and Mn contents of the alloy are low; caution has to be taken against possible die soldering. When the alloy has a

  19. Investigation of HVOF spraying on magnesium alloys

    Microsoft Academic Search

    Maria Parco; Lidong Zhao; Jochen Zwick; Kirsten Bobzin; Erich Lugscheider

    2006-01-01

    Magnesium alloys are promising alternatives to other lightweight alloys such as aluminum alloys due to their high specific strength and stiffness. However, the use of magnesium alloys is limited by their poor wear behaviour and corrosion performance. Recent studies have shown an enormous potential of thermal spray techniques for the surface modification of Mg alloys. The high particle velocities and

  20. Properties of Porous TiNbZr Shape Memory Alloy Fabricated by Mechanical Alloying

    E-print Network

    Zheng, Yufeng

    Properties of Porous TiNbZr Shape Memory Alloy Fabricated by Mechanical Alloying and Hot IsostaticNb-6Zr (at.%) shape memory alloys produced using elemental powders by means of mechanical alloying strength. Keywords hot isostatic pressing, mechanical alloying, shape memory alloy 1. Introduction Porous

  1. Reduction in Defect Content of ODS Alloys

    SciTech Connect

    Ritherdon, J

    2003-11-17

    The work detailed within this report is a continuation of earlier work carried out under contract number 1DX-SY382V. The earlier work comprises a literature review of the sources and types of defects found principally in Fe-based ODS alloys as well as experimental work designed to identify defects in the prototype ODS-Fe{sub 3}Al alloy, deduce their origins and to recommend methods of defect reduction. The present work is an extension of the experimental work already reported and concentrates on means of reduction of defects already identified rather than the search for new defect types. This report also includes work regarding the manipulation of grain structures via deformation processing and further results gathered during powder separation trials involving the separation of different metallic powders in terms of their differing densities. The scope and objectives of the present work were laid out in the technical proposal ''Reduction in Defect Content in ODS Alloys-IV''. All the work proposed in the ''Statement of Work'' section of the technical proposal has been carried out except for some of that dependent on the acquisition of materials from other sources. However, wherever omissions from the ''Plan of Action'' detailed in the ''Statement of Work'' have occurred due to lack of suitable materials, other related experimental work has been devised to fill the gaps where possible. All work extra to the ''Statement of Work'' falls within the context of an ODS-Fe{sub 3}Al alloy of improved overall quality and potential creep performance in the consolidated form. The outturn of the experimental work performed is reported in the following sections.

  2. Structure of dental gallium alloys.

    PubMed

    Herø, H; Simensen, C J; Jørgensen, R B

    1996-07-01

    The interest in gallium alloys as a replacement for amalgam has increased in recent years due to the risk of environmental pollution from amalgam. Alloy powders with compositions close to those for alloys of amalgam are mixed with a liquid gallium alloy. The mix is condensed into a prepared cavity in much the same way as for amalgam. The aim of the present work was to study the structure of: (1) two commercial alloy powders containing mainly silver, tin and copper, and (2) the phases formed by mixing these powders with a liquid alloy of gallium, indium and tin. One of the alloy powders contained 9 wt% palladium. Cross-sections of cylindrical specimens made by these gallium mixes were investigated by scanning electron microscopy, energy dispersive spectroscopy and X-ray diffraction. Discrete grains of the following phases were found to be present in both gallium alloys: hexagonal Ag2Ga, tetragonal Cu(Pd)Ga2, cubic Ag9In4 and tetragonal beta-Sn. Indications of hexagonal or orthorhombic Ag2Sn were found in the remaining, unreacted alloy particles. In the palladium-containing alloy the X-ray reflections indicate a minor fraction of cubic Cu9Ga4 in addition to the Cu(Pd)Ga2 phase. Particles of beta-Sn are probably precipitated because Sn-Ga phases cannot be formed according to the binary phase diagram. PMID:8805980

  3. Transport properties of doped GeSn alloys

    NASA Astrophysics Data System (ADS)

    D'Costa, Vijay R.; Tolle, John; Xie, Junqi; Menéndez, José; Kouvetakis, John

    2010-01-01

    We present a systematic study of the transport properties of n- and p-type Ge0.98Sn0.02 alloys using infrared spectroscopic ellipsometry and electrical measurements. We measure the dielectric function of our samples in the infrared range where the response is mainly due to free carrier absorption. In the case of p-type material, we observe, in addition to the free carrier response, optical transitions between split-off (SO), light (LH), and heavy-hole (HH) bands. The electron and hole mobilities for Ge0.98Sn0.02 alloys with carrier concentrations >1018 cm-3 are comparable to those found in Ge samples with similar doping concentrations. The electron and hole effective masses of Ge0.98Sn0.02 alloys are close to that of n-doped and p-doped Ge respectively.

  4. Positron lifetime studies of decomposition in 2024 (Al-Cu-Mg) and 7010 (Al-Zn-Cu-Mg) alloys

    SciTech Connect

    Dlubek, G. [ITA Inst. fuer Innovative Technologien GmbH, Halle (Germany)] [ITA Inst. fuer Innovative Technologien GmbH, Halle (Germany); [Martin-Luther-Univ. Halle-Wittenberg, Halle (Germany). Fachbereich Physik; Lademann, P.; Krause, H.; Krause, S.; Unger, R. [Martin-Luther-Univ. Halle-Wittenberg, Halle (Germany). Fachbereich Physik] [Martin-Luther-Univ. Halle-Wittenberg, Halle (Germany). Fachbereich Physik

    1998-09-04

    In the current paper, the decomposition behavior of the engineering alloys 2024 (Al-Cu-Mg) and 7010 (Al-Zn-Cu-Mg) is studied using positron lifetime measurements. Positrons probe open volume defects such as vacancies and dislocations. However, they may also be used to investigate coherent zones and incoherent precipitates. In order to understand the rather complicated precipitation sequences and the response of positrons to different type of precipitates occurring in 2024 and 7010 alloys, binary and ternary laboratory alloys were also investigated under the same experimental conditions as the engineering alloys. The interpretations of the results are based on experiences of the group from extensive positron studies of laboratory alloys such as Al-Zn, Al-Zn-Mg, Al-Cu, and further Al alloys (see also the review (4)). Their collected results are shown as lifetimes and curve-shape parameters S of the electron-positron momentum distribution curves characteristic for different precipitates in Al alloys.

  5. Casting behavior of titanium alloys in a centrifugal casting machine.

    PubMed

    Watanabe, K; Miyakawa, O; Takada, Y; Okuno, O; Okabe, T

    2003-05-01

    Since dental casting requires replication of complex shapes with great accuracy, this study examined how well some commercial titanium alloys and experimental titanium-copper alloys filled a mold cavity. The metals examined were three types of commercial dental titanium [commercially pure titanium (hereinafter noted as CP-Ti), Ti-6Al-4V (T64) and Ti-6Al-7Nb (T67)], and experimental titanium-copper alloys [3%, 5% and 10% Cu (mass %)]. The volume percentage filling the cavity was evaluated in castings prepared in a very thin perforated sheet pattern and cast in a centrifugal casting machine. The flow behavior of the molten metal was also examined using a so-called "tracer element technique." The amounts of CP-Ti and all the Ti-Cu alloys filling the cavity were similar; less T64 and T67 filled the cavity. However, the Ti-Cu alloys failed to reach the end of the cavities due to a lower fluidity compared to the other metals. A mold prepared with specially designed perforated sheets was effective at differentiating the flow behavior of the metals tested. The present technique also revealed that the more viscous Ti-Cu alloys with a wide freezing range failed to sequentially flow to the end of the cavity. PMID:12593955

  6. Surface segregation in MCrAlY alloys

    NASA Astrophysics Data System (ADS)

    Briant, C. L.; Luthra, K. L.

    1988-08-01

    This paper presents a study of surface segregation in NiCrAlY and FeCrAlY type alloys. The segre-gation was measured using Auger electron spectroscopy. Samples were heated in the spectrometer to temperatures between 800 and 1100 °C, and segregation was measured at temperature as a function of time. The results show that when yttrium and sulfur were present in the alloy, they segregated to the surface where their concentrations were greatly enriched over their bulk concentrations. The presence of yttrium in the alloy did not eliminate sulfur segregation. The surface concentration of aluminum appeared, in most cases, to be greater than its bulk concentration. However, because of uncertainty in sensitivity factors for Auger emission, this point could not be conclusively proven. Cobalt and chromium, in contrast, were depleted from the surface. Sulfur segregation was also ex-amined in Ni-S, Cr-S, Al-S, and Y-S binary alloys. Sulfur was found to segregate extensively in the nickel and chromium alloys, but to a much less extent in aluminum. No sulfur segregation was ob-served in the yttrium alloy.

  7. Low modulus Ti-Nb-Hf alloy for biomedical applications.

    PubMed

    González, M; Peña, J; Gil, F J; Manero, J M

    2014-09-01

    ?-Type titanium alloys with a low elastic modulus are a potential strategy to reduce stress shielding effect and to enhance bone remodeling in implants used to substitute failed hard tissue. For biomaterial application, investigation on the mechanical behavior, the corrosion resistance and the cell response is required. The new Ti25Nb16Hf alloy was studied before and after 95% cold rolling (95% C.R.). The mechanical properties were determined by tensile testing and its corrosion behavior was analyzed by potentiostatic equipment in Hank's solution at 37°C. The cell response was studied by means of cytotoxicity evaluation, cell adhesion and proliferation measurements. The stress-strain curves showed the lowest elastic modulus (42GPa) in the cold worked alloy and high tensile strength, similar to that of Ti6Al4V. The new alloy exhibited better corrosion resistance in terms of open circuit potential (EOCP), but was similar in terms of corrosion current density (iCORR) compared to Ti grade II. Cytotoxicity studies revealed that the chemical composition of the alloy does not induce cytotoxic activity. Cell studies in the new alloy showed a lower adhesion and a higher proliferation compared to Ti grade II presenting, therefore, mechanical features similar to those of human cortical bone and, simultaneously, a good cell response. PMID:25063170

  8. Laser surface alloying of silicon into aluminum casting alloys

    Microsoft Academic Search

    Zhiyue Xu; Keng H. Leong; Paul G. Sanders

    2000-01-01

    Aluminum alloys that are easily castable tend to have lower silicon content, and hence, lower wear resistance. The use of laser surface alloying to improve the surface wear resistance of 319 and 320 aluminum alloys was examined. A silicon layer was painted onto the surface to be treated. A high power pulsed Nd:yttrium-aluminum-garnet laser with fiber-optic beam delivery was used

  9. Magneto-Thermo-Mechanical Response and Magneto-Caloric Effect in Magnetic Shape Memory Alloys 

    E-print Network

    Yegin, Cengiz

    2012-07-16

    Ni-Co-Mn-In system is a new type of magnetic shape memory alloys (MSMAs) where the first order structural and magnetic phase transitions overlap. These materials can generate large reversible shape changes due to ...

  10. Filler metal alloy for welding cast nickel aluminide alloys

    DOEpatents

    Santella, Michael L. (Knoxville, TN); Sikka, Vinod K. (Oak Ridge, TN)

    1998-01-01

    A filler metal alloy used as a filler for welding east nickel aluminide alloys contains from about 15 to about 17 wt. % chromium, from about 4 to about 5 wt. % aluminum, equal to or less than about 1.5 wt. % molybdenum, from about 1 to about 4.5 wt. % zirconium, equal to or less than about 0.01 wt. % yttrium, equal to or less than about 0.01 wt. % boron and the balance nickel. The filler metal alloy is made by melting and casting techniques such as are melting the components of the filler metal alloy and east in copper chill molds.

  11. Corrosion behavior of cast and forged cobalt-based alloys for double-alloy joint endoprostheses.

    PubMed

    Süry, P; Semlitsch, M

    1978-09-01

    An ideal combination of mechanical and corrosion properties of long-term implants such as joint endoprostheses has yet to be found. Besides being resistant to pitting and crevice attack, which can lead to corrosion fatigue and stress corrosion cracking failures, the implant material must be highly resistant to wear and abrasion. Two cobalt-based alloys, wrought CoNiMoTi and air-cast CoCrMo, were subjected to a number of selected in vitro electrochemically and chemically accelerated corrosion tests in chloride-containing solutions with wrought AISI-316L used as a reference alloy. A limited number of immersion tests in FeCl3 and acidified FeCl3 solutions were also conducted. It is found that the mechanical properties of wrought CoNiCrMoTi alloy qualify it as a substitute for cast CoCrMo alloy and wrought AISI-316L in anchorage shaft production for all types of joint endoprostheses. Wrought CoNiCrMoTi has a higher resistance to fatigue cracking compared with cast CoCrMo and is as resistant to selective corrosion phenomena such as stress corrosion cracking. PMID:701305

  12. Alternative for evaluating sour gas resistance of low-alloy steels and corrosion-resistant alloys

    SciTech Connect

    Tsujikawa, S. (Univ. of Tokyo (Japan)); Miyasaka, A. (Nippon Steel Corp., Aichi (Japan)); Ueda, M. (Sumitomo Metal Ind., Hyogo (Japan)); Ando, S. (Univ. of Osaka Prefecture, Sakai (Japan)); Shibata, T.; Haruna, T. (Osaka Univ. (Japan)); Katahira, M. (NKK Corp., Hiroshima (Japan)); Yamane, Y. (Kawasaki Steel Corp. (Japan)); Aoki, T. (National Research Inst. for Metals, Tokyo (Japan)); Yamada, T. (Nagoya Municipal Industrial Research Inst. (Japan))

    1993-05-01

    Thiosulfate ion was used as a substitute for hydrogen sulfide (H[sub 2]S) to simulate stress corrosion cracking (SCC) of corrosion-resistant alloys (CRAs) and sulfide stress cracking (SSC) of high-strength, low-alloy steels. Several SCC tests using a variety of stress application techniques showed the brine containing thiosulfate exhibited similar severity to brine containing H[sub 2]S in regard to SCC when plastic strain was applied to the CRAs. Materials that exhibited SCC susceptibility in brine containing thiosulfate agreed well the SCC susceptibility of those in brine containing H[sub 2]S. Types 304 (UNS S30400) and 316L (UNS S31603) stainless steels and duplex stainless steel exhibited in both environments. However, high-nickel austenitic alloys such as alloys 904L (UNS N08904) and 825 (UNS N08825) did not. A10[sup [minus]3] to 10[sup [minus]2] mol/l S[sub 2]O[sub 3][sup 2[minus

  13. Two phase titanium aluminide alloy

    DOEpatents

    Deevi, Seetharama C. (Midlothian, VA); Liu, C. T. (Oak Ridge, TN)

    2001-01-01

    A two-phase titanic aluminide alloy having a lamellar microstructure with little intercolony structures. The alloy can include fine particles such as boride particles at colony boundaries and/or grain boundary equiaxed structures. The alloy can include alloying additions such as .ltoreq.10 at % W, Nb and/or Mo. The alloy can be free of Cr, V, Mn, Cu and/or Ni and can include, in atomic %, 45 to 55% Ti, 40 to 50% Al, 1 to 5% Nb, 0.3 to 2% W, up to 1% Mo and 0.1 to 0.3% B. In weight %, the alloy can include 57 to 60% Ti, 30 to 32% Al, 4 to 9% Nb, up to 2% Mo, 2 to 8% W and 0.02 to 0.08% B.

  14. Magnesium-lithium casting alloys

    NASA Technical Reports Server (NTRS)

    Latenko, V. P.; Silchenko, T. V.; Tikhonov, V. A.; Maltsev, V. P.; Korablin, V. P.

    1974-01-01

    The strength properties of magnesium-lithium alloys at room, low, and high temperatures are investigated. It is found that the alloys may have practical application at ambient temperatures up to 100 C, that negative temperatures have a favorable influence on the alloy strength, and that cyclic temperature variations have practically no effect on the strength characteristics. The influence of chemical coatings on corrosion resistance of the MgLi alloys is examined. Several facilities based on pressure casting machines, low-pressure casting machines, and magnetodynamic pumps were designed for producing MgLi alloy castings. Results were obtained for MgLi alloys reinforced with fibers having a volumetric content of 15%.

