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Sample records for rapidly solidified al-fe

  1. High damping Al-Fe-Mo-Si/Zn-Al composites produced by rapidly solidified powder metallurgy process

    SciTech Connect

    Li, P.Y.; Dai, S.L.; Chai, S.C.; Li, Y.R.

    2000-05-10

    The metallic materials commonly used in aircraft and aerospace fields, such as aluminum and titanium alloys, steels, etc., show extremely low damping capacity (usually of the order of or less than 10{sup {minus}3}). Thus, some problems related to vibration may emerge and influence the reliability, safety and life of airplanes, satellites, etc. It has been reported that almost two thirds of errors for rockets and satellites are related to vibration and noise. One effective way to solve these vibration-related problems is to adopt high damping metallic materials. Conventional high damping alloys exhibit damping capacity above 10{sup {minus}2}, however, their densities are usually great than 5 x 10{sup 3} kg m{sup {minus}3}, or their strengths are less than 200 MPa (for alloys based on dislocation damping), making them impossible to be applied to aircraft and aerospace areas. Recently, some low-density high-damping metal/metal composites based on aluminum and high damping alloys have been developed in Beijing Institute of Aeronautical Materials (BIAM) by the rapidly solidified power metallurgy process. This paper aims to report the properties of the composites based on a high temperature Al-Fe-Mo-Si alloy and a high damping Zn-Al alloy, and compare them with that of 2618-T61 alloy produced by the ingot metallurgy process.

  2. Cellular and dendritic growth in rapidly solidified Al-Fe and Al-Cu alloys

    SciTech Connect

    Lu, Shu Zu; Hunt, J.D. . Dept. of Materials); Gilgien, P.; Kurz, W. )

    1994-05-01

    A recent numerical model of cellular and dendritic growth has been extended into the high velocity region where the distribution coefficient, liquids slope and diffusion coefficients depend on the growth velocity. The primary spacing selection mechanism is modeled so that no a priori assumptions need be made about a spacing selection condition. The results are compared with experimental primary spacing measurements obtained using rapid laser resolidification and good agreement is found. The numerical results for undercooling and tip radii are compared with those predicted for dendrites using marginal stability arguments, showing the potential and limits of the analytical models. The effect of high velocity on microsegregation is examined and microsegregation profiles are predicted.

  3. Selective aluminum dissolution as a means to observe the microstructure of nanocrystalline intermetallic phases from Al-Fe-Cr-Ti-Ce rapidly solidified alloy.

    PubMed

    Michalcová, Alena; Vojtěch, Dalibor; Novák, Pavel

    2013-02-01

    Rapidly solidified aluminum alloys are promising materials with very fine microstructure. The microscopy observation of these materials is complicated due to overlay of fcc-Al matrix and different intermetallic phases. A possible way to solve this problem is to dissolve the Al matrix. By this process powder formed by single intermetallic phase particles is obtained. In this paper a new aqueous based dissolving agent for Al-based alloy is presented. The influence of oxidation agent (FeCl(3)) concentration on quality of extraction process was studied. PMID:23177792

  4. Rapidly solidified metal coatings by peen plating

    NASA Technical Reports Server (NTRS)

    Chu, H. P.

    1987-01-01

    Specimens of 7075-T6 aluminum alloy were peen plated with rapidly solidified tin-lead and aluminum powders, and the cross-sections of the coated specimens were examined by light and electron microscopy. The properties of the peen plated specimens were also compared with those of shot peened specimens without any coating. It is found that peen plating with rapidly solidified metals improves the fatigue properties of the coated samples to a greater extent than shot peening alone. Specimens of 7075-T6 alloy peen plated with rapidly solidified tin-lead and aluminum exhibited better fatigue resistance than shot peened specimens in both air and salt water.

  5. Rapidly solidified NiAl and FeAl

    NASA Technical Reports Server (NTRS)

    Gaydosh, D. J.; Crimp, M. A.

    1984-01-01

    Melt spinning was used to produce rapidly solidified ribbons of the B2 intermetallics NiAl and FeAl. Both Fe-40Al and Fe-45Al possessed some bend ductility in the as spun condition. The bend ductility of Fe-40Al, Fe-45Al, and equiatomic NiAl increased with subsequent heat treatment. Heat treatment at approximately 0.85 T (sub m) resulted in significant grain growth in equiatomic FeAl and in all the NiAl compositions. Low bend ductility in both FeAl and NiAl generally coincided with intergranular failure, while increased bend ductility was characterized by increasing amounts of transgranular cleavage fracture.

  6. Microstructures in rapidly solidified niobium aluminides

    NASA Technical Reports Server (NTRS)

    Hebsur, Mohan G.; Locci, Ivan E.

    1988-01-01

    The microstructures of niobium aluminides produced by chill block melt spinning were compared to those of niobium aluminides produced by conventional casting. The rapidly solidified alloys were rapidly solidified by melt spinning in an argon atmosphere, and the melt-spun ribbons were examined by optical, X-ray, and TEM techniques. Microstructures were found to range from single-phase for Nb-75 at. pct Al (NbAl3) to two phase for Nb-46 at. pct Al (NbAl3 + Nb2Al). It was found that the melt spinning of Nb-aluminides produced finer grained microstructures than those produced in induction-melted ingots or in powders produced by the rotating electrode process. Ternary additions such as Cr, Ti, and Si tended to form intermetallic phases along the grain boundaries.

  7. Cation distributions on rapidly solidified cobalt ferrite

    NASA Technical Reports Server (NTRS)

    De Guire, Mark R.; Kalonji, Gretchen; O'Handley, Robert C.

    1990-01-01

    The cation distributions in two rapidly solidified cobalt ferrites have been determined using Moessbauer spectroscopy at 4.2 K in an 8-T magnetic field. The samples were obtained by gas atomization of a Co0-Fe2O3-P2O5 melt. The degree of cation disorder in both cases was greater than is obtainable by cooling unmelted cobalt ferrite. The more rapidly cooled sample exhibited a smaller departure from the equilibrium cation distribution than did the more slowly cooled sample. This result is explained on the basis of two competing effects of rapid solidification: high cooling rate of the solid, and large undercooling.

  8. Diamond grooving of rapidly solidified optical aluminium

    NASA Astrophysics Data System (ADS)

    Abou-El-Hossein, Khaled; Hsu, Wei-Yao; Ghobashy, Sameh; Cheng, Yuan-Chieh; Mkoko, Zwelinzima

    2015-10-01

    Traditional optical aluminium grades such as Al 6061 are intensively used for making optical components for applications ranging from mould insert fabrication to laser machine making. However, because of their irregular microstructure and relative inhomogeneity of material properties at micro scale, traditional optical aluminium may exhibit some difficulties when ultra-high precision diamond turned. Inhomogeneity and micro-variation in the material properties combined with uneven and coarse microstructure may cause unacceptable surface finish and accelerated tool wear, especially in grooving operation when the diamond tool edge is fully immersed in the material surface. Recently, new grades of optical aluminium that are featured by their ultra-fine microstructure and improved material properties have been developed to overcome the problem of high tool wear rates. The new aluminium grades have been developed using rapid solidification process which results in extremely small grain sizes combined with improved mechanical properties. The current study is concerned with investigating the performance of single-point diamond turning when grooving two grades of rapidly solidified aluminium (RSA) grades: RSA905 which is a high-alloyed aluminium grade and RSA443 which has a high silicon content. In this study, two series of experiments employed to create radial microgrooves on the two RSA grades. The surface roughness obtained on the groove surface is measured when different combinations of cutting parameters are used. Cutting speed is varied while feed rate and depth of cut were kept constant. The results show that groove surface roughness produced on RSA443 is higher than that obtained on RSA905. Also, the paper reports on the effect of cutting speed on surface roughness for each RSA grade.

  9. Al-Fe-Zr alloys for high temperature applications produced by rapid quenching from the melt

    SciTech Connect

    Okazaki, K.; Skinner, D.J.

    1984-09-01

    The melt-spinning technique to produce microstructure for high temperature-high strength Al-Fe-Zr alloys, meeting aerospace structural requirements, is presented, including the investigations for the improvement of the thermal stability of iron aluminide dispersoids by addition of Zr. The alloys containing about 27 to 30 percent volume fraction of dispersoids would be the optimum to meet the requirements from the strength and ductility viewpoint. The thermal stability of the alloys was determined by measuring the microvickers hardness on the isochronally annealed ribbons. 9 references.

  10. Superconductivity and magnetism in rapidly solidified perovskites

    SciTech Connect

    O'Handley, R.C.; Kalonji, G.

    1991-01-01

    The report is divided into six parts, reflecting major thrusts of our work since 1987. The six areas are: molecular orbital theory of high {Tc} superconductivity; rapid solidification processing of oxide superconductors; time dependent magnetic and superconducting properties of these inhomogeneous materials; excess Gd in Gd{sub 1+x}Ba{sub 2-x}Cu{sub 3}O{sub 7-{delta}} perovskites; rapid solidification and directional annealing to achieve high Jc; and Mossbauer studies of T = Fe, Co and Ni site selection in YBa{sub 2}(CuT){sub 3}O{sub 7-{delta}} and GdBa{sub 2}(CuT){sub 3}O{sub 7-{delta}}.

  11. Rapidly solidified titanium alloys by melt overflow

    NASA Technical Reports Server (NTRS)

    Gaspar, Thomas A.; Bruce, Thomas J., Jr.; Hackman, Lloyd E.; Brasmer, Susan E.; Dantzig, Jonathan A.; Baeslack, William A., III

    1989-01-01

    A pilot plant scale furnace was designed and constructed for casting titanium alloy strips. The furnace combines plasma arc skull melting techniques with melt overflow rapid solidification technology. A mathematical model of the melting and casting process was developed. The furnace cast strip of a suitable length and width for use with honeycomb structures. Titanium alloys Ti-6Al-4V and Ti-14Al-21 Nb were successfully cast into strips. The strips were evaluated by optical metallography, microhardness measurements, chemical analysis, and cold rolling.

  12. Rapidly solidified titanium alloys by melt overflow

    SciTech Connect

    Gaspar, T.A.; Bruce, T.J. Jr.; Hackman, L.E.; Brasmer, S.E.; Dantzig, J.A.; Baeslack, W.A. III.

    1989-09-01

    A pilot plant scale furnace was designed and constructed for casting titanium alloy strips. The furnace combines plasma arc skull melting techniques with melt overflow rapid solidification technology. A mathematical model of the melting and casting process was developed. The furnace cast strip of a suitable length and width for use with honeycomb structures. Titanium alloys Ti-6Al-4V and Ti-14Al-21 Nb were successfully cast into strips. The strips were evaluated by optical metallography, microhardness measurements, chemical analysis, and cold rolling.

  13. Rapidly solidified ceramics: Processing, structure, and magnetic properties

    SciTech Connect

    Kalonji, G.M.; O'Handley, R.C.

    1985-01-01

    Since its initiation in September 1984, work under this contract has progressed in two areas: construction of a gas atomizer for rapid solidification of ceramics; and characterization of rapidly solidified materials in the SrO-Fe{sub 2}O{sub 3}, BaO-Fe{sub 2}O{sub 3}, MnFe{sub 2}O{sub 4}-SiO{sub 2}, and CoFe{sub 2}O{sub 4}-SiO{sub 2} systems. This report summarize this work.

  14. Two-dimensional grain growth in rapidly solidified succinonitrile films

    NASA Astrophysics Data System (ADS)

    Palmer, M.; Rajan, K.; Glicksman, M.; Fradkov, V.; Nordberg, J.

    1995-05-01

    The kinetics and topological mechanisms of normal grain growth have been examined through in situ dynamic studies on rapidly solidified succinonitrile (SCN). The in situ studies allowed for continuous monitoring of the evolution of individual grains during growth. We have assessed the Mullins—Von Neumann topological grain growth law and the Burke—Turnbull parabolic rate law and have determined rate constants that describe grain growth. This work demonstrates that both laws are both obeyed globally and consistently. These in situ studies permit one to follow the unit operations associated with grain growth kinetics. This article demonstrates the usefulness of succinonitrile as a model analog system for studying grain growth.

  15. Shape anisotropy in zero-magnetostrictive rapidly solidified amorphous nanowires

    NASA Astrophysics Data System (ADS)

    Rotărescu, C.; Atitoaie, A.; Stoleriu, L.; Óvári, T.-A.; Lupu, N.; Chiriac, H.

    2016-04-01

    The magnetic behavior of zero-magnetostrictive rapidly solidified amorphous nanowires has been investigated in order to understand their magnetic bistability. The study has been performed both experimentally - based on inductive hysteresis loop measurements - and theoretically, by means of micromagnetic simulations. Experimental hysteresis loops have shown that the amorphous nanowires display an axial magnetic bistability, characterized by a single-step magnetization reversal when the applied field reaches a critical value called switching field. The simulated loops allowed us to understand the effect of shape anisotropy on coercivity. The results are key for understanding and controlling the magnetization processes in these novel nanowires, with important application possibilities in new miniaturized sensing devices.

  16. Microsegregation studies of rapidly solidified binary aluminum-copper alloys

    NASA Astrophysics Data System (ADS)

    Prasad, Arvind

    Most of the materials that we use in our day-to-day activities undergo solidification at some stage of manufacturing. Normal solidification of alloys can result in chemical inhomogeneity (microsegregation) and coarse structure that can make the material weak. Rapid solidification has been known to reduce microsegregation and produce materials with improved properties. To control the microstructure obtained from rapid solidification, and thus attain desired properties, requires an understanding of microstructure evolution and the resulting microsegregation. We have studied microsegregation in rapidly solidified Al-Cu alloys using a combination of experiments and modeling. Rapidly solidified Al-Cu alloys were produced using Impulse Atomization. Microsegregation studies were performed on the droplets for different alloy chemistry (Al-4.3%Cu, Al-5%Cu, Al-10%Cu and Al-17%Cu), droplet sizes and gas type. The droplets produced were characterized using X-Ray Tomography, Neutron Diffraction, Electron Microscopy and Stereology. Using these techniques, nucleation and microstructure formation were studied and eutectic amount measured within the droplets. Modeling involved developing a microsegregation model for a droplet solidifying during Impulse Atomization. Rappaz-Thevoz microsegregation model was used coupled with LKT dendrite kinetic model with modification for off-center nucleation. The results from the experiment and model show that the droplets undergo a nucleation undercooling of approximately 20K with a single, off-center, nucleation event. Individual droplets showed gradation in microstructure believed to be caused due to recalescence. The observed trend in microsegregation showed that the segregation decreases as the alloy composition is increased. Microsegregation also showed a slight decrease with increasing cooling rate, but the trend was not very clear. Based on the alloy composition, droplet size ranges studied and type of gas used (He or N2) the estimated

  17. Superplastic forming and diffusion bonding of rapidly solidified, dispersion strengthened aluminum alloys for elevated temperature structural applications

    NASA Technical Reports Server (NTRS)

    Ting, E. Y.; Kennedy, J. R.

    1989-01-01

    Rapidly solidified alloys, based upon the Al-Fe-V-Si system and designed for elevated temperature applications, were evaluated for superplasticity and diffusion bonding behavior. Alloys with 8, 16, 27, and 36 volume percent silicide dispersoids were produced; dispersoid condition was varied by rolling at 300, 400, and 500 C (572, 752, and 932 F). Superplastic behavior was evaluated at strain rates from 1 x 10(exp -6)/s to 8.5/s at elevated temperatures. The results indicate that there was a significant increase in elongation at higher strain rates and at temperatures above 600 C (1112 F). However, the exposure of the alloys to temperatures greater than 600 C (1112 F) resulted in the coarsening of the strengthening dispersoid and the degradation of mechanical properties. Diffusion bonding was possible using low gas pressure at temperatures greater than 600 C (1112 F) which also resulted in degraded properties. The bonding of Al-Fe-V-Si alloys to 7475 aluminum alloy was performed at 516 C (960 F) without significant degradation in microstructure. Bond strengths equal to 90 percent that of the base metal shear strength were achieved. The mechanical properties and microstructural characteristics of the alloys were investigated.

  18. Structure and properties of rapidly solidified pure tin

    NASA Astrophysics Data System (ADS)

    El-Ashram, T.

    2006-03-01

    A comparison has been made between rapidly solidified (RS) pure Sn using melt-spinning technique and Sn produced by conventional casting, using X-ray diffraction (XRD) analysis, differential thermal analysis (DTA), temperature dependence of resistivity (TDR), density measurement and the dynamical resonance method (DRM) for measuring Young's modulus and internal friction. From the XRD and density measurement, it is found that high concentration of vacancies is present in pure Sn RS, the vacancy concentration is found to be 7x10(-3) . From the DTA measurements, we know that there is an increase in the thermodynamic functions such as enthalpy (Delta H), entropy (Delta S) and free energy (Delta G), and also, there is a decrease in the melting temperature. From the TDR results it follows that the resistivity at room temperature is increased and the temperature coefficient of resistivity is decreased. Finally, DRM results show that Young's modulus is decreased and the internal friction is increased.

  19. The weldability of consolidated rapidly solidified Type 304 SS powders

    SciTech Connect

    Clark, D.E.; Korth, G.E.

    1988-01-01

    The joining requirements of rapidly solidified materials were evaluated. Type 304 stainless steel produced by centrifugal atomization and consolidated by hot extrusion was the primary material tested; vacuum gas atomized Type 304 SS materials and other consolidation methods, inluding HIP and dynamic (explosive) consolidation, were also examined. Several welding processes were evaluated, including gas tungsten arc, electron beam, friction, capacitor discharge, and explosive welding. Heat-affected zone grain growth was suppressed. Residual helium in the centrifugally atomized material was found to form moderate to severe porosity in all fusion welding processes; porosity appeared to be suppressed in friction and explosive welding. High energy density fusion welding processes (electron beam and capacitor discharge) were thermally modeled, and solidification was found to occur at cooling rates far exceeding those of the original powder material and to produce correspondingly fine microstrucures. 10 refs., 9 figs., 2 tabs.

  20. Laser welding of an advanced rapidly-solidified titanium alloy

    NASA Astrophysics Data System (ADS)

    Baeslack, W. A., III; Chiang, S.; Albright, C. A.

    1990-06-01

    The laser weldability of a complex RS titanium alloy containing yttrium is investigated by evaluating comparatively the microstructures, mechanical properties, and fracture characteristics of the base metal and the rapidly solidified weld fusion zone. To prevent atmospheric contamination the specimen was enclosed in a helium-purged plastic bag during the welding process. After welding, the coupons were sectioned transverse to the laser beam direction of traverse, epoxy mounted, polished down to 0.05 micron SiO2 and etched with Kroll's reagent for examination utilizing light and SEM and energy-dispersive X-ray analysis. Results indicate that laser welding is effective in producing a fine fusion zone dispersoid structure in the RS Ti composite.

  1. Dilatometer study of rapidly solidified aluminium-silicon based alloys

    NASA Astrophysics Data System (ADS)

    Varga, B.; Fazakas, E.; Hargitai, H.; Varga, L. K.

    2009-01-01

    Aluminum-Silicon alloys are sought in a large number of automotive and aerospace applications due to their low coefficient of thermal expansion and high wear resistance. The present study focused on structural transformations as a function of the temperature of rapidly solidified hypereutectic Al100-xSix (x = 12, 22 and 40) alloys. Different structures out of equilibrium have been obtained after casting in sand, graphite and copper moulds and by melt spinning. The retained Si content in supersaturated alpha Al and the precipitation of Si is discussed in the light of the dilatometer studies [1, 2, 3] complemented by metallographic microscopy, XRD and DSC [4] measurements. A Kissinger analysis was used to determine the activation energy for the precipitation of supersaturated Si content.

  2. Investigation of diamond turning: of rapidly solidified aluminum alloys

    NASA Astrophysics Data System (ADS)

    Cheng, Yuan-Chieh; Hsu, Wei-Yao; Abou-El-Hossein, Khaled; Olufayo, Oluwole; Otieno, Timothy

    2014-09-01

    Aluminum 6061 is often considered the preferred material for manufacturing optical components for ground-based astronomical applications. One reason for using this material is its high specific stiffness and excellent thermal properties. Moreover, a large amount of data exists for this material and commercially available aluminum 6061 can be diamond turned to achieve surface roughness values of approximately 4 to 8 nm, which is adequate for applications that involve the infrared spectral range, but not for the near-ultraviolet wavelength (NUV) spectral range. In this study, we used a novel aluminum material, fabricated using a rapid solidification process that is equivalent to the conventional aluminum 6061 alloy grade. Using rapidly solidified aluminum (RSA) can achieve improved surface finish and enhanced optical performance. The rapid solidification process was realized using a melt spinning operation, which achieves a high cooling rate to yield a fine microstructure. The properties of RSA 6061 are similar to those of conventional aluminum 6061, but its grain size is extremely small. In this paper, the background of RSA is introduced, and the diamond turnability characteristics and coating processes for both traditional aluminum 6061 and RSA are discussed. The surface roughness and grain structure of RSA were evaluated using white light interferometers and the surface roughness during coating of the reflectance multilayers of samples were analyzed using near-ultraviolet wavelengths. Finally, indicators such as optimal cutting parameters and optical performance are discussed.

  3. Corrosion behavior of rapidly solidified magnesium-aluminium-zinc alloys

    SciTech Connect

    Daloz, D.; Michot, G.; Steinmetz, P.

    1997-12-01

    Rapidly solidified magnesium alloys with 8 at%, 15 at%, and 20 at% Al and 1 at% and 3 at% Zn were fabricated by centrifugal atomization followed by hot extrusion. Microstructure of the alloys was composed of a fine-grain magnesium matrix (0.5 {micro}m) with {beta}-Mg{sub 17}Al{sub 12} precipitates. Electrochemical and weight-loss tests were performed in borate and ASTM D 1384 solution (chloride, carbonate, and sulfate). In both media, corrosion current f the alloys decreased with increases in aluminum or zinc content. In borate solution, a passivating plateau was observed from the corrosion potential (E{sub corr}) to E{sub corr} + 1,200 mV. Current density decreased with aluminum and zinc concentrations. Electrochemical behavior of the synthesized matrix and precipitates was characterized. Zinc increased E{sub corr} of the two phases, with a corresponding decrease of corrosion current. The same trend was noticed for aluminum but with a less dramatic effect. The corrosion mechanism was suggested result from galvanic coupling of the matrix and the second phase. The galvanic corrosion, however, was reduced strongly by passivation of the matrix as a result of the surrounding precipitates. The positive influence of rapid solidification (corrosion rate decreased 1 order of magnitude) was the creation of a fine, highly homogeneous microstructure through this fabrication process.

  4. Nanoscale microstructure effects on hydrogen behavior in rapidly solidified aluminum alloys

    SciTech Connect

    Tashlykova-Bushkevich, Iya I.

    2015-12-31

    The present work summarizes recent progress in the investigation of nanoscale microstructure effects on hydrogen behavior in rapidly solidified aluminum alloys foils produced at exceptionally high cooling rates. We focus here on the potential of modification of hydrogen desorption kinetics in respect to weak and strong trapping sites that could serve as hydrogen sinks in Al materials. It is shown that it is important to elucidate the surface microstructure of the Al alloy foils at the submicrometer scale because rapidly solidified microstructural features affect hydrogen trapping at nanostructured defects. We discuss the profound influence of solute atoms on hydrogen−lattice defect interactions in the alloys. with emphasis on role of vacancies in hydrogen evolution; both rapidly solidified pure Al and conventionally processed aluminum samples are considered.

  5. Faceted Surface Grain Morphology of Rapidly Solidified Alumina: Characterization and Potential Applications

    SciTech Connect

    Harimkar, Sandip; Kenik, Edward A; Shim, Sanghoon; Dahotre, Narendra B

    2009-01-01

    This communication reports on the characterization of novel surface microstructure formed in rapidly solidified porous alumina ceramic. Advanced characterization techniques such as Orientation Imaging Microscopy (OIM) and Atomic Force Microscopy (AFM) are used to understand the crystallographic and morphological aspects of the resultant microstructure. Potential applications of laser surface modified alumina ceramics are presented.

  6. Tempering rapidly solidified ductile cast iron by pulsed laser beam reprocessing

    SciTech Connect

    Wang, H.M. . Dept. of Materials Science and Engineering); Bergmann, H.W. . Materials Science Dept.)

    1994-08-15

    During laser surface rapid remelting of cast irons, the melt pool solidifies rapidly and metastably (i.e. according to the metastable Fe-Fe[sub 3]C system) producing an ultra-fine ledeburite hard surface which is much more abrasion resistant than the original substrate. Previous literature mainly focused on remelting various grey and ductile irons with high power CO[sub 2] lasers for improved wear resistance and other surface properties, and on studying the physical metallurgy of laser remelted surfaces. Unfortunately, the unstable nature and rapid tempering behavior of the rapidly solidified ledeburite were generally neglected, although some publications mentioned the tempering phenomenon during successive overlap remelting. In this paper, a laser remelted ductile case iron surface was tempered by rapid pulsed laser beam reprocessing. The rapidly solidified ductile iron was found to be rapidly graphitized, as a result, a layer of Fe-base alloy containing ultra-fine graphite particles was produced. The unusual rapid graphitization phenomenon was preliminarily discussed.

  7. Microstructural observations in rapidly-solidified and heat-treated Ni3Al-Cr alloys

    NASA Technical Reports Server (NTRS)

    Carro, G.; Flanagan, W. F.

    1992-01-01

    The microstructural development following heat treatments of several rapidly-solidified Ni3Al-Cr and Ni3Al-Cr-B alloys is presented. Depending on composition, the as-solidified samples were either 100 percent gamma-prime phase - in the form of fine antiphase domains (APD) - or a mixture of gamma-prime (APDs) and beta phases. Upon annealing, the as-solidified microstructures transform to either APD-free gamma-prime or mixtures of gamma and gamma-prime phases. For those compositions where the quenched microstructures were 100 percent gamma-prime it was observed that APD coarsening followed conventional grain-growth kinetics, but when gamma phase precipitated on the APD boundaries the rate constant changed abruptly while the time exponent remained unaffected. It was also found that alloys containing critical amounts of chromium and boron are susceptible to precipitation of the boride Cr5B3.

  8. Research on microstructures of sub-rapidly solidified AZ61 Magnesium Alloy

    SciTech Connect

    Teng Haitao; Zhang Xiaoli; Zhang Zhongtao; Li Tingju; Cockcroft, Steve

    2009-06-15

    AZ61 magnesium alloy foils of 0.5-3.0 mm thick were successfully produced by using sub-rapid solidification technique. Microstructures of conventionally solidified (CS) and sub-rapidly solidified (sub-RS) alloys were examined by optical microscope (OM) and scanning electron microscope (SEM). The results showed that the cellular grain of 1.8-13.5 {mu}m can be obtained during sub-rapid solidification process. Phase compositions and microdistribution of the alloying elements in the foils were analyzed by X-ray diffraction (XRD) and electron probe microanalyzer (EPMA), respectively. The eutectic transformation L {yields} {alpha}-Mg + {beta}-Mg{sub 17}Al{sub 12} and microsegregation in conventionally solidified AZ61 alloy were remarkably suppressed in sub-rapid solidification process. As a consequence, the alloying elements Al, Zn, Mn showed much higher solid solubility and the sub-rapid solidification microstructures dominantly consisted of supersaturated {alpha}-Mg solid solution. Meanwhile, the {beta}-Mg{sub 17}Al{sub 12} phases located in the {alpha}-Mg grain boundaries are largely decreased due to high solidification cooling rate.

  9. Rapidly solidified ceramics: Processing, structure, and magnetic properties. Progress report, September 1984--January 1985

    SciTech Connect

    Kalonji, G.M.; O`Handley, R.C.

    1985-12-31

    Since its initiation in September 1984, work under this contract has progressed in two areas: construction of a gas atomizer for rapid solidification of ceramics; and characterization of rapidly solidified materials in the SrO-Fe{sub 2}O{sub 3}, BaO-Fe{sub 2}O{sub 3}, MnFe{sub 2}O{sub 4}-SiO{sub 2}, and CoFe{sub 2}O{sub 4}-SiO{sub 2} systems. This report summarize this work.

  10. Damping capacity measurements of degradation in advanced materials. [Rapidly solidified alloys

    SciTech Connect

    Mantena, R.; Gibson, R.F.; Place, T.A.

    1986-04-01

    This paper describes the application of damping capacity measurements for characterization of degradation in advanced materials. A recently developed impulse-frequency response technique was used to obtain damping capacity measurements on crossplied E-glass/epoxy laminates that had been subjected to four-point bending and cantilever bending to produce matrix cracking in the transverse plies. The size and location of the damage zone were correlated with changes to damping. With the expected introduction of Rapidly Solidified Alloys (RSA) as effective alternatives to conventional materials, the applicability of damping capacity measurements as a non destructive means of evaluating degradation in these materials was also studied. 17 references, 15 figures.

  11. Microstructures of rapidly solidified powder and extruded rod of Ni{sub 3}Ge

    SciTech Connect

    Fang, J.; Schulson, E.M.

    1996-07-01

    Rapidly solidified powders and extruded rods of Ni{sub 3}Ge with and without 0.06 at. % boron were characterized using optical microscopy, scanning electron microscopy, transmission electron microscopy, and X-ray diffraction. The powders were generally spherical and exhibited both dendritic and lamellar structures. The increase in lattice parameter per atom fraction of boron, {var_epsilon}, was estimated to be 0.33. Extrusion of the powders produced fine grains of about 2 {micro}m in diameter. The extruded materials were partially recrystallized and showed a minor preference for [111] orientation. Annealing at 950 C resulted in a fully recrystallized structure and a nearly random orientation. The addition of 0.06 at. % boron had no observable effect on the morphology, microstructure, and texture. Precipitates of borides were observed in the annealed boron-doped alloy, suggesting that the solubility of boron in Ni{sup 3}Ge may be below about 0.06 at. %.

  12. Size-dependent microstructures in rapidly solidified uranium-niobium powder particles

    DOE PAGESBeta

    McKeown, Joseph T.; Hsiung, Luke L.; Park, Jong M.; Ryu, Ho J.; Turchi, Patrice E. A.; King, Wayne E.