  15. Fatigue strength of welded joints in 6N01 aluminium alloy extrusions

    Microsoft Academic Search

    K. Matsuoka; S. Chiaki; T. Uemura; K. Kamata

    1994-01-01

    In this paper, the fatigue strength of welded joints in 6N01 aluminium alloy extrusions is discussed. Low copper content (?0.02%) alloys were chosen, considering corrosion resistance in sea water. Two series of specimens were prepared. One had two longitudinal stiffeners welded on both sides of the main plate (L?TYPE), and the other a non?load carrying fillet welded cruciform joint (T?TYPE).

  16. Icosahedral quasicrystal and 1\\/1 cubic approximant in Au-Al-Yb alloys

    Microsoft Academic Search

    Tsutomu Ishimasa; Yukinori Tanaka; Shiro Kashimoto

    2011-01-01

    A P-type icosahedral quasicrystal is formed in Au-Al-Yb alloy of which 6-dimensional lattice parameter a6D = 7.448 {\\\\AA}. The composition of the quasicrystal was analyzed to be Au51Al34Yb15. This quasicrystal is formed in as-cast alloys, and is regarded as metastable because of decomposition into other crystalline phases by annealing at 700 \\\\degree C. Among Tsai-type quasicrystals, this quasicrystal is situated

  17. Alloy Interface Interdiffusion Modeled

    NASA Technical Reports Server (NTRS)

    Bozzolo, Guillermo H.; Garces, Jorge E.; Abel, Phillip B.

    2003-01-01

    With renewed interest in developing nuclear-powered deep space probes, attention will return to improving the metallurgical processing of potential nuclear fuels so that they remain dimensionally stable over the years required for a successful mission. Previous work on fuel alloys at the NASA Glenn Research Center was primarily empirical, with virtually no continuing research. Even when empirical studies are exacting, they often fail to provide enough insight to guide future research efforts. In addition, from a fundamental theoretical standpoint, the actinide metals (which include materials used for nuclear fuels) pose a severe challenge to modern electronic-structure theory. Recent advances in quantum approximate atomistic modeling, coupled with first-principles derivation of needed input parameters, can help researchers develop new alloys for nuclear propulsion.

  18. Surface Segregation in Ternary Alloys

    NASA Technical Reports Server (NTRS)

    Good, Brian; Bozzolo, Guillermo H.; Abel, Phillip B.

    2000-01-01

    Surface segregation profiles of binary (Cu-Ni, Au-Ni, Cu-Au) and ternary (Cu-Au-Ni) alloys are determined via Monte Carlo-Metropolis computer simulations using the BFS method for alloys for the calculation of the energetics. The behavior of Cu or Au in Ni is contrasted with their behavior when both are present. The interaction between Cu and Au and its effect on the segregation profiles for Cu-Au-Ni alloys is discussed.

  19. Intraoral behaviour and biocompatibility of gold versus non precious alloys.

    PubMed

    Glantz, P O

    1984-03-01

    The costs of traditional dental gold alloys have increased rapidly over the last fifteen years, and numerous attempts have therefore been made to develop and produce less expensive alternatives for use in the manufacture of fixed dental appliances. A review is presented of the various types of alloys currently available in the western world, as well as of the biological, technical and clinical aspects of their use in dentistry. Special attention is paid to the possible risks of various types of pathological reactions associated with alternative alloys containing nickel, beryllium or cadmium. Technical aspects covered include constructional problems and those associated with casting, finishing and the clinical adjustment of fixed appliances produced by traditional and alternative alloys. In conclusion, it is stated that even if rapid progress in this area makes long-term predictions difficult there is no evidence at present to suggest that the costs of dental treatment have in general become noticably lower to the patients when alternative alloys have been used instead of traditional gold based ones. PMID:6368534

  20. Evaluation of a hydrogen resistant titanium aluminide alloy

    NASA Technical Reports Server (NTRS)

    Chan, K. S.

    1991-01-01

    The Ti-24Al-11Nb (Ti-24-11) alloy heat treated to the fine basketweave microstructure was shown previously to be hydrogen tolerant. In order to assess its limit of hydrogen tolerance, the tensile, creep, fracture toughness, and sustained load crack growth behaviors of this alloy were studied as a function of hydrogen content. All test specimens were thermally charged with internal hydrogen and tested at 25 and 600 C. Coupon specimens were used for developing the hydrogen charging procedures and for studying compatibility of the alloy with high temperature, high pressure gaseous hydrogen. The mechanical test results indicated that the fine basketweave microstructure was tolerant to hydride embrittlement for hydrogen contents up to approximately 1500 wt. ppm, providing that the hydride formed was of the TiH2 type. On the other hand, hydrogen charging experiments indicated that the Ti-24-11 alloy was severely cracked and pulverized under zero load when the hydrogen content exceeded 3000 wt. ppm. X-ray diffraction results revealed that the dichotomous behaviors might be due to the formation of TiH(1.924) type hydrides at higher hydrogen contents. Thus, hydrogen embrittlement in the Ti-24-11 alloy with the fine basketweave microstructure depends on hydrogen content and the nature of the hydrides formed.

  1. Alloy Design Data Generated for B2-Ordered Compounds

    NASA Technical Reports Server (NTRS)

    Noebe, Ronald D.; Bozzolo, Guillermo; Abel, Phillip B.

    2003-01-01

    Developing alloys based on ordered compounds is significantly more complicated than developing designs based on disordered materials. In ordered compounds, the major constituent elements reside on particular sublattices. Therefore, the addition of a ternary element to a binary-ordered compound is complicated by the manner in which the ternary addition is made (at the expense of which binary component). When ternary additions are substituted for the wrong constituent, the physical and mechanical properties usually degrade. In some cases the resulting degradation in properties can be quite severe. For example, adding alloying additions to NiAl in the wrong combination (i.e., alloying additions that prefer the Al sublattice but are added at the expense of Ni) will severely embrittle the alloy to the point that it can literally fall apart during processing on cooling from the molten state. Consequently, alloying additions that strongly prefer one sublattice over another should always be added at the expense of that component during alloy development. Elements that have a very weak preference for a sublattice can usually be safely added at the expense of either element and will accommodate any deviation from stoichiometry by filling in for the deficient component. Unfortunately, this type of information is not known beforehand for most ordered systems. Therefore, a computational survey study, using a recently developed quantum approximate method, was undertaken at the NASA Glenn Research Center to determine the preferred site occupancy of ternary alloying additions to 12 different B2-ordered compounds including NiAl, FeAl, CoAl, CoFe, CoHf, CoTi, FeTi, RuAl, RuSi, RuHf, RuTi, and RuZr. Some of these compounds are potential high temperature structural alloys; others are used in thin-film magnetic and other electronic applications. The results are summarized. The italicized elements represent the previous sum total alloying information known and verify the computational method used to establish the table. Details of the computational procedures used to determine the preferred site occupancy can be found in reference 2. As further substantiation of the validity of the technique, and its extension to even more complicated systems, it was applied to two simultaneous alloying additions in an ordered alloy.

  2. Shape memory alloy actuator

    DOEpatents

    Varma, Venugopal K. (Knoxville, TN)

    2001-01-01

    An actuator for cycling between first and second positions includes a first shaped memory alloy (SMA) leg, a second SMA leg. At least one heating/cooling device is thermally connected to at least one of the legs, each heating/cooling device capable of simultaneously heating one leg while cooling the other leg. The heating/cooling devices can include thermoelectric and/or thermoionic elements.

  3. Nanocrystal dispersed amorphous alloys

    NASA Technical Reports Server (NTRS)

    Perepezko, John H. (Inventor); Allen, Donald R. (Inventor); Foley, James C. (Inventor)

    2001-01-01

    Compositions and methods for obtaining nanocrystal dispersed amorphous alloys are described. A composition includes an amorphous matrix forming element (e.g., Al or Fe); at least one transition metal element; and at least one crystallizing agent that is insoluble in the resulting amorphous matrix. During devitrification, the crystallizing agent causes the formation of a high density nanocrystal dispersion. The compositions and methods provide advantages in that materials with superior properties are provided.

  4. The manufacture of superplastic alloys

    NASA Astrophysics Data System (ADS)

    Grimes, R.

    1987-08-01

    Amongst aluminum alloys, the Al-6 percent Cu-0.4 percent Zr system that typifies the Supral alloys requires a specially developed casting system in order to achieve a very high level of supersaturation with zirconium. Subsequent manufacturing is fairly conventional, the sheet product recrystallizing dynamically during superplastic forming. The higher strength aluminum alloys are conventionally cast but achieve a very fine grain size at sheet stage by careful thermal mechanical treatment during the later stages of semi-fabrication. With titanium, the standard production route for the Ti-6Al-4V alloy results in a product with superplastic capabilities perfectly adequate for most applications.

  5. Melt Infiltration Processing of Foams Using Glass-Forming Alloys

    Microsoft Academic Search

    C. San Marchi; A. Brothers; D. C. Dunand

    2003-01-01

    Processing of foams from bulk metallic glass (BMG) alloys, using melt infiltration techniques, is reported for the first time. Foaming methods based on infiltration of two types of pattern materials are described: investment of a continuous refractory yielding very low relative density structures (5% dense relative to the BMG), and investment of a discontinuous refractory pellet bed yielding higher relative

  6. Global phase diagram for binary alloys with one magnetic component

    Microsoft Academic Search

    V. Talanquer; C. Varea; A. Robledo

    1989-01-01

    We describe the global mean-field phase diagram for a binary alloy that contains one magnetic component. We obtain 12 types of system phase diagrams, each of which displays a different interaction of chemical (segregration or ordering) and magnetic (ferromagnetic or antiferromagnetic) long-range order. Our results follow from the known features of the phase diagrams along the symmetric sections of Griffiths's

  7. Creep properties of phosphorus + boron-modified alloy 718

    SciTech Connect

    McKamey, C.G.; Carmichael, C.A. [Oak Ridge National Lab., TN (United States). Metals and Ceramics Div.] [Oak Ridge National Lab., TN (United States). Metals and Ceramics Div.; Cao, W.D.; Kennedy, R.L. [Allvac, Monroe, NC (United States)] [Allvac, Monroe, NC (United States)

    1998-01-06

    Creep-rupture testing of modified alloy 718 has confirmed the beneficial effect of optimum additions of P and B. Activation energies and creep exponent analyses suggest some type of pinning mechanism is involved in this strengthening. However, the exact mechanism of this improvement is still unclear.

  8. Mechanical properties and microstructures of new Ti–Fe–Ta and Ti–Fe–Ta–Zr system alloys

    Microsoft Academic Search

    Daisuke Kuroda; Hironori Kawasaki; Akiko Yamamoto; Sachiko Hiromoto; Takao Hanawa

    2005-01-01

    ?-type titanium alloys consisting of non-toxic elements, Ti–8Fe–8Ta, Ti–8Fe–8Ta–4Zr, and Ti–10Fe–10Ta–4Zr, were newly designed and developed for biomedical applications. Changes in the mechanical properties of the designed alloys with various heat treatments were discussed on the basis of the resultant microstructures. In addition, the corrosion resistance of the designed alloys was evaluated by polarization testing in Hank's solution. Conventional biomedical

  9. Magnetic and corrosion properties comparison of FeSi-based, FeZr-based and FeCo-based alloys

    Microsoft Academic Search

    J. E. May; C. A. C. Souza; C. L. Morelli; N. A. Mariano; S. E. Kuri

    2005-01-01

    The main reason for the study of Fe-based (FINEMET and NANOPERM) alloys was their magnetic properties. The nanocrystalline phases ?-FeSi and ?-Fe are responsible for the soft magnetic properties of FINEMET and NANOPERM alloys, respectively. A new type of amorphous and nanocrystalline FeCo-based alloy (HITPERM) has recently been produced. Its soft magnetic properties, which are attributed to the formation of

  10. Fireside corrosion testing of candidate superheater tube alloys, coatings, and claddings

    SciTech Connect

    Van Weele, S. (Foster Wheeler Development Corp., Livingston, NJ (United States))

    1991-08-01

    Fireside corrosion, caused by liquid alkali-iron trisulfates, has been an obstacle to higher steam temperatures and to efficient utilization of high-sulfur coals. Tests simulating the environment in the superheater bank of a pulverized-coal-fired boiler were conducted on several promising new alloys and claddings. Alloys were exposed to a variety of synthetic ash and simulated flue gas compositions at 650 and 700{degrees}C for times ranging up to 800 hours. Included in the testing program were new high-chromium/high-nickel alloys, modified commercial alloys, lean stainless steels (modified Type 316) clad with high-chromium/high-nickel alloys, and intermetallic aluminides. Thickness loss measurements indicated that resistance to attach improved with increasing chromium level. Silicon and aluminum were also helpful in resisting attack, while molybdenum was detrimental to the resistance of the alloys to attack. Three different attack modes were observed on the alloys tested. Alloys with low resistance to attack exhibited uniform wastage, while pitting was observed in more resistant alloys. In addition to surface fluxing by molten alkali-iron trisulfates, subsurface sulfur penetration and intergranular attack also occurred.

  11. Fireside corrosion testing of candidate superheater tube alloys, coatings, and claddings. Final report

    SciTech Connect

    Van Weele, S. [Foster Wheeler Development Corp., Livingston, NJ (United States)

    1991-08-01

    Fireside corrosion, caused by liquid alkali-iron trisulfates, has been an obstacle to higher steam temperatures and to efficient utilization of high-sulfur coals. Tests simulating the environment in the superheater bank of a pulverized-coal-fired boiler were conducted on several promising new alloys and claddings. Alloys were exposed to a variety of synthetic ash and simulated flue gas compositions at 650 and 700{degrees}C for times ranging up to 800 hours. Included in the testing program were new high-chromium/high-nickel alloys, modified commercial alloys, lean stainless steels (modified Type 316) clad with high-chromium/high-nickel alloys, and intermetallic aluminides. Thickness loss measurements indicated that resistance to attach improved with increasing chromium level. Silicon and aluminum were also helpful in resisting attack, while molybdenum was detrimental to the resistance of the alloys to attack. Three different attack modes were observed on the alloys tested. Alloys with low resistance to attack exhibited uniform wastage, while pitting was observed in more resistant alloys. In addition to surface fluxing by molten alkali-iron trisulfates, subsurface sulfur penetration and intergranular attack also occurred.

  12. The study of quantitativeness in atom probe analysis of alloying elements in steel.

    PubMed

    Yamaguchi, Y; Takahashi, J; Kawakami, K

    2009-04-01

    The quantitativeness in atom probe analysis of dilute solute alloying elements in steel was systematically investigated. The samples of binary Fe-Si, Fe-Ti, Fe-Cr, Fe-Cu, Fe-Mn and Fe-Mo alloys were prepared for present study. The apparent compositions of alloying elements were examined by three-dimensional atom probe (3DAP) under various experimental conditions. The temperature dependence of the apparent compositions varied largely with the alloys, which indicated that the degree of preferential evaporation or retention varied with the alloying elements. Furthermore, the analysis direction dependence of the apparent Mn composition was examined in the Fe-Mn alloy. The experimental results indicated that the order of the field evaporation rate of elements in steel was Cu>Cr>Mn approximately Mo>Fe>Ti approximately Si. The field evaporability of alloying elements in steel was discussed in terms of the solution enthalpy of the alloying elements and the phase types of the binary Fe alloys. PMID:19144470

  13. Cellular response to metallic ions released from nickel-chromium dental alloys.

    PubMed

    Bumgardner, J D; Lucas, L C

    1995-08-01

    Concerns exist over the potential release of elevated levels of metal ions such as Ni and Be from Ni-Cr dental casting alloys, due to their susceptibility to accelerated corrosion. In this investigation, we evaluated the release of metal ions from four commercial Ni-Cr alloys, representing a range of compositions, in three-day cell culture tests. Metal ion release, as measured by atomic absorption spectroscopy, was correlated to changes in cellular morphology, viability, and proliferation. The results showed that the test alloys and their corrosion products did not affect cellular morphology or viabilities, but did decrease cellular proliferation. The types and amounts of metal ions released, which corresponded to the alloys' reported surface and corrosion properties, also correlated to observed decreases in cellular proliferation after 72 h. Neptune, which caused the smallest decrease in cellular proliferation as compared with control cells, released the lowest amount of corrosion products, due to its corrosion-resistant, high-Cr-Mo-containing, homogeneous surface oxide. The other test alloys, which were susceptible to accelerated corrosion processes, released higher levels of metal ions that correlated to larger decreases in thymidine incorporation. Metal ion levels increased with test time for all alloys but were not proportional to bulk alloy compositions. Ni ions were released at slightly higher than bulk alloy compositions, while Be was released at from four to six times that of bulk alloy compositions. The elevated release of Be ions was associated with reduced cellular proliferation.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:7560409

  14. Aluminum Alloy and Article Cast Therefrom

    NASA Technical Reports Server (NTRS)

    Lee, Jonathan A. (Inventor); Chen, Po-Shou (Inventor)

    2003-01-01

    A cast article from an aluminum alloy, which has improved mechanical properties at elevated temperatures, has the following composition in weight percent: Silicon 14 - 25.0, Copper 5.5 - 8.0, Iron 0.05 - 1.2, Magnesium 0.5 - 1.5, Nickel 0.05 - 0.9, Manganese 0.05 - 1.0, Titanium 0.05 - 1.2, Zirconium 0.05 - 1.2, Vanadium 0.05 - 1.2, Zinc 0.05 - 0.9, Phosphorus 0.001 - 0.1, and the balance is Aluminum, wherein the silicon-to-magnesium ratio is 10 - 25, and the copper-to-magnesium ratio is 4 - 15. The aluminum alloy contains a simultaneous dispersion of three types of Al3X compound particles (X=Ti, V, Zr) having a LI2, crystal structure, and their lattice parameters are coherent to the aluminum matrix lattice. A process for producing this cast article is also disclosed, as well as a metal matrix composite, which includes the aluminum alloy serving as a matrix and containing up to about 60% by volume of a secondary filler material.

  15. Modification of alloy surfaces using pulsed energy

    SciTech Connect

    Clark, R.A. (Failure Analysis Associates, Inc., Redmond, WA (United States))

    1991-10-01

    A method to improve the quality and bonding of surface coatings is explored. The method involves application of radio frequency (rf) induction heating to coated metallic surfaces. By tailoring the rf frequency, depth of induction heating penetration can be controlled. Total heat input is a function of the duration of rf power application. Induction heating using high frequencies and short pulses provides a mechanism for controlled penetration heating. The objective of this project was to demonstrate coating consolidation and metallurgical alloying of an inductively coupled coating into the substrate material, without affecting the bulk substrate material properties. A metallurgically alloyed coating to substrate interface improves coating adherence and can provide graded properties in the interface region. Coating consolidation serves to improve the coating integrity through the elimination of porosity and cracks. This report details experimental studies to place palladium, nickel and chromium coatings over substrates of Inconel alloys 182 and 600, and Type 316NG stainless steel. Continuously bonded coatings of palladium were produced. Preliminary thermal cycling studies indicate coating stability.

  16. Differential equation of hysteresis: Application to partial martensitic transformation in shape-memory alloys. [NiTi alloy

    SciTech Connect

    Likhachev, A.A. (Ukrainian Academy of Sciences, Kiev (Ukraine). Inst. of Metal Physics)

    1995-02-15

    Many unusual thermomechanical properties of shape-memory alloys are directly connected with martensitic type phase transitions in these systems. Because the martensitic transformations, as a rule, are the first order transitions, a special attention should be given to a hysteretic behavior of shape-memory alloys. The most important characteristics of the temperature- or stress-induced martensitic transformation, have been previously studied in detail. It has been shown that such macroscopic state variables as inelastic strain or volume fraction of the martensite are always complex multi-valued functions of the temperature and external stress. Therefore, the shape-memory alloys should be considered as systems having an infinite number of state equations, representing inelastic strain and volume fraction of martensite as functions of the external stress and temperature, correspondingly. Some of the phenomenological approaches for the thermomechanical state equations for shape memory alloys were recently published. In particular, a special type of differential equation describing evolution of the inelastic macroscopic strain and volume fraction of martensite as a function of the temperature has been proposed. Its application to partial temperature cycling processes in shape-memory alloys and some other problems associated with the irreversible processes caused by hysteresis are discussed in the present paper.

  17. Rare-earth metals in nickel aluminide-based alloys: III. Structure and properties of multicomponent Ni3Al-based alloys

    NASA Astrophysics Data System (ADS)

    Bazyleva, O. A.; Povarova, K. B.; Kazanskaya, N. K.; Drozdov, A. A.

    2009-04-01

    The possibility of increasing the life of heterophase cast light Ni3Al-based superalloys at temperatures higher than 0.8 T m of Ni3Al is studied when their directional structure is additionally stabilized by nanoprecipitates, which form upon additional alloying of these alloys by refractory and active metals, and using special methods for preparing and melting of an alloy charge. The effect of the method of introducing the main components and refractory reaction-active and surface-active alloying elements into Ni3Al-based cast superalloys, which are thermally stable natural composite materials of the eutectic type, on the structure-phase state and the life of these alloys is studied. When these alloys are melted, it is necessary to perform a set of measures to form particles of refractory oxide cores covered with the ?-NiAl phase and, then, ?'prim-Ni3Al phase precipitates during solidification. The latter phase forms the outer shell of grain nuclei, which provides high thermal stability and hot strength of an intermetallic compound-based alloy. As a result, a modified structure that is stabilized by the nanoprecipitates of nickel and aluminum lanthanides and the nanoprecipitates of phases containing refractory metals is formed. This structure enhances the life of the alloy at 1000 °C by a factor of 1.8-2.5.

  18. DIMENSIONALLY STABLE URANIUM ALLOYS. III. URANIUM-CARBON ALLOYS

    Microsoft Academic Search

    I. Sheinhartz; J. L. Zambrow

    1959-01-01

    In an attempt to improve the strength at elevated temperatures of a 1.5% ; molybdenum in uranium alloy, a network of uranium carbide was incorporated within ; the structure of the alloy by use of powder-metallurgical techniques. ; Compositions containing up to 10% uranium carbide were evaluated by the use of ; hot hardness tests at temperatures up to 700

  19. Welding Metallurgy of Alloy HR-160

    SciTech Connect

    DuPont, J.N.; Michael, J.R.; Newbury, B.D.

    1999-05-28

    The solidification behavior and resultant solidification cracking susceptibility of autogenous gas tungsten arc fusion welds in alloy HR-160 was investigated by Varestraint testing, differential thermal analysis, and various microstructural characterization techniques. The alloy exhibited a liquidus temperature of 1387 {deg}C and initiated solidification by a primary L - {gamma} reaction in which Ni, Si, and Ti segregated to the interdendritic liquid and Co segregated to the {gamma} dendrite cores. Chromium exhibited no preference for segregation to the solid or liquid phase during solidification. Solidification terminated at {approx} 1162 {deg}C by a eutectic-type L - [{gamma}+ (Ni,Co){sub 16}(Ti,Cr){sub 6}Si{sub 7}] reaction. The (Ni,Co){sub 16}(Ti,Cr){sub 6}Si{sub 7} phase is found to be analogous to the G phase which forms in the Ni-Ti-Si and Co-Ti-Si ternary systems, and similarities are found to exist between the solidification behavior of this commercial multicomponent alloy and the simple Ni-Si and Ni-Ti binary systems. Reasonable agreement is obtained between the calculated and measured volume percent of the [{gamma} +(Ni,Co){sub l6}(Ti,Cr){sub 6}Si{sub 7}] eutectic-typr constituent with the Scheil equation using experimentally determined k values for Si and Ti from electron microprobe data. The alloy exhibited a very high susceptibility to solidification cracking in the Varestraint test. This is attributed to a large solidification temperature range of 225 {deg}C and the presence of 2 to 5 vol% solute rich interdendritic liquid which preferentially wets the grain boundaries and interdendritic regions.

  20. Dendrite growth morphologies in aluminum alloys

    SciTech Connect

    Henry, S. [Ecole Polytechnique Federale de Lausanne (Switzerland). Lab. de Metallurgie Physique] [Ecole Polytechnique Federale de Lausanne (Switzerland). Lab. de Metallurgie Physique; [Pechiney Centre de Recherches de Voreppe (France); Minghetti, T.; Rappaz, M. [Ecole Polytechnique Federale de Lausanne (Switzerland). Lab. de Metallurgie Physique] [Ecole Polytechnique Federale de Lausanne (Switzerland). Lab. de Metallurgie Physique

    1998-11-20

    Different aluminum alloys, in particular Al-Cu, Al-Mg and Al-Si, have been directionally solidified under well-controlled thermal and convection conditions. For relatively high solidification rates, particular growth morphologies were observed. The most common is linked with the formation of feathery grains: these are constituted by series of twinned lamellae, in which the dendrites have {l_angle}110{r_angle} trunks cut through by {l_brace}111{r_brace} twin planes. These grains undergo a selection mechanism which is similar to that occurring for regular {l_angle}100{r_angle} dendritic grains. The dendritic growth along {l_angle}110{r_angle} crystallographic directions is supposed to be due to a change in the anisotropy of certain properties of the alloy, such as the solid/liquid interfacial energy and/or the atom attachment kinetics. When solidification conditions become less favorable to {l_angle}110{r_angle} growth morphologies, a mixed dendritic form containing {l_angle}110{r_angle} trunks and {l_angle}100{r_angle} arms may be obtained. In the case of the 5182 Al-Mg type alloy, {l_angle}110{r_angle} columnar grains which were not twinned could be observed together with feathery crystals. The possibility of such changes in the growth direction of aluminum alloys was further demonstrated by the observation of dendrites of Al-Cu-Mg solidified in a Bridgman device. In this case, {l_angle}112{r_angle} dendrites grow and progressively change their growth direction, thus showing curved shapes.

  1. Radiation Effects in Refractory Alloys

    NASA Astrophysics Data System (ADS)

    Zinkle, Steven J.; Wiffen, F. W.

    2004-02-01

    In order to achieve the required low reactor mass per unit electrical power for space reactors, refractory alloys are essential due to their high operating temperature capability that in turn enables high thermal conversion efficiencies. One of the key issues associated with refractory alloys is their performance in a neutron irradiation environment. The available radiation effects data are reviewed for alloys based on Mo, W, Re, Nb and Ta. The largest database is associated with Mo alloys, whereas Re, W and Ta alloys have the least available information. Particular attention is focused on Nb-1Zr, which is a proposed cladding and structural material for the reactor in the Jupiter Icy Moons Orbiter (JIMO) project. All of the refractory alloys exhibit qualitatively similar temperature-dependent behavior. At low temperatures up to ~0.3TM, where TM is the melting temperature, the dominant effect of radiation is to produce pronounced radiation hardening and concomitant loss of ductility. The radiation hardening also causes a dramatic decrease in the fracture toughness of the refractory alloys. These low temperature radiation effects occur at relatively low damage levels of ~0.1 displacement per atom, dpa (~2×1024 n/m2, E>0.1 MeV). As a consequence, operation at low temperatures in the presence of neutron irradiation must be avoided for all refractory alloys. At intermediate temperatures (0.3 to 0.6 TM), void swelling and irradiation creep are the dominant effects of irradiation. The amount of volumetric swelling associated with void formation in refractory alloys is generally within engineering design limits (<5%) even for high neutron exposures (>>10 dpa). Very little experimental data exist on irradiation creep of refractory alloys, but data for other body centered cubic alloys suggest that the irradiation creep will produce negligible deformation for near-term space reactor applications.

  2. Corrosion protection of DLC coatings on magnesium alloy

    Microsoft Academic Search

    J. Choi; S. Nakao; J. Kim; M. Ikeyama; T. Kato

    2007-01-01

    Anti-corrosion properties of DLC films deposited on magnesium alloy, AZ31 (Mg–3%Al–1%Zn) were investigated. The DLC and Si-incorporated DLC (Si–DLC) films were prepared on sputter-deposited AZ31 films using a bi-polar type plasma based ion implantation and deposition (PBII&D). The AZ31 films were prepared on glass plates using an ECR-type ion beam sputter with an AZ31 target. The potentiodynamic polarization curves were

  3. A new servo motor using shape memory alloy

    Microsoft Academic Search

    Katsutoshi Kuribayashi

    1989-01-01

    A light and high-torque servo motor using SMA (shape memory alloy) is presented. Its design method is derived using the dynamical properties of SMA and the geometrical relationships of the SMA motor. A fixed-ring-type SMA motor with a synchronous belt was designed, and its torque and maximum rotary speed were calculated. In a trial production, a fixed-ring-type SMA motor with

  4. New package cooling technology using low melting point alloys

    Microsoft Academic Search

    Yoshitake Fukuoka; Masaru Ishizuka

    1990-01-01

    A novel package cooling technology concept using two kinds of inexpensive low-melting-point alloys is presented. One alloy is Bi-18.0Pb-11.6Sn-21.0In (in wt pct), with a melting point of 57 C; the other is Bi-17.3Sn-25.2In, with a melting point of 77 C. This type of package cooling techology may be extremely useful for high-power circuit packages which are only required to operate

  5. Silicon Solar Cells with Front Hetero-Contact and Aluminum Alloy Back Junction: Preprint

    SciTech Connect

    Yuan, H.-C.; Page, M. R.; Iwaniczko, E.; Xu, Y.; Roybal, L.; Wang, Q.; Branz, H. M.; Meier, D. L.

    2008-05-01

    We prototype an alternative n-type monocrystalline silicon (c-Si) solar cell structure that utilizes an n/i-type hydrogenated amorphous silicon (a-Si:H) front hetero-contact and a back p-n junction formed by alloying aluminum (Al) with the n-type Si wafer.

  6. Soft typing with conditional types

    Microsoft Academic Search

    Alexander Aiken; Edward L. Wimmers; T. K. Lakshmant

    1994-01-01

    We present a simple and powerful type inference method for dynamically typed languages where no type information is supplied by the user. Type inference is reduced to the problem of solvability of a system of type inclusion constraints over a type language that includes function types, constructor types, union, intersection, and recursive types, and conditional types. Conditional types enable us

  7. Aluminum and its light alloys

    NASA Technical Reports Server (NTRS)

    Merica, Paul D

    1920-01-01

    Report is a summary of research work which has been done here and abroad on the constitution and mechanical properties of the various alloy systems with aluminum. The mechanical properties and compositions of commercial light alloys for casting, forging, or rolling, obtainable in this country are described.

  8. MEMORANDUM ON URANIUM TITANIUM ALLOYS

    Microsoft Academic Search

    Wyman

    1949-01-01

    A series of four U--Ti alloys containing 15, 26.4, 35, and 45 wt.% Ti ; were run in the precision differential dilatometer. With the possible exception ; of the high temperature transformation in the 15% Ti alloy, all the changes took ; place over an appreciable range of temperature. (W.L.H.)

  9. Generation of Nanosized Particles during Mechanical Alloying and Their Evolution through the Hot Extrusion Process in Bismuth-Telluride-Based Alloys

    Microsoft Academic Search

    D. Vasilevskiy; M. S. Dawood; J.-P. Masse; S. Turenne; R. A. Masut

    2010-01-01

    Our extensive studies of extruded alloys have shown that mechanically strong polycrystalline alloys also deliver surprisingly high thermoelectric performance with ZT > 1 for p-type material in the temperature range from 25°C to 90°C, which was traditionally attributed to the strong texture generated by the extrusion process. Optical and low-resolution scanning electron microscopy observations of the powder produced by mechanical

  10. Heat storage in alloy transformations

    NASA Technical Reports Server (NTRS)

    Birchenall, C. E.; Gueceri, S. I.; Farkas, D.; Labdon, M. B.; Nagaswami, N.; Pregger, B.