    2016-06-14

    The microstructures of rapidly solidified U-6wt%Nb powder particles synthesized by centrifugal atomization were characterized using scanning electron microscopy and transmission electron microscopy. Observed variations in microstructure are related to particle sizes. All of the powder particles exhibited a two-zone microstructure. The formation of this two-zone microstructure is described by a transition from solidification controlled by internal heat flow and high solidification rate during recalescence (micro-segregation-free or partitionless growth) to solidification controlled by external heat flow with slower solidification rates (dendritic growth with solute redistribution). The extent of partitionless solidification increased with decreasing particle size due to larger undercoolings in smallermore » particles prior to solidification. The metastable phases that formed are related to variations in Nb concentration across the particles. Lastly, the microstructures of the powders were heavily twinned.« less

  13. The microstructure of rapidly solidified and heat-treated Ti alloys containing La

    SciTech Connect

    Court, S.A.; Stanley, J.T.; Fraser, H.L. ); Konitzer, D.G. ); Loretto, M.H. )

    1988-06-01

    Ti and Ti-Al containing La additions have been rapidly solidified using laser surface melting. The microstructure consists of a distribution of particles in a matrix of ..cap alpha..-Ti. The particles have been identified as LA (f.c.c.) using microdiffraction, and microchemical analysis (energy dispersive X-ray spectroscopy and electron energy loss spectroscopy). The La particles obey an orientation relationship with the matrix. On aging at 700/sup 0/C, the La particles are internally oxidized, the nature of the particles being determined again by techniques given above. The oxide particles, with an hexagonal crystal structure, have an orientation relationship with respect to the matrix and the shape of the particles may be described as an hexagonal prism, which is consistent with the sharing of symmetry defined by this orientation relationship. A small number of particles are also formed as a result of annealing at 700/sup 0/C. These are formed from decomposition of the slightly supersaturated matrix. The behavior of these alloys containing La is different from that of alloys containing either Er or Y, where relatively concentrated supersaturations of these rare-earth elements may be effected by rapid solidification. An explanation for this difference is given which is based on whether rapid solidification involves an eutectic (Er and Y) or monotectic (La) reaction.

  14. A new phase in rapidly solidified Ti[sub 3]Al-based alloys

    SciTech Connect

    Xu Rui; Xu Daming; Li Qingchun . Dept. of Materials Science and Engineering); Li Dong; Cui Yuyou; Hu Zhuangqi . State Key Lab. for RSA)

    1995-01-15

    Rapid solidification processing has been developed to improve the properties of alloys through refining microstructures, disordering and forming metastable phases. The as-melt spun Ti[sub 3]Al-based alloy with Nb additions above 5-at%, which consist of [alpha][sub 2] and [beta][sub 0] phases in a normal condition, exhibited as single [beta][sub 0] structure. Jackson et al have carried out a comparative study of I/M and RS Ti[sub 3]Al-1 Zr(at%) alloy. Their study revealed that considerable refinement of grains and anti-phase domains was achieved in the rapidly solidified material prepared by the pendant drop melt extraction process (PDME). It is suggested that rapid solidification processing can reduce the ordering of the Ti[sub 3]Al-based alloy. In the past years, it was found that the Ti[sub 3]Al-based alloy with alloying additions (mainly Nb) has been studied extensively, and some new phases such as T and O have been observed in the alloys, but less attention has been given to alloys with low Nb additions. The RS Ti[sub 3]Al-base alloys with Nb below 5-at% have been investigated systematically and a new metastable phase, ordering martensite [alpha][double prime][sub 0] (orthogonal), has been observed in these alloys.

  15. Solidifying Safety

    NASA Technical Reports Server (NTRS)

    Covault, Craig

    2003-01-01

    Contents include the following: 1. Solidifying Safety: NASA s new safety organization spools up, as the 1SS program grapples with long-term risk. 2. Earth to Orbit O'Keefe telling skeptical lawmakers Orbital Space Plan (OSP) will cover exploration vision. China's rapid pace.

  16. Solidification characterization of a new rapidly solidified Ni-Cr-Co based superalloy

    SciTech Connect

    Wu, Kai; Liu, Guoquan; Hu, Benfu; Li, Feng; Zhang, Yiwen; Tao, Yu; Liu, Jiantao

    2012-11-15

    The solidification characterization of a new rapidly solidified Ni-Cr-Co based superalloy prepared by plasma rotating electrode process was investigated by means of optical microscope, scanning electron microscope, and transmission electron microscope. The results show that the solidification microstructure changes from dendrites to cellular and microcrystal structures with decreasing powder size. The elements of Co, Cr, W and Ni are enriched in the dendrites, while Mo, Nb and Ti are higher in the interdendritic regions. The relationships between powder size with the average solid-liquid interface moving rate, the average interface temperature gradient and the average cooling rate are established. Microsegregation is increased with larger powder size. The geometric integrity of MC Prime type carbides in the powders changes from regular to diverse with decreasing powder size. The morphology and quantity of carbides depend on the thermal parameters and non-equilibrium solute partition coefficients during rapid solidification. - Highlights: Black-Right-Pointing-Pointer The relations of solidification thermal parameters with powder size are established. Black-Right-Pointing-Pointer The relation of non-equilibrium solute partition with powder size is investigated. Black-Right-Pointing-Pointer The solidification microstructure is related to thermal parameters. Black-Right-Pointing-Pointer The segregation behavior is linked to non-equilibrium partition coefficients. Black-Right-Pointing-Pointer The morphology and quantity of carbides depend on the above combined factors.

  17. Characterization of Rapidly Solidified Al-27 Si Hypereutectic Alloy: Effect of Solidification Condition

    NASA Astrophysics Data System (ADS)

    Cai, Zhiyong; Wang, Richu; Zhang, Chun; Peng, Chaoqun; Xie, Lichuan; Wang, Linqian

    2015-03-01

    Rapidly solidified Al-27wt.%Si hypereutectic alloy was fabricated by gas atomization, and its characterization as a function of particle size was investigated. A relationship between the particle size and solidification condition was established to understand the microstructural characteristics. While the irregular primary Si phase transformed to quasi-spherical shape, and its size decreased gradually with the particle size, the primary Si morphology similar to that in ingot metallurgy sample was found from the deep-etched images. In the fine powder, the eutectic Si phase formed a network structure densely distributed in the matrix, while a tangled dendritic formed at the surface. From the distribution of the Si phase, it is suggested that the microstructure inhomogeneity increased as the particle size decreases. The structural distortion of the Al matrix was observed from x-ray diffraction patterns and differential scanning calorimetry curves. From the calculated results, an undercooling of 33 K (or interface velocity of 8 mm/s) was sufficient to suppress the primary Si to less than 2 μm in the present composition. The microhardness increased significantly while the particle size decreases. The microstructure and properties of the bulk material consolidated by hot pressing of the powders obtained were also conducted.

  18. Microstructure simulation of rapidly solidified ASP30 high-speed steel particles by gas atomization

    NASA Astrophysics Data System (ADS)

    Ma, Jie; Wang, Bo; Yang, Zhi-liang; Wu, Guang-xin; Zhang, Jie-yu; Zhao, Shun-li

    2016-03-01

    In this study, the microstructure evolution of rapidly solidified ASP30 high-speed steel particles was predicted using a simulation method based on the cellular automaton-finite element (CAFE) model. The dendritic growth kinetics, in view of the characteristics of ASP30 steel, were calculated and combined with macro heat transfer calculations by user-defined functions (UDFs) to simulate the microstructure of gas-atomized particles. The relationship among particle diameter, undercooling, and the convection heat transfer coefficient was also investigated to provide cooling conditions for simulations. The simulated results indicated that a columnar grain microstructure was observed in small particles, whereas an equiaxed microstructure was observed in large particles. In addition, the morphologies and microstructures of gas-atomized ASP30 steel particles were also investigated experimentally using scanning electron microscopy (SEM). The experimental results showed that four major types of microstructures were formed: dendritic, equiaxed, mixed, and multi-droplet microstructures. The simulated results and the available experimental data are in good agreement.

  19. Martensitic transformation behaviors of rapidly solidified Ti–Ni–Mo powders

    SciTech Connect

    Kim, Yeon-wook

    2012-10-15

    For the fabrication of bulk near-net-shape shape memory alloys and porous metallic biomaterials, consolidation of Ti–Ni–Mo alloy powders is more useful than that of elemental powders of Ti, Ni and Mo. Ti{sub 50}Ni{sub 49.9}Mo{sub 0.1} shape memory alloy powders were prepared by gas atomization, and transformation temperatures and microstructures of those powders were investigated as a function of powder size. XRD analysis showed that the B2–R–B19 martensitic transformation occurred in powders smaller than 150 μm. According to DSC analysis of the as-atomized powders, the B2–R transformation temperature (T{sub R}) of the 25–50 μm powders was 18.4 °C. The T{sub R} decreased with increasing powder size, however, the difference in T{sub R} between 25–50 μm powders and 100–150 μm powders is only 1 °C. Evaluation of powder microstructures was based on SEM examination of the surface and the polished and etched powder cross sections and the typical images of the rapidly solidified powders showed cellular morphology. Porous cylindrical foams of 10 mm diameter and 1.5 mm length were fabricated by spark plasma sintering (SPS) at 800 °C and 5 MPa. Finally these porous TiNi alloy samples are heat-treated for 1 h at 850 °C, and then quenched in ice water. The bulk samples have 23% porosity and 4.6 g/cm{sup 3} density and their T{sub R} is 17.8 °C.

  20. Investigation on microstructure characterization and property of rapidly solidified Mg-Zn-Ca-Ce-La alloys

    SciTech Connect

    Zhou Tao; Chen Zhenhua; Yang Mingbo; Hu Jianjun; Xia Hua

    2012-01-15

    Rapidly solidified (RS) Mg-Zn-Ca-Ce-La (wt.%) alloys have been produced via atomizing the alloy melt and subsequent splat-quenching on the water-cooled copper twin-rollers in the form of flakes. Microstructure characterization, phase compositions and thermal stability of the alloys have been systematically investigated. The results showed that with addition of RE (Ce and La) to the Mg-6Zn-5Ca alloy, the stable intermetallic compounds i.e. the Mg{sub x}Zn{sub y}RE{sub z} phase with a few Ca (about 3 at.%), shortened as the T Prime phase, were formed at the expense of the binary Mg-Zn and Ca{sub 2}Mg{sub 6}Zn{sub 3} phases, which was possibly beneficial to the enhanced thermal stability of the alloy. In the Mg-6Zn-5Ca-3Ce-0.5La alloy, the composition of the T Prime phase in the grain interior was different from that at the grain boundaries, in which the segregation of the La elements was found, and the atomic percentage ratio of Zn to Ce in the T Prime phase within the grains was close to 2. Moreover, the stable Mg{sub 2}Ca phases were detected around the T Prime phases at the grain boundaries in the alloy. - Research Highlights: Black-Right-Pointing-Pointer The phase constitution of RS Mg-6Zn-5Ca alloy can be improved by RE additions. Black-Right-Pointing-Pointer In the Mg-Zn-Ca-Ce-La alloys, the Mg{sub x}Zn{sub y}RE{sub z} phase with a few Ca (T Prime phase) is formed. Black-Right-Pointing-Pointer The formation of the T Prime phase leads to the loss of the Mg-Zn and Ca{sub 2}Mg{sub 6}Zn{sub 3} phases. Black-Right-Pointing-Pointer The composition of the T Prime phase differs from the grain interior to the grain boundary.

  1. Magnetic and mechanical properties of rapidly solidified FeSi 6.5 wt% alloys and their interpretation

    NASA Astrophysics Data System (ADS)

    Viala, B.; Degauque, J.; Baricco, M.; Ferrara, E.; Pasquale, M.; Fiorillo, F.

    1996-07-01

    The structural, mechanical and magnetic properties of FeSi 6.5 wt% rapidly solidified alloys have been investigated following recrystallization annealing and different rates of cooling through the B 2 + DO 3 ordering region (1 ≤ T ≤ 1500° C min -1). A transition from ductile to brittle behavior is observed for T < ˜ 1000°C min -1, chiefly due to B 2 ordering and the associated formation of superlattice dislocations, having reduced glide and cross-slip capability. The magnetic behavior appears, however, to be weakly dependent on T, with the energy losses minimized for average grain size around 100-150 μm.

  2. Irradiation effects in rapidly and conventionally solidified alloys. Phase stability in rapidly solidified N i-Nb under Ni ion irradiation

    NASA Technical Reports Server (NTRS)

    1982-01-01

    Two alloy compositions in the Ni-Nb system (Ni60Nb40 and Ni85Nb15) were produced by rapidly quenching from the melt with the piston anvil technique. The Ni60Nb40 was transformed to a metastable, partially crystalline state by heat treatment in a differential scanning calorimeter. The Ni85Nb15 was fully crystalline, with the majority of the grains composed of collections of primary dendrite arms. Both compositions were irradiated with 4 MeV Ni++ ions. The irradiation induced microstructures were examined by transmission electron microscopy and compared with thermally aged samples. The thermal evolution was arrested by ion irradiation in the temperature range studied, by inhibiting the nucleation of the NiNb phase. No irradiation induced voids were observed. It is found that the ion irradiation drives the microstructure along a different path than thermal evolution.

  3. Microstructure characterization and room temperature deformation of a rapidly solidified NiAl-based eutectic alloy containing trace Dy

    NASA Astrophysics Data System (ADS)

    Li, Hutian; Guo, Jianting; Huai, Kaiwen; Ye, Hengqiang

    2006-04-01

    The microstructure and room temperature compressive deformation behavior of a rapidly solidified NiAl-Cr(Mo)-Dy eutectic alloy fabricated by water-cooled copper mold method were studied by a combination of SEM, EDS and compressive tests. The morphology stability after hot isostatic pressing (HIP) treatment was evaluated. Rapid solidification resulted in a shift in the coupled zone for the eutectic growth towards the Cr(Mo) phase, indicating a hypoeutectic composition, hence increasing the volume fraction of primary dendritic NiAl. Meanwhile, significantly refined microstructure and lamellar/rod-like Cr(Mo) transition were observed due to trace rare earth (RE) element Dy addition and rapid solidification effects. Compared with the results in literature [H.E. Cline, J.L. Walter, Metall. Trans. 1(1970)2907-2917; P. Ferrandini, W.W. Batista, R. Caram, J. Alloys Comp. 381(2004)91-98], an interesting phenomenon, viz., NiAl halos around the primary Cr(Mo) dendrites in solidified NiAl-Cr(Mo) hypereutectic alloy, was not observed in this study. This difference was interpreted in terms of their different reciprocal nucleation ability. In addition, it was proposed that the localized destabilization of morphology after HIP treatment is closely related to the presence of primary NiAl dendrites. The improved mechanical properties can be attributed to the synergistic effects of rapid solidification and Dy addition, which included refined microstructure, suppression of the crack development along eutectic grain boundaries, enhancement of density of geometrically necessary dislocations located at NiAl/Cr(Mo) interfaces and the Cr solubility extension in NiAl.

  4. Dendrite growth morphologies in rapidly solidified Al-4.5wt.%Cu droplets

    NASA Astrophysics Data System (ADS)

    Bedel, M.; Reinhart, G.; Bogno, A.-A.; Nguyen-Thi, H.; Boller, E.; Gandin, Ch-A.; Henein, H.

    2016-03-01

    The impulse atomization process developed at the University of Alberta (Canada) enables metallic powders to be solidified with controlled process parameters and improved properties. In order to investigate the microstructure morphologies in droplets of Al- 4.5wt.%Cu alloys, three-dimensional reconstructions of several droplets are obtained by using synchrotron X-ray micro-tomography, allowing a visualization of the inner microstructure in three dimensions. The analysis of the reconstructed volumes reveals that a wide range of morphology, from highly branched to “finger-bundle”, can be obtained for different droplets of similar diameter and produced in the same batch. Unexpectedly for this alloy, microstructural features also indicate that the development of the dendrite arms (primary and of higher orders) occurs in most droplets along <111> crystallographic axes, instead of the usual <100> directions observed in conventional casting technologies.

  5. A Study on the Physical Properties and Interfacial Reactions with Cu Substrate of Rapidly Solidified Sn-3.5Ag Lead-Free Solder

    NASA Astrophysics Data System (ADS)

    Ma, Hai-Tao; Wang, Jie; Qu, Lin; Zhao, Ning; Kunwar, A.

    2013-08-01

    A rapidly solidified Sn-3.5Ag eutectic alloy produced by the melt-spinning technique was used as a sample in this research to investigate the microstructure, thermal properties, solder wettability, and inhibitory effect of Ag3Sn on Cu6Sn5 intermetallic compound (IMC). In addition, an as-cast Sn-3.5Ag solder was prepared as a reference. Rapidly solidified and as-cast Sn-3.5Ag alloys of the same size were soldered at 250°C for 1 s to observe their instant melting characteristics and for 3 s with different cooling methods to study the inhibitory effect of Ag3Sn on Cu6Sn5 IMC. Experimental techniques such as scanning electron microscopy, differential scanning calorimetry, and energy-dispersive spectrometry were used to observe and analyze the results of the study. It was found that rapidly solidified Sn-3.5Ag solder has more uniform microstructure, better wettability, and higher melting rate as compared with the as-cast material; Ag3Sn nanoparticles that formed in the rapidly solidified Sn-3.5Ag solder inhibited the growth of Cu6Sn5 IMC during aging significantly much strongly than in the as-cast material because their number in the rapidly solidified Sn-3.5Ag solder was greater than in the as-cast material with the same soldering process before aging. Among the various alternative lead-free solders, this study focused on comparison between rapidly solidified and as-cast solder alloys, with the former being observed to have better properties.

  6. Pre-irradiation spatial distribution and stability of boride particles in rapidly solidified boron-doped stainless steels

    SciTech Connect

    Kanani, N.; Arnberg, L.; Harling, O.K.

    1981-01-01

    The time temperature behavior of boride particles has been studied in rapidly solidified ultra low carbon and nitrogen modified 316 stainless steel with 0.088% boron and 0.45% zirconium. The results show that the as-splat-cooled specimens exhibit precipitates at the grain boundaries and triple junctions. For temperatures up to about 750/sup 0/C no significant microstructural changes occur for short heat treatment times. In the temperature range of 750 to 950/sup 0/C, however, particles typically 100 to 500 A in diameter containing Zr and B are formed within the grains. Higher temperatures enhance the formation of such particles and give rise to particle networks. The results show that a fine and uniform distribution of the boride particles almost exclusively within the grains can be achieved if proper annealing conditions are chosen. This type of distribution is an important requirement for the homogeneous production of helium during neutron irradiation in fast reactors.

  7. Structural, Magnetic, and Microstructural Properties of Rapidly Solidified Ni54Fe21Ga25-xAlx Ribbons

    NASA Astrophysics Data System (ADS)

    Al-Omari, Imaddin; Aich, S.; Kumar, K.

    2014-03-01

    Polycrystalline rapidly solidified Ni54Fe21Ga25-xAlx ribbons (x =0, 1, 2, 3, 4) were prepared by arc-melting followed by vacuum melt spinning. The microstructures and phase formations of the cast alloys and ribbons were investigated by X-ray diffraction, scanning electron microscope, and transmission electron microscope. These studies indicated that upon rapid solidification processing the occurrence of γ-phase is suppressed leading to the formation of a structure consisting of only L21 ordered phase, while after annealing the γ-phase can be reappeared. The changes in various phase transformation temperatures were investigated by differential scanning calorimeter and found that there is a decrease in the glass transition temperature and in delta Cp with increasing the Al concentration. The magnetic behaviors of these ribbons were studied using a vibrating sample magnetometer and found that all the samples under investigation were ferromagnetic in nature. The magnetization at room temperature and at an applied magnetic field of 13.5 kOe was found to decrease with increasing the Al percentage. We would like to acknowledge the IIT-Kharagpur, India for every kind of supports provided at different stages throughout the research, and the Sultan Qaboos University for the financial support under Grant number IG/SCI/PHYS/12/02.

  8. A versatile powder production and collection system for rapidly solidified metal and ceramic powders

    NASA Astrophysics Data System (ADS)

    Khor, K. A.

    1992-08-01

    A versatile system is described which is capable of producing fine metal and ceramic powders using three different modes of a plasma solidification process: microatomization-plasma rapid solidification using air or inert gas as the quenching medium and plasma rapid solidification using water as the quenching medium. The testing and evaluation of the system is carried out using stainless steel 316 and yttria stabilized zirconia for microatomization experiments and alumina for other plasma solidification experiments. The microatomized powders are spherical with particle sizes ranging from 0.5 to 50 microns. The productivity of the pilot-scale system is 4 kg/hr.

  9. Superconductivity and magnetism in rapidly solidified perovskites. Final report, September 1, 1988--August 31, 1991

    SciTech Connect

    O`Handley, R.C.; Kalonji, G.

    1991-12-31

    The report is divided into six parts, reflecting major thrusts of our work since 1987. The six areas are: molecular orbital theory of high {Tc} superconductivity; rapid solidification processing of oxide superconductors; time dependent magnetic and superconducting properties of these inhomogeneous materials; excess Gd in Gd{sub 1+x}Ba{sub 2-x}Cu{sub 3}O{sub 7-{delta}} perovskites; rapid solidification and directional annealing to achieve high Jc; and Mossbauer studies of T = Fe, Co and Ni site selection in YBa{sub 2}(CuT){sub 3}O{sub 7-{delta}} and GdBa{sub 2}(CuT){sub 3}O{sub 7-{delta}}.

  10. The microstructure and properties of rapidly solidified, dispersion-strengthened NiAl

    NASA Technical Reports Server (NTRS)

    Jha, S. C.; Ray, R.

    1990-01-01

    An advanced rapid solidification technology for processing reactive and refractory alloys, utilized to produce large quantities of melt-spun filaments of NiAl, is presented. The melt-spun filaments are pulverized to fine particle sizes, and subsequently consolidated by hot extrusion or hot isostatic pressing. Rapid solidification process gives rise to very fine-grained microstructures. However, exposure to elevated temperature during hot consolidation leads to grain growth. Alloying agents such as borides, carbides, and tungsten can pin the grain boundaries and retard the grain growth. Various alloy compositions are investigated. The eventual goal is to utilize the hot-extruded and forged stock to grow single-crystal NiAl blades for advanced gas-turbine engine applications. Single-crystal NiAl, containing a uniform dispersion of carbide strengthening precipitates, is expected to lead to highly creep-resistant turbine blades, and is of considerable interest to the aerospace propulsion industry.

  11. Structures and properties of rapidly solidified 9Cr-lMo steel

    NASA Astrophysics Data System (ADS)

    Megusar, J.; Lavernia, E.; Domalavage, P.; Harling, O. K.; Grant, N. J.

    1984-05-01

    Irradiation induced shifts of the DBTT and possible hydrogen embrittlement of ferritic steels are currently considered major problems for CTR applications. Rapid solidification and in particular liquid dynamic compaction (LDC) has been studied in developing 9Cr-1Mo steel as a candidate first wall material. Structural refinements such as reduction of segregation, fine grain size and fine size of second phase particles are retained in this process and this will have a favorable effect on fracture properties. LDC has also the potential of preparing first wall components directly from the melt and this would have an economic advantage over conventional ingot technology.

  12. Glass formation and cluster evolution in the rapidly solidified monatomic metallic liquid Ta under high pressure

    NASA Astrophysics Data System (ADS)

    Jiang, Dejun; Wen, Dadong; Tian, Zean; Liu, Rangsu

    2016-12-01

    Molecular dynamics (MD) simulations have been performed to examine the glass formation and cluster evolution during the rapid solidification of monatomic metallic liquid Ta under high pressure. The atomic structures in the systems are characterized by the radical distribution function (RDF), Honeycutt-Anderson (H-A) bond-type index method and cluster-type index method (CTIM). It is observed that the defective icosahedra play the critical role in the formation of Ta monatomic metallic glasses (MGs) rather than (12 0 12 0) perfect icosahedra, which have been identified as the basic local atomic units in many multi-component MGs. With the increase of pressure P, the fraction of icosahedral type clusters decreases remarkably in Ta MGs, while the fraction of bcc type clusters rises evidently. The evolution of vitrification degree (DSRO or DMRO) of the rapidly cooled metal Ta system further reveals that a higher pressure P is disadvantageous to the formation of Ta monatomic MGs. The weaker glass forming ability (GFA) of liquid metal Ta obtained under higher pressure P can be contributed to the decrease of DSRO or DMRO which is induced by increasing high pressure P to some extent.

  13. Investigation of rapidly solidified aluminum by using diamond turning and a magnetorheological finishing process

    NASA Astrophysics Data System (ADS)

    Cheng, Yuan-Chieh; Hsu, Wei-Yao; Kuo, Ching-Hsiang; Abou-El-Hossein, Khaled; Otieno, Timothy

    2015-08-01

    The metal mirror has been widely used in optical application for a longtime. Especially the aluminum 6061 is often considered the preferred material for manufacturing optical components for ground-based astronomical applications. One reason for using this material is its high specific stiffness and excellent thermal properties. However, a large amount of data exists for this material and commercially available aluminum 6061 using single point diamond turning (SPDT) and polishing process can achieve surface roughness values of approximately 2 to 4 nm, which is adequate for applications that involve the infrared spectral range, but not for the shorter spectral range. A novel aluminum material, fabricated using a rapid solidification process that is equivalent to the conventional aluminum 6061 alloy grade has been used in optical applications in recent years because of its smaller grain size. In this study, the surface quality of the rapid solidification aluminum after single point diamond turning and followed by magnetorheological finish (MRF) process is investigated and compared with conventional aluminum 6061. Both the surface roughness Ra was evaluated using white light interferometers. Finally, indicators such as optimal fabrication parameter combination and optical performance are discussed.

  14. Mechanical properties of rapidly solidified Al-Si-Ni-Ce P/M alloys

    SciTech Connect

    Lee, T.H. |; Kawamura, Yoshihito; Inoue, Akihisa; Masumoto, Tsuyoshi; Cho, S.S.

    1997-02-15

    To meet current and future materials needs for structural members or engine parts in aircraft, motorcycle and automobile, it is needed to develop high-performance light weight alloys with higher room-temperature strength, higher elevated temperature strength, higher wear resistance and lower thermal expansion. Powder metallurgy (P/M) alloys with novel mechanical properties have been developed by a rapid solidification technique. The improved properties result from structural modifications such as reduction of segregation, refinement of grain size and increase in solid solubility limit. The aim of this paper is to examine the effect of adding of glass-forming elements, Ni and Ce, to a RS P/M Al-19at.%Si alloy for the development of high strength and good wear resistance aluminum alloys.

  15. High-temperature oxidation of a rapidly solidified amorphous Ta-Ir alloy

    NASA Technical Reports Server (NTRS)

    Cotell, Catherine M.; Yurek, Gregory J.

    1986-01-01

    The oxidation products formed at 500 and 700 C on an amorphous Ta-44.5 at. pct Ir alloy in an Ar-0.1 percent O2 gas mixture were characterized using SEM, XRD, EPMA, TEM, STEM, AES, and XPS. Initially, a thin (3-4 nm) layer of Ta2O5 formed at the surface of the alloy. Continued growth of the Ta2O5, which occurred very rapidly, involved diffusion of oxygen anions from the Ta2O5/gas interface to the alloy/Ta2O5 interface, where tantalum was selectively oxidized. Because the oxide grew more quickly than iridium could diffuse back into the alloy, the iridium coalesced into platelets of crystalline iridium-rich alloy that were oriented approximately parallel to the oxide/alloy interface, and which became embedded in a matrix of Ta2O5. The unoxidized core remained in the glassy state. The oxidation process and/or the dissolution of oxygen into the unoxidized alloy caused the alloy to become embrittled.

  16. Thermal mixing of Al-Fe multilayers

    NASA Astrophysics Data System (ADS)

    Meyer, M.; Mendoza Zélis, L.; Sánchez, F. H.; Traverse, A.

    1994-12-01

    Al-Fe multilayers have been mixed by thermal treatment and their evolution followed by conversion electron Mössbauer spectroscopy. The initial and final states have been characterized by Rutherford backscattering spectrometry. The results are compared with those previously obtained in the ion beam mixing of similar systems.

  17. Formation ranges of icosahedral, amorphous and crystalline phases in rapidly solidified Ti-Zr-Hf-Ni alloys

    SciTech Connect

    Chen, N. . E-mail: asyzxy@imr.edu; Louzguine, D.V.; Ranganathan, S.; Inoue, A.

    2005-02-01

    From the quaternary Ti-Zr-Hf-Ni phase diagram, the cross-section at 20 at.% Ni was selected for investigation. The icosahedral quasicrystalline, crystalline and amorphous phases were observed to form in nine kinds of rapidly solidified (Ti{sub x}Zr{sub y}Hf{sub z}){sub 80}Ni{sub 20} (x + y + z = 1) alloys at different compositions. The quasilattice constants of 0.519 and 0.531 nm were obtained for the icosahedral phase formed in the melt-spun Ti{sub 40}Zr{sub 20}Hf{sub 20}Ni{sub 20} and Ti{sub 20}Zr{sub 40}Hf{sub 20}Ni{sub 20} alloys, respectively. The icosahedral phase formed in the melt-spun Ti{sub 40}Zr{sub 20}Hf{sub 20}Ni{sub 20} alloy especially is thermodynamically stable. The supercooled liquid region of the Ti{sub 20}Zr{sub 20}Hf{sub 40}Ni{sub 20} glassy alloy reached 64 K. From these results a comparison of quasicrystal-forming and glass-forming abilities was carried out. The quasicrystal-forming ability was reduced and glass-forming ability was improved with an increase in Hf and Zr contents in the (Ti{sub x}Zr{sub y}Hf{sub z}){sub 80}Ni{sub 20} alloys. On the other hand, an increase in Ti content caused an improvement in quasicrystal-forming ability.

  18. Effect of initial microstructure on the compactability of rapidly solidified Ti-rich TiAl powder

    SciTech Connect

    Nishida, M.; Chiba, A.; Morizono, Y.; Kai, T.; Sugimoto, J.