    1981-01-01

    The feasibility of using metal alloys as thermal energy storage media was determined. The following major elements were studied: (1) identification of congruently transforming alloys and thermochemical property measurements; (2) development of a precise and convenient method for measuring volume change during phase transformation and thermal expansion coefficients; (3) development of a numerical modeling routine for calculating heat flow in cylindrical heat exchangers containing phase change materials; and (4) identification of materials that could be used to contain the metal alloys. Several eutectic alloys and ternary intermetallic phases were determined. A method employing X-ray absorption techniques was developed to determine the coefficients of thermal expansion of both the solid and liquid phases and the volume change during phase transformation from data obtained during one continuous experimental test. The method and apparatus are discussed and the experimental results are presented. The development of the numerical modeling method is presented and results are discussed for both salt and metal alloy phase change media.

  11. Irradiation Resistance of Multicomponent Alloys

    NASA Astrophysics Data System (ADS)

    Egami, T.; Guo, W.; Rack, P. D.; Nagase, T.

    2014-01-01

    High-entropy alloys (HEAs) are characterized not only by high values of entropy but also by high atomic-level stresses originating from mixing of elements with different atomic sizes. Particle irradiation on solids produces atomic displacements and thermal spikes. The high atomic-level stresses in HEAs facilitate amorphization upon particle irradiation, followed by local melting and re-crystallization due to thermal spikes. We speculate that this process will leave much less defects in HEAs than in conventional alloys. For this reason, they may be excellent candidates as new nuclear materials. We discuss initial results of computer simulation on model binary alloys and an electron microscopy study on Zr-Hf-Nb alloys, which demonstrate extremely high irradiation resistance of these alloys against electron damage to support this speculation.

  12. Normal evaporation of binary alloys

    NASA Technical Reports Server (NTRS)

    Li, C. H.

    1972-01-01

    In the study of normal evaporation, it is assumed that the evaporating alloy is homogeneous, that the vapor is instantly removed, and that the alloy follows Raoult's law. The differential equation of normal evaporation relating the evaporating time to the final solute concentration is given and solved for several important special cases. Uses of the derived equations are exemplified with a Ni-Al alloy and some binary iron alloys. The accuracy of the predicted results are checked by analyses of actual experimental data on Fe-Ni and Ni-Cr alloys evaporated at 1600 C, and also on the vacuum purification of beryllium. These analyses suggest that the normal evaporation equations presented here give satisfactory results that are accurate to within an order of magnitude of the correct values, even for some highly concentrated solutions. Limited diffusion and the resultant surface solute depletion or enrichment appear important in the extension of this normal evaporation approach.

  13. Equivalent crystal theory of alloys

    NASA Technical Reports Server (NTRS)

    Bozzolo, Guillermo; Ferrante, John

    1991-01-01

    Equivalent Crystal Theory (ECT) is a new, semi-empirical approach to calculating the energetics of a solid with defects. The theory has successfully reproduced surface energies in metals and semiconductors. The theory of binary alloys to date, both with first-principles and semi-empirical models, has not been very successful in predicting the energetics of alloys. This procedure is used to predict the heats of formation, cohesive energy, and lattice parameter of binary alloys of Cu, Ni, Al, Ag, Au, Pd, and Pt as functions of composition. The procedure accurately reproduces the heats of formation versus composition curves for a variety of binary alloys. The results are then compared with other approaches such as the embedded atom and lattice parameters of alloys from pure metal properties more accurately than Vegard's law is presented.

  14. The influence of containerless undercooling and rapid solid-state quenching on the superconductive and magnetic properties of some clustering alloy systems

    NASA Technical Reports Server (NTRS)

    Collings, E. W.

    1984-01-01

    The properties of clustering alloy systems and the manner in which they are influenced by rapid quenching from a containerless undercooled melt are discussed. It was postulated that rapid quenching under such conditions would result in highly disordered metastable alloys, and furthermore, that alloys in such conditions would possess physical properties characteristically different from those of alloys in the annealed equilibrium state. The scope of the program is essentially to gauge the influence of containerless undercooling on the submicrostructure of clustering-type alloys, using certain physical properties as diagnostic tools. Microstructures and macrostructures were to be examined using optical- and scanning-electron microscopy.

  15. SCC Initiation in Alloy 600 Heat Affected Zones Exposed to High Temperature Water

    SciTech Connect

    E Richey; DS Morton; RA Etien; GA Young; RB Bucinell

    2006-11-03

    Studies have shown that grain boundary chromium carbides improve the stress corrosion cracking (SCC) resistance of nickel based alloys exposed to high temperature, high purity water. However, thermal cycles from welding can significantly alter the microstructure of the base material near the fusion line. In particular, the heat of welding can solutionize grain boundary carbides and produce locally high residual stresses and strains, reducing the SCC resistance of the Alloy 600 type material in the heat affected zone (HAZ). Testing has shown that the SCC growth rate in Alloy 600 heat affected zone samples can be {approx}30x faster than observed in the Alloy 600 base material under identical testing conditions due to fewer intergranular chromium rich carbides and increased plastic strain in the HAZ [1, 2]. Stress corrosion crack initiation tests were conducted on Alloy 600 HAZ samples at 360 C in hydrogenated, deaerated water to determine if these microstructural differences significantly affect the SCC initiation resistance of Alloy 600 heat affected zones compared to the Alloy 600 base material. Alloy 600 to EN82H to Alloy 600 heat-affected-zone (HAZ) specimens where fabricated from an Alloy 600 to Alloy 600 narrow groove weld with EN82H filler metal. The approximate middle third of the specimen gauge region was EN82H such that each specimen had two HAZ regions. Tests were conducted with in-situ monitored smooth tensile specimens under a constant load, and a direct current electric potential drop was used for in-situ detection of SCC. Test results suggest that the SCC initiation resistance of Alloy 600 and its weld metal follows the following order: EN82H > Alloy 600 HAZ > Alloy 600. The high SCC initiation resistance observed to date in Alloy 600 heat affected zones compared to wrought Alloy 600 is unexpected based on the microstructure of HAZ versus wrought material and based on prior SCC growth rate studies. The observed behavior for the HAZ specimens is likely not related to differences in the environment, differences in surface stress/strain between the various specimen regions (weld, HAZ, wrought), differences in surface residual stress, or differences in the microstructure of the various specimen regions (weld, HAZ, wrought). The behavior may be related to differences in the creep behavior of the various weld regions or differences in the surface area of the various materials (weld, HAZ, wrought) exposed to high temperature water.

  16. Microstructures and mechanical properties of Ti-Mo alloys cold-rolled and heat treated

    SciTech Connect

    Zhou Yinglong, E-mail: yinglongzhou@126.com [Department of Mechatronics Engineering, Foshan University, 18 Jiangwan Yi Rd, Foshan 528000, Guangdong Province (China); Luo Dongmei [Department of Civil Engineering, Foshan University, 18 Jiangwan Yi Rd, Foshan 528000, Guangdong Province (China)

    2011-10-15

    In this study, the microstructures and mechanical properties of Ti-10Mo and Ti-20Mo alloys (mass%) are investigated to assess the potential use in biomedical applications. The microstructures are examined by X-ray diffraction analysis (XRD) and scanning electron microscopy (SEM). The mechanical properties are determined from uniaxial tensile tests. The experimental results indicate that the microstructures and mechanical properties of Ti-Mo alloys are dependent upon the cold rolling, solution heat treatment, and Mo content. The Ti-10Mo alloy exhibits ({alpha}'' + {beta}) and ({beta} + {omega}) phases under the cold rolling (CR) and solution treatment (ST), respectively. By contrast, the Ti-20Mo alloy comprises only {beta} phase under such conditions. The quenched Ti-20Mo alloy has the lowest elastic modulus and CR Ti-20Mo alloy has the highest tensile strength. The quenched Ti-10Mo alloy exhibits the excellent ductility and two-stage yielding from stress-strain curves due to the stress-induced martensite transformation from {beta} to {alpha}'' during tensile deformation. These Ti-Mo alloys exhibit low yield strength and good ductility, and they are more suitable for biomedical applications than the conventional metallic biomaterials from the viewpoint of better mechanical compatibility. The quenched Ti-10Mo alloy has some advantages over the other {beta} binary Ti-Mo alloys for biomedical applications. {beta} type Ti-Mo-Sn alloys are expected to be promising candidates for novel metallic biomaterials. - Highlights: {yields} The microstructures and mechanical properties of Ti-Mo alloys are dependent upon the cold rolling, solution heat treatment, and Mo content. {yields} The quenched Ti-10Mo alloy exhibits the excellent ductility and two-stage yielding due to stress-induced martensite transformation from beta to alpha double prime during tensile deformation. {yields} The Ti-Mo alloys are more suitable for biomedical applications than the conventional metallic biomaterials from the viewpoint of better mechanical compatibility. {yields} The quenched Ti-10Mo alloy has more advantages over the other beta binary Ti-Mo alloys for biomedical applications.

  17. Effect of microstructure and load spectrum on fatigue crack growth in 7050 and P\\/M X7091 aluminum alloys

    Microsoft Academic Search

    J. Telesman; S. D. Antolovich

    2008-01-01

    The influence of microstructure on fatigue crack propagation under both constant amplitude and complex spectrum loading was evaluated for two aluminum alloys with similar chemical compositions and tensile properties. However, microstructural characteristics such as grain size, inclusion size and distribution, and dispersoid type were quite different due to the difference in processing. Alloy 7050 showed better fatigue crack growth resistance

  18. Electrodeposition of cobalt-chromium alloy from trivalent chromium solutions

    SciTech Connect

    Dasarathy, H.; Riley, C.; Coble, H.D. (Univ. of Alabama, Huntsville, AL (United States). Dept. of Chemistry and Materials Science)

    1994-07-01

    Cobalt-chromium alloy was deposited from plating solutions containing cobalt(II) chloride and chromium(III) chloride at 3.5 pH. The deposits were obtained using both single and mixed complex solutions. Deposit morphology showed significant dependence on the complexing agent(s) used. Partitioning of the two components in the deposit as determined by energy dispersive spectroscopy depended on plating parameters such as concentration ratio of the two salts in the solution, complexing agent, type of current (both dc and pulsed current were studied), and current density. X-ray photoelectron spectroscopy spectra collected from as-deposited alloy revealed the presence of both oxides and metals. X-ray diffraction spectra for the alloy deposit indicated solid solution formation.

  19. Cryogenic mechanical behavior of 5000- and 6000-series aluminum alloys: Issues on application to offshore plants

    NASA Astrophysics Data System (ADS)

    Park, Doo-Hwan; Choi, Sung-Woong; Kim, Jeong-Hyeon; Lee, Jae-Myung

    2015-06-01

    The mechanical behavior of aluminum alloys was investigated in terms of four aspects: temperature, strain rate, material type, and fracture shape. The candidate materials were 5000- and 6000-series alloys. The material characteristics were investigated and summarized as a function of low temperature (110-293 K) and quasi-static strain rate (10-4 and 10-2 s-1). The results confirmed that the strength and ductility of aluminum alloys improved with a decrease in the temperature. The aluminum alloys showed a strain rate effect only in terms of the ductility of the 5000-series alloys. In addition, fractography analyses were performed on the fracture specimens to explain the material behavior at cryogenic temperatures.

  20. Industrial Experience on the Caustic Cracking of Stainless Steels and Nickel Alloys - A Review

    SciTech Connect

    Rebak, R B

    2005-10-09

    Caustic environments are present in several industries, from nuclear power generation to the fabrication of alkalis and alumina. The most common material of construction is carbon steel but its application is limited to a maximum temperature of approximately 80 C. The use of Nickel (Ni) alloys is recommended at higher temperatures. Commercially pure Ni is the most resistant material for caustic applications both from the general corrosion and the stress corrosion cracking (SCC) perspectives. Nickel rich alloys also offer a good performance. The most important alloying elements are Ni and chromium (Cr). Molybdenum (Mo) is not a beneficial alloying element and it dissolves preferentially from the alloy in presence of caustic environments. Austenitic stainless steels such as type 304 and 316 seem less resistant to caustic conditions than even plain carbon steel. Experimental evidence shows that the most likely mechanism for SCC is anodic dissolution.

  1. [Nickel solubility of dental alloys in the immersions-test and in the mouth].

    PubMed

    Pfeiffer, P; Schwickerath, H

    1991-01-01

    The nickel solubility of 7 different nickel-alloys was tested in vivo and in vitro. The results revealed that the solubility of the alloys, after encasing them in lactic-acid solution of pH 4.2 for a period of seven days, allows to find out those alloys, which will also clinically dissolve small amounts of ions only. The Ni59-65Cr26-23Mo11-9 mass per cent alloys dissolved the smallest quantities of nickel in the in vitro and the in vivo tests and are therefore recommended for clinical use instead of the type Ni74-85Cr15-13Mo5-3 alloys. PMID:1816842

  2. Stress Corrosion Cracking of Certain Aluminum Alloys

    NASA Technical Reports Server (NTRS)

    Hasse, K. R.; Dorward, R. C.

    1983-01-01

    SC resistance of new high-strength alloys tested. Research report describes progress in continuing investigation of stress corrosion (SC) cracking of some aluminum alloys. Objective of program is comparing SC behavior of newer high-strength alloys with established SC-resistant alloy.

  3. Manufacturing development of low activation vanadium alloys

    Microsoft Academic Search

    J. P. Smith; W. R. Johnson; C. B. Baxi

    1996-01-01

    General Atomics is developing manufacturing methods for vanadium alloys as part of a program to encourage the development of low activation alloys for fusion use. The culmination of the program is the fabrication and installation of a vanadium alloy structure in the DIII-D tokamak as part of the Radiative Divertor modification. Water-cooled vanadium alloy components will comprise a portion of

  4. Physical metallurgy of recycling wrought aluminum alloys

    Microsoft Academic Search

    J. B. Hess

    1983-01-01

    It is quite characteristic of aluminum alloys that if the amount of any element addition is gradually increased, then an upper limit (a tolerance limit) is eventually reached where some important aspect of the alloy's overall behavior is affected harmfully. Although alloy compositional registers and specifications commonly list upper limits for only the main alloying additions and usual impurities, in

  5. Towards an Operational Semantics for Alloy

    NASA Astrophysics Data System (ADS)

    Giannakopoulos, Theophilos; Dougherty, Daniel J.; Fisler, Kathi; Krishnamurthi, Shriram

    The Alloy modeling language has a mathematically rigorous denotational semantics based on relational algebra. Alloy specifications often represent operations on a state, suggesting a transition-system semantics. Because Alloy does not intrinsically provide a notion of state, however, this interpretation is only implicit in the relational-algebra semantics underlying the Alloy Analyzer.