    1997-12-31

    Initial microstructure dependence of compactability at elevated temperature in rapidly solidified Ti-rich TiAl alloy powders produced by plasma rotating electrode process (PREP) has been investigated. There were two kinds of powders with respect to the microstructure. The first one had a surface relief of a martensitic phase, which was referred as M powder. The second one had a dendritic structure, which was referred as D powder. {alpha}{sub 2}+{gamma} microduplex and {alpha}{sub 2}/{gamma} lamellar structures were formed in M and D powders of the Ti-40 at%Al alloy by heat treatment at 1,273 K, respectively. The microduplex structure consisted of {gamma} precipitate in the twin related {alpha}{sub 2} matrix with the usual orientation relationship. It was difficult to compact the D powder by hot pressing at 1,273 K under 50 MPa for 14.4 ks. On the other hand, the M powder was compacted easily by hot pressing with the same condition. The twin related {alpha}{sub 2} and {alpha}{sub 2} boundary changed to random ones and the {alpha}{sub 2} and {gamma} phases lost the usual orientation relationship in the duplex structure during the hot pressing. In other words, the low energy boundaries were changed to the high energy ones suitable for grain boundary sliding. Dislocations were scarcely observed inside of both the {alpha}{sub 2} and {gamma} crystal grains. It was concluded that the grain boundary sliding was a predominant deformation mode in the M powder during the hot pressing. D and M powders in Ti-45 and 47 at%Al alloys showed the same tendency as those in Ti-40 at%Al alloy during hot pressing.

  19. Electrochemical properties of rapidly solidified Si-Ti-Ni(-Cu) base anode for Li-ion rechargeable batteries

    NASA Astrophysics Data System (ADS)

    Kwon, Hye Jin; Sohn, Keun Yong; Park, Won-Wook

    2013-11-01

    In this study, rapidly solidified Si-Ti-Ni-Cu alloys have been investigated as high capacity anodes for Li-ion secondary batteries. To obtain nano-sized Si particles dispersed in the inactive matrix, the alloy ribbons were fabricated using the melt spinning process. The thin ribbons were pulverized using ball-milling to make a fine powder of ˜ 4 µm average size. Coin-cell assembly was carried out under an argon gas in a glove box, in which pure lithium was used as a counter-electrode. The cells were cycled using the galvanostatic method in the potential range of 0.01 V and 1.5 V vs. Li/Li+. The microstructure and morphology were examined using an x-ray diffractometer, Field-Emission Scanning Electron Microscopy and High Resolution Transmission Electron Microscopy. Among the anode alloys, the Si70Ti15Ni15 electrodes had the highest discharge capacity (974.1 mAh/g) after the 50th cycle, and the Si60Ti16Ni16Cu8 electrode showed the best coulombic efficiency of ˜95.9% in cyclic behavior. It was revealed that the Si7Ni4Ti4 crystal phase coexisting with an amorphous phase, could more efficiently act as a buffer layer than the fully crystallized Si7Ni4Ti4 phase. Consequently, the electrochemical properties of the anode materials pronouncedly improved when the nano-sized primary Si particle was dispersed in the inactive Si7Ni4Ti4-based matrix mixed with an amorphous structure.

  20. Microstructure and properties of rapidly solidified beryllium-transition metal alloys. [With small amounts of Ti, Zr and Y (1-3 wt %)

    SciTech Connect

    Jacobson, L.A.; Richardson, S.

    1988-01-01

    Alloys of beryllium with small amounts of Ti, Zr and Y (1-3 wt %) were rapidly solidified using an arc hammer splat technique. Each of these elements forms a dilute eutectic with beryllium, and has very low solid solubility in the alpha phase. In the case of Ti, the Be-rich compound is TiBe/sub 12/, and for Zr and Y, the compound is MBe. The objective of the work was to achieve a fine, uniform dispersion of particles of the intermetallic compound. Since these compounds have very high melting points, it was expected that rapidly solidified microstructures would be relatively stable at elevated temperatures. This microstructural stability should result in improved high temperature properties for the alloys. Microstructures have been characterized using optical, scanning and transmission electron microscopy. Microhardness measurements have been made in order to determine the effects of rapid solidification and to evaluate the effects of high temperature exposure on microstructural stability and property retention. The results will be presented in light of the potential of these alloys for intermediate temperature application. 12 refs., 8 figs.

  1. Evolution of the microstructure and hardness of a rapidly solidified/melt-spun AZ91 alloy upon aging at different temperatures

    SciTech Connect

    Wang Baishu; Liu Yongbing; An Jian; Li Rongguang; Su Zhenguo; Su Guihua; Lu You; Cao Zhanyi

    2009-04-15

    The effect of aging at different temperatures on a rapidly solidified/melt-spun AZ91 alloy has been investigated in depth. The microstructures of as-spun and aged ribbons with a thickness of approximately 60 {mu}m were characterized using X-ray diffraction, transmission electron microscopy and laser optical microscopy; microhardness measurements were also conducted. It was found that the commercial AZ91 alloy undergoes a cellular/dendritic transition during melt-spinning at a speed of 34 m/s. A strengthening effect due to aging was observed: a maximum hardness of 110 HV/0.05 and an age-hardenability of 50% were obtained when the ribbon was aged at 200 deg. C for 20 min. The {beta}-Mg{sub 17}Al{sub 12} phase exhibits net and dispersion types of distribution during precipitation. The dispersion of precipitates in dendritic grains or cells is the main source of strengthening.

  2. Phase Stability of Al-5Fe-V-Si Coatings Produced by Cold Gas Dynamic Spray Process Using Rapidly Solidified Feedstock Materials

    NASA Astrophysics Data System (ADS)

    Bérubé, G.; Yandouzi, M.; Zúñiga, A.; Ajdelsztajn, L.; Villafuerte, J.; Jodoin, B.

    2012-03-01

    In this study, aluminum alloy Al-5Fe-V-Si (in wt.%) feedstock powder, produced by rapid solidification (RS) using the gas atomization process, was selected to produce high-temperature resistant Al-alloy coatings using the cold gas dynamic spraying process (CGDS). The alloy composition was chosen for its mechanical properties at elevated temperature for potential applications in internal-combustion (IC) engines. The CGDS spray process was selected due to its relatively low operating temperature, thus preventing significant heating of the particles during spraying and as such allowing the original phases of the feedstock powder to be preserved within the coatings. The microstructure and phases stability was investigated by means of Scanning Electron Microscopy, transmission electron microscopy, X-ray diffraction and differential scanning calorimetery techniques. The coatings mechanical properties were evaluated through bond strength and microhardness testing. The study revealed the conservation of the complex microstructure of the rapid solidified powder during the spray process. Four distinct microstructures were observed as well as two different phases, namely a Al13(Fe,V)3Si silicide phase and a metastable (Al,Si) x (Fe,V) Micro-quasicrystalline Icosahedral (MI) phase. Aging of the coating samples was performed and confirmed that the phase transformation of the metastable phases and coarsening of the nanosized precipitates will occurs at around 400 °C. The metastable MI phase was determined to be thermally stable up to 390 °C, after which a phase transformation to silicide starts to occur.

  3. Rapidly solidified Ag-Cu eutectics: A comparative study using drop-tube and melt fluxing techniques

    NASA Astrophysics Data System (ADS)

    Yu, Y.; Mullis, A. M.; Cochrane, R. F.

    2016-03-01

    A comparative study of rapid solidification of Ag-Cu eutectic alloy processed via melt fluxing and drop-tube techniques is presented. A computational model is used to estimate the cooling rate and undercooling of the free fall droplets as this cannot be determined directly. SEM micrographs show that both materials consist of lamellar and anomalous eutectic structures. However, below the critical undercooling the morphologies of each are different in respect of the distribution and volume of anomalous eutectic. The anomalous eutectic in flux- undercooled samples preferentially forms at cell boundaries around the lamellar eutectic in the cell body. In drop-tube processed samples it tends to distribute randomly inside the droplets and at much smaller volume fractions. That the formation of the anomalous eutectic can, at least in part, be suppressed in the drop-tube is strongly suggestive that the formation of anomalous eutectic occurs via remelting process, which is suppressed by rapid cooling during solidification.

  4. Precipitation of coherent FeRh nanoparticles with highly suppressed magnetostructural transition temperatures in rapidly solidified (FeRh)5Cu95 alloys

    NASA Astrophysics Data System (ADS)

    Barua, Radhika; Jiang, Xiujuan; Shield, Jeff; Heiman, Don; Lewis, Laura

    2012-02-01

    Magnetostructural phase transitions have the capability of delivering large functional effects in response to small excursions in magnetic field, temperature and strain; this potential might be amplified in nanostructured systems by virtue of large surface:volume ratios. Nanoprecipitates (˜10nm) of FeRh, a well-known magnetostructural material, were studied with structural and magnetic probes in a rapidly solidified phase-separated system of (FeRh)5Cu95. Magnetization studies indicate a dramatic reduction in the magnetostructural phase transition temperature (Tt) of the nanoscaled FeRh phase relative to the bulk value (δT=Tt,Bulk - Tt,Nano = 220 K). Transmission electron microscopy (TEM) and selected area electron diffraction (SAED) reveals a coherent orientational relationship between the FeRh (aFeRh = 3.09 å)and Cu (aCu = 3.78 å) phases. At the matrix/precipitate interface a constrained misfit strain of ɛ = 0.18 is observed. The reduction of the magnetostructural phase transition temperature and evolution of the magnetic properties with system annealing is analyzed in the context of the strain between the FeRh nanoparticles and the Cu matrix.

  5. Magnetic properties of bulk, and rapidly solidified nanostructured (Nd1-xCex)2Fe14-yCoyB ribbons

    DOE PAGESBeta

    Pathak, Arjun K.; Khan, M.; Gschneidner, Jr., K. A.; McCallum, R. W.; Zhou, L.; Sun, K.; Kramer, M. J.; Pecharsky, V. K.

    2015-11-06

    Magnetic properties of Ce and Co co-doped (Nd1-xCex)2Fe14-yCoyB compounds have been investigated both in bulk polycrystalline and rapidly solidified nanostructured ribbon forms. For certain Ce concentrations the materials exhibit spin re-orientation transitions below 140 K. The Curie temperatures, saturation magnetizations, and other magnetic properties relevant for applications as permanent magnets are controlled by Ce and Co substitutions for Nd and Fe, respectively. Most importantly, the results show that Ce, Co co-doped compounds are excellent replacements for several Dy-based high performance permanent magnets (dysprosium is one of the critical elements and is, therefore, in short supply). As a result, the highmore » temperature (>375 K) magnetic properties for Nd–Ce–Fe–Co–B based alloys show promise not only as a replacement for Dy-doped Nd2Fe14B permanent magnets, but the new alloys also require significantly lower amounts of Nd, which too is the critical element that can be replaced by a more abundant Ce.« less

  6. Influence of Mn incorporation for Ni on the magnetocaloric properties of rapidly solidified off-stoichiometric NiMnGa ribbons

    NASA Astrophysics Data System (ADS)

    Dey, Sushmita; Singh, Satnam; Roy, R. K.; Ghosh, M.; Mitra, A.; Panda, A. K.

    2016-01-01

    The present investigation addresses the magnetocaloric behaviour in a series of Ni77-xMnxGa23 (x=23, 24, 25, 27 and 29) rapidly solidified alloys prepared in the form of ribbons by melt spinning technique. The approach of the study is to identify the off-stoichiometric composition wherein room temperature magneto-structural transformation is achieved. The alloy chemistry was tailored through Mn incorporation for Ni such that the magnetic and structural transitions were at close proximity to achieve highest entropy value of ΔS equal to 8.51 J Kg-1 K-1 for #Mn24 ribbon measured at an applied field of 3 T. When such transitions are more staggered as in #Mn29 the entropy value of ribbon reduced to as low as 1.61 J Kg-1 K-1. Near room temperature transformations in #Mn24 ribbon have been observed through calorimetric and thermomagnetic evaluation. Reverse martensitic transformation (martensite→autstenite) temperature indicates not only distinct change in the saturation flux density but also an inter-martensitic phase. Microstructural analysis of #Mn24 alloy ribbon revealed structural ordering with the existence of plate morphology evidenced for martensitic phase.

  7. Room-Temperature Indentation Creep and the Mechanical Properties of Rapidly Solidified Sn-Sb-Pb-Cu Alloys

    NASA Astrophysics Data System (ADS)

    Kamal, Mustafa; El-Bediwi, A.; Lashin, A. R.; El-Zarka, A. H.

    2016-05-01

    In this paper, we study the room-temperature indentation creep and the mechanical properties of Sn-Sb-Pb-Cu alloys. Rapid solidification from melt using the melt-spinning technique is applied to prepare all the alloys. The experimental results show that the magnitude of the creep displacement increases with the increase in both time and applied load, and the stress exponent increases with the increase in the copper content in the alloys which happens primarily due to the existence of the intermetallic compounds SbSn and Cu6Sn5. The calculated values of the stress exponent are in the range of 2.82 to 5.16, which are in good agreement with the values reported for the Sn-Sb-Pb-Cu alloys. We have also studied and analyzed the structure, elastic modulus, and internal friction of the Sn-Sb-Pb-Cu alloys.

  8. Deformation characteristics of the rapidly solidified Al-8. 5% Fe-1. 2% V-1. 7% Si alloy

    SciTech Connect

    Hariprasad, S.; Sastry, S.M.L.; Jerina, K.L. )

    1993-08-15

    Dispersion strengthened Al-8.5% Fe-1.2% V-1.7% Si (8009) alloy containing 40-80 nm diameter dispersoids and exhibiting attractive elevated temperature strengths can be successfully produced by rapid solidification techniques such as Planar Flow Casting (PFC) and Atomized Melt Deposition (AMD). The grain sizes of alloys produced by PFC and AMD are typically O.5 to 1.0 [mu]m. Fine grain sized aluminum alloys have been found to exhibit plastic instabilities such as yield drop, formation of Lueder's bands and positive deviation from Hall-Petch relationship. The stress-strain behavior at room and elevated temperature of the fine grained dispersion strengthened Al-8.5% Fe-1.2% V-1.7% Si alloy produced by PFC and the AMD processes was determined with the objective of delineating the effect of fine grain size on the deformation behavior.

  9. Quantification of Primary Dendritic and Secondary Eutectic Nucleation Undercoolings in Rapidly Solidified Hypo-Eutectic Al-Cu Droplets

    NASA Astrophysics Data System (ADS)

    Bogno, A.-A.; Khatibi, P. Delshad; Henein, H.; Gandin, Ch.-A.

    2016-09-01

    This paper reports on the quantification of primary dendritic and secondary eutectic nucleation undercoolings during rapid solidification of impulse atomized hypo-eutectic Al-Cu droplets. The procedure consists in determining the eutectic fraction of each investigated droplet from the fraction of intermetallic Al2Cu obtained by Rietveld refinement analysis of neutrons scattering data. The corresponding eutectic nucleation undercooling is then deduced from the metastable phase diagram of the alloy. The primary dendritic nucleation undercooling is subsequently determined using semi-empirical coarsening models of secondary dendrite arms. The two nucleation undercoolings are finally used as input variables to run a microsegregation model for binary alloys. The fractions of eutectic computed by the microsegregation model compare very favorably with the experimental results.

  10. Quantification of Primary Dendritic and Secondary Eutectic Nucleation Undercoolings in Rapidly Solidified Hypo-Eutectic Al-Cu Droplets

    NASA Astrophysics Data System (ADS)

    Bogno, A.-A.; Khatibi, P. Delshad; Henein, H.; Gandin, Ch.-A.

    2016-06-01

    This paper reports on the quantification of primary dendritic and secondary eutectic nucleation undercoolings during rapid solidification of impulse atomized hypo-eutectic Al-Cu droplets. The procedure consists in determining the eutectic fraction of each investigated droplet from the fraction of intermetallic Al2Cu obtained by Rietveld refinement analysis of neutrons scattering data. The corresponding eutectic nucleation undercooling is then deduced from the metastable phase diagram of the alloy. The primary dendritic nucleation undercooling is subsequently determined using semi-empirical coarsening models of secondary dendrite arms. The two nucleation undercoolings are finally used as input variables to run a microsegregation model for binary alloys. The fractions of eutectic computed by the microsegregation model compare very favorably with the experimental results.

  11. Air-assisted liquid-liquid microextraction by solidifying the floating organic droplets for the rapid determination of seven fungicide residues in juice samples.

    PubMed

    You, Xiangwei; Xing, Zhuokan; Liu, Fengmao; Zhang, Xu

    2015-05-22

    A novel air assisted liquid-liquid microextraction using the solidification of a floating organic droplet method (AALLME-SFO) was developed for the rapid and simple determination of seven fungicide residues in juice samples, using the gas chromatography with electron capture detector (GC-ECD). This method combines the advantages of AALLME and dispersive liquid-liquid microextraction based on the solidification of floating organic droplets (DLLME-SFO) for the first time. In this method, a low-density solvent with a melting point near room temperature was used as the extraction solvent, and the emulsion was rapidly formed by pulling in and pushing out the mixture of aqueous sample solution and extraction solvent for ten times repeatedly using a 10-mL glass syringe. After centrifugation, the extractant droplet could be easily collected from the top of the aqueous samples by solidifying it at a temperature lower than the melting point. Under the optimized conditions, good linearities with the correlation coefficients (γ) higher than 0.9959 were obtained and the limits of detection (LOD) varied between 0.02 and 0.25 μgL(-1). The proposed method was applied to determine the target fungicides in juice samples and acceptable recoveries ranged from 72.6% to 114.0% with the relative standard deviations (RSDs) of 2.3-13.0% were achieved. Compared with the conventional DLLME method, the newly proposed method will neither require a highly toxic chlorinated solvent for extraction nor an organic dispersive solvent in the application process; hence, it is more environmentally friendly. PMID:25937106

  12. Fitness trade-offs of Selenastrum capricornutum strains selected for rapid growth on copper-spiked solidified nutrient medium

    SciTech Connect

    Benjamin, R.B.; Klaine, S.J.

    1995-10-01

    Stock (ancestral) cultures of Selenastrum capricornutum grew optimally in low Cu liquid nutrient medium (LNM) containing .004 {micro}g L{sup {minus}1}Cu{sup 2+}. Cell strains (clones) were isolated from unusually large colonies on high Cu SNM (1,000 {micro}g L{sup {minus}1}Cu{sup 2+}). Most isolated strains performed the same as ancestral populations in high Cu LNM (50 {micro}g L{sup {minus}1}Cu{sup 2+}), but three strains grew more slowly. These ``variant strains`` were Cu tolerant on SNM (equal growth with low and high Cu) and produced larger colonies than did the ancestral population on both low and high Cu SNM. In contrast, colonies from ancestral cell samples grew more slowly in high versus low Cu SNM. No significant growth differences were observed between ancestral populations and variant strains in low Cu LNM, suggesting low fixed costs of adaptation to SNM. However, slower growth of variant strains in high Cu LNM constituted a fitness trade-off associated with adaptation. Rapid adaptation to pollution may often result in important biological trade-offs even when costs of adaptive mechanisms are low.

  13. Structure and properties of a rapidly solidified Al-Li-Mn-Zr Alloy for high-temperature applications: Part I. inert gas atomization processing

    NASA Astrophysics Data System (ADS)

    Ruhr, Michael; Baram, Joseph

    1991-10-01

    A new Al-Li alloy containing 2.3 wt pct Li, 6.5 wt pct Mn, and 0.65 wt pet Zr, for high-temperature applications, has been processed by a rapid solidification (RS) technique (as powders by inert gas atomization) and then thermomechanically treated by hot isostatic pressing (hipping) and hot extrusion. As-received and thermomechanically treated powders (of various size fractions) were characterized by X-ray diffraction and scanning and transmission electron microscopy (SEM and TEM, respectively). Phase analyses in the as-processed materials revealed the presence of two Mn phases (Al4Mn and Al6Mn), one Zr phase (Al3Zr), two Li phases (the stable AlLi and the metastable Al3Li), and the αAl solid solution with high excess in Mn solubility (up to close the nominal composition in the as-atomized powders). Extruded pieces were solutionized at 370 °C and 530 °C for various soaking times (2 to 24 hours). A variety of aging treatments was practiced to check for the optimal (for tensile properties) aging procedure, which was found to be the following: solutioning at 370 °C for 2 hours and water quenching + 1 pct mechanical stretching + one step aging at 120 °C for 3 hours. The mechanical properties, at room and elevated temperatures, of the “hipped” and hot extruded powders are compared following the optimal solutioning and aging treatments. The results indicate that Mn is indeed a favorable alloying element for rapidly solidified Al-Li alloys to retain about 85 to 95 pct of the room-temperature tensile properties even at 250 °C, though room-temperature strength is not satisfactory in itself. However, specific moduli are by 20 to 25 pet higher than those of the 2024 series duralumin-type alloys. Ductilities at room temperatures are in the low 1 to 2.5 pct range and show no improvement over other Al-Li alloys.

  14. An Assessment of the Al- Fe- N System

    NASA Astrophysics Data System (ADS)

    Hillert, Mats; Jonsson, Stefan

    1992-11-01

    The thermodynamic properties of the Al-Fe-N system are assessed, taking various types of information into account. For solid AIN, a description very similar to that given by JANAF is found to yield reasonable predictions for the solubility of A1N in face-centered cubic (fcc) Fe and in liquid Fe. An ionic two-sublattice model is applied to the liquid phase, containing two N species, N-3 and N0 The melting point of A1N is taken as 3068 K, and a required gas pressure of 9.75 bar is predicted. A sublimation point of 2690 K at 1 bar is also predicted. A plot of the liquidus surfaces in the Fe-rich end of the Al-Fe-N system is presented.

  15. Formation mechanism for the nanoscale amorphous interface in pulse-welded Al/Fe bimetallic systems

    NASA Astrophysics Data System (ADS)

    Li, Jingjing; Yu, Qian; Zhang, Zijiao; Xu, Wei; Sun, Xin

    2016-05-01

    Pulse or impact welding traditionally has been referred to as "solid-state" welding. By integrating advanced interface characterizations and diffusion calculations, we report that the nanoscale amorphous interface in the pulse-welded Al/Fe bimetallic system is formed by rapid heating and melting of a thin Al layer at the interface, diffusion of iron atoms in the liquid aluminum, and subsequent rapid quenching with diffused iron atoms in solution. This finding challenges the commonly held belief regarding the solid-state nature of the impact-based welding process for dissimilar metals. Elongated ultra-fine grains with high dislocation density and ultra-fine equiaxed grains also are observed in the weld interface vicinity on the steel and aluminum sides, respectively, which further confirms that melting and the subsequent recrystallization occurred on the aluminum side of the interface.

  16. Formation of the icosahedral quasicrystalline phase in a rapidly solidified Al{sub 52}Cu{sub 25.5}Fe{sub 12.5}Si{sub 1} alloy

    SciTech Connect

    Wang Yan; Zhang Zhonghua . E-mail: zh_zhang@sdu.edu.cn; Geng Haoran; Yang Zhongxi

    2006-04-15

    In the present work, the effect of wheel speed (quenching rate) on the formation of the quasicrystalline phase in a rapidly solidified Al{sub 52}Cu{sub 25.5}Fe{sub 12.5}Si{sub 1} alloy has been investigated using X-ray diffraction (XRD), differential thermal analysis (DTA), differential scanning calorimetry (DSC) and transmission electron microscopy (TEM). The results show that rapid solidification has no effect on the phase constitution of the Al{sub 52}Cu{sub 25.5}Fe{sub 12.5}Si{sub 1} alloy. The addition of Si decreases the stability of the quasicrystalline phase in the conventionally cast Al{sub 52}Cu{sub 25.5}Fe{sub 12.5}Si{sub 1} alloy. The thermal stability of the quasicrystalline phase in the melt-spun alloy depends upon the quenching rate. Moderate-rate rapid solidification can improve the thermal stability of the quasicrystalline phase in the melt-spun alloy. Higher quenching rate instigates the transformation of the quasicrystalline phase into the cubic approximant phase and decreases the stability of the quasicrystalline phase. Furthermore, the transformation temperature decreases with increasing Si addition into the Al{sub (62-x)}Cu{sub 25.5}Fe{sub 12.5}Si{sub x}.

  17. Changes in solidified microstructures

    NASA Technical Reports Server (NTRS)

    Wallace, J. F.

    1984-01-01

    The properties and casting behavior of metals are significantly affected by their cast structure. This structure is optimized by producing columnar versus equiaxed grains and coarse versus fine grains by controlling solidification conditions. The transition from columnar to equiaxed grains is favored by: constitutional supercooling with effective nucleation of free dendrites; melting off and transport of dendrite tips and arms; mechanical vibration; falling down of free dendrites from a chilled top surface; and induced flow in the solidifying structure by oscillation of rotation.

  18. Tensile deformation of 2618 and Al-Fe-Si-V aluminum alloys at elevated temperatures

    NASA Technical Reports Server (NTRS)

    Leng, Y.; Porr, W. C., Jr.; Gangloff, R. P.

    1990-01-01

    The present study experimentally characterizes the effects of elevated temperature on the uniaxial tensile behavior of ingot metallurgy 2618 Al alloy and the rapidly solidified FVS 0812 P/M alloy by means of two constitutive formulations: the Ramberg/Osgood equation and the Bodner-Partom (1975) incremental formulation for uniaxial tensile loading. The elastoplastic strain-hardening behavior of the ingot metallurgy alloy is equally well represented by either formulation. Both alloys deform similarly under decreasing load after only 1-5 percent uniform tensile strain, a response which is not described by either constitutive relation.

  19. Magnetic properties of bulk, and rapidly solidified nanostructured (Nd1-xCex)2Fe14-yCoyB ribbons

    SciTech Connect

    Pathak, Arjun K.; Khan, M.; Gschneidner, Jr., K. A.; McCallum, R. W.; Zhou, L.; Sun, K.; Kramer, M. J.; Pecharsky, V. K.

    2015-11-06

    Magnetic properties of Ce and Co co-doped (Nd1-xCex)2Fe14-yCoyB compounds have been investigated both in bulk polycrystalline and rapidly solidified nanostructured ribbon forms. For certain Ce concentrations the materials exhibit spin re-orientation transitions below 140 K. The Curie temperatures, saturation magnetizations, and other magnetic properties relevant for applications as permanent magnets are controlled by Ce and Co substitutions for Nd and Fe, respectively. Most importantly, the results show that Ce, Co co-doped compounds are excellent replacements for several Dy-based high performance permanent magnets (dysprosium is one of the critical elements and is, therefore, in short supply). As a result, the high temperature (>375 K) magnetic properties for Nd–Ce–Fe–Co–B based alloys show promise not only as a replacement for Dy-doped Nd2Fe14B permanent magnets, but the new alloys also require significantly lower amounts of Nd, which too is the critical element that can be replaced by a more abundant Ce.

  20. Structure and properties of a rapidly solidified Al-Li-Mn-Zr alloy for high-temperature applications: Part II. spray atomization and deposition processing

    NASA Astrophysics Data System (ADS)

    Baram, Joseph

    1991-10-01

    A new Al-Li alloy containing 2.3 wt pct Li, 6.5 wt pct Mn, and 0.65 wt pet Zr for high-temperature applications has been processed by a rapid solidification (RS) technique (as compacts by spray atomization and deposition) and then thermomechanically treated by hot extrusion. As-received and thermomechanically treated deposits were characterized by X-ray diffraction and scanning electron microscopy (SEM). Phase analyses in the as-processed materials revealed the presence of two Mn phases (Al4Mn and Al6Mn), one Zr phase (Al3Zr), two Li phases (the stable AlLi and the metastable Al3Li), and the aAl solid solution with high excess in Mn solubility (up to close the nominal composition in the as-atomized powders). As-deposited and extruded pieces were given heating treatments at 430 °C and 530 °C. A two-step aging treatment was practiced, to check for the optimal (for tensile properties) aging procedure, which was found to be the following: solutioning at 430 °C for 1 hour and water quenching + a first-step aging at 120 °C for 12 hours + a second-step aging at 175 °C for 15 hours. The mechanical properties, at room and elevated temperatures, of the hot extruded deposits are compared, following the optimal solutioning and aging treatments. The room-temperature (RT) strength of the proposed alloy is distinctly better for the as-deposited specimens (highest yield strength, 320 MPa) than for the as-atomized (highest yield strength, 215 MPa), though less than 65 pct of the RT strength is conserved at 250 °C. Ultimate strengths are quite comparable (in the 420 to 470 MPa range). Ductilities at RTs are in the low 1.5 to 2.5 pct range and show no improvement over other Al-Li alloys.

  1. Thermodynamic Assessment of the Aluminum Corner of the Al-Fe-Mn-Si System

    NASA Astrophysics Data System (ADS)

    Lacaze, Jacques; Eleno, Luiz; Sundman, Bo

    2010-09-01

    A new assessment of the aluminum corner of the quaternary Al-Fe-Mn-Si system has been made that extends beyond the COST-507 database. This assessment makes use of a recent, improved description of the ternary Al-Fe-Si system. In the present work, modeling of the Al-rich corner of the quaternary Al-Fe-Mn-Si system has been carried out by introducing Fe solubility into the so-called alpha-AlMnSi and beta-AlMnSi phases of the Al-Mn-Si system. A critical review of the data available on the quaternary system is presented and used for the extension of the description of these ternary phases into the quaternary Al-Fe-Mn-Si.

  2. Synthesis and characterization of quasicrystals in an Al-Fe-W alloy

    SciTech Connect

    Mukhopadhyay, N.K.; Weatherly, G.C.; Embury, J.D. ); Lloyd, D.J. )

    1992-07-01

    After the discovery of quasicrystals (QC) in an al-14% Mn alloy, many attempts have been made to find alloy systems which form quasicrystals. Much effort has been devoted to the study of the Al-Fe system and its modification by Cu and other elements such as Mn, Cr, Mo and Ta to improve the ease of forming icosahedral quasicrystals (IQC). Although the Al-Fe system does not form IQC, the formation of a decagonal quasicrystal (DQC) being favored, these elements promote the IQC phase. This paper considers the Al-Fe system and its modification by W and demonstrates the existence of IQC in an Al-Fe-W ternary alloy.

  3. Directionally solidified mullite fibers

    SciTech Connect

    Sayir, A.; Farmer, S.C.

    1995-10-01

    Directionally solidified fibers with nominal mullite compositions of 3Al{sub 2}O{sub 3} {center_dot} 2SiO{sub 2} were grown by the laser heated float zone (LHFZ) method at NASA Lewis. High resolution digital images from an optical microscope evidence the formation of a liquid-liquid miscibility gap during crystal growth. Experimental evidence shows that the formation of mullite in aluminosilicate melts is in fact preceded by liquid immiscibility. The average fiber tensile strength is 1.15 GPa at room temperature. The mullite fibers retained 80% of their room temperature tensile strength at 1,450 C. SEM analysis revealed that the fibers were strongly faceted and that the facets act as critical flaws. Examined in TEM, these mullite single crystals are free of dislocations, low angle boundaries and voids. Single crystal mullite showed a high degree of oxygen vacancy ordering. Regardless of the starting composition, the degree of order observed in polycrystalline fibers was lower than that observed in the mullite single crystals.

  4. Precipitation during infiltration of A201 aluminum alloy into Al-Fe-V-Si preform

    SciTech Connect

    Yang, C.C.; Chen, Y.C.; Chang, E.

    1996-04-01

    The newly developed Al-Fe-V-Si aluminum alloy, produced by melt spinning into ribbons, comminution of ribbon to particles, and then consolidation of particles by extrusion and forging, is being considered for high temperature applications due to the material`s characteristics of high elevated temperature strength, low density, good toughness and thermal stability. In order to extend the near-net shaping capability of the material, the authors have proposed a new process that Al-Fe-V-Si aluminum alloy particles can be consolidated by casting, in which the liquid aluminum alloy was infiltrated around the Al-Fe-V-Si particles to form a FVS1212/A201 composite material. Preliminary study of the Al-Fe-V-Si particle reinforced A201 aluminum alloy composite demonstrated that the compression strength at 300 C can be twice as high as A201 aluminum alloy. This work constitutes a continuation of the previous efforts to understand the microstructural evolution sequences, particularly the precipitation events during infiltration of the liquid aluminum into Al-Fe-V-Si preform.

  5. Preparation and properties of the Ni-Al/Fe-Al intermetallics composite coating produced by plasma cladding

    NASA Astrophysics Data System (ADS)

    Zhang, Li-Min; Liu, Bang-Wu; Sun, Dong-Bai

    2011-12-01

    A novel approach to produce an intermetallic composite coating was put forward. The microstructure, microhardness, and dry-sliding wear behavior of the composite coating were investigated using X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive spectrum (EDS) analysis, microhardness test, and ball-on-disc wear experiment. XRD results indicate that some new phases FeAl, Fe0.23Ni0.77Al, and Ni3Al exit in the composite coating with the Al2O3 addition. SEM results show that the coating is bonded with carbon steel metallurgically and exhibits typical rapid directional solidification structures. The Cr7C3 carbide and intermetallic compounds co-reinforced composite coating has a high average hardness and exhibits an excellent wear resistance under dry-sliding wear test compared with the Cr7C3 carbide-reinforced composite coating. The formation mechanism of the intermetallic compounds was also investigated.

  6. Microstructure selection maps for Al-Fe alloys

    SciTech Connect

    Gilgien, P.; Zryd, A.; Kurz, W.

    1995-09-01

    The solidification microstructures for Al-0.5-4 at.% Fe alloys under constrained growth conditions have been calculated using analytical models of the growth kinetics of dendritic, eutectic and plane front interface morphologies of stable and metastable phases. Laser remelting experiments are carried out on an Al-4 at.% Fe alloy with low beam velocity (10 mm/s) in order to complete previous experimental results on the solidification microstructures obtained at intermediate growth rates by Bridgman experiments and at a high growth rates by rapid laser resolidification. Comparison of predicted with experimentally determined solidification microstructure maps shows satisfactory agreement in view of the limited knowledge of the thermophysical properties of this system. These maps are useful for the interpretation of microstructures and phases forming under medium to high solidification rates and for the understanding and development of rapid solidification processing. Further the modeling is useful for improving available phase diagram information.

  7. Dynamic Mechanical Behavior Characterization of Epoxy-Cast Al + Fe2O3 Thermite Mixture Composites

    NASA Astrophysics Data System (ADS)

    Ferranti, Louis; Thadhani, Naresh N.

    2007-11-01

    The dynamic mechanical behavior characterization of epoxy-cast stoichiometric mixtures of nano- or micron-scale aluminum and hematite (Fe2O3) powders is investigated in this work. Experiments conducted on rod-shaped samples, using instrumented reverse Taylor impact tests employing high-speed imaging and velocity interferometry, show that these composites exhibit viscoelastic deformation and brittle fracture behaviors. Upon impact, the samples display significant elastic and plastic deformation during both the loading and unloading stages, as determined from quantitative high-speed camera measurements of the transient deformation states. Approximately 50 pct elastic recovery of total axial strain was observed to occur rapidly (within tens of microseconds) after impact. A one-dimensional elastic-plastic wave propagation analysis was used for estimating the composite’s dynamic average yield stress and total plastic strain. The results reveal that the nano-Al + Fe2O3-containing epoxy composite is most resilient, has the highest strength, and is more capable of absorbing impact energy. The analysis additionally provides detailed information about elastic and plastic wave interactions for discrete times, up to the final state of the material. Calculations and observations through the coupling of high-speed camera images and velocity interferometry (VISAR) measurements show that the elastic recovery coincides with peak axial strain and the interaction of elastic and plastic waves propagating within the rod-shaped specimen. Hence, such an instrumented Taylor test provides a detailed view of the general wave structure within the material upon impact and, at the same time, enables a complete description of the stress-strain response.

  8. Radial spreading of viscous-gravity currents with solidifying crust

    NASA Technical Reports Server (NTRS)

    Fink, Jonathan H.; Griffiths, Ross W.

    1990-01-01

    In the present investigation of solidifying-crust effects on the dynamics and surface morphology of radial viscous-gravity currents, polyethylene glycol inflows into the base of a tank holding a cold sucrose solution are used as analogs. As the radial current advanced away from the inlet, its surface solidified and deformed through a combination of folding anf fracturing. When cooling was sufficiently rapid, solid crust formed and caused the spreading rate to increase; progressively colder experiments revealed a sequence of surface morphologies resembling features of cooling lava flows and lava lakes, including multiarmed rift structures with shear offsets and bulbous lobate forms resembling pillow lavas on the ocean floor.

  9. Modulus measurements in ordered Co-Al, Fe-Al, and Ni-Al alloys

    NASA Technical Reports Server (NTRS)

    Harmouche, M. R.; Wolfenden, A.

    1985-01-01

    The composition and/or temperature dependence of the dynamic Young's modulus for the ordered B2 Co-Al, Fe-Al, and Ni-Al aluminides has been investigated using the piezoelectric ultrasonic composite oscillator technique (PUCOT). The modulus has been measured in the composition interval 48.49 to 52.58 at. pct Co, 50.87 to 60.2 at. pct Fe, and 49.22 to 55.95 at. pct Ni for Co-Al, Fe-Al, and Ni-Al, respectively. The measured values for Co-Al are in the temperature interval 300 to 1300 K, while those for the other systems are for ambient temperature only. The data points show that Co-Al is stiffer than Fe-Al, which is stiffer than Ni-Al. The data points for Fe-Al and Ni-Al are slightly higher than those reported in the literature.

  10. Adsorption of perchlorate from aqueous solution by the calcination product of Mg/(Al-Fe) hydrotalcite-like compounds.

    PubMed

    Yang, Yiqiong; Gao, Naiyun; Chu, Wenhai; Zhang, Yongji; Ma, Yan

    2012-03-30

    The calcination products containing Mg(II), Al(III), and Fe(III) in the brucite-like layers with varying Mg/Al/Fe molar ratios at 550°C were used as the adsorbent to remove perchlorate from aqueous solution, while the Mg/(Al-Fe) hydrotalcite compounds were synthesized by co-precipitation method at a constant pH value. The Mg/(Al-Fe) hydrotalcite compounds (HMAF) were characterized by XRD, FT-IR and TG-DTA. The characteristics showed that the layered double hydroxides structures in the HMAF were lost during calcination at 550°C, but were reconstructed subsequent to adsorption of perchlorate, indicating that the 'memory effect' appeared to play an important role in perchlorate adsorption. Batch adsorption studies were conducted under various equilibration conditions, such as molar ratios of Mg/Al/Fe, calcined temperature, different initial solution pH, adsorbent dose, initial perchlorate concentration, and co-existing anions. It was found that the existence of ferric iron in calcined Mg/(Al-Fe) hydrotalcite compound (CHMAF) was favorable to removal of perchlorate from water, and the best ratio of Mg/Al/Fe is 3:0.8:0.2 (CHMAF5%). This study demonstrated that the calcination product of Mg/(Al-Fe) hydrotalcite-like compound was a promising adsorbent for control of the perchlorate pollution in water. PMID:22325635

  11. Comparison of Na/S and LiAl/FeS batteries

    NASA Astrophysics Data System (ADS)

    Knoedler, R.

    NaS and LiAl/FeS batteries, both promising candidates for electric-vehicle propulsion and load leveling applications, are compared by assessing 25 different properties of each system. The most important of these properties, including the specific energy of cells and batteries, maximum specific power, lifetime, safety, key technical problems, and economic considerations, are discussed in detail. It is shown that both types of batteries qualify as high-performance batteries. The NaS system has a slight advantage for applications in West Germany (mainly electric vehicle propulsion; no Li resources); for applications in the United States (electric vehicle propulsion and load leveling), both systems are equally suitable.

  12. Method for solidifying radioactive wastes

    SciTech Connect

    Dippel, T.; Loida, A.

    1985-08-13

    A process is claimed for solidifying radioactive wastes by producing compact blocks which are to be disposed in transporting or permanent storage containers. The compact blocks are produced from prefabricated ceramic tablets which contain radioactive substances and a matrix which continuously surrounds these ceramic tablets and is solid in its final state. Glass powder or a mixture of oxidic non-clay minerals or a mixture of both is used as the matrix material. The ceramic tablets and the matrix material are filled into the container and are compressed. The resulting compressed mixture is heated to a temperature in the range from 1423/sup 0/ K. to 1623/sup 0/ K., is held at this temperate range for one to three hours, and is finally gradually cooled to room temperature.

  13. Comparison of metals extractability from Al/Fe-based drinking water treatment residuals.

    PubMed

    Wang, Changhui; Bai, Leilei; Pei, Yuansheng; Wendling, Laura A

    2014-12-01

    Recycling of drinking water treatment residuals (WTRs) as environment amendments has attracted substantial interest due to their productive reuse concomitant with waste minimization. In the present study, the extractability of metals within six Al/Fe-hydroxide-comprised WTRs collected throughout China was investigated using fractionation, in vitro digestion and the toxicity characteristic leaching procedure (TCLP). The results suggested that the major components and structure of the WTRs investigated were similar. The WTRs were enriched in Al, Fe, Ca, and Mg, also contained varying quantities of As, Ba, Be, Cd, Co, Cr, Cu, K, Mn, Mo, Na, Ni, Pb, Sr, V, and Zn, but Ag, Hg, Sb, and Se were not detected. Most of the metals within the WTRs were largely non-extractable using the European Community Bureau of Reference (BCR) procedure, but many metals exhibited high bioaccessibility based on in vitro digestion. However, the WTRs could be classified as non-hazardous according to the TCLP assessment method used by the US Environmental Protection Agency (USEPA). Further analysis showed the communication factor, which is calculated as the ratio of total extractable metal by BCR procedure to the total metal, for most metals in the six WTRs, was similar, whereas the factor for Ba, Mn, Sr, and Zn varied substantially. Moreover, metals in the WTRs investigated had different risk assessment code. In summary, recycling of WTRs is subject to regulation based on assessment of risk due to metals prior to practical application. PMID:25023656

  14. Degradation behaviour of Al-Fe coatings in wet-seal area of molten carbonate fuel cells

    NASA Astrophysics Data System (ADS)

    Jun, JaeHo; Jun, JoongHwan; Kim, KyooYoung

    The corrosion resistance of Al-Fe coatings increases as a protective LiAlO 2 layer forms. If, however, the Al-Fe coatings lack sufficient aluminium for maintaining this protective layer, the corrosion resistance of the coating is degraded by the growth of non-protective scales, such as LiFeO 2. In this study, the degradation behaviour of Al-Fe coatings is investigated in the wet-seal environment of molten carbonate fuel cells (MCFC). Al-Fe coated specimens with various amounts of aluminium in the range 8-70 at.% and bulk specimens of Fe-23.9 Al (at.%) are prepared. A corrosion test is performed in Li/K carbonate systems at 650 °C with a single-cell and an immersion test. Test results reveal that aluminium contents in the coatings should be higher than 25 at.% in order to form and maintain a protective LiAlO 2 layer. In addition to aluminium content, the influence of microstructural features on the degradation behaviour of Al-Fe coatings is discussed.

  15. Effects of metallurgical parameters on the decomposition of pi-AlFeMgSi phase in Al-Si-Mg alloys and its influence on the mechanical properties

    NASA Astrophysics Data System (ADS)

    Elsharkawi, Ehab A.

    2011-12-01

    The formation of the pi-AlFeMgSi iron intermetallic phase in Al-Si-Mg alloys is known for its detrimental effect on ductility and strength, in that it is controlled by the Fe and Mg content of the alloy, as well as by the cooling rate. The current study was carried out with a view to investigating all the metallurgical parameters affecting the formation of the pi-phase iron intermetallic and, in turn, the role of the pi-phase as it relates to the tensile and impact properties of Al-Si-Mg alloys. Microstructural assessment was carried out by means of quantitative metallography using electron probe microanalysis (EPMA) and scanning electron microscopy (SEM). The results indicate that increasing the Mg and Fe content increases the amount of the pi-AlMgFeSi phase formed. All the alloys containing low levels of iron regardless of the amount of Mg-content show low amounts of pi-phase iron intermetallic. The addition of trace amounts of Be has an observable effect in reducing the amount of the pi-phase formed in all the alloys studied. The pi-phase iron intermetallic particles appear to be segregated away from the modified Si in the Sr-modified alloys, particularly those solidified at a low cooling rate. The effects of different solution treatment times on the decomposition of the pi-phase were investigated in order to examine how this type of decomposition affected the chemistry of the matrix itself. After 8 hours of solution heat treatment and at Mg content of 0.4wt%, the pi-phase showed complete decomposition into fine beta-phase needles. The a-phase, however, showed only partial decomposition into beta-AlFeSi phase needles at Mg levels of over 0.4%wt. This type of decomposition was examined for the purposes of this study over extended periods of solution heat treatment time in Al-7Si-0.55Mg-0.1Fe alloy samples obtained at different cooling rates in order to evaluate the mechanism of pi to beta-phase decomposition. The results obtained show that the volume fraction of

  16. Growth and characterization of insulating ferromagnetic semiconductor (Al,Fe)Sb

    NASA Astrophysics Data System (ADS)

    Anh, Le Duc; Kaneko, Daiki; Hai, Pham Nam; Tanaka, Masaaki

    2015-12-01

    We investigate the crystal structure, transport, and magnetic properties of Fe-doped ferromagnetic semiconductor (Al1-x,Fex)Sb thin films up to x = 14% grown by molecular beam epitaxy. All the samples show p-type conduction at room temperature and insulating behavior at low temperature. The (Al1-x,Fex)Sb thin films with x ≤ 10% maintain the zinc blende crystal structure of the host material AlSb. The (Al1-x,Fex)Sb thin film with x = 10% shows intrinsic ferromagnetism with a Curie temperature (TC) of 40 K. In the (Al1-x,Fex)Sb thin film with x = 14%, a sudden drop of the hole mobility and TC was observed, which may be due to the microscopic phase separation. The observation of ferromagnetism in (Al,Fe)Sb paves the way to realize a spin-filtering tunnel barrier that is compatible with well-established III-V semiconductor devices.

  17. Exchange bias effects in Heusler alloy Ni2MnAl/Fe bilayers

    NASA Astrophysics Data System (ADS)

    Tsuchiya, Tomoki; Kubota, Takahide; Sugiyama, Tomoko; Huminiuc, Teodor; Hirohata, Atsufumi; Takanashi, Koki

    2016-06-01

    Ni2MnAl Heusler alloy thin films were epitaxially grown on MgO(1 0 0) single crystal substrates by ultra-high-vacuum magnetron sputtering technique. X-ray diffraction and transmission electron microscopy observation revealed that the structures of all the Ni2MnAl thin films were B2-ordered regardless of the deposition temperature ranging from room temperature to 600 °C. The temperature dependence of electrical resistivity showed a kink about 280 K, which was consistent with a reported value of the Néel temperature for antiferromagnetic B2-Ni2MnAl. The magnetization curves of Ni2MnAl/Fe bilayer samples showed a shift caused by the interfacial exchange interaction at 10 K. The maximum value of the exchange bias field H ex was 55 Oe corresponding to the exchange coupling energy J k of 0.03 erg cm‑2.

  18. On the mechanism of milling induced disordering in AlFe

    SciTech Connect

    Clavaguera-Mora, M.T.; Zhu, J.; Meyer, M.; Mendoza-Zelis, L.; Sanchez, F.H.; Clavaguera, N.

    1997-12-31

    The evolution of the B2-AlFe phase during mechanical grinding in Ar has been examined as a function of milling time by X-Ray diffraction, transmission Moessbauer spectroscopy and differential scanning calorimetry. Short and long range disorder was observed to increase with the mechanical treatment up to the attainment of a steady state. The evolution of the long range order parameter and of the local atomic configurations at Fe sites were analyzed in terms of possible mechanisms for milling induced disordering. The kinetics of the thermal reordering was studied under continuous heating and isothermal calorimetric regimes. Modeling of the reordering processes by diffusion controlled growth of pre-existing ordered grains is presented as well as the estimated values of both the enthalpy and the activation energy of the reordering process. The results are consistent with a nonuniform distribution of disorder throughout the sample and will be compared with preceding information on related systems.

  19. Morphology and phase evolution in microwave synthesized Al/FeO4 system.

    PubMed

    Chuan, Lee Chang; Yoshikawaa, Noboru; Taniguchia, Shoji

    2011-01-01

    Thermite reaction between Al/Fe3O4 raised by microwave (MW) heating under N2 atmosphere has been investigated, and compared with that by the electric furnace. In addition to the stoichiometric ratio for the production of metallic iron and alumina, mixture with slightly Lower in Al content is also studied. As thermite reaction is highly exothermic, melting of reaction product and destruction of microstructure may occur, which corresponds to the enthalpy and adiabatic temperature of the reaction. Hence, to avoid this problem, reaction coupled with a smaller driving force by controlling the MW ignition condition at low temperature exotherm has been investigated. The phase and microstructure evolution during the reaction were analyzed by differential thermal analysis (DTA), X-ray diffraction (XRD), and scanning electron microscopy (SEM). Thermogram of the DTA analysis, irrespective of their mole ratio, recorded two exothermic peaks, one at - 1310 degrees C and another one at - 1370 degrees C. When heated by microwave at 955 degrees C, the main products were identified as Al, FeO and Fe, minor amount of Fe3O4 and some Fe and alumina were detected. When heating to 1155 degrees C, Al and Fe3O4 peaks disappeared, formation of Fe-Al alloy was observed. For sample heated at 1265 degrees C, a porous body was obtained. Micron sized metal particles with complex morphology, irregular in size and shapes were formed, uniformly distributed within the spinel hercynite and/or alumina matrix. In contrast, conventional heating produced no porous products. Formation of alumina is also observed around the metal particles. Controlling of the reaction progress was possible while heating the sample by MW around the low temperature exotherm region, whereas the combustion wave could not be self-propagated. PMID:24427878

  20. Al-Ca and Al-Fe metal-metal composite strength, conductivity, and microstructure relationships

    SciTech Connect

    Kim, Hyong June

    2011-01-01

    Deformation processed metal-metal composites (DMMC’s) are composites formed by mechanical working (i.e., rolling, swaging, or wire drawing) of two-phase, ductile metal mixtures. Since both the matrix and reinforcing phase are ductile metals, the composites can be heavily deformed to reduce the thickness and spacing of the two phases. Recent studies have shown that heavily drawn DMMCs can achieve anomalously high strength and outstanding combinations of strength and conductivity. In this study, Al-Fe wire composite with 0.07, 0.1, and 0.2 volume fractions of Fe filaments and Al-Ca wire composite with 0.03, 0.06, and 0.09 volume fractions of Ca filaments were produced in situ, and their mechanical properties were measured as a function of deformation true strain. The Al-Fe composites displayed limited deformation of the Fe phase even at high true strains, resulting in little strengthening effect in those composites. Al-9vol%Ca wire was deformed to a deformation true strain of 13.76. The resulting Ca second-phase filaments were deformed to thicknesses on the order of one micrometer. The ultimate tensile strength increased exponentially with increasing deformation true strain, reaching a value of 197 MPa at a true strain of 13.76. This value is 2.5 times higher than the value predicted by the rule of mixtures. A quantitative relationship between UTS and deformation true strain was determined. X-ray diffraction data on transformation of Al + Ca microstructures to Al + various Al-Ca intermetallic compounds were obtained at the Advanced Photon Source at Argonne National Laboratory. Electrical conductivity was measured over a range of true strains and post-deformation heat treatment schedules.

  1. Floc properties of polyaluminum ferric chloride in water treatment: The effect of Al/Fe molar ratio and basicity.

    PubMed

    Cao, Baichuan; Gao, Baoyu; Wang, Mengmeng; Sun, Xiaomei; Wang, Jin

    2015-11-15

    Producing flocs with desired properties is significant for contaminants removal in water treatment works. In this study, an inorganic composite coagulant, polyaluminum ferric chloride (PAFC), was prepared and used in surface water treatment, and the influence of Al/Fe molar ratio and basicity (B) on floc properties was investigated. The contribution of metal species analysis showed a competition relationship between Al and Fe in the pre-hydrolysis, while the monomeric contents decreased with the increase of B value. The investigation of floc properties was conducted on a laser scattering instrument, in terms of floc size, strength, recovery capacity and fractal dimension (Df). The largest floc size and the highest growth rate was achieved when Al/Fe=7:1 and B=1.5. Floc formed at the Al/Fe ratios of 5:1 and 7:1 were considered to be more compact. Meanwhile, the Df value increased when B value was increased. At Al/Fe=7:1 and B=1.5, strongest flocs were obtained. During the breakage period, the Df value increased. As lower shear was replaced, the floc size decreased continuously, with a further increase of Df value. However, after breakage at higher shear, all of the PAFC flocs showed capacity for regrowth and loose structures were formed. PMID:26232731

  2. Room temperature nonlinear magnetoelectric effect in lead-free and Nb-doped AlFeO{sub 3} compositions

    SciTech Connect

    Cótica, Luiz F.; Santos, Guilherme M.; Santos, Ivair A.; Freitas, Valdirlei F.; Coelho, Adelino A.; Pal, Madhuparna; Guo, Ruyan; Bhalla, Amar S.; Garcia, Ducinei; Eiras, José A.

    2015-02-14

    It is still a challenging problem to obtain technologically useful materials displaying strong magnetoelectric coupling at room temperature. In the search for new effects and materials to achieve this kind of coupling, a nonlinear magnetoelectric effect was proposed in the magnetically disordered relaxor ferroelectric materials. In this context, the aluminum iron oxide (AlFeO{sub 3}), a room temperature ferroelectric relaxor and magnetic spin glass compound, emerges as an attractive lead-free magnetoelectric material along with nonlinear magnetoelectric effects. In this work, static, dynamic, and temperature dependent ferroic and magnetoelectric properties in lead-free AlFeO{sub 3} and 2 at. % Nb-doped AlFeO{sub 3} multiferroic magnetoelectric compositions are studied. Pyroelectric and magnetic measurements show changes in ferroelectric and magnetic states close to each other (∼200 K). The magnetoelectric coefficient behavior as a function of H{sub bias} suggests a room temperature nonlinear magnetoelectric coupling in both single-phase and Nb-doped AlFeO{sub 3}-based ceramic compositions.

  3. Speciation of Al, Fe, and P in recent sediment from three lakes in Maine, USA.

    PubMed

    Norton, Stephen A; Coolidge, Kyle; Amirbahman, Aria; Bouchard, Roy; Kopácek, Jirí; Reinhardt, Raquel

    2008-10-15

    Sequential extraction of sediments [Psenner R, Pucsko R. Die Fraktionierung organischer und anorganischer Phosphorverbindungen von Sedimenten. Arch Hydrobiol/Suppl 1988. 70(1): 111-155.] from short, (210)Pb-dated cores from three lakes in Maine USA demonstrates that sediment P is dominantly associated with the NaOH-extractable fraction (P-NaOH(25)) and less with the bicarbonate-dithionite extractable fraction (P-BD). The ratios (Al-NaOH(25))/(Fe-BD) and (Al-NaOH(25))/(P-NH(4)Cl+P-BD) for upper sediment for two oligo-mesotrophic lakes exceeded 3 and 25, the thresholds for preventing substantial release of P from sediments during hypolimnetic anoxia [Kopácek J, Borovec J, Hejzlar J, Ulrich K-U, Norton SA, Amirbahman A. Aluminum control of phosphorus sorption by lake sediments. Environ Sci Technol 2005a;39:8784-8789.]. Hypolimnetic water chemistry verifies this effect. The third lake, currently eutrophic, has values for the ratios that are below the thresholds and this lake has substantial release of P from recent sediment. The sediment characteristics remain relatively constant over the last 150+ years, indicating that the processes responsible for P retention have operated long before atmospheric acidification of watersheds might have influenced the flux of Al and Fe to the lake. In 2002, the pH of inlets and the lakes was generally between 6 and 8. Input to the lakes had high concentrations of acid-soluble particulate and dissolved Al, Fe, and P, and dissolved Al and Fe complexed with dissolved organic carbon (DOC). Lake water column and outlet Al, Fe, and P were typically 90-95% lower than inlet concentrations over a 12 month period. Photo-oxidation of Al-DOC and Fe-DOC in the lake, liberation of inorganic Al and Fe, precipitation of Al(OH)(3) and Fe(OH)(3), adsorption of P by the hydroxides, and sedimentation are responsible for the changes in water quality and long-term sediment characteristics. PMID:18440053

  4. Growth and characterization of insulating ferromagnetic semiconductor (Al,Fe)Sb

    SciTech Connect

    Anh, Le Duc Kaneko, Daiki; Tanaka, Masaaki; Hai, Pham Nam

    2015-12-07

    We investigate the crystal structure, transport, and magnetic properties of Fe-doped ferromagnetic semiconductor (Al{sub 1−x},Fe{sub x})Sb thin films up to x = 14% grown by molecular beam epitaxy. All the samples show p-type conduction at room temperature and insulating behavior at low temperature. The (Al{sub 1−x},Fe{sub x})Sb thin films with x ≤ 10% maintain the zinc blende crystal structure of the host material AlSb. The (Al{sub 1−x},Fe{sub x})Sb thin film with x = 10% shows intrinsic ferromagnetism with a Curie temperature (T{sub C}) of 40 K. In the (Al{sub 1−x},Fe{sub x})Sb thin film with x = 14%, a sudden drop of the hole mobility and T{sub C} was observed, which may be due to the microscopic phase separation. The observation of ferromagnetism in (Al,Fe)Sb paves the way to realize a spin-filtering tunnel barrier that is compatible with well-established III-V semiconductor devices.

  5. Transformation of polymetallic dust in the organic horizon of Al-Fe-humus podzol (field experiment)

    NASA Astrophysics Data System (ADS)

    Lyanguzova, I. V.; Goldvirt, D. K.; Fadeeva, I. K.

    2015-07-01

    Scanning electron microscopy with an X-ray spectral microanalysis showed that the ash matter from the organic horizons (after ignition) of control and experimental plots mainly (>85%) consists of different soil-forming minerals and iron oxides (particularly magnetite). From 10% to 15% of particles in the organic horizon of Al-Fe-humus podzol (Albic Rustic Podzol) of the experimental plot were represented by polymetallic ball-shaped dust particles that were preserved in the soil without significant transformation for 14 years after their artificial application. The total contents of Cu, Pb, As, and Ni in the organic horizon on the experimental plot were 22-100 times higher than those in the control; the contents of Zn and Fe were 2-5 times higher. The sequence of chemical elements according to their total contents in the samples of control and experimental plots was different. The portion of available forms of heavy metal (Ni, Cu, and Co) compounds extractable with 1.0 M HCl averaged 20-30% of their total contents in the soil. More than 80% of acid-soluble forms of heavy metals were concentrated in the organic horizon of contaminated podzol soil, which represents the biogeochemical barrier to the migration of pollutants down the soil profile. Durable fixation of heavy metals in the organic horizon and their weak migration into the mineral soil layers significantly hamper the processes of self-purification of contaminated soils.

  6. CWPO of 4-CP and industrial wastewater with Al-Fe pillared clays.

    PubMed

    Molina, C B; Zazo, J A; Casas, J A; Rodriguez, J J

    2010-01-01

    Catalysts based on pillared clays with Al-Fe have been synthesised from a commercial bentonite and tested for catalytic wet peroxide oxidation (CWPO) of aqueous 4-Chlorophenol (4-CP) solution and industrial wastewater from cosmetics manufacture. The effect of the synthesis procedure, the iron load and reaction temperature on the catalytic activity was studied using 4-CP as target compound. A lower temperature in the preparation of the pillaring solution, as well as a higher Fe load, gave rise to a higher catalytic activity, but also a higher leaching of the active phase. The best catalyst, in terms of catalytic activity, was also tested for treating cosmetic wastewater by CWPO. Experiments were carried out at 90 degrees C and atmospheric pressure and the influence of Fe load, catalyst concentration and H(2)O(2)/COD ratio (between 0.5 and 2 times the stoichiometric ratio) were analysed. Higher values of these parameters favour COD reduction. The Fe leaching in all cases was lower than 1.2 mg/L, indicating that these catalysts have a high stability under these experimental conditions. PMID:20389016

  7. FP-LAPW study of structural, electronic, elastic, mechanical and thermal properties of AlFe intermetallic

    NASA Astrophysics Data System (ADS)

    Jain, Ekta; Pagare, Gitanjali; Sanyal, S. P.