  6. High-Alloy Materials for Offshore Applications

    Microsoft Academic Search

    T. F. Lemke; J. A. Harris

    1983-01-01

    High-alloy materials possessing good corrosion resistance in hot, sour brines are being seriously considered for offshore applications. These alloys are available in a wide range of strength levels which can be attained by the methods of cold working or precipitation hardening. Results of testing INCONEL alloys 625 and 718 and INCOLOY alloys 825 and 925 for resistance to general corrosion,

  7. Effect of Al, B, Ti and Zr additive elements on the electrochemical hydrogen storage performance of MgNi alloy

    Microsoft Academic Search

    Mustafa Anik; Gizem Özdemir; Nilüfer Küçükdeveci; Bedri Baksan

    2011-01-01

    MgNi, Mg0.9(M)0.1Ni and Mg0.8(M)0.2Ni (M = Al, B, Ti, Zr) type alloys were synthesized by mechanical alloying and their electrochemical hydrogen storage characteristics were investigated. X-ray diffraction studies showed that although 15 h milling was enough to obtain amorphous\\/nano-crystalline MgNi alloy structure, the dissolution of all Ni in the main phase required at least 25 h milling. The discharge capacities of alloys were observed

  8. Oxidation resistant alloys, method for producing oxidation resistant alloys

    SciTech Connect

    Dunning, John S. (Corvallis, OR); Alman, David E. (Salem, OR)

    2002-11-05

    A method for producing oxidation-resistant austenitic alloys for use at temperatures below 800.degree. C. comprising of: providing an alloy comprising, by weight %: 14-18% chromium, 15-18% nickel, 1-3% manganese, 1-2% molybdenum, 2-4% silicon, 0% aluminum and the balance being iron; heating the alloy to 800.degree. C. for between 175-250 hours prior to use in order to form a continuous silicon oxide film and another oxide film. The method provides a means of producing stainless steels with superior oxidation resistance at temperatures above 700.degree. C. at a low cost

  9. Evaluation of surface modifications for oxidation protection of vanadium-base alloys in helium-cooled blanket designs

    NASA Astrophysics Data System (ADS)

    Tobin, A.; Busch, G.

    1986-11-01

    Vanadium-base alloys are currently being considered for application to high-temperature helium-cooled fusion reactor blanket designs. A major drawback is their known sensitivity to low levels of oxidizing impurities that would normally be present as water vapor in the helium coolant gas. Although baseline data on the oxidation resistance of vanadium alloys are lacking, protection of vanadium alloy surfaces exposed to the helium coolant will probably be necessary for contiuous blanket operation at temperatures above 875 K. Surface alloying of vanadium-base alloys appears to be a feasible method of creating an oxidation-resistant surface. To examine this approach, a series of V-15Cr-5Ti alloy sheet specimens was surface alloyed with chromium. Oxidation tests were then conducted in flowing helium containing up to 100 vppm H 2O. Temperatures up to 925 K and times up to 1000 h were utilized. Control samples of unmodified V-15Cr-5Ti and a Type 316 stainless steel were also included. Significant reductions in oxygen pickup were observed with surface-alloyed specimens. These results suggest that surface alloying techniques offer great promise for protecting vanadium alloy surfaces against oxidation at blanket operating temperatures.

  10. New Amorphous Silicon Alloy Systems

    NASA Astrophysics Data System (ADS)

    Kapur, Mridula N.

    1990-01-01

    The properties of hydrogenated amorphous silicon (a-Si:H) have been modified by alloying with Al, Ga and S respectively. The Al and Ga alloys are in effect quaternary alloys as they were fabricated in a carbon-rich discharge. The alloys were prepared by the plasma assisted chemical vapor deposition (PACVD) method. This method has several advantages, the major one being the relatively low defect densities of the resulting materials. The PACVD system used to grow the alloy films was designed and constructed in the laboratory. It was first tested with known (a-Si:H and a-Si:As:H) materials. Thus, it was established that device quality alloy films could be grown with the home-made PACVD setup. The chemical composition of the alloys was characterized by secondary ion mass spectrometry (SIMS), and electron probe microanalysis (EPMA). The homogeneous nature of hydrogen distribution in the alloys was established by SIMS depth profile analysis. A quantitative analysis of the bulk elemental content was carried out by EPMA. The analysis indicated that the alloying element was incorporated in the films more efficiently at low input gas concentrations than at the higher concentrations. A topological model was proposed to explain the observed behavior. The optical energy gap of the alloys could be varied in the 0.90 to 1.92 eV range. The Al and Ga alloys were low band gap materials, whereas alloying with S had the effect of widening the energy gap. It was observed that although the Si-Al and Si-Ga alloys contained significant amounts of C and H, the magnitude of the energy gap was determined by the metallic component. The various trends in optical properties could be related to the binding characteristics of the respective alloy systems. A quantitative explanation of the results was provided by White's tight binding model. The dark conductivity-temperature dependence of the alloys was examined. A linear dependence was observed for the Al and Ga systems. Electronic conduction in the S-alloys appeared to proceed by a two step mechanism. The thermal activation energies for the high Al content and S-alloys were close to half the band gap value. The photoresponse of the films was determined from the light to dark conductivity ratio. The best photoresponse (sigma_ {L}/sigma_{D} = 4 times 10^2) was obtained for the Si-S alloys showing that they are promising electrode materials for solar cell application. A single unit photovoltaic electrolyzer was constructed by combining a-Si:H solar cells with an electrolysis cell. Several different configurations ((PIN), (PIN)^2 , and (PIN)^3) of the solar cells were tested. Both electric power and chemical energy (H_2) could be simultaneously drawn from the electrolyzer.

  11. Physical metallurgy of recycling wrought aluminum alloys

    Microsoft Academic Search

    J. B. Hess

    1983-01-01

    It is quite characteristic of aluminum alloys that if the amount of any element addition is gradually increased, then an upper\\u000a limit (a tolerance limit) is eventually reached where some important aspect of the alloy’s overall behavior is affected harmfully.\\u000a Although alloy compositional registers and specifications commonly list upper limits for only the main alloying additions\\u000a and usual impurities, in

  12. Heat storage in alloy transformations

    NASA Technical Reports Server (NTRS)

    Birchenall, C. E.

    1980-01-01

    The feasibility of using metal alloys as thermal energy storage media was investigated. The elements selected as candidate media were limited to aluminum, copper, magnesium, silicon, zinc, calcium, and phosphorus on the basis of low cost and latent heat of transformation. Several new eutectic alloys and ternary intermetallic phases were determined. A new method employing X-ray absorption techniques was developed to determine the coefficients of thermal expansion of both the solid and liquid phases and the volume change during phase transformation. The method and apparatus are discussed and the experimental results are presented for aluminum and two aluminum-eutectic alloys. Candidate materials were evaluated to determine suitable materials for containment of the metal alloys. Graphite was used to contain the alloys during the volume change measurements. Silicon carbide was identified as a promising containment material and surface-coated iron alloys were also evaluated. System considerations that are pertinent if alloy eutectics are used as thermal energy storage media are discussed. Potential applications to solar receivers and industrial furnaces are illustrated schematically.

  13. Heat storage in alloy transformations

    NASA Astrophysics Data System (ADS)

    Birchenall, C. E.

    1980-04-01

    The feasibility of using metal alloys as thermal energy storage media was investigated. The elements selected as candidate media were limited to aluminum, copper, magnesium, silicon, zinc, calcium, and phosphorus on the basis of low cost and latent heat of transformation. Several new eutectic alloys and ternary intermetallic phases were determined. A new method employing X-ray absorption techniques was developed to determine the coefficients of thermal expansion of both the solid and liquid phases and the volume change during phase transformation. The method and apparatus are discussed and the experimental results are presented for aluminum and two aluminum-eutectic alloys. Candidate materials were evaluated to determine suitable materials for containment of the metal alloys. Graphite was used to contain the alloys during the volume change measurements. Silicon carbide was identified as a promising containment material and surface-coated iron alloys were also evaluated. System considerations that are pertinent if alloy eutectics are used as thermal energy storage media are discussed. Potential applications to solar receivers and industrial furnaces are illustrated schematically.

  14. Nucleation of shear bands in amorphous alloys.

    PubMed

    Perepezko, John H; Imhoff, Seth D; Chen, Ming-Wei; Wang, Jun-Qiang; Gonzalez, Sergio

    2014-03-18

    The initiation and propagation of shear bands is an important mode of localized inhomogeneous deformation that occurs in a wide range of materials. In metallic glasses, shear band development is considered to center on a structural heterogeneity, a shear transformation zone that evolves into a rapidly propagating shear band under a shear stress above a threshold. Deformation by shear bands is a nucleation-controlled process, but the initiation process is unclear. Here we use nanoindentation to probe shear band nucleation during loading by measuring the first pop-in event in the load-depth curve which is demonstrated to be associated with shear band formation. We analyze a large number of independent measurements on four different bulk metallic glasses (BMGs) alloys and reveal the operation of a bimodal distribution of the first pop-in loads that are associated with different shear band nucleation sites that operate at different stress levels below the glass transition temperature, Tg. The nucleation kinetics, the nucleation barriers, and the density for each site type have been determined. The discovery of multiple shear band nucleation sites challenges the current view of nucleation at a single type of site and offers opportunities for controlling the ductility of BMG alloys. PMID:24594599

  15. Influence of chemical composition of zirconium alloy E110 on embrittlement under LOCA conditions - Part 1: Oxidation kinetics and macrocharacteristics of structure and fracture

    NASA Astrophysics Data System (ADS)

    Nikulin, S. A.; Rozhnov, A. B.; Belov, V. A.; Li, E. V.; Glazkina, V. S.

    2011-11-01

    Exploratory investigations of the influence of alloying and impurity content in the E110 alloy cladding tubes on the behavior under conditions of Loss of Coolant Accidents (LOCA) has been performed. Three alloys of E110 type have been tested: E110 alloy of nominal composition Zr-1%Nb (E110), E110 alloy of modified composition Zr-1%Nb-0.12%Fe-0.13%O (E110M), E110 alloy of nominal composition Zr-1%Nb with reduced impurity content (E110G). Alloys E110 and E110M were manufactured on the electrolytic basis and alloy E110G was manufactured on the basis of zirconium sponge. The high temperature oxidation tests in steam ( T = 1100 °C, 18% of equivalent cladding reacted (ECR)) have been conducted, kinetics of oxidation was investigated. Quantitative research of structure and fracture macrocharacteristics was performed by means of optical and electron microscopy. The results received were compared with the residual ductility of specimens. The results of the investigation showed the existence of "breakaway oxidation" kinetics and white spalling oxide in E110 and E110M alloys while the specimen oxidation kinetics in E110G alloy was characterized by a parabolic law and specimens had a dense black oxide. Oxygen and iron alloying in the E110 alloy positively changed the macrocharacteristics of structure and fracture. However, in general, it did not improve the resistance to embrittlement in LOCA conditions apparently because of a strong impurity influence caused by electrolytic process of zirconium production.

  16. Novel Ti-base superelastic alloys with large recovery strain and excellent biocompatibility.

    PubMed

    Fu, Jie; Yamamoto, Akiko; Kim, Hee Young; Hosoda, Hideki; Miyazaki, Shuichi

    2015-04-01

    In this study, a new Ti-Zr-Nb-Sn alloy system was developed as Ni-free biomedical superelastic alloys with a large recovery strain and excellent biocompatibility. Ti-18Zr-(9-16)Nb-(0-4)Sn alloys were prepared by an Ar arc melting method and the effect of composition on the crystal structure and superelastic properties was investigated. A large superelastic recovery strain of 6.0% was observed in Ti-18Zr-12.5Nb-2Sn, Ti-18Zr-11Nb-3Sn, and Ti-18Zr-9.5Nb-4Sn alloys subjected to cold-rolling and solution treatment. XRD results showed that the large recovery strain of Sn-added alloys is due to a combination effect of a large transformation strain and a strong recrystallization texture. The Ti-18Zr-11Nb-3Sn alloy exhibited excellent cyclic stability with an extremely narrow stress hysteresis about 20MPa. Cytocompatibility was also examined using three types of cell lines, murine fibroblast L929, human osteosarcoma SaOS-2, and human umbilical vein endothelial cell HUVEC and the results showed that the Ti-18Zr-11Nb-3Sn alloy exhibited larger cell covering ratios when compared with those of the Ti-50.5Ni alloy for all kinds of cells. PMID:25676584

  17. Dynamic compressive behavior of Pr-Nd alloy at high strain rates and temperatures

    SciTech Connect

    Wang Huanran; Cai Canyuan; Chen Danian [Mechanics and Materials Science Research Center, Ningbo University, Ningbo, Zhejiang 315211 (China); Ma Dongfang [Mechanics and Materials Science Research Center, Ningbo University, Ningbo, Zhejiang 315211 (China); School of Civil Engineering, Henan Polytechnic University, Jiaozuo, Henan 454000 (China)

    2012-07-01

    Based on compressive tests, static on 810 material test system and dynamic on the first compressive loading in split Hopkinson pressure bar (SHPB) tests for Pr-Nd alloy cylinder specimens at high strain rates and temperatures, this study determined a J-C type [G. R. Johnson and W. H. Cook, in Proceedings of Seventh International Symposium on Ballistics (The Hague, The Netherlands, 1983), pp. 541-547] compressive constitutive equation of Pr-Nd alloy. It was recorded by a high speed camera that the Pr-Nd alloy cylinder specimens fractured during the first compressive loading in SHPB tests at high strain rates and temperatures. From high speed camera images, the critical strains of the dynamic shearing instability for Pr-Nd alloy in SHPB tests were determined, which were consistent with that estimated by using Batra and Wei's dynamic shearing instability criterion [R. C. Batra and Z. G. Wei, Int. J. Impact Eng. 34, 448 (2007)] and the determined compressive constitutive equation of Pr-Nd alloy. The transmitted and reflected pulses of SHPB tests for Pr-Nd alloy cylinder specimens computed with the determined compressive constitutive equation of Pr-Nd alloy and Batra and Wei's dynamic shearing instability criterion could be consistent with the experimental data. The fractured Pr-Nd alloy cylinder specimens of compressive tests were investigated by using 3D supper depth digital microscope and scanning electron microscope.

  18. In vitro degradation behavior and cytocompatibility of Mg–Zn–Zr alloys

    PubMed Central

    Huan, Z. G.; Leeflang, M. A.; Fratila-Apachitei, L. E.; Duszczyk, J.

    2010-01-01

    Zinc and zirconium were selected as the alloying elements in biodegradable magnesium alloys, considering their strengthening effect and good biocompatibility. The degradation rate, hydrogen evolution, ion release, surface layer and in vitro cytotoxicity of two Mg–Zn–Zr alloys, i.e. ZK30 and ZK60, and a WE-type alloy (Mg–Y–RE–Zr) were investigated by means of long-term static immersion testing in Hank’s solution, non-static immersion testing in Hank’s solution and cell-material interaction analysis. It was found that, among these three magnesium alloys, ZK30 had the lowest degradation rate and the least hydrogen evolution. A magnesium calcium phosphate layer was formed on the surface of ZK30 sample during non-static immersion and its degradation caused minute changes in the ion concentrations and pH value of Hank’s solution. In addition, the ZK30 alloy showed insignificant cytotoxicity against bone marrow stromal cells as compared with biocompatible hydroxyapatite (HA) and the WE-type alloy. After prolonged incubation for 7 days, a stimulatory effect on cell proliferation was observed. The results of the present study suggested that ZK30 could be a promising material for biodegradable orthopedic implants and worth further investigation to evaluate its in vitro and in vivo degradation behavior. PMID:20532960

  19. Dissimilar friction welding of titanium alloys to alloy 718

    SciTech Connect

    Kuo, M.; Albright, C.E.; Baeslack, W.A. III

    1994-12-31

    The design of advanced, high-performance gas-turbine engines will require the utilization of elevated-temperature titanium-based materials, including conventional alloys, titanium aluminides, and titanium metal-matrix composites. The most efficient utilization of these materials in the engine compressor section would be achieved by directly joining these materials to existing nickel-base superalloys, such as Alloy 718. To date, the dissimilar welding of titanium alloys to nickel-based alloys has not been common practice because intermetallic compounds form in the weld and cause embrittlement. Special welding techniques must be developed to inhibit this compound formation and to provide high strength welds. In this investigation, a friction welding process was developed for joining titanium alloys (Ti-6Al-2Sn-4Zr-2Mo and Ti-6Al-4V) to nickel-based superalloy Alloy 718. An interlayer system comprised of copper and niobium sheet layers was employed as a diffusion barrier and weld deformation enhancer. A postweld heat treatment (PWHT, 700{degrees}C for 20 min in vacuum) under axial pressure (Ksi) was used to improve the joint strength consistency. The following conclusions can be drawn from this investigation: (1) A friction welding technique has been developed for joining titanium alloys (Ti-6Al-2Sn-4Zr-2Mo and Ti-6Al-4V) to Alloy 718 using an interlayer system of niobium and copper. Joint strengths averaging approximately 50 Ksi were achieved. (2) Deformation was concentrated in the interlayers, especially the copper interlayer, during friction welding. Increased reduction in length (RIL) during friction welding resulted in a decrease in the interlayer thicknesses. (3) The EDS results showed that the niobium and copper interlayers prevent interdiffusion between the two parent metals, producing formation of detrimental phases.