    2016-05-01

    The structural, electronic, elastic, mechanical and thermal properties of AlFe intermetallic compound in B2-type (CsCl) structure have been investigated using first-principles calculations. The exchange-correlation term was treated within generalized gradient approximation. Ground state properties i.e. lattice constants (a0), bulk modulus (B) and first-order pressure derivative of bulk modulus (B') are presented. The density of states are derived which show the metallic character of present compound. Our results for C11, C12 and C44 agree well with previous theoretical data. Using Pugh's criteria (B/GH < 1.75), brittle character of AlFe is satisfied. In addition shear modulus (GH), Young's modulus (E), sound wave velocities and Debye temperature (θD) have also been estimated.

  8. Critical Assessment and Thermodynamic Modeling of the Al-Fe-O System

    NASA Astrophysics Data System (ADS)

    Shishin, Denis; Prostakova, Viktoria; Jak, Evgueni; Decterov, Sergei A.

    2016-02-01

    A complete literature review, critical evaluation, and thermodynamic modeling of the phase diagrams and thermodynamic properties of phases in the Al-Fe-O system at 1 atm total pressure are presented. Optimized model equations for the thermodynamic properties of all phases are obtained, which reproduce all available thermodynamic and phase-equilibrium data within experimental error limits from 298.15 K (25 °C) to above the liquidus temperatures at all compositions and oxygen partial pressures from metal saturation to 1 atm. The complex phase relationships in the system have been elucidated, and discrepancies among the data have been resolved. The database of the model parameters can be used along with software for Gibbs-energy minimization in order to calculate all thermodynamic properties and any type of phase diagram section. The modified quasichemical model was used for the liquid oxide phase. A sublattice model, based upon the Compound Energy Formalism, was developed for spinel, which expands from magnetite, Fe3O4, to hercynite, FeAl2O4. The distribution of cations between octahedral and tetrahedral sites and oxygen nonstoichiometry in spinel are taken into account. The model for metallic liquid assumes random mixing of associates: Fe, Al, O, AlO, and Al2O. It describes well the minimum that is observed on the solubility of oxygen in liquid iron as a function of the Al content. The solid solution between hematite and corundum exhibiting a miscibility gap, as well as a small solubility of Al2O3 in wüstite are quantitatively described by a simple Bragg-Williams model.

  9. Synthesis of Cd/(Al+Fe) layered double hydroxides and characterization of the calcination products

    SciTech Connect

    Perez, M.R.; Barriga, C.; Fernandez, J.M.; Rives, V.; Ulibarri, M.A.

    2007-12-15

    Layered double hydroxides (LDHs) containing Cd(II), Al(III), and Fe(III) in the brucite-like layers with different starting Fe/Al atomic ratios and with nitrate as counteranion have been prepared following the coprecipitation method at a constant pH value of 8. An additional Cd(II),Al(III)-LDH sample interlayered with hexacyanoferrate(III) ions has been prepared by ionic exchange at pH 9. The samples have been characterized by elemental chemical analysis, powder X-ray diffraction (PXRD), and FT-IR spectroscopy. Their thermal stability has been assessed by thermogravimetric and differential thermal analyses (TG-DTA) and mass spectrometric analysis of the evolved gases. The PXRD patterns of the solids calcined at 800 deg. C show diffraction lines corresponding to Cd(Al)O and spinel-type materials, which precise nature (CdAl{sub 2}O{sub 4}, Cd{sub 1-x}Fe{sub 2+x}O{sub 4}, or Cd{sub x}Fe{sub 2.66}O{sub 4}) depends on location and concentration of iron in the parent material or precursor. - Graphical abstract: Layered double hydroxides (LDHs) containing Cd(II), Al(III), and Fe(III) in the brucite-like layers with different starting Fe/Al atomic ratios and with nitrate as counteranion have been prepared following the coprecipitation method. An additional Cd(II),Al(III)-LDH sample interlayered with hexacyanoferrate(III) ions has been prepared by ionic exchange. Calcination at 800 deg. C shows diffraction lines corresponding to CdO and to spinel-type materials. SEM micrograph of sample CdAlFe-N-0.

  10. X-rays structural analysis and thermal stability studies of the ternary compound {alpha}-AlFeSi

    SciTech Connect

    Roger, J.; Bosselet, F.; Viala, J.C.

    2011-05-15

    From literature data presently available, the decomposition temperature and the nature of the decomposition reaction of the ternary compound {alpha}-AlFeSi (also designated as {alpha}{sub H} or {tau}{sub 5}) are not clearly identified. Moreover, some uncertainties remain concerning its crystal structure. The crystallographic structure and thermochemical behaviour of the ternary compound {alpha}-AlFeSi were meticulously studied. The crystal structure of {alpha}-AlFeSi was examined at room temperature from X-ray single crystal intensity data. It presents hexagonal symmetry, space group P6{sub 3}/mmc with unit cell parameters (293 K) a=12.345(2) A and c=26.210(3) A (V=3459 A{sup 3}). The average chemical formula obtained from refinement is Al{sub 7.1}Fe{sub 2}Si. From isothermal reaction-diffusion experiments and Differential Thermal Analysis, the title compound decomposes peritectically upon heating into {theta}-Fe{sub 4}Al{sub 13}(Si), {gamma}-Al{sub 3}FeSi and a ternary Al-rich liquid. Under atmospheric pressure, the temperature of this reversible transformation has been determined to be 772{+-}12 {sup o}C. -- Graphical abstract: Partial representation of the crystal structure of the {alpha}-Al{sub 7.1}Fe{sub 2}Si compound. Display Omitted Highlights: The main findings of our work are: {yields} a detailed X-rays crystal structure determination of the ternary compound {alpha}-AlFeSi. {yields} The precision of the silicon atoms positions in the crystal structure. {yields} A precised determination of the decomposition temperature of this compound.

  11. Major soil element (Ca, Mg, K, Na, Al, Fe) distribution along the Qinghai-Tibet Railway

    NASA Astrophysics Data System (ADS)

    Wang, Z.; Zhang, Y.; Zhang, H.; Ding, M.; Lin, X.

    2011-12-01

    The Tibetan Plateau (TP), which has been called the third polar region, is the highest plateau in the world. There are a series of special soils present in the TP, which are extremely important in soil sciences for their particularities. Soil chemical composition is one of the necessary indices of soil characteristics. The major element content of the soil, such as Ca, Mg, K, Na, not only can affect the soil pH value and soil fertility but also are the main drivers of soil geochemical processes. It is helpful to understand the TP environmental characteristics, to study the major soil element content.The Qinghai-Tibet Railway (QTR) is the highest-elevation and the longest highland railway on earth. There are nearly all types of TP soil along the QTR. Most of the areas along the QTR are in fairly pristine condition. This offers a good platform to study the natural environmental characteristics of the soil. This study selected 240 soil samples from 28 sample areas along the Qinghai-Tibet Railway, and the aluminum, iron, calcium, sodium, potassium and magnesium content in the soil were measured with ICP-AES. The results indicated: (1) Compared with the national soil background values, the Ca content in soil was higher along the QTR and Al was lower; but the Fe, Mg, K and Na contents were similar. (2) Along the whole QTR, the soil Al, Fe and Mg content showed a decreasing trend from Xining to Lhasa, the changes in K and Na values were relatively complex, and the distribution of Ca could be divided three sections. (3) The soil element contents varied with different soil types and parent materials. Most of the six elements content was minimum in soil, which derived from debris materials for ice and water, and the elements content was maximum in soil, which evolved from debris for flood, and the content of soil Ca developed from debris for lake was maximum. The amount of each element present in the Hapli-Cryic Aridosols and Calci-Cryic Aridosols was relatively higher than

  12. Determination of acute Hg emissions from solidified/stabilized cement waste forms

    SciTech Connect

    Hamilton, W.P.; Bowers, A.R.

    1997-12-31

    The chemical form of mercury in wastes to be solidified/stabilized may lead to volatile losses from the finished solidified/stabilized monolith. Elemental mercury vapor (Hg vapor) was detected in the headspace of batch reactors that contained solidified/stabilized ordinary Portland cement doped with mercuric oxide (HgO) or liquid elemental mercury [Hg{degree}(1)]. Vapor concentrations increased as a function of time and temperature; the headspace over the HgO samples was saturated in about one hour, while the samples containing Hg{degree}(1) reached approx. 20% of saturation in about two hours. Increased temperatures due to cement hydrolysis lead to increased Hg vapor evolution. Mercury solidified/stabilized as mercuric sulfide (HgS, black) emitted no Hg vapor. Data for the HgO and Hg{degree}(1) experiments were fit to a reversible first-order rate expression. Samples containing HgO displayed the greatest volatility as a result of the rapid dissolution of HgO and the subsequent formation of a strong driving force across the air-water interface. The evolution of Hg vapor from samples solidified/stabilized as Hg{degree}(1) is limited by mass transfer resistances that kinetically limit the dissolution of Hg{degree}(1) into the aqueous phase. The inert character of HgS prevents the evolution of detectable Hg in wastes solidified/stabilized as HgS. The findings of these studies may be important when considering treatment and disposal scenarios for Hg-containing wastes.

  13. Instability of a solidifying binary mixture

    NASA Technical Reports Server (NTRS)

    Antar, B. N.

    1982-01-01

    An analysis is performed on the stability of a solidifying binary mixture due to surface tension variation of the free liquid surface. The basic state solution is obtained numerically as a nonstationary function of time. Due to the time dependence of the basic state, the stability analysis is of the global type which utilizes a variational technique. Also due to the fact that the basic state is a complex function of both space and time, the stability analysis is performed through numerical means.

  14. Solidifying Cast Iron in Low Gravity

    NASA Technical Reports Server (NTRS)

    Hendrix, J. C.; Curreri, P. A.; Stefanescu, D. M.

    1986-01-01

    Report describes study of solidification of cast iron in low and normal gravity. Because flotation, sedimentation, and convection suppressed, alloys that solidify at nearly zero gravity have unusual and potentially useful characteristics. Study conducted in airplane that repeatedly flew along parabolic trajectories. Appears iron/carbon alloys made at low gravity have greater carbon content (as high as 5 to 10 percent) than those made of Earth gravity because carbon particles do not float to top of melt.

  15. Directionally solidified article with weld repair

    NASA Technical Reports Server (NTRS)

    Smashey, Russell W. (Inventor); Snyder, John H. (Inventor); Borne, Bruce L. (Inventor)

    2003-01-01

    A directionally solidified nickel-base superalloy article has a defect therein extending parallel to the solidification direction. The article is repaired by removing any foreign matter present in the defect, and then heating the article to a repair temperature of from about 60 to about 98 percent of the solidus temperature of the base material in a chamber containing a protective gas that inhibits oxidation of the base material. The defect is filled with a filler metal while maintaining the article at the repair temperature. The filling is accomplished by providing a source of the filler metal of substantially the same composition as the base material of the directionally solidified article, and melting the filler metal into the defect progressively while moving the source of the filler metal relative to the article in a direction parallel to the solidification direction. Optionally, additional artificial heat extraction is accomplished in a heat-flow direction that is within about 45 degrees of the solidification direction, as the filler metal solidifies within the defect. The article may thereafter be heat treated.

  16. Weld repair of directionally solidified articles

    NASA Technical Reports Server (NTRS)

    Smashey, Russell W. (Inventor); Snyder, John H. (Inventor); Borne, Bruce L. (Inventor)

    2002-01-01

    A directionally solidified nickel-base superalloy article has a defect therein extending parallel to the solidification direction. The article is repaired by removing any foreign matter present in the defect, and then heating the article to a repair temperature of from about 60 to about 98 percent of the solidus temperature of the base material in a chamber containing a protective gas that inhibits oxidation of the base material. The defect is filled with a filler metal while maintaining the article at the repair temperature. The filling is accomplished by providing a source of the filler metal of substantially the same composition as the base material of the directionally solidified article, and melting the filler metal into the defect progressively while moving the source of the filler metal relative to the article in a direction parallel to the solidification direction. Optionally, additional artificial heat extraction is accomplished in a heat-flow direction that is within about 45 degrees of the solidification direction, as the filler metal solidifies within the defect. The article may thereafter be heat treated.

  17. Magnetocaloric effect in AlFe2B2: toward magnetic refrigerants from earth-abundant elements.

    PubMed

    Tan, Xiaoyan; Chai, Ping; Thompson, Corey M; Shatruk, Michael

    2013-06-26

    AlFe2B2 was prepared by two alternative synthetic routes, arc melting and synthesis from Ga flux. In the layered crystal structure, infinite chains of B atoms are connected by Fe atoms into two-dimensional [Fe2B2] slabs that alternate with layers of Al atoms. As expected from the theoretical analysis of electronic band structure, the compound exhibits itinerant ferromagnetism, with the ordering temperature of 307 K. The measurement of magnetocaloric effect (MCE) as a function of applied magnetic field reveals isothermal entropy changes of 4.1 J kg(-1) K(-1) at 2 T and 7.7 J kg(-1) K(-1) at 5 T. These are the largest values observed near room temperature for any metal boride and for any magnetic material of the vast 122 family of layered structures. Importantly, AlFe2B2 represents a rare case of a lightweight material prepared from earth-abundant, benign reactants which exhibits a substantial MCE while not containing any rare-earth elements. PMID:23731263

  18. Particle Engulfment and Pushing by Solidifying Interfaces

    NASA Technical Reports Server (NTRS)

    Stefanescu, Doru M.; Juretzko, Frank R.; Dhindaw, Brij K.; Sen, Subhayu; Curren, Peter A.

    1999-01-01

    The scientific objectives of the work on Particle Engulfment and Pushing by Solidifying Interfaces (PEP) include: (1) to enhance the fundamental understanding of the physics of interaction between inert particles and the solidification interface, and (2) to investigate aspects of melt processing of particulate metal matrix composites in the unique microgravity environment that will yield some vital information for terrestrial applications. The proposal itself calls for a long-term effort on the Space Station. This paper reports on ground experiments performed to date, as well as on the results obtained from two flight opportunities, the LMS mission (1996) and the USMP-4 mission (1997).

  19. Characterization of directionally solidified lead chloride

    NASA Technical Reports Server (NTRS)

    Singh, Narsingh Bahadur; Duval, W. M. B.; Rosenthal, B. N.

    1988-01-01

    A directionally solidified PbCl2 material was prepared and analyzed and subsequently used to grow single crystals. It was found that silicon, halogens, sulfur, magnesium, and phosphorus were the hardest impurities to remove by the single-pass directional freezing. Single crystals grown from the purified material displayed good scattering beam quality and showed no absorption peaks between 0.30 to 20 microns. Direct photographic observations of the solid-liquid interface at several G/V (denoting the temperature gradient and the translation velocity, respectively) ratio values showed that, as the G/V ratio decreased, the interface varied from a smooth convex surface to dendritic.

  20. Fabrication of a novel light emission material AlFeO3 by a modified polyacrylamide gel route and characterization of the material

    NASA Astrophysics Data System (ADS)

    Wang, Shi-Fa; Zhang, Chuanfei; Sun, Guangai; Chen, Bo; Xiang, Xia; Wang, Hong; Fang, Leiming; Tian, Qiang; Ding, Qingping; Zu, XiaoTao

    2013-12-01

    AlFeO3 powders have been prepared by a modified polyacrylamide gel method and their thermal expansion and photoluminescence properties have been studied for the first time. The phase, morphology and thermal expansion behavior of as-prepared samples were analyzed via X-ray diffraction (XRD), Scanning electron microscope (SEM), and thermal dilatometer. XRD analysis indicates that the as-synthesized AlFeO3 has the same structure as α-Fe2O3 without the presence of any other impurities. SEM observation shows that the morphology of AlFeO3 powder is significantly dependent on the sintering temperature. The thermal expansion and differential scanning calorimetry (DSC) curves of AlFeO3 sample analysis indicates that a phase transition near 700 °C. The crystal growth mechanisms, coordination mechanisms, phase transformation process and luminescence mechanisms of AlFeO3 have been discussed on the basis of the experimental results. The blue light emission at 2.76 eV is due to intracenter 4T1 → 6A1 transitions in Fe3+ ions.

  1. On the Influence of Dispersoids on the Particle Stimulated Nucleation of Recrystallization in an Al-Fe-Si Model Alloy

    SciTech Connect

    Engler, O.

    1997-12-31

    The recrystallization of Al-alloys is controlled by precipitates. Whereas large particles generally promote recrystallization by particle stimulated nucleation, finely dispersed precipitates - either already present in the as-deformed state or precipitating during the recrystallization anneal - are known to strongly retard recrystallization. It was the aim of the present study to elucidate these concurring effects of large particles and small dispersoids on recrystallization in a ternary Al-Fe-Si model alloy. For that purpose, samples were prepared according to different pre-annealing treatments so as to comprise different states of precipitation and supersaturation. The evolution of microstructure and texture during rolling and recrystallization was characterized by metallography and by conventional X-ray texture analysis. EBSD-local texture investigations were employed to yield information on the efficiency of nucleation at the various nucleation sites and, consequently, on the influence of dispersoids on recrystallization.

  2. Structure and magnetic properties of a Ni3(Al, Fe, Cr) single crystal subjected to high-temperature deformation

    NASA Astrophysics Data System (ADS)

    Kazantseva, N. V.; Rigmant, M. B.; Stepanova, N. N.; Davydov, D. I.; Shishkin, D. A.; Terent'ev, P. B.; Vinogradova, N. I.

    2016-05-01

    The structure and magnetic properties of the Ni3(Al, Fe, Cr) single crystal subjected to high-temperature tensile deformation to failure at 850-900°C have been studied. No recrystallized grains and metastable phases were found. The rupture zone of the alloy subjected to deformation (at 900°C) to the highest degree demonstrates the fragmentation accompanied by rotation of atomic layers and changes of the chemical composition in the nickel and aluminum sublattices. Magnetic studies of the alloy have shown the existence of two Curie temperatures for samples cut from the rupture zone. Samples cut away from the rupture zone exhibit no additional magnetic transitions; twines and planar stacking faults in the alloy structure. The alloy deformed to the lower degree of deformation (at 850°C) also demonstrates twins; no ferromagnetic state was found to form.

  3. AFM study of the effects of laser surface remelting on the morphology of Al-Fe aerospace alloys

    SciTech Connect

    Pariona, Moises Meza; Teleginski, Viviane; Santos, Kelly dos; Leandro Ribeiro dos Santos, Everton; Aparecida de Oliveira Camargo de Lima, Angela; Riva, Rudimar

    2012-12-15

    Laser beam welding has recently been incorporated into the fabrication process of aircraft and automobile structures. Surface roughness is an important parameter of product quality that strongly affects the performance of mechanical parts, as well as production costs. This parameter influences the mechanical properties such as fatigue behavior, corrosion resistance, creep life, etc., and other functional characteristics such as friction, wear, light reflection, heat transmission, lubrification, electrical conductivity, etc. The effects of laser surface remelting (LSR) on the morphology of Al-Fe aerospace alloys were examined before and after surface treatments, using optical microscopy (OM), scanning electron microscopy (SEM), low-angle X-ray diffraction (LA-XRD), atomic force microscopy (AFM), microhardness measurements (Vickers hardness), and cyclic voltammetry. This analysis was performed on both laser-treated and untreated sanded surfaces, revealing significant differences. The LA-XRD analysis revealed the presence of alumina, simple metals and metastable intermetallic phases, which considerably improved the microhardness of laser-remelted surfaces. The morphology produced by laser surface remelting enhanced the microstructure of the Al-Fe alloys by reducing their roughness and increasing their hardness. The treated surfaces showed passivity and stability characteristics in the electrolytic medium employed in this study. - Highlights: Black-Right-Pointing-Pointer The samples laser-treated and untreated showed significant differences. Black-Right-Pointing-Pointer The La-XRD revealed the presence of alumina in Al-1.5 wt.% Fe. Black-Right-Pointing-Pointer The laser-treated reducing the roughness and increasing the hardness. Black-Right-Pointing-Pointer The laser-treated surfaces showed characteristic passive in the electrolytic medium. Black-Right-Pointing-Pointer The laser-treated is a promising technique for applications technological.

  4. Directionally solidified iron-base eutectic alloys

    NASA Technical Reports Server (NTRS)

    Tewari, S. N.

    1976-01-01

    Pseudobinary eutectic alloys with nominal compositions of Fe-25Ta-22Ni-10Cr and Fe-15.5Nb-14.5Ni-6.0Cr were directionally solidified at 0.5 centimeter per hour. Their microstructure consisted of the fcc, iron solid-solution, matrix phase reinforced by about 41-volume-percent, hcp, faceted Fe2Ta fibers and 41-volume-percent, hcp, Fe2Nb lamellae for the tantalum- and niobium-containing alloys, respectively. The microstructural stability under thermal cycling and the temperature dependence of tensile properties were investigated. These alloys showed low elevated-temperature strength and were not considered suitable for application in aircraft-gas-turbine blades although they may have applicability as vane materials.

  5. Characterization of directionally solidified lead chloride

    NASA Astrophysics Data System (ADS)

    Singh, Narsingh Bahadur; Duval, W. M. B.; Rosenthal, B. N.

    1988-06-01

    A complete analysis has been carried out on directionally solidified lead(II) chloride material. Purification by directional freezing consistently produced high purity material suitable for subsequent growth of single crystals. It was observed that silicon, magnesium, halogens, sulfur and phosphorous were the hardest impurities to remove from the supplied material. Direct photographic observations of the solid-liquid interface were taken at several values of G/ v ratios (denoting the temperature gradient and the translation velocity, respectively) to study the morphology of the interface and optimize the growth conditions. The solid-liquid interface morphology varied from a smooth convex shape to dendritic as the G/ v ratio decreased. Single crystals subsequently grown from the material purified by the present method showed no optical distortion, exhibited a transmission range from 0.30 to 20 μm, and displayed extremely low beam scattering.

  6. Directionally solidified eutectic alloy gamma-beta

    NASA Technical Reports Server (NTRS)

    Tewari, S. N.

    1977-01-01

    A pseudobinary eutectic alloy composition was determined by a previously developed bleed-out technique. The directionally solidified eutectic alloy with a composition of Ni-37.4Fe-10.0Cr-9.6Al (in wt%) had tensile strengths decreasing from 1,090 MPa at room temperature to 54 MPa at 1,100 C. The low density, excellent microstructural stability, and oxidation resistance of the alloy during thermal cycling suggest that it might have applicability as a gas turbine vane alloy while its relatively low high temperature strength precludes its use as a blade alloy. A zirconium addition increased the 750 C strength, and a tungsten addition was ineffective. The gamma=beta eutectic alloys appeared to obey a normal freezing relation.

  7. Carbon-14 analysis in solidified product of non-metallic solid waste by a combination of alkaline fusion and gaseous CO2 trapping.

    PubMed

    Ishimori, Ken-ichiro; Kameo, Yutaka; Matsue, Hideaki; Ohki, Yoshiyuki; Nakashima, Mikio; Takahashi, Kuniaki

    2011-02-01

    In order to establish a simple and rapid analytical method for (14)C in solidified products made from non-metallic low-level radioactive solid wastes such as concrete, mortar and glass by melting treatment, a radiochemical analysis in combination with alkaline fusion as a sample decomposition method was examined. A simulated solidified product containing (14)C, which was prepared by using nuclear reaction (14)N(n, p)(14)C with thermal neutron irradiation, was analyzed by the present method to compare with a conventional radiochemical analysis using oxidizing combustion. The reproducible and quantitative recovery of (14)C from the simulated solidified product indicates that the present method is more efficient for (14)C analysis in solidified products than the conventional method using oxidizing combustion. PMID:21074999

  8. Reduction Kinetics of Electric Arc Furnace Oxidizing Slag by Al-Fe Alloy

    NASA Astrophysics Data System (ADS)

    Lee, Jaehong; Oh, Joon Seok; Lee, Joonho

    2016-07-01

    Effects of temperature and slag basicity on the reduction rate of iron oxide in molten synthetic electric arc furnace oxidizing slag by Al-40 wt.%Fe alloy was investigated. An alloy sample was dropped into molten slag in an MgO crucible. When the initial slag temperature was 1723 K, there was no reduction. However, when the initial slag temperature was 1773 K and the slag basicity was 1.1, the reduction was initiated and the temperature of the slag rapidly increased. When the slag basicity was 1.1, increasing the initial slag temperature from 1773 K to 1823 K increases the reaction rate. As the slag basicity increased from 1.1 to 1.4 at 1773 K, the reaction rate increased. From SEM analysis, it was found that an Al2O3 or a spinel phase at the slag-metal interface inhibited the reaction at a lower temperature and a lower slag basicity.

  9. Template-free electrodeposition of AlFe alloy nanowires from a room-temperature ionic liquid as an anode material for Li-ion batteries.

    PubMed

    Chen, Gang; Chen, Yuqi; Guo, Qingjun; Wang, Heng; Li, Bing

    2016-08-15

    AlFe alloy nanowires were directly electrodeposited on copper substrates from trimethylamine hydrochloride (TMHC)-AlCl3 ionic liquids with small amounts of FeCl3 at room temperature without templates. Coin cells composed of AlFe alloy nanowire electrodes and lithium foils were assembled to characterize the alloy electrochemical properties by galvanostatic charge/discharge tests. Effects of FeCl3 concentration, potential and temperature on the alloy morphology, composition and cyclic performance were examined. Addition of Fe into the alloy changed the nanowires from a 'hill-like' bulk morphology to a free-standing morphology, and increased the coverage area of the alloy on Cu substrates. As an inactive element, Fe could also buffer the alloys' large volume changes during Li intercalation and deintercalation. AlFe alloy nanowires composed of a small amount of Fe with an average diameter of 140 nm exhibited an outstanding cyclic performance and delivered a specific capacity of about 570 mA h g(-1) after 50 cycles. This advanced template-free method for the direct preparation of high performance nanostructure AlFe alloy anode materials is quite simple and inexpensive, which presents a promising prospect for practical application in Li-ion batteries. PMID:27200436

  10. Removal of fluoride from drinking water using tea waste loaded with Al/Fe oxides: A novel, safe and efficient biosorbent

    NASA Astrophysics Data System (ADS)

    Cai, Hui-mei; Chen, Gui-jie; Peng, Chuan-yi; Zhang, Zheng-zhu; Dong, Yang-yang; Shang, Guang-zhi; Zhu, Xiao-hui; Gao, Hong-jian; Wan, Xiao-chun

    2015-02-01

    A low-cost and highly efficient biosorbent was prepared by loading Al/Fe oxides onto tea waste and was tested for the ability to remove fluoride from drinking water. Key factors, including adsorbent dosage, initial fluoride concentration, contact time and initial pH of the biosorbent, were investigated. It was found that the solution pH played an important role in the removal of fluoride. The biosorbent combinations Tea-Al or Tea-Al-Fe could reduce the fluoride concentration to below 1.5 mg/L in the drinking water, a level which meets the drinking water standard recommended by the World Health Organization (WHO). In addition, the residual concentrations of Al and Fe in the drinking water after Tea-Al-Fe treatment were below the standards set by WHO when treatment was conducted at pH values ranging from 5.0 to 10.0. The experimental data were analyzed using two-parameter theoretical models. The maximum fluoride adsorption capacities for the original tea, Tea-Fe, Tea-Al and Tea-Al-Fe biosorbents were 3.83, 10.47, 13.79 and 18.52 mg/g, respectively. These findings demonstrate the suitability of a prepared biosorbent based on tea waste for the removal of fluoride from drinking water.

  11. Spray Forming of Bulk Ultrafine-Grained Al-Fe-Cr-Ti

    NASA Astrophysics Data System (ADS)

    Banjongprasert, C.; Hogg, S. C.; Liotti, E.; Kirk, C. A.; Thompson, S. P.; Mi, J.; Grant, P. S.

    2010-12-01

    An Al-2.7Fe-1.9Cr-1.8Ti alloy has been spray formed in bulk and the microstructure and properties compared with those of similar alloys produced by casting, powder aomization (PA), and mechanical alloying (MA) routes. In PA and MA routes, a nanoscale metastable icosahedral phase is usually formed and is known to confer high tensile strength. Unlike previous studies of the spray forming of similar Al-based metastable phase containing alloys that were restricted to small billets with high porosity, standard spray forming conditions were used here to produce a ~98 pct dense 19-kg billet that was hot isostatically pressed (“HIPed”), forged, and/or extruded. The microstructure has been investigated at all stages of processing using scanning electron microscopy (SEM), electron backscatter diffraction (EBSD), and synchrotron X-ray diffraction (XRD) at the Diamond Light Source. Consistent with the relatively low cooling rate in spray forming under standard conditions, the microstructure showed no compelling evidence for the formation of metastable icosahedral phases. Nonetheless, after downstream processing, the spray-formed mechanical properties as a function of temperature were very similar to both PA rapid solidification (RS) materials and those made by MA. These aspects have been rationalized in terms of the typical phases, defects, and residual strains produced in each process route.