  20. Processing of aluminium alloys containing titanium addition by mechanical alloying

    Microsoft Academic Search

    K. R. Cardoso; C. A. D. Rodrigues; W. J. Botta F

    2004-01-01

    In this work, mechanical alloying was used to produce precursor powders of 2024 and 7050 aluminium alloys containing titanium addition. Milling was performed in a planetary mill using a ball to powder weight ratio of 20:1 and a milling time varying from 10 to 100h. Characterisation of the milled powders was performed by X-ray diffraction (XRD), differential scanning calorimetry (DSC)

  1. Microstructural characterization of superaustenitic stainless steel surface alloys formed using laser treatment

    NASA Astrophysics Data System (ADS)

    Sridhar, K.; Deshmukh, M. B.; Khanna, A. S.; Gasser, A.

    2000-09-01

    Conventional stainless steels (SS’s) such as AISI type 304 SS are used in many industrial applications due to their excellent weldability and good mechanical properties. However, in contacts with chlorides, they suffer from localized corrosion. AISI type 304 SS was alloyed at the surface with chromium, nickel, and molybdenum using a CO2 laser carried under varying laser processing parameters. The objective is to create a surface alloy with composition and microstructure, suitable for marine environments. The surface alloys were characterized using optical microscopy and scanning electron microscopy (SEM) and revealed the presence of the austenitic phase. Analysis by SEM-energy dispersive analysis (EDAX) revealed good compositional homogeneity with molybdenum contents in the range of 3 to 15 wt.%. The dendrite arm spacing (DAS) measured at the surface and bottom of the surface alloy using an image analyzer was found to be in good correlation with calculated cooling rates.

  2. Oxide Film Aging on Alloy 22 in Halide Containing Solutions

    SciTech Connect

    Rodriguez, Martin A.; Carranza, Ricardo M. [Dept. Materiales, Comision Nacional de Energia Atomica, Av. Gral. Paz 1499, Villa Maipu, 1650 (Argentina); Rebak, Raul B. [Lawrence Livermore National Laboratory, 7000 East Ave, L-631, Livermore, CA, 94550-9698 (United States)

    2007-07-01

    Passive and corrosion behaviors of Alloy 22 in chloride and fluoride containing solutions, changing the heat treatment of the alloy, the halide concentration and the pH of the solutions at 90 deg. C, was investigated. The study was implemented using electrochemical techniques, which included open circuit potential monitoring over time, potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) measurements carried out at open circuit and at passivity potentials. Corrosion rates obtained by EIS measurements after 24 h immersion in naturally aerated solutions were below 0.5 {mu}m/year. The corrosion rates were practically independent of solution pH, alloy heat treatment and halide ion nature and concentration. EIS low frequency resistance values increased with applied potential in the passive domain and with polarization time in pH 6 - 1 M NaCl at 90 deg. C. This effect was attributed to an increase in the oxide film thickness and oxide film aging. High frequency capacitance measurements indicated that passive oxide on Alloy 22 presented a double n-type/p-type semiconductor behavior in the passive potential range. (authors)

  3. Electronic structure and activation energy of hydrogen in NEG alloy using nonlinear response theory

    Microsoft Academic Search

    N. Singh; D. K. Avasthi; A. Tripathi

    1999-01-01

    Electronic structure of hydrogen in NEG alloy [Zr0.70V0.246Fe0.054] is calculated by using nonlinear response theory [Kohn and Sham,Phys. Rev.\\u000a A140,1133 (1965)]. The configurational energy is calculated by assuming the ideal hcp structure for NEG alloy. The calculated\\u000a configurational energy predicts that hydrogen prefers octahedral (0)-site in NEG alloy.s-Type shallow bound state of energy -1.580 x 10-5 Ryd. suggests that hydrogen

  4. [MRO] Oligocrystalline Shape Memory Alloys

    E-print Network

    Chen, Ying

    Copper-based shape memory alloys (SMAs) exhibit excellent shape memory properties in single crystalline form. However, when they are polycrystalline, their shape memory properties are severely compromised by brittle fracture ...

  5. Complex stacking fault energy of Cr-alloyed ?-TiAl

    NASA Astrophysics Data System (ADS)

    Zheng, J. G.; Li, Q.; Liu, Z. G.; Feng, D.; Frommeyer, G.

    1994-12-01

    The {1}/{2}<1 overline10] extended dislocations were first observed in Cr-alloyed ?-TiAl lamellae of the Ti-45 at.% Al-3 at.% Cr alloy by high resolution electron microscopy. The equilibrium width and the energy of the complex stacking fault (CSF) ribbon bordered by two {1}/{6}<1 overline21| -type partial dislocations were determined experimentally. The results show that Cr addition drastically decreases the CSF energy in ?-TiAl.

  6. Charge-Density-Shear-Moduli Relationships in Aluminum-Lithium Alloys

    Microsoft Academic Search

    Mark Eberhart

    2001-01-01

    Using the first principles full-potential linear-augmented-Slater-type orbital technique, the energies and charge densities of aluminum and aluminum-lithium supercells have been computed. The experimentally observed increase in aluminum's shear moduli upon alloying with lithium is argued to be the result of predictable changes to aluminum's total charge density, suggesting that simple rules may allow the alloy designer to predict the effects

  7. Crystal structure of martensitic phases in Ni–Mn–Ga shape memory alloys

    Microsoft Academic Search

    J. Pons; V. A. Chernenko; R. Santamarta; E. Cesari

    2000-01-01

    The crystal structures of the different martensitic phases observed in a wide variety of Ni–Mn–Ga alloy compositions have been studied in detail. Similarly to the Ni–Al alloys, the non-modulated martensite can be well described by the L10 lattice, although it must be “doubled” in order to account for the L21 type of order of the parent phase. Concerning the well

  8. High-Thermoelectric Performance of Nanostructured Bismuth Antimony Telluride Bulk Alloys

    Microsoft Academic Search

    Bed Poudel; Qing Hao; Yi Ma; Yucheng Lan; Austin Minnich; Xiao Yan; Dezhi Wang; Andrew Muto; Daryoosh Vashaee; Xiaoyuan Chen; M. S. Dresselhaus; Mildred S. Dresselhaus; Gang Chen; Zhifeng Ren

    2008-01-01

    The dimensionless thermoelectric figure of merit (ZT) in bismuth antimony telluride (BiSbTe) bulk alloys has remained around 1 for more than 50 years. We show that a peak ZT of 1.4 at 100°C can be achieved in a p-type nanocrystalline BiSbTe bulk alloy. These nanocrystalline bulk materials were made by hot pressing nanopowders that were ball-milled from crystalline ingots under

  9. Seebeck coefficient of nanostructured phosphorus-alloyed bismuth telluride thick films

    Microsoft Academic Search

    J. Zhou; S. Li; H. M. A. Soliman; M. S. Toprak; M. Muhammed; D. Platzek; E. Müller

    2009-01-01

    Nanostructured phosphorous-alloyed Bi2Te3 thick films have been prepared by electrochemical deposition. The average grain size of the films was calculated to be 14–26nm based on Scherrer's equation. The effect of P on the Seebeck coefficient of the Bi2Te3 thick film was investigated. The results show that P-alloyed thick film has n-type conductivity with the Seebeck coefficient of ?35?V\\/K. The correlation

  10. Complex stacking fault energy of Cr-alloyed gamma-TiAl

    Microsoft Academic Search

    J. G. Zheng; Q. Li; Z. G. Liu; D. Feng; G. Frommeyer

    1994-01-01

    The 1\\/2<110] extended dislocations were first observed in Cr-alloyed gamma-TiAl lamellae of the Ti-45 at.% Al-3 at.% Cr alloy by high resolution electron microscopy. The equilibrium width and the energy of the complex stacking fault (CSF) ribbon bordered by two 1\\/6<121-type partial dislocations were determined experimentally. The results show that Cr addition drastically decreases the CSF energy in gamma-TiAl.

  11. Internal friction and anelastic properties of vanadium and V–Ti–Cr alloys

    Microsoft Academic Search

    V. M. Chernov; B. K. Kardashev; L. M. Krjukova; L. I. Mamaev; O. A. Plaksin; A. E. Rusanov; M. I. Solonin; V. A. Stepanov; S. N. Votinov; L. P. Zavialski

    1998-01-01

    Using an acoustic technique of composite oscillator, the effect of preliminary deformation on the amplitude dependence (amplitude range from 10?6 to 3×10?4) of ultrasound damping and the Young's modulus (resonance frequencies) for V and V–(4–10)Ti–(4–10)Cr alloys has been studied. The alloys differed in composition, manufacture technology and also irradiation type (protons, neutrons), environments and fluence were varied. Neutron irradiation (fast

  12. Improvement of the fatigue life of titanium alloys for biomedical devices through microstructural control.

    PubMed

    Niinomi, Mitsuo; Akahori, Toshikazu

    2010-07-01

    A limited number of reports exist regarding the systematic investigation or comparison of the fatigue strength of titanium alloys for medical devices, including plain, fretting and notch fatigue, for improvement through various treatments and processes, with respect to related microstructures. This article focuses on the changes and improvements in fatigue strength of newly developed beta-type and practically used alpha + beta-titanium alloys for medical devices through heat treatments, thermomechanical treatments and surface modifications. PMID:20583885

  13. Low-temperature electrical resistivity study of deformed Inconel alloy 600

    NASA Astrophysics Data System (ADS)

    Chan, Feng Shiu; Yao, Yeong Der; Wang, Shing Hoa

    2006-09-01

    The electrical resistivity of a plastic deformed Inconel alloy 600 (alloy of Ni 72 Cr 16 Fe 8) as function of temperature between 25 K and 300 K was studied. The deformation does not affect the Curie temperature much; it is roughly near 176 K of the deflected point at electrical resistivity, except for the sample with 75% deformation. The ?-type behavior of the electrical resistivity is a typical signal for the magnetic phase transition.

  14. Precipitation characteristics of ?-phase in wrought nickel-base alloys and its effect on their properties

    Microsoft Academic Search

    H. M. Tawancy

    1996-01-01

    Thermal exposures consisting of 1–16000 h at 540, 650, 760, and 870°C were used to study the susceptibility of selected nickel-base alloys to precipitation of µ-phase and its effect on mechanical strength and corrosion resistance. Analytical electron microscopy and X-ray diffraction were used to characterize the µ-phase. A µ-phase of the type Mo6Ni7 in nickel-base alloys was found to be

  15. X-ray diffraction study of ?-stabilized plutonium alloys under pressure

    Microsoft Academic Search

    Ph Faure; C. Genestier

    2010-01-01

    Previous extensive studies of the ????-phase transformation induced by temperature and\\/or by pressure in ?-stabilized plutonium alloys indicate strong dependence on parameters such as solute type, solute distribution, chemical impurities, kinetics, thermodynamic path….The present paper reports results obtained on two Pu–2.3at.%Ga binary alloys differing by solute homogenization treatment and studied under pressure by in situ by X-ray diffraction in diamond

  16. Effect of aging time and temperature on intergranular corrosion of aluminium alloys

    Microsoft Academic Search

    Fuad M. Khoshnaw; Ramadhan H. Gardi

    2006-01-01

    Purpose – Two types of aluminium alloys, 2024-T3 and 7075-T6, having been selected, this study aims to investigate the effect of metallurgical aspects on intergranular corrosion. Design\\/methodology\\/approach – To determine and evaluate the metallurgical effects of heat treatments on corrosion behaviour of these alloys, G67 ASTM test was selected. Findings – The results showed that with increasing the aging time

  17. Development of preferential intergranular oxides in nickel-aluminum alloys at high temperatures

    Microsoft Academic Search

    Y. Shida; F. H. Stott; B. D. Bastow; D. P. Whittle; G. C. Wood

    1982-01-01

    The development of intergranular oxides in dilute Ni-Al alloys containing 0.55–4.10% Al in Ni-NiO packs and in 1 atm oxygen at 800–1100°C has been examined. In the Ni-NiO packs, preferential intergranular oxide penetration as well as internal oxidation occurs in every case, except in the higher aluminum-containing alloys at 1100°C. Several different types of intergranular oxide morphology were observed, depending

  18. Formation stages of bcc (Fe44Co44)Sn12 extended solid solution by mechanical alloying

    E-print Network

    Paris-Sud XI, Université de

    with a progressive and simultaneous dissolution of Co and Sn into bcc Fe. Keywords: Mechanical alloying, Fe-Co Near-equiatomic FeCo alloys are b.c.c. below ~1250 K [1]. The b.c.c. phase (A2) orders to a CsCl type on near- equiatomic FeCo were thoroughly investigated [1]. The addition of a small amount of vanadium

  19. Microstructure of a pressure die cast magnesium—4wt.% aluminium alloy modified with rare earth additions

    Microsoft Academic Search

    G. Pettersen; H. Westengen; R. Høier; O. Lohne

    1996-01-01

    Addition of cerium-rich mixtures of rare earth (RE) elements to aluminium-containing magnesium pressure die cast alloys is known to improve the creep properties at elevated temperatures. In the present investigation, a detailed description of the microstructure of a magnesium-4 wt.% aluminium alloy containing 1.4 wt.% of a cerium-rich mixture of RE elements is presented. Particle types occurring and their distribution

  20. Electrochemical behavior of Ni-Al-Fe alloys in simulated human body solution

    Microsoft Academic Search

    I. E. Castañeda; J. G. Gonzalez-Rodriguez; J. Colin; M. A. Neri-Flores

    2010-01-01

    An investigation about the corrosion resistance of Ni-Al-Fe intermetallic alloys in simulated human body fluid environments\\u000a has been carried out using electrochemical techniques. Tested alloys included 57 (wt%) Ni-(20 to 30) Al-(12 to 23) Fe using\\u000a the Hank's solution because the high corrosion resistance provided by protective Al2O3 external layer. For comparison, AISI 316L type stainless steel has also been

  1. Ratchetting deformation of super-elastic and shape-memory NiTi alloys

    Microsoft Academic Search

    Guozheng Kang; Qianhua Kan; Linmao Qian; Yujie Liu

    2009-01-01

    The ratchetting deformation of super-elastic NiTi alloy was first observed by uniaxial stress-controlled cyclic tests, and the dependence of ratchetting upon the applied stress and loading type was discussed. The evolutions of responded peak\\/valley strain, nominal elastic modulus and transformation stress, as well as dissipation energy of the alloy during the stress-controlled cyclic loading were investigated. It is shown that

  2. Chemical analysis of uranium-niobium alloys by wavelength dispersive spectroscopy at the sigma complex

    SciTech Connect

    Papin, Pallas A.

    2012-06-01

    Uranium-niobium alloys play an important role in the nation's nuclear stockpile. It is possible to chemically quantify this alloy at a micron scale by using a technique know as wavelength dispersive spectroscopy. This report documents how this technique was used and how it is possible to reproduce measurements of this type. Discussion regarding the accuracy and precision of the measurements, the development of standards, and the comparison of different ways to model the matrices are all presented.

  3. Corrosion of metals and alloys in mixed gas environments at elevated temperatures

    Microsoft Academic Search

    C. S. Giggins; F. S. Pettit

    1980-01-01

    The attack of nickel, cobalt, iron, and alloys of these metals containing chromium and aluminum, by gases containing sulfur-oxygen,\\u000a carbon-oxygen, and nitrogen-oxygen has been studied at temperatures of 600 and 900C. The degradation of these metals and\\u000a alloys was characterized by using standard analytical techniques with emphasis on optical metallography. Three types of accelerated\\u000a degradation were identified for the attack

  4. Warm Forming of Aluminum Alloys using a Coupled ThermoMechanical Anisotropic Material Model

    Microsoft Academic Search

    Nader Abedrabbo; Farhang Pourboghrat; John E. Carsley

    2005-01-01

    Temperature-dependant anisotropic material models for two types of automotive aluminum alloys (5754-O and 5182-O) were developed and implemented in LS-Dyna as a user material subroutine (UMAT) for coupled thermo-mechanical finite element analysis (FEA) of warm forming of aluminum alloys. The anisotropy coefficients of the Barlat YLD2000 plane stress yield function for both materials were calculated for the range of temperatures

  5. Forming characteristics of austenitic stainless steel sheet alloys under warm hydroforming conditions

    Microsoft Academic Search

    Muammer Koç; Sasawat Mahabunphachai; Eren Billur

    2011-01-01

    Stainless steel sheet alloys have been increasingly used in heating, ventilating, and air conditioning; appliance; sanitary\\u000a and medical devices; as well as several structural and transportation applications, due to their high strength-to-weight ratio,\\u000a corrosion resistance, biomedical compatibility, and esthetic appearance. Among various stainless steel alloys, austenitic\\u000a stainless steels are the most commonly used type. Due to the forming limitations into

  6. Magnetic properties of Ni-Rh alloys near the critical composition for ferromagnetism

    Microsoft Academic Search

    W. C. Muellner; J. S. Kouvel

    1975-01-01

    The magnetizations of Ni-Rh alloys on either side of the critical composition for ferromagnetism (ccrit~63-at.% Ni) were measured between 4.2 and 250°K in fields up to 56 kOe. The initial paramagnetic susceptibility of each alloy is shown to be resolvable into a Curie-Weiss component and a weakly temperature-dependent component of the exchange-enhanced Pauli type. The latter component, which is essentially

  7. Local magnetism of Rh in Ni-Rh alloys near the critical composition for ferromagnetism

    NASA Astrophysics Data System (ADS)

    Krishnamurthy, V. V.; Mishra, S. N.; Kumar, Ravi; Devare, S. H.; Devare, H. G.

    1993-03-01

    Local magnetic behaviour of Rh implanted into Ni-Rh alloys near the critical Rh composition x=0.37 has been studied using the TDPAC method. The observed Curie-Weiss type local susceptibility reflects the presence of large d spin polarization around Rh yielding a total moment of 4.7 ?B. Our results show that the magnetism of Rh in the alloys depends strongly on the number of Ni near neighbour atoms.

  8. Local magnetism of Rh in Ni-Rh alloys near the critical composition for ferromagnetism

    Microsoft Academic Search

    V. V. Krishnamurthy; S. N. Mishra; Ravi Kumar; S. H. Devare; H. G. Devare

    1993-01-01

    Local magnetic behaviour of Rh implanted into Ni-Rh alloys near the critical Rh compositionx=0.37 has been studied using the TDPAC method. The observed Curie-Weiss type local susceptibility reflects the presence of large d spin polarization around Rh yielding a total moment of 4.7 µB. Our results show that the magnetism of Rh in the alloys depends strongly on the number

  9. Casting Characteristics of Aluminum Die Casting Alloys

    SciTech Connect

    Makhlouf M. Makhlouf; Diran Apelian

    2002-02-05

    The research program investigates the casting characteristics of selected aluminum die casting alloys. Specifically, the alloys' tendencies towards die soldering and sludge formation, and the alloys' fluidity and machinability are evaluated. It was found that: When the Fe and Mn contents of the alloy are low; caution has to be taken against possible die soldering. When the alloy has a high sludge factor, particularly a high level of Fe, measures must be taken to prevent the formation of large hardspots. For this kind of alloy, the Fe content should be kept at its lowest allowable level and the Mn content should be at its highest possible level. If there are problems in die filling, measures other than changing the alloy chemistry need to be considered first. In terms of alloy chemistry, the elements that form high temperature compounds must be kept at their lowest allowable levels. The alloys should not have machining problems when appropriate machining techniques and machining parameters are used.

  10. Volatilization from PCA steel alloy

    SciTech Connect

    Hagrman, D.L.; Smolik, G.R.; McCarthy, K.A.; Petti, D.A. [Lockheed Martin Idaho Technologies Company, Idaho Falls, ID (United States)

    1996-12-31

    The mobilizations of key components from Primary Candidate Alloy (PCA) steel alloy have been measured with laboratory-scale experiments. The experiments indicate most of the mobilization from PCA steel is due to oxide formation and spalling but that the spalled particles are large enough to settle rapidly. Based on the experiments, models for the volatilization of iron, manganese, and cobalt from PCA steel in steam and molybdenum from PCA steel in air have been derived. 6 refs., 3 figs.

  11. Sintered titanium carbide hard alloys

    Microsoft Academic Search

    G. V. Samsonov; N. N. Sergeev; G. T. Dzodziev; V. K. Vitryanyuk; L. V. Latyaeva

    1971-01-01

    1.A study was made of the preparation of titanium carbide hard alloys with a nickel binder. It is shown that satisfactory mechanical properties (bend strength 107–115 kg\\/mm2, hardness 90–90.5 HRA) are exhibited by 80% TiC-20% Ni alloys produced from fine-milled mixtures by sintering in a vacuum of 5·10-3 mm Hg at a temperature of 1300‡C and an isothermal holding time

  12. Castable hot corrosion resistant alloy

    NASA Technical Reports Server (NTRS)

    Barrett, Charles A. (inventor); Holt, William H. (inventor)

    1988-01-01

    Some 10 wt percent nickel is added to an Fe-base alloy which has a ferrite microstructure to improve the high temperature castability and crack resistance while about 0.2 wt percent zirconium is added for improved high temperatur cyclic oxidation and corrosion resistance. The basic material is a high temperature FeCrAl heater alloy, and the addition provides a material suitable for burner rig nozzles.

  13. The mechanism of mechanical alloying

    Microsoft Academic Search

    J. S. Benjamin; T. E. Volin

    1974-01-01

    The mechanical alloying process is a new method for producing composite metal powders with controlled microstructures. It\\u000a is unique in that it is an entirely solid state process, permitting dispersion of insoluble phases such as refractory oxides\\u000a and addition of reactive alloying elements such as aluminum and titanium. Interdispersion of the ingredients occurs by repeated\\u000a cold welding and fracture of

  14. Overview of ODS Alloy Development

    Microsoft Academic Search

    Ian G Wright; Bruce A Pint

    2005-01-01

    The overall goal of this effort is to address the materials-related barriers to expediting the use of oxide dispersion-strengthened (ODS) alloys in components required in the U.S. Department of Energy's (DOE's) Office of Fossil Energy's advanced coal combustion, gasification, and utilization processes to operate at temperatures higher than are possible with conventionally-strengthened alloys. The project is focused on the needs

  15. Superplastic forming of alloy 718

    SciTech Connect

    Smith, G.D.; Flower, H.L. (Inco Alloys International Inc., Huntington, WV (United States))

    1994-04-01

    Inconel Alloy 718 (UNS N07718) is now available in a fine-grained, controlled composition modification that can be super-plastically formed. The new superplastic forming (SPF) capability allows the manufacture of large, complex, and detailed parts, which improves integrity by reducing the need for joining. Furthermore, it allows designers to fabricate components having higher strength, fatigue resistance, and temperature capability than parts made of aluminum or titanium alloys.

  16. Carbon-rich hexagonal (BN)C alloys

    NASA Astrophysics Data System (ADS)

    Uddin, M. R.; Li, J.; Lin, J. Y.; Jiang, H. X.

    2015-06-01

    Thin films of hexagonal boron nitride carbon, h-(BN)1-x(C2)x, alloys in the C-rich side have been synthesized by metal-organic chemical vapor deposition (MOCVD) on c-plane sapphire substrates. X-ray diffraction measurements confirmed single hexagonal phase of h-(BN)1-x(C2)x epilayers. Electrical transport and Raman spectroscopy measurements results revealed evidences that homogenous h-(BN)1-x(C2)x alloys with x ? 95% can be synthesized by MOCVD at a growth temperature of 1300 °C. The variable temperature Hall-effect measurements suggested that a bandgap opening of about 93 meV with respect to graphite has been obtained for h-(BN)1-x(C2)x with x = 0.95, which is consistent with the expected value deduced from the alloy dependence of the energy gap of homogenous h-(BN)1-x(C2)x alloys. Atomic composition results obtained from x-ray photoelectron spectroscopy measurements revealed that the carrier type in C-rich h-(BN)1-x(C2)x alloys is controlled by the stoichiometry ratio between the B and N via changing the V/III ratio during the growth. The demonstration of bandgap opening and conductivity control in C-rich h-(BN)1-x(C2)x alloys provide feasibilities for realizing technologically significant devices including infrared (IR) emitters and detectors active from near to far IR and multi-spectral IR emitters and detectors.

  17. Ni{sub 3}Al aluminide alloys

    SciTech Connect

    Liu, C.T.

    1993-10-01

    This paper provides a brief review of the recent progress in research and development of Ni{sub 3}Al and its alloys. Emphasis has been placed on understanding low ductility and brittle fracture of Ni{sub 3}Al 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}Al 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.

  18. Choosing An Alloy For Automotive Stirling Engines

    NASA Technical Reports Server (NTRS)

    Stephens, Joseph R.

    1988-01-01

    Report describes study of chemical compositions and microstructures of alloys for automotive Stirling engines. Engines offer advantages of high efficiency, low pollution, low noise, and ability to use variety of fuels. Twenty alloys evaluated for resistance to corrosion permeation by hydrogen, and high temperature. Iron-based alloys considered primary candidates because of low cost. Nickel-based alloys second choice in case suitable iron-based alloy could not be found. Cobalt-based alloy included for comparison but not candidate, because it is expensive strategic material.

  19. Lithium alloy anode for thermal cells

    SciTech Connect

    Cupp, E.B.; Cottingham, D.R.

    1986-12-02

    This patent describes as an article of manufacture, an anode wafer for a thermal cell, the anode wafer comprising particles of a lithium anode alloy bonded with particles of a metal binder, the lithium anode alloy being of the class consisting of lithium-aluminum alloys; lithium-silicon alloys; and lithium-boron alloys, the metal binder being of the class consisting of unalloyed iron, copper, nickel, manganese; and mixtures thereof, and wherein substantially all the metal binder in the wafer remains present as a discrete phase, unalloyed with the lithium alloy.

  20. Nickel-based gadolinium alloy for neutron adsorption application in RAM packages.

    SciTech Connect

    Mizia, Ronald A. (Idaho National Laboratory, Idaho Falls, ID); Dupont, John Neuman (Lehigh University, Bethlehem, PA); McConnell, Paul E.; Robino, Charles Victor

    2005-02-01

    The National Spent Nuclear Fuel Program, located at the Idaho National Laboratory (INL), coordinates and integrates national efforts in management and disposal of US Department of Energy (DOE)-owned spent nuclear fuel. These management functions include development of standardised systems for long-term disposal in the proposed Yucca Mountain repository. Nuclear criticality control measures are needed in these systems to avoid restrictive fissile loading limits because of the enrichment and total quantity of fissile material in some types of the DOE spent nuclear fuel. This need is being addressed by development of corrosion-resistant, neutron-absorbing structural alloys for nuclear criticality control. This paper outlines results of a metallurgical development programme that is investigating the alloying of gadolinium into a nickel-chromium-molybdenum alloy matrix. Gadolinium has been chosen as the neutron absorption alloying element due to its high thermal neutron absorption cross section and low solubility in the expected repository environment. The nickel-chromium-molybdenum alloy family was chosen for its known corrosion performance, mechanical properties, and weldability. The workflow of this programme includes chemical composition definition, primary and secondary melting studies, ingot conversion processes, properties testing, and national consensus codes and standards work. The microstructural investigation of these alloys shows that the gadolinium addition is present in the alloy as a gadolinium-rich second phase. The mechanical strength values are similar to those expected for commercial Ni-Cr-Mo alloys. The alloys have been corrosion tested with acceptable results. The initial results of weldability tests have also been acceptable. Neutronic testing in a moderated critical array has generated favourable results. An American Society for Testing and Materials material specification has been issued for the alloy and a Code Case has been submitted to the American Society of Mechanical Engineers for code qualification.

  1. Nickel-based gadolinium alloy for neutron adsorption application in ram packages.

    SciTech Connect

    Mizia, Ronald A. (Idaho National Engineering & Environmental Laboratory, Idaho Falls, ID); McConnell, Paul E.; Robino, Charles Victor

    2004-09-01

    The National Spent Nuclear Fuel Program, located at the Idaho National Laboratory (INL), coordinates and integrates national efforts in management and disposal of US Department of Energy (DOE)-owned spent nuclear fuel. These management functions include development of standardized systems for long-term disposal in the proposed Yucca Mountain repository. Nuclear criticality control measures are needed in these systems to avoid restrictive fissile loading limits because of the enrichment and total quantity of fissile material in some types of the DOE spent nuclear fuel. This need is being addressed by development of corrosion-resistant, neutron-absorbing structural alloys for nuclear criticality control. This paper outlines results of a metallurgical development program that is investigating the alloying of gadolinium into a nickel-chromium-molybdenum alloy matrix. Gadolinium has been chosen as the neutron absorption alloying element due to its high thermal neutron absorption cross section and low solubility in the expected repository environment. The nickel-chromium-molybdenum alloy family was chosen for its known corrosion performance, mechanical properties, and weldability. The workflow of this program includes chemical composition definition, primary and secondary melting studies, ingot conversion processes, properties testing, and national consensus codes and standards work. The microstructural investigation of these alloys shows that the gadolinium addition is present in the alloy as a gadolinium-rich second phase. The mechanical strength values are similar to those expected for commercial Ni-Cr-Mo alloys. The alloys have been corrosion tested with acceptable results. The initial results of weldability tests have also been acceptable. Neutronic testing in a moderated critical array has generated favorable results. An American Society for Testing and Materials material specification has been issued for the alloy and a Code Case has been submitted to the American Society of Mechanical Engineers for code qualification.

  2. Electrical transport properties of (BN)-rich hexagonal (BN)C semiconductor alloys

    SciTech Connect

    Uddin, M. R.; Doan, T. C.; Li, J.; Lin, J. Y.; Jiang, H. X., E-mail: hx.jiang@ttu.edu [Department of Electrical and Computer Engineering, Texas Tech University, Lubbock, TX 79409 (United States); Ziemer, K. S. [Department of Chemical Engineering, Northeastern University, Boston, MA 02115 (United States)

    2014-08-15

    The layer structured hexagonal boron nitride carbon semiconductor alloys, h-(BN)C, offer the unique abilities of bandgap engineering (from 0 for graphite to ?6.4 eV for h-BN) and electrical conductivity control (from semi-metal for graphite to insulator for undoped h-BN) through alloying and have the potential to complement III-nitride wide bandgap semiconductors and carbon based nanostructured materials. Epilayers of (BN)-rich h-(BN){sub 1-x}(C{sub 2}){sub x} alloys were synthesized by metal-organic chemical vapor deposition (MOCVD) on (0001) sapphire substrates. Hall-effect measurements revealed that homogeneous (BN)-rich h-(BN){sub 1-x}(C{sub 2}){sub x} alloys are naturally n-type. For alloys with x = 0.032, an electron mobility of about 20 cm{sup 2}/Vs at 650?°K was measured. X-ray photoelectron spectroscopy (XPS) was used to determine the chemical composition and analyze chemical bonding states. Both composition and chemical bonding analysis confirm the formation of alloys. XPS results indicate that the carbon concentration in the alloys increases almost linearly with the flow rate of the carbon precursor (propane (C{sub 3}H{sub 8})) employed during the epilayer growth. XPS chemical bonding analysis showed that these MOCVD grown alloys possess more C-N bonds than C-B bonds, which possibly renders the undoped h-(BN){sub 1-x}(C{sub 2}){sub x} alloys n-type and corroborates the Hall-effect measurement results.