  12. Dilatant shear bands in solidifying metals.

    PubMed

    Gourlay, C M; Dahle, A K

    2007-01-01

    Compacted granular materials expand in response to shear, and can exhibit different behaviour from that of the solids, liquids and gases of which they are composed. Application of the physics of granular materials has increased the understanding of avalanches, geological faults, flow in hoppers and silos, and soil mechanics. During the equiaxed solidification of metallic alloys, there exists a range of solid fractions where the microstructure consists of a geometrically crowded disordered assembly of crystals saturated with liquid. It is therefore natural to ask if such a microstructure deforms as a granular material and what relevance this might have to solidification processing. Here we show that partially solidified alloys can exhibit the characteristics of a cohesionless granular material, including Reynolds' dilatancy and strain localization in dilatant shear bands 7-18 mean crystals wide. We show that this behaviour is important in defect formation during high pressure die casting of Al and Mg alloys, a global industry that contributes over $7.3 billion to the USA's economy alone and is used in the manufacture of products that include mobile-phone covers and steering wheels. More broadly, these findings highlight the potential to apply the principles and modelling approaches developed in granular mechanics to the field of solidification processing, and also indicate the possible benefits that might be gained from exploring and exploiting further synergies between these fields. PMID:17203058

  13. Characterization of solidifiers used for oil spill remediation.

    PubMed

    Sundaravadivelu, Devi; Suidan, Makram T; Venosa, Albert D; Rosales, Pablo I

    2016-02-01

    The physical characteristics and chemical composition of oil spill solidifiers were studied, and correlation of these properties with product effectiveness enabled determination of characteristics that are desirable in a good solidifier. The analyses revealed that the commercial products were primarily comprised of organic polymers and a few trace elements. A natural sorbent, which was composed entirely of plant based matter, was also evaluated, and it had the highest oil removal capacity, but it did not produce a solid mat-like final product. Generally, solidifiers with a carbonate group, pore size greater than 5 μm, and bulk densities lower than 0.3 g cm(-3) were found to have better efficiency and produced a cohesive rubbery final product that facilitated removal compared to sorbents. The importance of bulk density and pore size in the performance of the solidifier suggest that the primary mechanism of action was likely physical sorption. PMID:26498096

  14. The effect of interfacial diffusion on the electrical resistivity of magnetron sputtered Al-Fe-Sn alloy thin film

    NASA Astrophysics Data System (ADS)

    Zhao, Guannan; Zhang, Qing; Zheng, Zeng; Zhang, Yong; Yan, Biao

    2016-03-01

    The effect of interfacial diffusion in post-deposition annealing on the electrical resistivity of AlFeSn alloy films was investigated for the first time. The microstructure of the film before and after annealing was characterized by Atomic Force Microscope and Transmission Electron Microscope. The temperature dependence of resistivity in the range from 30 to 300 K suggests the presence of electron localization in both as-deposited and annealed films. The electron localization in the as-deposited film could be attributed to structural discontinuity. However, the electron localization in the annealed samples could probably be attributed to the diffusion of Si atoms into the film. An electrical resistivity as low as 1.43 μΩ cm was achieved for a 60 nm thick sample, which is considerably lower than predicted and previously reported. We propose the supreme conductivity of the annealed films could be partly due to the contribution from the electron localization. Our results provide new insight into developing highly conductive metallic materials.

  15. Gusev Rocks Solidified from Lava (False Color)

    NASA Technical Reports Server (NTRS)

    2006-01-01

    In recent weeks, as NASA's Mars Exploration Rover Spirit has driven through the basin south of 'Husband Hill,' it has been traversing mainly sand and dune deposits. This week, though, Spirit has been maneuvering along the edge of an arc-shaped feature called 'Lorre Ridge' and has encountered some spectacular examples of basaltic rocks with striking textures. This panoramic camera (Pancam) image shows a group of boulders informally named 'FuYi.' These basaltic rocks were formed by volcanic processes and may be a primary constituent of Lorre Ridge and other interesting landforms in the basin.

    Spirit first encountered basalts at its landing site two years ago, on a vast plain covered with solidified lava that appeared to have flowed across Gusev Crater. Later, basaltic rocks became rare as Spirit climbed Husband Hill. The basaltic rocks that Spirit is now seeing are interesting because they exhibit many small holes or vesicles, similar to some kinds of volcanic rocks on Earth. Vesicular rocks form when gas bubbles are trapped in lava flows and the rock solidifies around the bubbles. When the gas escapes, it leaves holes in the rock. The quantity of gas bubbles in rocks on Husband Hill varies considerably; some rocks have none and some, such as several here at FuYi, are downright frothy.

    The change in textures and the location of the basalts may be signs that Spirit is driving along the edge of a lava flow. This lava may be the same as the basalt blanketing the plains of Spirit's landing site, or it may be different. The large size and frothy nature of the boulders around Lorre Ridge might indicate that eruptions once took place at the edge of the lava flow, where the lava interacted with the rocks of the basin floor. Scientists hope to learn more as Spirit continues to investigate these rocks.

    As Earth approaches the Chinese New Year (The Year of the Dog), the Athena science team decided to use nicknames representing Chinese culture and geography

  16. Gusev Rocks Solidified from Lava (3-D)

    NASA Technical Reports Server (NTRS)

    2006-01-01

    In recent weeks, as NASA's Mars Exploration Rover Spirit has driven through the basin south of 'Husband Hill,' it has been traversing mainly sand and dune deposits. This week, though, Spirit has been maneuvering along the edge of an arc-shaped feature called 'Lorre Ridge' and has encountered some spectacular examples of basaltic rocks with striking textures. This panoramic camera (Pancam) image shows a group of boulders informally named 'FuYi.' These basaltic rocks were formed by volcanic processes and may be a primary constituent of Lorre Ridge and other interesting landforms in the basin.

    Spirit first encountered basalts at its landing site two years ago, on a vast plain covered with solidified lava that appeared to have flowed across Gusev Crater. Later, basaltic rocks became rare as Spirit climbed Husband Hill. The basaltic rocks that Spirit is now seeing are interesting because they exhibit many small holes or vesicles, similar to some kinds of volcanic rocks on Earth. Vesicular rocks form when gas bubbles are trapped in lava flows and the rock solidifies around the bubbles. When the gas escapes, it leaves holes in the rock. The quantity of gas bubbles in rocks on Husband Hill varies considerably; some rocks have none and some, such as several here at FuYi, are downright frothy.

    The change in textures and the location of the basalts may be signs that Spirit is driving along the edge of a lava flow. This lava may be the same as the basalt blanketing the plains of Spirit's landing site, or it may be different. The large size and frothy nature of the boulders around Lorre Ridge might indicate that eruptions once took place at the edge of the lava flow, where the lava interacted with the rocks of the basin floor. Scientists hope to learn more as Spirit continues to investigate these rocks.

    As Earth approaches the Chinese New Year (The Year of the Dog), the Athena science team decided to use nicknames representing Chinese culture and geography

  17. Directionally solidified composite systems under evaluation

    NASA Technical Reports Server (NTRS)

    Ashbrook, R. L.

    1974-01-01

    The directionally solidified eutectic in-situ composites being evaluated for use as turbine materials range from ductile-ductile systems, where both matrix and reinforcement are ductile, to brittle-brittle systems, where both phases are brittle. The alloys most likely to be used in gas turbine engines in the near term are the lamellar ductile-semi ductile alloys gamma prime-delta, Ni3Al-Ni3Nb and gamma/gamma prime-delta Ni,Cr,Cb,Al/Ni3Al-Ni3Nb and the fibrous ductile-brittle alloys M-MC CoTaC or NiTaC and M-M7C3(Co,Cr,Al)-(Cr,Co)7C3. The results of tests are given which indicate that gamma prime strengthened NiTaC alloys and a (Co,Cr,Al)7C3 have greater tensile strength than the strongest superalloys at temperatures up to about 600 C. The gamma prime-delta and gamma/gamma prime-delta alloys in the Ni,Al,Nb(Cr) systems have greater tensile strength than the superalloys at temperatures greater than 800 C. At low stresses fibrous carbide reinforced eutectic alloys have longer lives at high temperatures than the strongest superalloys. Lamellar delta, Ni3Nb reinforced eutectic alloys have longer lives at high temperatures than the strongest superalloys at all stresses. The experience currently being gained in designing with the brittle ceramics SiC and Si3N4 may eventually be applied to ceramic matrix eutectic in-situ composites. However, the refractory metal fiber reinforced brittle-ductile systems may find acceptance as turbine materials before the ceramic-ceramic brittle-brittle systems.

  18. Particle Engulfment and Pushing By Solidifying Interfaces

    NASA Technical Reports Server (NTRS)

    Stefanescu, Doru M.; Mukherjee, Sundeep; Juretzko, Frank Robert; Catalina, A.drian V.; Sen, Subhayu; Curreri, P. A.

    2001-01-01

    The phenomenon of interaction of particles with solid-liquid interfaces (SLI) has been studied since the mid 1960's. While the original interest stemmed from geology applications (frost heaving in soil), researchers soon realized that fundamental understanding of particles behavior at solidifying interfaces might yield practical benefits in other fields, including metallurgy. In materials engineering the main issue is the location of particles with respect to grain boundaries at the end of solidification. Considerable experimental and theoretical research was lately focused on applications to metal matrix composites produced by casting or spray forming techniques, and on inclusion management in steel. Another application of particle SLI interaction is in the growing of Y1Ba2Cu3O(7-delta) (123) superconductor crystals from an undercooled liquid. The oxide melt contains Y2Ba1Cu1O5 (211) precipitates, which act as flux pinning sites. The experimental evidence on transparent organic materials, as well as the recent in situ observations on steel demonstrates that there exist a critical velocity of the planar SLI below which particles are pushed ahead of the interface, and above which particles are engulfment. The engulfment of a SiC particle in succinonitrile is exemplified. However, in most commercial alloys dendritic interfaces must be considered. Indeed, most data available on metallic alloys are on dendritic structures. The term engulfment is used to describe incorporation of a particle by a planar or cellular interface as a result of local interface perturbation, as opposed to entrapment that implies particle incorporation at cells or dendrites boundaries. During entrapment the particles are pushed in the intercellular or interdendritic regions and then captured when local solidification occurs. The physics of these two phenomena is fundamentally different.

  19. Biodegradation testing of solidified low-level waste streams

    SciTech Connect

    Piciulo, P.L.; Shea, C.E.; Barletta, R.E.

    1985-05-01

    The NRC Technical Position on Waste Form (TP) specifies that waste should be resistant to biodegradation. The methods recommended in the TP for testing resistance to fungi, ASTM G21, and for testing resistance to bacteria, ASTM G22, were carried out on several types of solidified simulated wastes, and the effect of microbial activity on the mechanical strength of the materials tested was examined. The tests are believed to be sufficient for distinguishing between materials that are susceptible to biodegradation and those that are not. It is concluded that failure of these tests should not be regarded of itself as an indication that the waste form will biodegrade to an extent that the form does not meet the stability requirements of 10 CFR Part 61. In the case of failure of ASTM G21 or ASTM G22 or both, it is recommended that additional data be supplied by the waste generator to demonstrate the resistance of the waste form to microbial degradation. To produce a data base on the applicability of the biodegradation tests, the following simulated laboratory-scale waste forms were prepared and tested: boric acid and sodium sulfate evaporator bottoms, mixed-bed bead resins and powdered resins each solidified in asphalt, cement, and vinyl ester-styrene. Cement solidified wastes supported neither fungal nor bacterial growth. Of the asphalt solidified wastes, only the forms of boric acid evaporator bottoms did not support fungal growth. Bacteria grew on all of the asphalt solidified wastes. Cleaning the surface of these waste forms did not affect bacterial growth and had a limited effect on the fungal growth. Only vinyl esterstyrene solidified sodium sulfate evaporator bottoms showed viable fungi cultures, but surface cleaning with solvents eliminated fungal growth in subsequent testing. Some forms of all the waste streams solidified in vinyl ester-styrene showed viable bacteria cultures. 13 refs., 12 tabs.

  20. Landscape types and pH control organic matter mediated mobilization of Al, Fe, U and La in boreal catchments

    NASA Astrophysics Data System (ADS)

    Köhler, Stephan J.; Lidman, Fredrik; Laudon, Hjalmar

    2014-06-01

    In this study we present data from a seven-year time series from 15 nested streams within a 68 km2 catchment, covering a pH gradient of almost three units. We demonstrate that the two landscape types, forest and wetlands, control the relative mobilization of Al and Fe in this boreal landscape. The La/U ratio is almost constant across the whole catchment despite large variations in pH, Al/Fe and TOC, whereas U and La mobilization increases with increasing contribution of deeper soils and groundwater further downstream. High Al/TOC ratios in the forested catchments suggest that Al originates from the underlying mineral soils, and low Al/TOC ratios derive from wetlands where Al is retained. We observe a competition effect on the binding to TOC between Al and La and also that the relationship between TOC, Al and La changes from the smaller (0.05-2 km2) catchments to larger (3-68 km2) downstream locations. As pH increase downstream, Al and Fe are gradually removed from the aqueous phase by precipitation of particulate gibbsite-like phases and ferrihydrite. This selective removal of Al and Fe from TOC binding sites results in higher La, and U concentrations downstream. Observed element patterns (U, La) and the range of upper continental crust normalized (La/Nd)UCC and (La/Yb)UCC in the near stream, riparian zone were very similar to the observed ratios across the whole catchment. The rising (La/Nd)UCC over (La/Yb)UCC may be due to a selective removal of REE binding to ferrihydrate in the riparian soil, the result of two distinctly different end-members but most probably not due to the in-stream precipitation of ferrihydrate or gibbsite-like phases.

  1. Dependence of catalytic properties of Al/Fe2O3 thermites on morphology of Fe2O3 particles in combustion reactions

    NASA Astrophysics Data System (ADS)

    Zhao, Ningning; He, Cuicui; Liu, Jianbing; Gong, Hujun; An, Ting; Xu, Huixiang; Zhao, Fengqi; Hu, Rongzu; Ma, Haixia; Zhang, Jinzhong

    2014-11-01

    Three Fe2O3 particle samples with the same crystal structure but different morphologies were prepared by the hydrothermal method and then combined with Al nanoparticles to produce Al/Fe2O3 thermites using ultrasonic mixing. The properties of Fe2O3 and Al/Fe2O3 were studied using a combination of experimental techniques including scanning electron microscopy (SEM), energy dispersive spectrometer (EDS), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and differential scanning calorimetry (DSC). The influences of the three Al/Fe2O3 thermites on the combustion properties of the AP/HTPB (ammonium perchlorate/hydroxyl-terminated polybutadiene) composite propellant were investigated in comparison to those of Fe2O3. The results show that the Al/Fe2O3 thermites are better than Fe2O3 in enhancing the combustion performance of AP/HTPB. Furthermore, the surface area, which depends on size and mophology, of Fe2O3 particles was found to play a vital role in improving the burning rate of the thermites-containing propellant formulation, with the smallest particles with the largest surface-to-volume (S/V) ratio performing the best. The enhanced catalytic property of the granular-shape Fe2O3 and the corresponding thermite is attributed to the large specific surface area of Fe2O3. The different thermal behaviors of these three superthemites were supposed to be attributed to the surface site of Fe2O3 particles. This work provides a better understanding on the catalytic properties of thermites that are important for combustion applications.

  2. Electrostatic interactions for directed assembly of high performance nanostructured energetic materials of Al/Fe2O3/multi-walled carbon nanotube (MWCNT)

    NASA Astrophysics Data System (ADS)

    Zhang, Tianfu; Ma, Zhuang; Li, Guoping; Wang, Zhen; Zhao, Benbo; Luo, Yunjun

    2016-05-01

    Electrostatic self-assembly in organic solvent without intensively oxidative or corrosive environments, was adopted to prepare Al/Fe2O3/MWCNT nanostructured energetic materials as an energy generating material. The negatively charged MWCNT was used as a glue-like agent to direct the self-assembly of the well dispersed positively charged Al (fuel) and Fe2O3 (oxide) nanoparticles. This spontaneous assembly method without any surfactant chemistry or other chemical and biological moieties decreased the aggregation of the same nanoparticles largely, moreover, the poor interfacial contact between the Al (fuel) and Fe2O3 (oxide) nanoparticles was improved significantly, which was the key characteristic of high performance nanostructured energetic materials. In addition, the assembly process was confirmed as Diffusion-Limited Aggregation. The assembled Al/Fe2O3/MWCNT nanostructured energetic materials showed excellent performance with heat release of 2400 J/g, peak pressure of 0.42 MPa and pressurization rate of 105.71 MPa/s, superior to that in the control group Al/Fe2O3 nanostructured energetic materials prepared by sonication with heat release of 1326 J/g, peak pressure of 0.19 MPa and pressurization rate of 33.33 MPa/s. Therefore, the approach, which is facile, opens a promising route to the high performance nanostructured energetic materials.

  3. Tuning the reactivity of Al/Fe{sub 2}O{sub 3} nanoenergetic materials via an approach combining soft template self-assembly with sol–gel process process

    SciTech Connect

    Zhang, Tianfu; Wang, Zhen; Li, Guoping; Luo, Yunjun

    2015-10-15

    A bottom-up approach combining soft template self-assembly with sol–gel process, was adopted to prepare the assembled Al/Fe{sub 2}O{sub 3} nanoenergetic materials, assembly-Al/Fe{sub 2}O{sub 3} sample. The other two unassembled Al/Fe{sub 2}O{sub 3}a nanoenergetic materials, sol–gel–Al/Fe{sub 2}O{sub 3} sample and mixing-Al/Fe{sub 2}O{sub 3} sample, were prepared by sol–gel method and physical mixing method respectively. The assembly process within the preparation of the assembly-Al/Fe{sub 2}O{sub 3} sample was analyzed through the changes in the average hydrodynamic diameters of the particles and the micelles in solution. SEM, EDS and TEM tests were performed to demonstrate a significant improvement regarding to dispersity and arrangements of the Al and Fe{sub 2}O{sub 3} particles in the assembled samples, compared to that of the unassembled Al/Fe{sub 2}O{sub 3} samples. DSC test was employed to characterize the reactivity of the samples. The heat release of the assembled Al/Fe{sub 2}O{sub 3} sample was 2088 J/g, about 400 and 990 J/g more than that of the sol–gel–Al/Fe{sub 2}O{sub 3} sample and mixing-Al/Fe{sub 2}O{sub 3} sample, respectively. - Graphical abstract: Modified aluminum (Al) nanoparticles with hydrophobic surface assembled into the Brij S10 micelle in Fe(III) sol, then the well dispersed system was transformed into Al/Fe{sub 2}O{sub 3} nanoenergetic materials with high reactivity. - Highlights: • An approach combining soft template self-assembly with sol–gel process was adopted. • The aggregation of Al nanoparticles in the final product was reduced significantly. • The reactivity of Al/Fe{sub 2}O{sub 3} nanoenergetic materials was improved to a large extent.

  4. Low-cost directionally-solidified turbine blades, volume 1

    NASA Technical Reports Server (NTRS)

    Sink, L. W.; Hoppin, G. S., III; Fujii, M.

    1979-01-01

    A low cost process of manufacturing high stress rupture strength directionally-solidified high pressure turbine blades was successfully developed for the TFE731-3 Turbofan Engine. The basic processing parameters were established using MAR-M 247 and employing the exothermic directional-solidification process in trial castings of turbine blades. Nickel-based alloys were evaluated as directionally-solidified cast blades. A new turbine blade, disk, and associated components were then designed using previously determined material properties. Engine tests were run and the results were analyzed and compared to the originally established goals. The results showed that the stress rupture strength of exothermically heated, directionally-solidified MAR-M 247 turbine blades exceeded program objectives and that the performance and cost reduction goals were achieved.

  5. Mechanical Properties of a Partially Solidified Cu-Zn Alloy

    NASA Astrophysics Data System (ADS)

    Kasuya, Naoki; Nakazawa, Tomoaki; Matsushita, Akira; Okane, Toshimitsu; Yoshida, Makoto

    2016-04-01

    For predicting solidification cracking by thermal stress analysis, the mechanical properties in the partially solidified state based on the experimental results are the best hope. However, the Young's modulus has never been investigated for copper alloys. In this study, stress-strain curves of a Cu-Zn alloy in the partially solidified state for various solid fractions were obtained using a specially developed horizontal tensile test device. Furthermore, by removing the load during the tensile test, the spring-back (elastic behavior) was observed and the Young's modulus was obtained.

  6. Detection of free liquid in containers of solidified radioactive waste

    DOEpatents

    Greenhalgh, Wilbur O.

    1985-01-01

    A method of nondestructively detecting the presence of free liquid within a sealed enclosure containing solidified waste by measuring the levels of waste at two diametrically opposite locations while slowly tilting the enclosure toward one of said locations. When the measured level remains constant at the other location, the measured level at said one location is noted and any measured difference of levels indicates the presence of liquid on the surface of the solidified waste. The absence of liquid in the enclosure is verified when the measured levels at both locations are equal.

  7. The stability of Al,Fe-bearing phase H and a new pyrite-type hydroxide at high pressures

    NASA Astrophysics Data System (ADS)

    Nishi, M.; Kuwayama, Y.; Tsuchiya, J.; Irifune, T.

    2015-12-01

    Water plays an important role in the structure, dynamics, and evolution of planets because hydrogen can affect the physical properties and stabilities of constituent minerals in the planets. Since alumimous phase H (MgSiO4H2-AlOOH) is stable over the entire pressure range of the lower mantle, the hydrated subducting plate may deliver a certain amount of water into the bottom of the Earth's mantle (Tsuchiya 2013, Nishi et al. 2013, Ohira et al. 2014, Walter et al. 2015). Compositional analysis of phase H grains synthesized from natural serpentine shows the presence of the Fe component in this phase (Nishi et al., 2015). This result suggests that phase H would also form solid solutions with ɛ-FeOOH, since ɛ-FeOOH is isostructural to phase H and δ-AlOOH. Moreover, an ab initio calculation has recently predicted that the new high pressure form of AlOOH, which has pyrite-type structure, would be stabilized at pressures above 170 GPa (Tsuchiya and Tsuchiya, 2011). Although this pyrite-type hydroxide has been found in InOOH, this structure in AlOOH has not been reported by experimental studies. Here we examine the composition and stability of Al,Fe-bearing phase H using a multi-anvil apparatus combined with sintered diamond anvils. Results show that large amounts of Fe and Al are partitioned into phase H relative to bridgmanite. Fe likely affects the stability of phase H in the lower mantle. Also, we conducted high pressure experiments on pure δ-AlOOH by using laser-heated diamond anvil cell (DAC) techniques up to 200 GPa and 2,500 K. In-situ X-ray diffraction (XRD) measurements indicated that the transition from the δ-AlOOH to the pyrite-type structure occurs at high pressures above 190 GPa. Our experimental results exhibited a density reduction of 2.6 wt.% through the structural transition, and both experimental data plots and theoretical calculations showed similar compressibilities of δ-AlOOH and pyrite-type AlOOH. In recent years, hundreds of extra

  8. Synthesis and performance evaluation of Al/Fe oxide coated diatomaceous earth in groundwater defluoridation: Towards fluorosis mitigation.

    PubMed

    Izuagie, Anthony A; Gitari, Wilson M; Gumbo, Jabulani R

    2016-08-23

    The quest to reduce fluoride in groundwater to WHO acceptable limit of 1.5 mg/L to prevent diseases such as teeth mottling and skeletal fluorosis was the motivation for this study. Al/Fe oxide-modified diatomaceous earth was prepared and its defluoridation potential evaluated by batch method. The sorbent with pHpzc 6.0 ± 0.2 is very reactive. The maximum 82.3% fluoride removal attained in 50 min using a dosage of 0.3 g/100 mL in 10 mg/L fluoride was almost attained within 5 min contact time; 81.3% being the percent fluoride removal at 5 min contact time. The sorbent has a usage advantage of not requiring solution pH adjustment before it can exhibit its fluoride removal potential. A substantial amount of fluoride (93.1%) was removed from solution when a sorbent dosage of 0.6 g/100 mL was contacted with 10 mg/L fluoride solution for 50 min at a mixing rate of 200 rpm. The optimum adsorption capacity of the adsorbent was 7.633 mg/g using a solution containing initially 100 mg/L fluoride. The equilibrium pH of the suspensions ranged between 6.77 and 8.26 for 10 and 100 mg/L fluoride solutions respectively. Contacting the sorbent at a dosage of 0.6 g/100 mL with field water containing 5.53 mg/L at 200 rpm for 50 min reduced the fluoride content to 0.928 mg/L-a value below the upper limit of WHO guideline of 1.5 mg/L fluoride in drinking water. The sorption data fitted to both Langmuir and Freundlich isotherms but better with the former. The sorption data obeyed only the pseudo-second-order kinetic, which implies that fluoride was chemisorbed. PMID:27220558

  9. Release of organic chelating agents from solidified decontamination wastes

    SciTech Connect

    Piciulo, P.L.; Adams, J.W.; Davis, M.S.; Milian, L.W.; Anderson, C.I.

    1986-07-01

    Data are presented on the release of organic complexing agents from solidified simulated decontamination resin wastes. The organic acids included were: ethylenediaminetetraacetic acid, oxalic acid, citric acid, picolinic acid, and formic acid. Additionally, samples were tested which contained the decontamination reagent LND-101A and a simulated resin waste expected with the LOMI (low-oxidation-state-metal ion) reagent. Ion-exchange resins equilibrated with the reagents were solidified in cement and vinyl ester-styrene. The release of the organic acids was measured using the standard procedure ANS 16.1, ''Measurements of the Leachability of Solidified Low-Level Radioactive Wastes.'' The data suggest that the release of the acids may follow a diffusion mechanism. Data are also presented which indicate that immersion in water can affect the compressive strength of solidified simulated decontamination resin wastes. Analytical methods are described which can be used to measure organic acids in waste form leachates. Ion chromatography proved to be the most versatile of the methods examined.

  10. Compositional Segregation in Unidirectionally Solidified Solid Solution Crystals

    NASA Technical Reports Server (NTRS)

    Wang, J. C.

    1983-01-01

    A computer program was developed to model compositional segregation in unidrectionally solidified solid-solution-semiconducting crystals. The program takes into account the variations of the interface segregation constant and solidification rate with composition. Calculations are performed for the HgCdTe solid solution system that is compared with experimental data.

  11. Flow, deformation, stress and failure in solidifying coatings

    NASA Astrophysics Data System (ADS)

    Lei, Herong

    As a coating solidifies by drying or curing, it tends to shrink. In early stages it is liquid enough that any stress is rapidly relieved by viscous flow. In later stages it becomes solid enough to support elastic stress, which results from shrinkage inhibited by adherence to the substrate. Stress can relax by viscous creep of the stress-free state. Thus the stress level is an outcome of competing shrinkage and relaxation. The one-dimensional model of drying a uniform planar coating has been developed to cover liquid deformation as well as diffusion and solid deformation. Propagation of the solidification front an yielding front downward into a drying coating is an output of the model. The model shows the effects of temperature, humidity, plasticizer, and yield stress level on stress development and relaxation. In-plane stress predictions compare well with measurements. The stress development in drying fibers and spheres after solidification has also been studied. A two-dimensional model of the early stages has been developed by coupling the Navier-Stokes system with the equations of Fickian diffusion and mass transfer in the overlying gas. Computer-aided solutions show how solvent concentration, pressure, viscous stress and surface topography evolve as a coating dries. In the later stages, Fickian diffusion and mass transfer are coupled with elasto-viscoplasticity. Predictions show that upon solidification, the highest stresses occur at the free surface. Stresses in a single-layer coating on a rigid substrate are highly concentrated near the edges of the coating and near crack tips if there are any at the edges or on the free surface. High stresses at such crack tips provide the driving force for edge delamination and crack propagation. Cracking and edge delamination in an elastic coating have been modeled with theoretical fracture mechanics. In the model, the energy release rate in both delamination and surface cracking are computed at different crack lengths. In

  12. Analysis of the molten/solidified zone in selective laser melted parts

    NASA Astrophysics Data System (ADS)

    Campanelli, Sabina Luisa; Casalino, Giuseppe; Contuzzi, Nicola; Angelastro, Andrea; Ludovico, Antonio D.

    2014-02-01

    The process of Selective Laser Melting (SLM) is an innovative technology for rapid prototyping that can be included among the SFF (Solid Freeform Fabrication) techniques, which are characterized by "free-form" manufacturing of solid parts. SLM is an additive technology that operates starting from the data encoded in the three-dimensional computer aided design (CAD) file of the component to be built. After the slicing operation made on the 3D model of the component, the consequent data file is sent to a computer-controlled laser device that fuses successive layers of metal powder to create the three-dimensional product. The SLM is a technological process which involves optical, thermal and solidification phenomena; thus the analysis of the process is rather complex. This work aims to study the molten/solidified zone in SLM samples through the experimental analysis of the shape and the size of laser tracks. The functional relationships between dimensional parameter of the molten/solidified track and the main parameters used to control the process was identified.

  13. The cyclic oxidation resistance at 1200 C of beta-NiAl, FeAl, and CoAl alloys with selected third element additions

    NASA Technical Reports Server (NTRS)

    Barrett, C. A.; Titran, R. H.

    1992-01-01

    The intermetallic compounds Beta-NiAl, FeAl, and CoAl were tested in cyclic oxidation with selected third element alloy additions. Tests in static air for 200 1-hr cycles at 1200 C indicated by specific weight change/time data and x-ray diffraction analysis that the 5 at percent alloy additions did not significantly improve the oxidation resistance over the alumina forming baseline alloys without the additions. Many of the alloy additions were actually deleterious. Ta and Nb were the only alloy additions that actually altered the nature of the oxide(s) formed and still maintained the oxidation resistance of the protective alumina scale.

  14. Solubility and release of fenbufen intercalated in Mg, Al and Mg, Al, Fe layered double hydroxides (LDH): The effect of Eudragit S 100 covering

    SciTech Connect

    Arco, M. del; Fernandez, A.; Martin, C.; Rives, V.

    2010-12-15

    Following different preparation routes, fenbufen has been intercalated in the interlayer space of layered double hydroxides with Mg{sup 2+} and Al{sup 3+} or Mg{sup 2+}, Al{sup 3+} and Fe{sup 3+} in the layers. Well crystallized samples were obtained in most of the cases (intercalation was not observed by reconstruction of the MgAlFe matrix), with layer heights ranging between 16.1 and 18.8 A. The presence of the LDH increases the solubility of fenbufen, especially when used as a matrix. The dissolution rate of the drug decreases when the drug is intercalated, and is even lower in those systems containing iron; release takes place through ionic exchange with phosphate anions from the solution. Preparation of microspheres with Eudragit S 100 leads to solids with an homogeneous, smooth surface with efficient covering of the LDH surface, as drug release was not observed at pH lower than 7. - Graphical abstract: LDHs containing Mg, Al, Fe increase fenbufen solubility, release takes place through ionic exchange with phosphate anions from the medium. Spherical solids with homogeneous, smooth surface are formed when using Eudragit S 100, efficiently covering the LDH surface. Display Omitted

  15. Release of organic reagents from solidified decontamination wastes

    SciTech Connect

    Piciulo, P.L.; Adams, J.W.

    1985-01-01

    In order to provide technical information needed by the US Nuclear Regulatory Commission to evaluate the adequacy of near-surface disposal of decontamination wastes, Brookhaven National Laboratory has measured the release of organic reagents from solidified simulated decontamination wastes. The waste streams consisted of either mixed-bed ion-exchange resins or anion exchange resins equilibrated with EDTA, oxalic acid, citric acid, picolinic acid or simulated LOMI decontamination reagent. These simulated resin wastes were solidified in either cement or vinyl ester-styrene. Samples were tested by a fixed interval leach procedure or according to the standard ANS 16.1 procedure. The leachability indices, which were calculated as prescribed in ANS 16.1, varied with leach period for some of the composites tested. 4 references, 6 figures, 2 tables.

  16. Directionally solidified eutectic gamma plus beta nickel-base superalloys

    NASA Technical Reports Server (NTRS)

    Jackson, M. R. (Inventor)

    1977-01-01

    A directionally solidified multivariant eutectic gamma + beta nickel-base superalloy casting having improved high temperature strength and oxidation resistance properties is provided. This comprises a two phase eutectic structure containing, on a weight percent basis, 5.0-15.0 tungsten, 8.5-14.5 aluminum, 0.0-35.0 cobalt and the balance being nickel. Embedded within the gamma phase nickel-base matrix are aligned eutectic beta phase (primarily (NiCo)Al reinforcing lamellae.

  17. A study of reduced chromium content in a nickel-base superalloy via element substitution and rapid solidification processing. Ph.D. ThesisFinal Report

    NASA Technical Reports Server (NTRS)

    Powers, William O.

    1987-01-01

    A study of reduced chromium content in a nickel base superalloy via element substitution and rapid solidification processing was performed. The two elements used as partial substitutes for chromium were Si and Zr. The microstructure of conventionally solidified materials was characterized using microscopy techniques. These alloys were rapidly solidified using the chill block melt spinning technique and the rapidly solidified microstructures were characterized using electron microscopy. The spinning technique and the rapidly solidified microstructures was assessed following heat treatments at 1033 and 1272 K. Rapidly solidified material of three alloys was reduced to particulate form and consolidated using hot isostatic pressing (HIP). The consolidated materials were also characterized using microscopy techniques. In order to evaluate the relative strengths of the consolidated alloys, compression tests were performed at room temperature and 1033 K on samples of as-HIPed and HIPed plus solution treated material. Yield strength, porosity, and oxidation resistance characteristics are given and compared.

  18. Effects of pH, surface finish and thermal treatment on the corrosion of AlFeNi aluminum alloy. Characterization of oxide layers

    NASA Astrophysics Data System (ADS)

    Nabhan, D.; Kapusta, B.; Billaud, P.; Colas, K.; Hamon, D.; Dacheux, N.

    2015-02-01

    The aluminum alloy AlFeNi used as fuel cladding for the Jules Horowitz Reactor (JHR) may undergo corrosion in the reactor environment. In order to qualify the corrosion behavior of the fuel elements of the JHR in accidental conditions, several specimens of AlFeNi have been corroded at 250 °C for different durations (9-34 days) in distilled water at various pH (4.9, 5.2 and 5.6) chosen to simulate that currently considered for the JHR. On all specimens, the only crystalline corrosion product formed is boehmite (AlOOH). The corrosion film is composed of three oxide layers which show through thickness chemical composition variations. The iron-nickel precipitates pre-existing in the metal matrix are present in the inner and intermediate oxide layers though oxidized. For long corrosion times, some of the iron and nickel particles are released in the water and some precipitation is observed at the surface of the oxide layer. The effect of surface finish (as received or polished) and thermal treatment (annealed and not annealed) on the oxide growth rate has also been investigated. For durations over 25 days, pH = 5.6 appears to be more favorable than pH = 5.2 and 4.9 in terms of oxide thickness and weight gain limitation. This effect of pH is however reduced on unpolished specimens. The effect of surface finish on the corrosion behavior as measured by optical microscopy appears to be strong, especially for pH = 4.9 where polished samples exhibited an accelerated evolution of the oxide thickness and of the mass gain. This could be due to the combined effect of a strong acid solution (pH = 4.9) and of the local microstructural changes formed at the interface through polishing. The effect of thermal treatment on the behavior of unpolished AlFeNi specimens during corrosion tests in the conditions investigated was found to be small. In this study, microstructural and chemical analyses were performed on the corroded specimens in order to get a better understanding of the

  19. Synthesis of high-quality, well-characterized CaAlFe-layered triple hydroxide with the combination of dry-milling and ultrasonic irradiation in aqueous solution at elevated temperature.

    PubMed

    Szabados, Márton; Pásztor, Krisztián; Csendes, Zita; Muráth, Szabolcs; Kónya, Zoltán; Kukovecz, Ákos; Carlson, Stefan; Sipos, Pál; Pálinkó, István

    2016-09-01

    The combination of mechanochemical and ultrasonic treatment was applied to synthesize CaAlFe-layered triple hydroxides with carbonate or chloride anions in the interlamellar space. The optimal parameters of the preparation were explored by altering the initial ratio of the metal ions and the temperature of ultrasonic irradiation. The resulting triple hydroxides were characterized by X-ray diffractometry, infrared and X-ray absorption spectroscopies, thermogravimetric analysis and scanning electron microscopy. The products were close-to-phase-pure CaAlFe-layered triple hydroxides. Elevation of the temperature transformed the CaAlFe-Cl(-)-layered triple hydroxide to rare oxyhalides (Ca2FeO3Cl and Ca12Al14O32Cl2). PMID:27150758

  20. Solubility and release of fenbufen intercalated in Mg, Al and Mg, Al, Fe layered double hydroxides (LDH): The effect of Eudragit ® S 100 covering

    NASA Astrophysics Data System (ADS)

    del Arco, M.; Fernández, A.; Martín, C.; Rives, V.

    2010-12-01

    Following different preparation routes, fenbufen has been intercalated in the interlayer space of layered double hydroxides with Mg 2+ and Al 3+ or Mg 2+, Al 3+ and Fe 3+ in the layers. Well crystallized samples were obtained in most of the cases (intercalation was not observed by reconstruction of the MgAlFe matrix), with layer heights ranging between 16.1 and 18.8 Å. The presence of the LDH increases the solubility of fenbufen, especially when used as a matrix. The dissolution rate of the drug decreases when the drug is intercalated, and is even lower in those systems containing iron; release takes place through ionic exchange with phosphate anions from the solution. Preparation of microspheres with Eudragit ® S 100 leads to solids with an homogeneous, smooth surface with efficient covering of the LDH surface, as drug release was not observed at pH lower than 7.

  1. On the crack growth resistance and strength of the B2 iron aluminides Fe-40Al, Fe-45Al, and Fe-10Ni-40Al (at. %)

    SciTech Connect

    Schneibel, J.H.; Maziasz, P.J.

    1994-09-01

    The crack growth resistance and yield strength of the B2 iron aluminides Fe-40Al, Fe-45Al, are Fe-10Ni-40Al (at. %) have been investigated at room temperature laboratory air. After fast cooling from 1273 K, Fe-45Al and Fe-10Ni-40Al are much stronger than Fe-40Al, and exhibit considerably lower crack growth resistance. The crack growth resistance decreases with decreasing crack propagation velocity. Low crack propagation velocities favor intergranular fracture, whereas high velocities can lead to significant contributions from transgranular fracture. Boron additions to Fe-40Al and Fe-10Ni-40Al improve the crack growth resistance, reduce its dependence on the crack propagation velocity, and cause the path to be predominantly transgranular. In a plot of fracture toughness versus yield strength, the properties of the iron aluminides are similar to those of typical aluminum alloys.

  2. Dynamics of gas condensate removal from an Al-Fe-humus podzol and its effect on the complexes of soil fungi

    NASA Astrophysics Data System (ADS)

    Evdokimova, G. A.; Korneikova, M. V.; Myazin, V. A.

    2013-03-01

    The time period for the removal of gas condensate from the cultivated and forest Al-Fe-humus podzols in the northwestern region of Russia was determined in an experiment. The content of the light fractions of oil decreased more slowly in the forest soil than in the cultivated soil due to the lower rates of evaporation and photochemical reactions under the forest canopy. During the first five days after applying the gas condensate, its content decreased by nearly 70% in the cultivated soils and by only 8% in the forest soil. In three months of the growing period, the gas condensate was completely removed from the cultivated soils and by 91% from the forest soil. The species composition and structure of the fungal communities significantly changed in the polluted soils with an increase in the portion of conventionally pathogenic fungi from 45% in the control soil to 60-70% in the polluted soil.

  3. Micro and Macro Segregation in Alloys Solidifying with Equiaxed Morphology

    NASA Technical Reports Server (NTRS)

    Stefanescu, Doru M.; Curreri, Peter A.; Leon-Torres, Jose; Sen, Subhayu

    1996-01-01

    To understand macro segregation formation in Al-Cu alloys, experiments were run under terrestrial gravity (1g) and under low gravity during parabolic flights (10(exp -2) g). Alloys of two different compositions (2% and 5% Cu) were solidified at two different cooling rates. Systematic microscopic and SEM observations produced microstructural and segregation maps for all samples. These maps may be used as benchmark experiments for validation of microstructure evolution and segregation models. As expected, the macro segregation maps are very complex. When segregation was measured along the central axis of the sample, the highest macro segregation for samples solidified at 1g was obtained for the lowest cooling rate. This behavior is attributed to the longer time available for natural convection and shrinkage flow to affect solute redistribution. In samples solidified under low-g, the highest macro-segregation was obtained at the highest cooling rate. In general, low-gravity solidification resulted in less segregation. To explain the experimental findings, an analytical (Flemings-Nereo) and a numerical model were used. For the numerical model, the continuum formulation was employed to describe the macroscopic transports of mass, energy, and momentum, associated with the microscopic transport phenomena, for a two-phase system. The model proposed considers that liquid flow is driven by thermal and solutal buoyancy, and by solidification shrinkage. The Flemings-Nereo model explains well macro segregation in the initial stages of low-gravity segregation. The numerical model can describe the complex macro segregation pattern and the differences between low- and high-gravity solidification.

  4. Lamellar nanostructures of silicon heterogeneously solidified on graphite sheets

    NASA Astrophysics Data System (ADS)

    Li, Y. F.; Yu, H. Q.; Li, H.; Liew, K. M.; Liu, X. F.

    2010-04-01

    Molecular dynamics simulations are performed to examine the heterogeneous solidification of silicon on foreign graphite sheets (GSs). It clearly indicates that silicon atoms are concentrated to form hierarchical nanostructures composed of equidistant nanolayers. Graphite plate induces strong ordered liquid silicon layers near the surfaces of GSs. This study suggests ordered liquid layers should be the early form of the solid crystal, which determine the subsequent nucleation. The confined nanospace between two GSs favors the solidification and results in the decrease in the distance between layers. GSs make silicon atoms solidify into an hcp crystal rather than fcc structure.

  5. 3D Synchrotron Imaging of a Directionally Solidified Ternary Eutectic

    NASA Astrophysics Data System (ADS)

    Dennstedt, Anne; Helfen, Lukas; Steinmetz, Philipp; Nestler, Britta; Ratke, Lorenz

    2016-03-01

    For the first time, the microstructure of directionally solidified ternary eutectics is visualized in three dimensions, using a high-resolution technique of X-ray tomography at the ESRF. The microstructure characterization is conducted with a photon energy, allowing to clearly discriminate the three phases Ag2Al, Al2Cu, and α-Aluminum solid solution. The reconstructed images illustrate the three-dimensional arrangement of the phases. The Ag2Al lamellae perform splitting and merging as well as nucleation and disappearing events during directional solidification.

  6. Macrosegregation in Directionally Solidified Pb-Sn Alloys

    NASA Technical Reports Server (NTRS)

    Tewari, Surendra N.

    1998-01-01

    Thermosolutal convection in the dendritic mushy zone occurs during directional solidification of hypoeutectic lead tin alloys in a positive thermal gradient, with the melt on the top and the solid below. This results in macrosegregation along the length of the solidified samples. The extent of macrosegregation increases with increasing primary dendrite spacings for constant mushy zone length. For constant primary spacings, the macrosegregation increases with decreasing mushy zone length. Presence of convection reduces the primary dendrite spacings. However, convection in the interdendritic melt has significantly more influence on the spacings as compared with that in the overlying melt, which is caused by the solutal build up at the dendrite tips.

  7. Constitutive Modeling of Superalloy Single Crystals and Directionally Solidified Materials

    NASA Technical Reports Server (NTRS)

    Walker, K. P.; Jordan, E. H.

    1985-01-01

    A unified viscoplastic constitutive relation based on crystallographic slip theory was developed for the deformation analysis of nickel base face centered cubic superalloy single crystals at elevated temperature. The single crystal theory is embedded in a self consistent method to derive a constitutive relation for a directionally solidified material comprised of a polycrystalline aggregate of columnar cylindrical grains. One of the crystallographic axes of the cylindrical crystals points in the columnar direction while the remaining crystallographic axes are oriented at random in the basal plane perpendicular to the columnar direction. These constitutive formulations are coded in FORTRAN for use in nonlinear finite element and boundary element programs.

  8. Detection of free liquid in containers of solidified radioactive waste

    DOEpatents

    Greenhalgh, W.O.

    Nondestructive detection of the presence of free liquid within a sealed enclosure containing solidified waste is accomplished by measuring the levels of waste at two diametrically opposite locations while slowly tilting the enclosure toward one of said locations. When the measured level remains constant at the other location, the measured level at said one location is noted and any measured difference of levels indicates the presence of liquid on the surface of the solifified waste. The absence of liquid in the enclosure is verified when the measured levels at both locations are equal.

  9. Creep in Directionally Solidified NiAl-Mo Eutectics

    SciTech Connect

    Dudova, Marie; Kucharova, Kveta; Bartak, Tomas; Bei, Hongbin; George, Easo P; Somsen, Ch.; Dlouhy, A.

    2011-01-01

    A directionally solidified NiAl-Mo eutectic and an NiAl intermetallic, having respective nominal compositions Ni-45.5Al-9Mo and Ni-45.2Al (at.%), were loaded in compression at 1073 and 1173 K. Formidable strengthening by regularly distributed Mo fibres (average diameter 600 nm, volume fraction 14%) was observed. The fibres can support compression stresses transferred from the plastically deforming matrix up to a critical stress of the order of 2.5 GPa, at which point they yield. Microstructural evidence is provided for the dislocation-mediated stress transfer from the NiAl to the Mo phase.

  10. Mechanical Behavior and Microstructure Characteristics of Directionally Solidified TWIP Steel

    NASA Astrophysics Data System (ADS)

    Wang, Dan; Wang, Kun; Man, Jianfeng; Yang, Jianzhong; Han, Fusheng

    2016-07-01

    The mechanical behavior and microstructure characteristics of three high Mn austenitic steels prepared by directional solidification at withdrawal rates of 60, 120, and 240 μm s-1 were investigated and compared with common TWIP steel with equiaxed grains. For each steel, the Hollomon analysis, differential C-J analysis, and modified C-J analysis as an alternative method to describe the work-hardening behavior were studied. The directionally solidified samples (DS samples) exhibited higher mechanical properties along the axis, five stages (A, B, C, D, and E) divided on the plot of stain hardening rate vs true strain, and a more stable and uniform deformation feature with larger strain-hardening coefficients when the true strain is over 0.25, in comparison with the common TWIP steel. The modified C-J analysis was found to be the best one for revealing the strain-hardening behavior characterized by several different stages with a definite work-hardening exponent n. In the case of DS samples, the dendrite spacings increase but the morphology becomes simple when decreasing the withdrawal rate. The larger volume fraction of twins and prevalent activation of twin systems, together with the fragmentations of the original grains in a sample solidified at a withdrawal rate of 120 μm s-1, lead to the best mechanical behavior in a medium-to-large strain range.

  11. Mechanical Behavior and Microstructure Characteristics of Directionally Solidified TWIP Steel

    NASA Astrophysics Data System (ADS)

    Wang, Dan; Wang, Kun; Man, Jianfeng; Yang, Jianzhong; Han, Fusheng

    2016-04-01

    The mechanical behavior and microstructure characteristics of three high Mn austenitic steels prepared by directional solidification at withdrawal rates of 60, 120, and 240 μm s-1 were investigated and compared with common TWIP steel with equiaxed grains. For each steel, the Hollomon analysis, differential C-J analysis, and modified C-J analysis as an alternative method to describe the work-hardening behavior were studied. The directionally solidified samples (DS samples) exhibited higher mechanical properties along the axis, five stages (A, B, C, D, and E) divided on the plot of stain hardening rate vs true strain, and a more stable and uniform deformation feature with larger strain-hardening coefficients when the true strain is over 0.25, in comparison with the common TWIP steel. The modified C-J analysis was found to be the best one for revealing the strain-hardening behavior characterized by several different stages with a definite work-hardening exponent n. In the case of DS samples, the dendrite spacings increase but the morphology becomes simple when decreasing the withdrawal rate. The larger volume fraction of twins and prevalent activation of twin systems, together with the fragmentations of the original grains in a sample solidified at a withdrawal rate of 120 μm s-1, lead to the best mechanical behavior in a medium-to-large strain range.

  12. Dependence of catalytic properties of Al/Fe{sub 2}O{sub 3} thermites on morphology of Fe{sub 2}O{sub 3} particles in combustion reactions

    SciTech Connect

    Zhao, Ningning; He, Cuicui; Liu, Jianbing; Gong, Hujun; An, Ting; Xu, Huixiang; Zhao, Fengqi; Hu, Rongzu; Ma, Haixia; Zhang, Jinzhong

    2014-11-15

    Three Fe{sub 2}O{sub 3} particle samples with the same crystal structure but different morphologies were prepared by the hydrothermal method and then combined with Al nanoparticles to produce Al/Fe{sub 2}O{sub 3} thermites using ultrasonic mixing. The properties of Fe{sub 2}O{sub 3} and Al/Fe{sub 2}O{sub 3} were studied using a combination of experimental techniques including scanning electron microscopy (SEM), energy dispersive spectrometer (EDS), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and differential scanning calorimetry (DSC). The influences of the three Al/Fe{sub 2}O{sub 3} thermites on the combustion properties of the AP/HTPB (ammonium perchlorate/hydroxyl-terminated polybutadiene) composite propellant were investigated in comparison to those of Fe{sub 2}O{sub 3}. The results show that the Al/Fe{sub 2}O{sub 3} thermites are better than Fe{sub 2}O{sub 3} in enhancing the combustion performance of AP/HTPB. Furthermore, the surface area, which depends on size and mophology, of Fe{sub 2}O{sub 3} particles was found to play a vital role in improving the burning rate of the thermites-containing propellant formulation, with the smallest particles with the largest surface-to-volume (S/V) ratio performing the best. The enhanced catalytic property of the granular-shape Fe{sub 2}O{sub 3} and the corresponding thermite is attributed to the large specific surface area of Fe{sub 2}O{sub 3}. The different thermal behaviors of these three superthemites were supposed to be attributed to the surface site of Fe{sub 2}O{sub 3} particles. This work provides a better understanding on the catalytic properties of thermites that are important for combustion applications. - Graphical abstract: Effects of Fe{sub 2}O{sub 3} and Al/Fe{sub 2}O{sub 3} have been compared for the first time by analyzing combustion properties of formulations containing them, suggesting their potential application in AP/HTPB composite propellant systems. - Highlights:

  13. Electrochemical and microstructural study of oxide films formed electrochemically at microcrystalline Al-Fe-V-Si alloys.

    PubMed

    Thomas, S C; Birss, V I; Steele, D; Tessier, D

    1995-07-01

    A recent advance in metallurgical technology has been the application of rapid solidification techniques to Al alloy production. FVS0812 is the designation given to a microcrystalline Al-based alloy consisting of 8 wt% Fe, 1 wt% V and 2 wt% Si. It is a two-phase alloy, consisting of ca. 27 vol percent of approximately spherical Fe-V-Si-rich dispersoids in an essentially pure Al matrix. The high strength, low density properties of this advanced material, and other related alloys, have not yet been realized, however, due, in part, to the inability of the alloy to form a thick, adherent, abrasion-resistant outer surface oxide film, a feature readily achieved at conventional Al alloys by normal anodizing methods. The present research has involved an electro-chemical study of oxide film growth at the 812 alloy, with the specific goals being to seek an understanding of the origin of the oxide film growth problem and ultimately to propose alternative approaches to the formation of a thick, stable oxide film at this material. The techniques used in this research have included electrochemical methodologies such as cyclic voltammetry and electrochemical impedance spectroscopy. Crucial information has been obtained through transmission electron microscopy (TEM) of ultramicrotomed specimens. Experiments were carried out initially in neutral borate solutions to characterize the compact barrier oxide film formed in this environment and expected to be present beneath the porous oxide film formed in the normal sulfuric acid anodizing medium.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:7549001

  14. Synthesis and Performance Characterization of a Nanocomposite Ternary Thermite: Al/Fe2O3/SiO2

    SciTech Connect

    Prentice, D; Pantoya, M L; Clapsaddle, B J

    2005-02-04

    Making solid energetic materials requires the physical mixing of solid fuels and oxidizers or the incorporation of fuel and oxidizing moieties into a single molecule. The former are referred to as composite energetic materials (i.e., thermites, propellants, pyrotechnics) and the latter are deemed monomolecular energetic materials (i.e., explosives). Mass diffusion between the fuel and oxidizer is the rate controlling step for composite reactions while bond breaking and chemical kinetics control monomolecular reactions. Although composites have higher energy densities than monomolecular species, they release that energy over a longer period of time because diffusion controlled reactions are considerably slower than chemistry controlled reactions. Conversely, monomolecular species exhibit greater power due to more rapid kinetics than physically mixed energetics. Reducing the diffusion distance between fuel and oxidizer species within an energetic composite would enhance the reaction rate. Recent advances in nanotechnology have spurred the development of nano-scale fuel and oxidizer particles that can be combined into a composite and effectively reduce diffusion distances to nano-scale dimensions or less. These nanocomposites have the potential to deliver the best of both worlds: high energy density of the physically mixed composite with the high power of the monomolecular species. Toward this end, researchers at Lawrence Livermore National Laboratory (LLNL) developed nano-particle synthesis techniques, based on sol-gel chemistry, for the production of thermite nanocomposites.

  15. Effects of leachate concentration on the integrity of solidified clay liners.

    PubMed

    Xue, Qiang; Zhang, Qian

    2014-03-01

    This study aimed to evaluate the impact of landfill leachate concentration on the degradation behaviour of solidified clay liners and to propose a viable mechanism for the observed degradation. The results indicated that the unconfined compressive strength of the solidified clay decreased significantly, while the hydraulic conductivity increased with the leachate concentration. The large pore proportion in the solidified clay increased and the sum of medium and micro pore proportions decreased, demonstrating that the effect on the solidified clay was evident after the degradation caused by exposure to landfill leachate. The unconfined compressive strength of the solidified clay decreased with increasing leachate concentration as the leachate changed the compact structure of the solidified clay, which are prone to deformation and fracture. The hydraulic conductivity and the large pore proportion of the solidified clay increased with the increase in leachate concentration. In contrast, the sum of medium and micro pore proportions showed an opposite trend in relation to leachate concentration, because the leachate gradually caused the medium and micro pores to form larger pores. Notably, higher leachate concentrations resulted in a much more distinctive variation in pore proportions. The hydraulic conductivity of the solidified clay was closely related to the size, distribution, and connection of pores. The proportion of the large pores showed a positive correlation with the increase of hydraulic conductivity, while the sum of the proportions of medium and micro pores showed a negative correlation. PMID:24532708

  16. Building towers, domes, and arches by self-organized solidifying flows

    NASA Astrophysics Data System (ADS)

    Chopin, Julien

    2013-03-01

    We demonstrate that a wide variety of delicate solid structures from slender towers to arches, and chiral pagodas can be created by simply pouring a mixture of grains and water on a liquid absorbing substrate [Phys. Rev. Lett. 107, 208304 (2011)]. The same suspension poured on a solid substrate would form a featureless puddle or a pile with an angle of repose. However, an absorbing substrate can quickly drain the liquid from the suspension, rapidly causing the solidification of the fluid into a mechanically stable structure. In a dripping regime, successive drops are observed to jam rapidly upon impact literally stacking on top of each other forming slender granular towers. In a jetting regime and using a moving substrate, the jet is found to bounce on and off the substrate forming regular arches. We will discuss the subtle interplay of the incoming flux of the granular suspension, the drainage efficiency of the substrate, and the mechanical properties of the solid structure. The drainage driven jamming of granular suspensions gives a new route to shape cohesive granular materials and, from a broader perspective, demonstrates the potential a solidifying fluid spreading on a substrate to create new morphologies harder to achieve by other techniques. Applications to surface patterning, rheology of dense suspension and mechanics of wet granular materials will be discussed.

  17. Magnetoresistance effect in Ag-Fe3O4 and Al-Fe3O4 composite films

    NASA Astrophysics Data System (ADS)

    Hsu, Jen-Hwa; Chen, Shang-Yi; Chang, Wen-Ming; Jian, T. S.; Chang, Ching-Ray; Lee, Shan-Fan

    2003-05-01

    The Agx-(Fe3O4)1-x and Agx-(Fe3O4)1-x composite films were prepared by dc sputtering on Si(100) substrates. The x-ray diffraction results show that the films contain essentially only the cubic inverse spinal phase from Fe3O4 and face-centered cubic phase from Ag or Al. The transmission electron microscopy images indicate that the metal granules are randomly distributed with Fe3O4 grains. The resistivity determined from the four-probe method decreases rapidly with increasing metal content. At x≒0.5, a percolation occurs. The conducting path is formed from metal granules in series with Fe3O4 grains. The magnetoresistance (MR) is defined to be {R(H=0.8 T)-R(H=0)}/R(H=0). It has been found that MR is isotropic and the appearance of Ag granules has significant impact on the MR effect. Furthermore, a positive MR region appears with 0.011

  18. Field validation of test methods for solidified waste evaluation -- a status report

    SciTech Connect

    Stegemann, J.A.; Caldwell, R.J.; Shi, C.

    1996-12-31

    Application of solidification/stabilization as a treatment technology for hazardous wastes has been hindered by the lack of a regulatory approval mechanism for solidified wastes. The Wastewater Technology Centre (WTC) has developed a protocol for evaluation of solidified wastes, which uses the performance of a solidified product in twelve laboratory test methods to recommend one of four categories of utilization and disposal. In order to facilitate acceptance of the protocol, a validation study of the test methods has been initiated by the WTC. A 63 m{sup 3} field test cell has been constructed using electric arc furnace dust solidified with an activated blast furnace slag binder system. The behavior of the solidified waste in the field will be investigated by monitoring of leachate and testing of core samples, and compared with properties measured in the laboratory.

  19. Estimation of the engineering elastic constants of a directionally solidified superalloy for finite element structural analysis

    NASA Technical Reports Server (NTRS)

    Abdul-Aziz, Ali; Kalluri, Sreeramesh

    1991-01-01

    The temperature-dependent engineering elastic constants of a directionally solidified nickel-base superalloy were estimated from the single-crystal elastic constants of nickel and MAR-MOO2 superalloy by using Wells' method. In this method, the directionally solidified (columnar-grained) nickel-base superalloy was modeled as a transversely isotropic material, and the five independent elastic constants of the transversely isotropic material were determined from the three independent elastic constants of a cubic single crystal. Solidification for both the single crystals and the directionally solidified superalloy was assumed to be along the (001) direction. Temperature-dependent Young's moduli in longitudinal and transverse directions, shear moduli, and Poisson's ratios were tabulated for the directionally solidified nickel-base superalloy. These engineering elastic constants could be used as input for performing finite element structural analysis of directionally solidified turbine engine components.

  20. Directionally solidified eutectic gamma-gamma nickel-base superalloys

    NASA Technical Reports Server (NTRS)

    Jackson, M. R. (Inventor)

    1977-01-01

    A directionally solidified multivariant eutectic gamma-gamma prime nickel-base superalloy casting having improved high temperature properties was developed. The alloy is comprised of a two phase eutectic structure consisting essentially of on a weight percent base, 6.0 to 9.0 aluminum, 5.0 to 17.0 tantalum, 0-10 cobalt, 0-6 vanadium, 0-6 rhenium, 2.0-6.0 tungsten, and the balance being nickel, subject to the proviso that the sum of the atomic percentages of aluminum plus tantalum is within the range of from 19-22, and the ratio of atomic percentages of tantalum to aluminum plus tantalum is within the range of from 0.12 to 0.23. Embedded within the gamma nickel-base matrix are aligned eutectic gamma prime phase (primarily nickel-aluminum-tantalum) reinforcing fibers.

  1. Method and apparatus for supercooling and solidifying substances

    NASA Technical Reports Server (NTRS)

    Lacy, L. L.; Robinson, M. B.; Rathz, T. J.; Katz, L.; Nisen, D. B. (Inventor)

    1983-01-01

    An enclosure provides a containerless environment in which a sample specimen is positioned. The specimen is heated in the containerless environment, and the specimen melt is dropped through the tube in which it cools by radiation. The tube is alternatively backfilled with an inert gas whereby the specimen melt cools by both radiation and convection during its free fall. During the free fall, the sample is in a containerless, low-gravity environment which enhances supercooling in the sample and prevents sedimentation and thermal convection influences. The sample continues to supercool until nucleation occurs which is detected by silicon photovoltaic detectors. The sample solidifies after nucleation and becomes completely solid before entering the detachable catcher. The amount of supercooling of the specimen can be measured by knowing the cooling ratio and determining the time for nucleation to occur.