  3. A New Series of Icosahedral Quasicrystals in Zn-M-Sc (M = Ag, Au, Pd, Pt) Alloys

    Microsoft Academic Search

    Shiro Kashimoto; Ryo Maezawa; Yoko Kasano; Tomokazu Mitani; Tsutomu Ishimasa

    2003-01-01

    A new series of icosahedral quasicrystals has been found in Zn75M10Sc15 (M = Ag, Au, Pd and Pt) as-cast alloys. Electron and powder X-ray diffraction analyses indicated that these quasicrystals are of the P-type (primitive type) and have six-dimensional lattice parameters a6D=0.7112--0.7151 nm. The quasicrystals are formed as main phases in these alloys. In the Zn80Ag5Sc15 alloy annealed at 981

  4. Effect of aging on mechanical properties of aluminum-alloy rivets

    NASA Technical Reports Server (NTRS)

    Roop, Frederick C

    1941-01-01

    Curves and tabular data present the results of strength tests made during and after 2 1/2 years of aging on rivets and rivet wire of 3/16-inch nominal diameter. The specimens were of aluminum alloy: 24S, 17S, and A17S of the duralumin type and 53S of the magnesium-silicide type.

  5. DEGRADATION MODES OF ALLOY 22 IN YUCCA MOUNTAIN REPOSITORY CONDITIONS

    SciTech Connect

    F. Hua; G.M. Gordon; R.B. Rebak

    2005-10-13

    The nuclear waste package design for Yucca Mountain (Nevada, USA), in its current configuration, consists of a double wall cylindrical container fabricated using a highly corrosion resistant Ni-based Alloy 22 for the outer barrier and type 316 stainless steel for the inner structural vessel. A mailbox-shaped drip shield fabricated primarily using Ti Grade 7 will cover the waste packages. The environmental degradation of the relevant materials have been extensively studied and modeled for over ten years. This paper reviews the state-of-the-art understanding of the degradation modes of Alloy 22 (N06022) due to its interaction with the predicted in-drift mountain conditions including temperature and types of electrolytes. Subjects discussed include thermal aging and phase stability, dry oxidation, general and localized corrosion, stress corrosion cracking and hydrogen induced cracking.

  6. Material properties of Ni-Cr-Al alloy and design of a 4 GPa class non-magnetic high-pressure cell

    NASA Astrophysics Data System (ADS)

    Uwatoko, Yoshiya; Todo, Sakae; Ueda, Kazuhiro; Uchida, Ahimusa; Kosaka, Masashi; Mori, Nobuo; Matsumoto, Takehiko

    2002-11-01

    The Ni-Cr-Al Russian alloy was prepared. Its magnetic and mechanical properties were better than those of MP35N alloy. We fabricated the a piston-cylinder-type hybrid high-pressure cell using the Ni-Cr-Al alloy. It has been found that the maximum working pressure can be repeatedly raised to 3.5 GPa at T = 2 K without any difficulties.

  7. Effect of Pore Size and Porosity on the Biomechanical Properties and Cytocompatibility of Porous NiTi Alloys

    PubMed Central

    Jian, Yu-Tao; Yang, Yue; Tian, Tian; Stanford, Clark; Zhang, Xin-Ping; Zhao, Ke

    2015-01-01

    Five types of porous Nickel-Titanium (NiTi) alloy samples of different porosities and pore sizes were fabricated. According to compressive and fracture strengths, three groups of porous NiTi alloy samples underwent further cytocompatibility experiments. Porous NiTi alloys exhibited a lower Young’s modulus (2.0 GPa ~ 0.8 GPa). Both compressive strength (108.8 MPa ~ 56.2 MPa) and fracture strength (64.6 MPa ~ 41.6 MPa) decreased gradually with increasing mean pore size (MPS). Cells grew and spread well on all porous NiTi alloy samples. Cells attached more strongly on control group and blank group than on all porous NiTi alloy samples (p < 0.05). Cell adhesion on porous NiTi alloys was correlated negatively to MPS (277.2 ?m ~ 566.5 ?m; p < 0.05). More cells proliferated on control group and blank group than on all porous NiTi alloy samples (p < 0.05). Cellular ALP activity on all porous NiTi alloy samples was higher than on control group and blank group (p < 0.05). The porous NiTi alloys with optimized pore size could be a potential orthopedic material. PMID:26047515

  8. Effect of Pore Size and Porosity on the Biomechanical Properties and Cytocompatibility of Porous NiTi Alloys.

    PubMed

    Jian, Yu-Tao; Yang, Yue; Tian, Tian; Stanford, Clark; Zhang, Xin-Ping; Zhao, Ke

    2015-01-01

    Five types of porous Nickel-Titanium (NiTi) alloy samples of different porosities and pore sizes were fabricated. According to compressive and fracture strengths, three groups of porous NiTi alloy samples underwent further cytocompatibility experiments. Porous NiTi alloys exhibited a lower Young's modulus (2.0 GPa ~ 0.8 GPa). Both compressive strength (108.8 MPa ~ 56.2 MPa) and fracture strength (64.6 MPa ~ 41.6 MPa) decreased gradually with increasing mean pore size (MPS). Cells grew and spread well on all porous NiTi alloy samples. Cells attached more strongly on control group and blank group than on all porous NiTi alloy samples (p < 0.05). Cell adhesion on porous NiTi alloys was correlated negatively to MPS (277.2 ?m ~ 566.5 ?m; p < 0.05). More cells proliferated on control group and blank group than on all porous NiTi alloy samples (p < 0.05). Cellular ALP activity on all porous NiTi alloy samples was higher than on control group and blank group (p < 0.05). The porous NiTi alloys with optimized pore size could be a potential orthopedic material. PMID:26047515

  9. Drilling of Intermetallic Alloys Gamma Tial

    NASA Astrophysics Data System (ADS)

    Beranoagirre, A.; Olvera, D.; López de Lacalle, L. N.; Urbicain, G.

    2011-01-01

    Due to their high strength/weight ratio and resistance to corrosion and wear, superalloys such as gamma TiAl or Inconel 718 appear as the best choice for the high mechanical/thermal demands in the vicinity of the combustion chamber of aircraft engines. There are assembled parts such as cases, disks or blisks; in the manufacturing of these components the last drilling operation could jeopardize the full work integrity adding new costs to the just very expensive parts. Therefore drilling is a high-added value step in the complete sequence. The present work is framed within the study of hole making in advanced materials used for lightweight applications in aerospace sector. Within this context, the paper presents the results from milling tests on three types of gamma TiAl alloys (extruded MoCuSi, ingot MoCuSi and TNB) to define an optimal set of cutting parameters, which will contribute to open the increase in use of these special alloys. Drilling tools made of integral hard metal were used, applying different feeds and cutting speeds. The influence of cutting speed and feed is discussed.

  10. Stress induced transformations in Beta III Ti alloy single crystals

    Microsoft Academic Search

    J. A. Roberson; S. Fujishiro; V. S. Arunachalam; C. M. Sargent

    1974-01-01

    A combination of X-ray metallographic and transmission electron microscopy techniques have been used to investigate deformation\\u000a modes and deformation products in Beta III Ti alloy single crystals. Crystallographic slip was observed on {110}, {112} and\\u000a {113} planes. Twinning occurred on {ll2}, {332} and {2, 4.8, 4.8} planes. A martensitic transformation of the type proposed\\u000a by Blackburn and Feeney1 took place;

  11. Magnetic Domain Structure of an Amorphous FePC Alloy

    Microsoft Academic Search

    Yoshihisa Obi; Hiroyasu Fujimori; Hideo Saito

    1976-01-01

    The domain structure of an amorphous Fe80P13C7 alloy ribbon produced by the centrifugal solidification technique was investigated using the magnetic powder pattern technique. Two different types of domains (a maze domain and a 180°-domain) were observed on the specimen surface. The relationship between the domain structure and the magnetization process was also investigated. The results showed that some of the

  12. Millimetre-size single quasicrystals in Al - Cu - Fe alloy

    Microsoft Academic Search

    T. Ishimasa; M. Mori

    1990-01-01

    Millimetre-sized grains of F-type icosahedral phase are formed in ingots of Al—Cu—Fe alloy, for which the nominal composition is Al—20.41 at.% Cu—13.27 at.% Fe. These grains are located in the upper half part of the ingots. The lower half does not include the icosahedral phase but ordinary crystalline phases. In order to form these grains, the following heat treatment was

  13. Directional solidification of cellular arrays in transparent alloys

    Microsoft Academic Search

    L. Sturz; H.-J. Diepers; G. Zimmermann; S. Rex

    2005-01-01

    The evolution of cellular patterns at the solid-liquid interface was investigated in directional solidification of the transparent\\u000a alloy succinonitrile-acetone in bulk samples under microgravity conditions on Space-Shuttle missions and different processing\\u000a parameters. Interface morphologies are observed from the top within a Bridgman-Stockbarger type furnace. A hexagonal arrangement\\u000a of cells on the interface with irregularities was found in all cases. The

  14. Residual stresses in copper-2% beryllium alloy strips

    Microsoft Academic Search

    K. E. Amin; S. Ganesh

    1981-01-01

    Residual-stress profiles were determined along the rolling direction in cold-rolled, annealed, and roller-leveled copper-2% beryllium alloy strips using the X-ray-diffraction technique. The data were corrected for the effects of beam penetration and subsurface-stress relaxation due to material removal.The type, magnitude and distribution of residual stresses were found to depend on the amount of cold reduction of the strips. Surface residual

  15. Solidification of eutectic system alloys in space (M-19)

    NASA Technical Reports Server (NTRS)

    Ohno, Atsumi

    1993-01-01

    It is well known that in the liquid state eutectic alloys are theoretically homogeneous under 1 g conditions. However, the homogeneous solidified structure of this alloy is not obtained because thermal convection and non-equilibrium solidification occur. The present investigators have clarified the solidification mechanisms of the eutectic system alloys under 1 g conditions by using the in situ observation method; in particular, the primary crystals of the eutectic system alloys never nucleated in the liquid, but instead did so on the mold wall, and the crystals separated from the mold wall by fluid motion caused by thermal convection. They also found that the equiaxed eutectic grains (eutectic cells) are formed on the primary crystals. In this case, the leading phase of the eutectic must agree with the phase of the primary crystals. In space, no thermal convection occurs so that primary crystals should not move from the mold wall and should not appear inside the solidified structure. Therefore no equiaxed eutectic grains will be formed under microgravity conditions. Past space experiments concerning eutectic alloys were classified into two types of experiments: one with respect to the solidification mechanisms of the eutectic alloys and the other to the unidirectional solidification of this alloy. The former type of experiment has the problem that the solidified structures between microgravity and 1 g conditions show little difference. This is why the flight samples were prepared by the ordinary cast techniques on Earth. Therefore it is impossible to ascertain whether or not the nucleation and growth of primary crystals in the melt occur and if primary crystals influence the formation of the equiaxed eutectic grains. In this experiment, hypo- and hyper-eutectic aluminum copper alloys which are near eutectic point are used. The chemical compositions of the samples are Al-32.4mass%Cu (Hypo-eutectic) and Al-33.5mass%Cu (hyper-eutectic). Long rods for the samples are cast by the Ohno Continuous Casting Process and they show the unidirectionally solidified structure. Each flight and ground sample was made of these same rods. The dimensions of all samples are 4.5 mm in diameter and 23.5 mm in length. Each sample is put in a graphite capsule and then vacuum sealed in a double silica ampoule. Then the ampoule is put in the tantalum cartridge and sealed by electron beam welding. For onbard experiments, a Continuous Heating Furnance (CHF) will be used for melting and solidifying samples under microgravity conditions. Six flight samples will be used. Four samples are hypo-eutectic and two are hyper-eutectic alloys. The surface of the two hypo-eutectic alloy samples are covered with aluminum oxide film to prevent Marangoni convection expected under microgravity conditions. Each sample will be heated to 700 C and held at that temperature for 5 min. After that the samples will be allowed to cool to 500 C in the furnace and they will be taken out of the furnace for He gas cooling. The heating and cooling diagrams for the flight experiments are shown. After collecting the flight samples, the solidified structures of the samples will be examined and the mechanisms of eutectic solidification under microgravity conditions will be determined. It is likely that successful flight experiment results will lead to production of high quality eutectic alloys and eutectic composite materials in space.

  16. Space applications of shape memory alloys 

    E-print Network

    Godard, Olivier Jean

    2002-01-01

    This work presents an investigation of two new possible space applications of shape memory alloys. The first application uses these alloys as active devices to optimally reorient solar panels in space. The thermal issues related to the actuation...

  17. Lower-cost tungsten-rhenium alloys

    NASA Technical Reports Server (NTRS)

    Klopp, W. D.; Raffo, P. L.; Witzke, W. R.

    1966-01-01

    Tungsten-rhenium alloys with a substantially more dilute rhenium content have ductilities and other mechanical properties which compare favorably with the tungsten-rhenium alloys having much higher concentrations of the costly rhenium.

  18. High strength forgeable tantalum base alloy

    NASA Technical Reports Server (NTRS)

    Buckman, R. W., Jr.

    1975-01-01

    Increasing tungsten content of tantalum base alloy to 12-15% level will improve high temperature creep properties of existing tantalum base alloys while retaining their excellent fabrication and welding characteristics.

  19. Interfacial shear bond strength between different base metal alloys and five low fusing feldspathic ceramic systems.

    PubMed

    Sipahi, Cumhur; Ozcan, Mutlu

    2012-01-01

    This study compared the bond strength between metal alloys and 5 ceramic systems. Ceramic systems (Vita VMK68, Ivoclar IPSd. SIGN, Ceramco II, Matchmaker and Finesse) were fired onto either Ni-Cr or Co-Cr base metal alloy. Metal-ceramic interfaces were subjected to shear loading until failure. The ceramic type significantly affected the bond strength results (p<0.05). For Ni-Cr alloy, the results ranged between 15.4-25.3 MPa and for Co-Cr alloy between 13.3-19.0 MPa. The highest mean bond strength value was obtained with the combination of Ni-Cr alloy-Ceramco II (25.3 MPa), the lowest bond strength was received from the combination of Co-Cr alloy-Ivoclar IPS d.SIGN ceramic (13.3 MPa). Adhesive failures between metal and ceramic were significantly more frequent with Ni-Cr alloy (31 out of 50) than with Co-Cr (20 out of 50) (p<0.05). Ceramco II presented the highest bond strength with both Ni-Cr and Co-Cr being significantly different from one another. PMID:22673457

  20. Investigation on Tool Wear Rate for Modified and Unmodified Aluminium-Silicon Casting Alloy

    NASA Astrophysics Data System (ADS)

    Haque, M. M.; Khan, A. A.; Ismail, Ahmad F.

    This study demonstrates and explains the effect of strontium modification on machinability of aluminium-silicon eutectic (LM-6 type) alloy. This alloy is known to have many favourable features including weight to strength ratio, high corrosion resistance and excellent castability. However, normal unmodified LM-6 alloy has poor machinability, which reduces its applications range. In this work, various samples of LM-6 alloy were cast using sand and metallic chill mould with and without strontium addition. Machining on each cast product, was carried out using recommended cutting parameters for Al-Si alloys. Strontium modified samples have recorded a reduction in average flank wear, an increase in shear plane angles and a reduction in chip thickness. The main reason for this improvement is the refining effect of strontium, which reduces the size of the hard silicon particles. As a result, their abrasive action on the tool face has reduced a lot. Dramatic reductions in tool wear rate were recorded when the microstructures were refined. On the other hand, when no refinement of microstructure occurs, tool wear rate becomes high. Chip analysis showed that strontium modified sample produced a thinner chip thickness with a larger shear plane angle, requiring less cutting forces. The tool wear depends not only on the phases present in the work material, but also on their sizes and distribution over entire structure. Thus, strontium modification has better effect on machinability of die cast alloy compared to that of the sand cast LM-6 alloy.