  2. Microstructure Evolution in the Near-Surface Region During Homogenization of a Twin-Roll Cast AlFeMnSi Alloy

    NASA Astrophysics Data System (ADS)

    Wang, Junjie; Zhou, Xiaorong; Thompson, George E.; Hunter, John A.; Yuan, Yudie

    2016-06-01

    A near-surface deformed layer, comprising ultrafine grains of 50-500 nm diameters with the grain boundaries being decorated by a high population density of fine cubic α-Al15(FeMn)3Si2 dispersoids and oxide/lubricant particles, was generated in a foil stock AlFeMnSi alloy during twin-roll casting due to severe shear deformation within the near-surface region. During a subsequent multi-step homogenization treatment at temperatures in the range of 713 K and 853 K (440 °C and 580 °C), the fine cubic α-Al15(FeMn)3Si2 dispersoids within the near-surface layer were dissolved, while sparse, large lath-shaped Al3Fe particles formed in the same region. Significant grain growth took place within the near-surface layer due to the loss of grain boundary pinning by the dispersoids, leading to the removal of the ultrafine-grained microstructure within the near-surface region. However, at local regions where the population density of oxide particles was sufficiently high to provide grain boundary pinning, the ultrafine-grained microstructure was preserved within the near-surface layer.

  3. Kinetic Analysis of Recovery, Recrystallization, and Phase Precipitation in an Al-Fe-Si Alloy Using JMAEK and Sesták-Berggren Models

    NASA Astrophysics Data System (ADS)

    Luiggi Agreda, Ney José

    2015-02-01

    When studying the phase changes process in a rolled AA8011 alloy using DSC, we find that the peaks associated with phase precipitation under this microstructural condition are different from those obtained in homogenized microstructures. The differences observed are attributable, first, to the recovery process occurring at temperatures below 423 K (150 °C), which interacts with the precipitation of Si-rich precipitates or with Guinier-Preston zones both coexistent in that temperature range; and second, to the recrystallization above 473 K (200 °C), which coexists with precipitation of the α-AlFeSi phase. In this work, the precipitation and recovery-recrystallization kinetics are experimentally obtained and deconvoluted in peaks characteristic for each of the mechanisms involved; i.e., precipitation of GP zones, recovery, precipitation of α phase, and recrystallization. The deconvolution is achieved using functions of Gauss, Weibull, and Fraser-Suzuki; and the characterization of each reaction deconvoluted is realized through both Jhonson-Melh-Avrami-Erofeev-Kolmorokov kinetic models and Sesták-Berggren combined kinetic model. The kinetic study evinces that in addition to the expected reactions, other reactions, necessary for good experimental adjustment, appear. An isoconversional study is undertaken to numerically evaluate the kinetic triplet of every process.

  4. Synthesis and characterization of phosphates in molten systems Cs 2O-P 2O 5-CaO- MIII2O 3 ( MIII—Al, Fe, Cr)

    NASA Astrophysics Data System (ADS)

    Zatovsky, Igor V.; Strutynska, Nataliya Yu.; Baumer, Vyacheslav N.; Slobodyanik, Nikolay S.; Ogorodnyk, Ivan V.; Shishkin, Oleg V.

    2011-03-01

    The crystallization of complex phosphates from the melts of Cs 2O-P 2O 5-CaO- MIII2O 3 ( MIII—Al, Fe, Cr) systems have been investigated at fixed value Cs/P molar ratios equal to 0.7, 1.0 and 1.3 and Са/Р=0.2 and Ca/ МIII=1. The fields of crystallization of CsCaP 3O 9, β-Ca 2P 2O 7, Cs 2CaP 2O 7, Cs 3CaFe(P 2O 7) 2, Ca 9MIII(PO 4) 7 ( MIII—Fe, Cr), Cs 0.63Ca 9.63Fe 0.37(PO 4) 7 and CsCa 10(PO 4) 7 were determined. Obtained phosphates were investigated using powder X-ray diffraction and FTIR spectroscopy. Novel whitlockite-related phases CsCa 10(PO 4) 7 and Cs 0.63Ca 9.63Fe 0.37(PO 4) 7 have been characterized by single crystal X-ray diffraction: space group R3c, a=10.5536(5) and 10.5221(4) Å, с=37.2283(19) and 37.2405(17) Å, respectively.

  5. SOx removal by calcined MgAlFe hydrotalcite-like materials: effect of the chemical composition and the cerium incorporation method.

    PubMed

    Cantú, Manuel; López-Salinas, Esteban; Valente, Jaime S; Montiel, Ramon

    2005-12-15

    Sulfur oxides are one of the most hazardous atmospheric pollutants since they contribute directly to acid rain formation. Consequently, stringent environmental regulations limit atmospheric SOx emissions, motivating research on efficient ways to reduce them. To supply an alternative to reduce these emissions in fluid catalytic cracking units, this study discloses efficient SOx reducing materials based on calcined MgAlFe hydrotalcite-like compounds (HT's). Thus, HT materials were synthesized by several methods including cerium addition. The adsorption of SO2 was carried out by contacting the calcined solid with a mixture of SO2 (1%) in air at 650 degrees C. It was demonstrated that the isomorphic incorporation of iron increased its reduction capability which was reflected in higher reduction rates and metal sulfate reduction grade at 550 degrees C. Moreover, when cerium was present in the iron-containing materials the saturation rate was improved, because cerium oxide promotes the oxidation of SO2 to SO3. The way cerium is incorporated influences the SO2 adsorption capacity. PMID:16475357

  6. Predictions of the Hunt-Lu array model compared with measurements for the growth undercooling of Al{sub 3}Fe dendrites in Al-Fe alloys

    SciTech Connect

    Liang, D.; Jones, H.

    1997-10-01

    Earlier contributions by the authors reported the first measurements of growth temperature as a function of growth velocity V and alloy concentration C{sub 0} for a dendritic intermetallic phase (Al{sub 3}Fe, in Al-rich Al-Fe alloys). Comparison with predictions of the model of Kurz, Giovanola and Trivedi (KGT model) of dendrite growth of a needle gave predicted {Delta}T a factor between 1.1 and 2.5 above the measured values. A subsequent paper presented evidence that the Al{sub 3}Fe dendrite tips were indeed needle-like under the conditions studied, as distinct from the plate-like morphology that develops behind the dendrite tips. The KGT model predicts T{sub G} and {Delta}T on the basis that marginal stability determines the operating condition at the dendrite tip. The present purpose is to compare the measurements with predictions of the more recently developed array model of Hunt and Lu.

  7. Microstructure Evolution in the Near-Surface Region During Homogenization of a Twin-Roll Cast AlFeMnSi Alloy

    NASA Astrophysics Data System (ADS)

    Wang, Junjie; Zhou, Xiaorong; Thompson, George E.; Hunter, John A.; Yuan, Yudie

    2016-08-01

    A near-surface deformed layer, comprising ultrafine grains of 50-500 nm diameters with the grain boundaries being decorated by a high population density of fine cubic α-Al15(FeMn)3Si2 dispersoids and oxide/lubricant particles, was generated in a foil stock AlFeMnSi alloy during twin-roll casting due to severe shear deformation within the near-surface region. During a subsequent multi-step homogenization treatment at temperatures in the range of 713 K and 853 K (440 °C and 580 °C), the fine cubic α-Al15(FeMn)3Si2 dispersoids within the near-surface layer were dissolved, while sparse, large lath-shaped Al3Fe particles formed in the same region. Significant grain growth took place within the near-surface layer due to the loss of grain boundary pinning by the dispersoids, leading to the removal of the ultrafine-grained microstructure within the near-surface region. However, at local regions where the population density of oxide particles was sufficiently high to provide grain boundary pinning, the ultrafine-grained microstructure was preserved within the near-surface layer.

  8. Experimental design optimization for the ICP-AES determination of Li, Na, K, Al, Fe, Mn and Zn in human serum.

    PubMed

    Bianchi, F; Maffini, M; Mangia, A; Marengo, E; Mucchino, C

    2007-01-17

    A chemometric approach based on experimental design and desirability functions was used to develop and validated a method for the determination of some metals of biological concern by a fast sequential ICP-AES. The elements considered are Al, Fe, Mn, Zn, Li, Na and K. The experimental design was used to investigate the effects of three instrumental most crucial parameters, such as sheath gas flow rate, pump speed and auxiliary gas flow rate. In order to improve the multielemental analysis speed, although a sequential instrument allows the use of a separate parameter set for each wavelength, regression models and desirability functions were applied to find the experimental conditions providing the highest global sensitivity. Validation was performed in terms of limits of detection (LOD), limits of quantitation (LOQ), linearity, precision and recovery. By using the 167.02 nm wavelength, aluminium LOD was 0.5 microg L(-1) while the highest LOD was found for K (65 microg L(-1)). A linear range of at least three orders of magnitude was statistically demonstrated for each element. Precision was evaluated by testing two concentration levels, and good results in terms of intra-day repeatability were obtained, with R.S.D. values lower than 4.1% at the lowest concentration level. Lacking a suitable certified reference material, trueness was estimated using the recovery rate on fortified samples. The validated method was then used in the quantification of the elements considered in a serum sample. PMID:17079109

  9. Printing low-melting-point alloy ink to directly make a solidified circuit or functional device with a heating pen

    PubMed Central

    Wang, Lei; Liu, Jing

    2014-01-01

    A new method to directly print out a solidified electronic circuit through low-melting-point metal ink is proposed. A functional pen with heating capability was fabricated. Several typical thermal properties of the alloy ink Bi35In48.6Sn16Zn0.4 were measured and evaluated. Owing to the specifically selected melting point of the ink, which is slightly higher than room temperature, various electronic devices, graphics or circuits can be manufactured in a short period of time and then rapidly solidified by cooling in the surrounding air. The liquid–solid phase change mechanism of the written lines was experimentally characterized using a scanning electron microscope. In order to determine the matching substrate, wettability between the metal ink Bi35In48.6Sn16Zn0.4 and several materials, including mica plate and silicone rubber, was investigated. The resistance–temperature curve of a printed resistor indicated its potential as a temperature control switch. Furthermore, the measured reflection coefficient of a printed double-diamond antenna accords well with the simulated result. With unique merits such as no pollution, no requirement for encapsulation and easy recycling, the present printing approach is an important supplement to current printed electronics and has enormous practical value in the future. PMID:25484611

  10. Printing low-melting-point alloy ink to directly make a solidified circuit or functional device with a heating pen.

    PubMed

    Wang, Lei; Liu, Jing

    2014-12-01

    A new method to directly print out a solidified electronic circuit through low-melting-point metal ink is proposed. A functional pen with heating capability was fabricated. Several typical thermal properties of the alloy ink Bi35In48.6Sn16Zn0.4 were measured and evaluated. Owing to the specifically selected melting point of the ink, which is slightly higher than room temperature, various electronic devices, graphics or circuits can be manufactured in a short period of time and then rapidly solidified by cooling in the surrounding air. The liquid-solid phase change mechanism of the written lines was experimentally characterized using a scanning electron microscope. In order to determine the matching substrate, wettability between the metal ink Bi35In48.6Sn16Zn0.4 and several materials, including mica plate and silicone rubber, was investigated. The resistance-temperature curve of a printed resistor indicated its potential as a temperature control switch. Furthermore, the measured reflection coefficient of a printed double-diamond antenna accords well with the simulated result. With unique merits such as no pollution, no requirement for encapsulation and easy recycling, the present printing approach is an important supplement to current printed electronics and has enormous practical value in the future. PMID:25484611

  11. Surface modification induced phase transformation and structure variation on the rapidly solidified recast layer of titanium

    SciTech Connect

    Tsai, Ming-Hung; Haung, Chiung-Fang; Shyu, Shih-Shiun; Chou, Yen-Ru; Lin, Ming-Hong; Peng, Pei-Wen; and others

    2015-08-15

    In this study, neodymium-doped yttrium orthovanadate (Nd:YVO{sub 4}) as a laser source with different scanning speeds was used on biomedical Ti surface. The microstructural and biological properties of laser-modified samples were investigated by means of optical microscope, electron microscope, X-ray diffraction, surface roughness instrument, contact angle and cell cytotoxicity assay. After laser modification, the rough volcano-like recast layer with micro-/nanoporous structure and wave-like recast layer with nanoporous structure were generated on the surfaces of laser-modified samples, respectively. It was also found out that, an α → (α + rutile-TiO{sub 2}) phase transition occurred on the recast layers of laser-modified samples. The Ti surface becomes hydrophilic at a high speed laser scanning. Moreover, the cell cytotoxicity assay demonstrated that laser-modified samples did not influence the cell adhesion and proliferation behaviors of osteoblast (MG-63) cell. The laser with 50 mm/s scanning speed induced formation of rough volcano-like recast layer accompanied with micro-/nanoporous structure, which can promote cell adhesion and proliferation of MG-63 cell on Ti surface. The results indicated that the laser treatment was a potential technology to enhance the biocompatibility for titanium. - Highlights: • Laser induced the formation of recast layer with micro-/nanoporous structure on Ti. • An α → (α + rutile-TiO{sub 2}) phase transition was observed within the recast layer. • The Ti surface becomes hydrophilic at a high speed laser scanning. • Laser-modified samples exhibit good biocompatibility to osteoblast (MG-63) cell.

  12. Corrosion inhibition of rapidly solidified Mg-3% Zn-15% Al magnesium alloy with sodium carboxylates

    SciTech Connect

    Daloz, D.; Michot, G.; Rapin, C.; Steinmetz, P.

    1998-06-01

    The ability of sodium linear-saturated carboxylates to protect magnesium alloys against aqueous corrosion was characterized. Electrochemical measurements of polarization resistance and corrosion current showed the inhibition efficiency of these compounds is a function of their concentration and of the length of the aliphatic chain. In every case studied, the efficiency increased with immersion time. At pH 8, the best inhibiting behavior was observed with 0.05 M sodium undecanoate. The potential-pH diagram of magnesium in an aqueous solution containing undecanoate anions was generated based upon the solubility determined for magnesium undecanoate (Mg[CH{sub 3}(CH{sub 2}){sub 9}COO]{sub 2}). According to this diagram, the very low corrosion rate was suspected to result from formation of Mg(CH{sub 3}[CH{sub 2}]{sub 9}COO){sub 2}. Infrared spectrometry carried out on both the synthesized magnesium carboxylate and the product from the magnesium alloy surface after inhibitive treatment confirmed this hypothesis.

  13. Magnetocaloric properties of rapidly solidified Dy{sub 3}Co alloy ribbons

    SciTech Connect

    Sánchez Llamazares, J. L. Flores-Zúñiga, H.; Sánchez-Valdés, C. F.; Álvarez-Alonso, Pablo

    2015-05-07

    The magnetic and magnetocaloric (MC) properties of melt-spun ribbons of the Dy{sub 3}Co intermetallic compound were investigated. Samples were fabricated in an Ar environment using a homemade melt spinner system at a linear speed of the rotating copper wheel of 40 ms{sup −1}. X-ray diffraction analysis shows that ribbons crystallize into a single-phase with the Fe{sub 3}C-type orthorhombic crystal structure. The M(T) curve measured at 5 mT reveals the occurrence of a transition at 32 K from a first to a second antiferromagnetic (AFM) state and an AFM-to-paramagnetic transition at T{sub N} = 43 K. Furthermore, a metamagnetic transition is observed below T{sub N}, but the magnetization change ΔM is well below the one reported for bulk alloys. Below 12 K, large inverse MC effect and hysteresis losses are observed. This behavior is related to the metamagnetic transition. For a magnetic field change of 5 T (2 T) applied along the ribbon length, the produced ribbons show a peak value of the magnetic entropy change ΔS{sub M}{sup peak} of −6.5 (− 2.1) Jkg{sup −1}K{sup −1} occurring close to T{sub N} with a full-width at half-maximum δT{sub FWHM} of 53 (37) K, and refrigerant capacity RC = 364 (83) Jkg{sup −1} (estimated from the product |ΔS{sub M}{sup peak}| × δT{sub FWHM})

  14. The structure and properties of rapidly solidified high alloy aluminum materials

    NASA Technical Reports Server (NTRS)

    Grant, N. J.

    1982-01-01

    A series of 2024 type aluminum alloys modified by additions of 1 to 2% Li were studied to determine the role of the Cu:Li and the (Cu + Mg):Li ratios on resultant strength, ductility, notch-tensile behavior, and crack propagation rates. Ultrasonically gas atomized powders with quench rates of 10 to 100 thousand degrees/s were atomized in an argon atmosphere, producing yields of powder such that almost 100% was finer than 250 microns. The powders are free of gases and porosity, are quite spherical, have few satellites (adhering fine powder particles) and are of uniform microstructure. Strength properties are such that yield strength is 20% greater than for lithium-free 2024 ingot alloy, tensile strength is 10% greater than that of 2024 ingot material, and ductilities are comparable. In terms of specific strength and specific modulus, these RS 2024-Li alloys are significantly better than IM 2024.

  15. Mechanisms of isothermal phase transformations in rapidly solidified Ti-24Al-11Nb

    NASA Technical Reports Server (NTRS)

    Hsiung, L. M.; Cai, W.; Wadley, H. N. G.

    1992-01-01

    A dynamic simulation for the motion of an isolated superdislocation (SD) under an applied stress is presented. The simulation incorporates the concept that cross slip from (111) planes to (010) planes can locally pin the SD. It is determined that the principal effect of cross-slip-pinning is not the reduction in the SD velocity, but rather the exhaustion of the density of mobile SDs.

  16. Influence of consolidation method on structure/properties of rapidly solidified Type 304 SS powders

    SciTech Connect

    Flinn, J.E.; Korth, G.E.; Wright, R.N.

    1988-01-01

    The structure/properties of consolidated, centrifugally atomized (CA) Type 304 SS powders containing approx.8 appM helium entrapped during powder processing were evaluated. Three powder consolidation methods were used in the study: hot extrusion, hot isostatic pressing (HIPping), and dynamic (using explosives). In addition, cold-rolled 50% HIPped material was included in the evaluation. The four forms of consolidated powders were fully dense and possessed good bond strengths. The bond strength of the HIPped powders was the lowest. The consolidated materials were subjected to 1 h heat treatments and their grain growth, tensile, and creep behaviors were compared with those of wrought ingot metallurgy Type 304 SS materials. Grain growth of the CA Type 304 SS consolidated powders was substantially lower than for the wrought material. Similarly, significant strengthening was observed for the powder materials. The apparent microstructure stability and strengthening observed for the consolidated powder materials is attributed to the entrapped helium. 5 figs., 4 tabs.

  17. Rapidly solidified Nd7Fe67B22Mo3Zr1 nanocomposite permanent magnets

    NASA Astrophysics Data System (ADS)

    Tao, Shan; Ahmad, Zubair; Ma, Tianyu; Yan, Mi

    2014-04-01

    Nd7Fe67B22Mo3Zr1 magnets in rods have been prepared by annealing the amorphous precursors produced through injection casting. Phase formation, microstructure and magnetic properties of Nd7Fe67B22Mo3Zr1 magnets have been investigated and discussed in the as-cast and annealed states. Cast Nd7Fe67B22Mo3Zr1 rods have the soft magnetic characteristics, which changed into magnetically hard by annealing. Magnetic properties in Nd7Fe67B22Mo3Zr1 magnets are influenced by the intrinsic properties of magnetically soft α-Fe (Fe3B) and hard Nd2Fe14B phases. The Zr and Mo elements in the Nd7Fe67B22Mo3Zr1 alloy promote the formation of amorphous phase and reduce the grain size of magnetic phases. Optimal annealed Nd7Fe67B22Mo3Zr1 rods of 2 mm in diameter and 52 mm in length presented maximum magnetic properties such as: remanence (Br) of 0.53 T, coercivity (iHc) of 1110 kA/m and maximum energy product (BH)max of 49.5 kJ/m3.

  18. Mechanical Properties and Fracture Behavior of Directionally Solidified NiAl-V Eutectic Composites

    NASA Astrophysics Data System (ADS)

    Milenkovic, Srdjan; Caram, Rubens

    2015-02-01

    Directional solidification of eutectic alloys has been recognized as promising technique for producing in situ composite materials exhibiting balance of properties. Therefore, an in situ NiAl-V eutectic composite has been successfully directionally solidified using Bridgman technique. The mechanical behavior of the composite including fracture resistance, microhardness, and compressive properties at room and elevated temperatures was investigated. Damage evolution and fracture characteristics were also discussed. The obtained results indicate that the NiAl-V eutectic retains high yield strength up to 1073 K (800 °C), above which there is a rapid decrease in strength. Its yield strength is higher than that of binary NiAl and most of the NiAl-based eutectics. The exhibited fracture toughness of 28.5 MPa√m is the highest of all other NiAl-based systems investigated so far. The material exhibited brittle fracture behavior of transgranular type and all observations pointed out that the main fracture micromechanism was cleavage.

  19. High temperature monotonic and cyclic deformation in a directionally solidified nickel-base superalloy

    NASA Technical Reports Server (NTRS)

    Huron, Eric S.

    1986-01-01

    Directionally solidified (DS) MAR-M246+Hf was tested in tension and fatigue, at temperatures from 20 C to 1093 C. Tests were performed on (001) oriented specimens at strain rates of 50 % and 0.5 % per minute. In tension, the yield strength was constant up to 704 C, above which the strength dropped off rapidly. A strong dependence of strength on strain rate was seen at the higher temperatures. The deformation mode was observed to change from heterogeneous to homogeneous with increasing temperature. Low Cycle Fatigue tests were done using a fully reversed waveform and total strain control. For a given plastic strain range, lives increased with increasing temperature. For a given temperature strain rate had a strong effect on life. At 704 C, decreasing strain rates decreased life, while at the higher temperatures, decreasing strain rates increased life, for a given plastic strain range. These results could be explained through considerations of the deformation modes and stress levels. At the higher temperatures, marked coarsening caused beneficial stress reductions, but oxidation limited the life. The longitudinal grain boundaries were found to influence slip behavior. The degree of secondary slip adjacent to the boundaries was found to be related to the degree of misorientation between the grains.

  20. Analysis of Radial Segregation in Directionally Solidified Hg(0.89)Mn(0.11)Te

    NASA Technical Reports Server (NTRS)

    Price, M. W.; Scripa, R. N.; Szofran, F. R.; Motakef, S.; Hanson, B.

    2003-01-01

    Bridgman growth experiments were performed on Hg(0.89)Mn(0.11)Te (MMT) to determine the extent of radial Manganese segregation during directional solidification. MMT crystals were directionally solidified at rates of 0.09 and 0.18 p d s and in axial thermal gradients of 83 and 68"C/cm. Wavelength Dispersive Spectroscopy (WDS) and Fourier Transform Infra-Red (FTIR) analytical techniques were used to determine the radial homogeneity in all boules and the deflection of the solid-liquid interface (SLI) in two boules that were rapidly quenched after 5 to 6 cm of directional solidification. For all growth runs, the measured radial coinpositional variations were on the order of 0.01 molar percent MnTe in the steady state region of growth. Comparison of the measured radial compositional results of the crystals to predicted values in the diffusion-limited regime indicate a strong influence of convection near the solid-liquid interface. This conclusion is supported by the weak influence of the translation rates and axial thermal gradients utilized in this study upon radial compositional homogeneity.

  1. Microstructural Response of Directionally Solidified René 80 Superalloy to Gas-Tungsten Arc Welding

    NASA Astrophysics Data System (ADS)

    Sidhu, R. K.; Ojo, O. A.; Chaturvedi, M. C.

    2009-01-01

    The microstructural response of directionally solidified René 80 (DS René 80) superalloy to gas-tungsten-arc (GTA) welding was investigated. Rapid heating during welding resulted in a significant grain-boundary liquation of solid-state reaction product γ' precipitates, intergranular elemental segregation induced M5B3 borides, and secondary solidification constituents MC carbides and sulfocarbides, which were all present in the preweld heat-treated alloy. Liquation of these particles embrittled the grain boundaries in the heat-affected zone (HAZ) and caused microfissuring along the liquated grain boundaries. Nevertheless, contrary to the generally observed increase in HAZ cracking in superalloys with an increase in Ti and Al concentration, due to increase in the alloy’s hardness, significantly reduced cracking was observed in DS René 80 compared to the conventionally cast IN738 welded under the same conditions, despite its hardness being higher than that of IN738. This was related to the nature of base-metal grain- boundary intersections at the fusion-zone boundary in these materials.

  2. Li {sub x}Pb{sup II} {sub 1-2x}M{sup III} {sub x}O (M = Al, Fe): A new solid solution series related to yellow PbO

    SciTech Connect

    Tripathy, Mamata; Mani, Rohini; Gopalakrishnan, J. . E-mail: gopal@sscu.iisc.ernet.in

    2006-12-14

    New series of oxides, Li {sub x}Pb{sub 1-2x}M {sub x}O (M = Al, Fe), for 0Al/Fe members as compared to the parent yellow PbO. Partial deintercalation of lithium occurs under oxidative conditions (Br{sub 2}/CH{sub 3}CN) with both the series.

  3. Genesis of the Doğankuzu and Mortaş Bauxite deposits, Taurides, Turkey: separation of Al, Fe, and Mn and implications for passive margin metallogeny

    USGS Publications Warehouse

    Öztürk, Hüseyin; Hein, James R.; Hanilçi, Nurullah

    2002-01-01

    large amounts of organic matter to the ocean. Alteration of the organic matter provided CO2 that contributed to formation of a relatively 12C-rich marine footwall limestone. Relative sea-level fall resulted from strike-slip faulting associated with closure of the ocean and local uplift of the passive margin. That uplift resulted in karstification and bauxite formation in topographic lows, as represented by the Doğankuzu and Mortaş deposits. During stage 1 of bauxite formation, Al, Fe, Mn, and Ti were mobilized from deeply weathered aluminosilicate parent rock under acidic conditions and accumulated as hydroxides at the limestone surface owing to an increase in pH. During stage 2, Al, Fe, and Ti oxides and clays from the incipient bauxite (bauxitic soil) were transported as detrital phases and accumulated in the fault-controlled depressions and sinkholes. During stage 3, the bauxitic material was concentrated by repeated desilicification, which resulted in the transport of Si and Mn to the ocean through a well-developed karst drainage system. The transported Mn was deposited in offshore muds as Mn carbonates. The sulfides also formed in stage 3 during early diagenesis. Transgression into the foreland basin resulted from shortening of the ocean basin and nappe emplacement during the latest Cretaceous. During that time bioclastic limestone was deposited on the nappe ramp, which overlapped bauxite accumulation.

  4. Composition and solidification microstructure selection in the interdendritic matrix between primary Al{sub 3}Fe dendrites in hypereutectic Al-Fe alloys

    SciTech Connect

    Liang, D.; Korgul, P.; Jones, H.

    1996-07-01

    The composition and constitution of matrix microstructure between plate-like Al{sub 3}Fe dendrites in Bridgman-grown hypereutectic Al-Fe alloys has been determined as a function of alloy concentration C{sub 0} and growth velocity V in the ranges 2.5 < C{sub 0} < 28.1 wt%Fe and 0.01 < V < 5.0 mm/s. The transition at V = 0.1 mm/s from a fully eutectic matrix at C{sub 0} = 3.5 wt%Fe to one containing {alpha}Al dendrites at C{sub 0} {ge} 4.7 wt%Fe is attributed to growth temperatures of {alpha}Al dendrites that are higher than those of eutectic in a matrix of lower iron-content, which results from these conditions. The matrix eutectic changes from irregular {alpha}-Al-Al{sub 3}Fe to regular {alpha}Al-Al{sub x}Fe with increasing V, the transition velocity increasing from 0.1 to 0.2 mm/s for C{sub 0} values of 9.5 and 14 wt%Fe up to 0.35--1.0 mm/s for C{sub 0} values of 18.7--28.1 wt%Fe. This increased transition velocity, compared with that for {alpha}-Al-Al{sub 3}Fe to {alpha}Al-Al{sub 6}Fe at lower concentration, is indicative of a lower formation temperature for the {alpha}Al-Al{sub x}Fe than the {alpha}Al-Al{sub 6}Fe eutectic.

  5. Instability and freezing in a solidifying melt conduit

    NASA Astrophysics Data System (ADS)

    Holmes-Cerfon, Miranda C.; Whitehead, J. A.

    2011-01-01

    Previous works have shown that when liquid flows in a pipe whose boundary temperature is below freezing, a tubular drainage conduit forms surrounded by solidified material that freezes shut under the appropriate combination of forcing conditions. We conduct laboratory experiments with wax in which the tube freezes shut below a certain value of flux from a pump. As the flux is gradually decreased to this value, the total pressure drop across the length of the tube first decreases to a minimum value and then rises before freezing. Previous theoretical models of a tube driven by a constant pressure drop suggest that once the pressure minimum is reached, the states for a lower flux should be unstable and the tube should therefore freeze-up. In our experiments, flux and pressure drop were coupled, and this motivates us to extend the theory for low Reynolds number flow through a tube with solidification to incorporate a simple pressure-drop-flux relationship. Our model predicts a steady-state relationship between flux and pressure drop that has a minimum pressure as the flux is varied. The stability properties of these steady states depend on the boundary conditions: for a fixed flux, they are all stable, whereas for fixed pressure drop, only those with a flux larger than that at the pressure drop minimum are stable. For a mixed pressure-flux condition, the stability threshold of the steady states lies between these two end members. This provides a possible mechanism for the experimental observations.

  6. Evaluation of directionally solidified eutectic superalloys for turbine blade applications

    NASA Technical Reports Server (NTRS)

    Henry, M. E.; Jackson, M. R.; Walter, J. L.

    1978-01-01

    Alloys from the following systems were selected for property evaluation: (1) gamma/gamma-Mo (Ni-base, rods of Mo); (2) gamma-beta (Ni-base, lamellae or rods of (Ni, Fe/Co Al); and (3) gamma-gamma (Ni-base rods of Ni3Al gamma). The three alloys were subjected to longitudinal and transverse tensile and rupture tests from 750 C to 1100 C, longitudinal shear strength was measured at several temperatures, resistance to thermal cycling to 1150 C was determined, cyclic oxidation resistance was evaluated at 750 C and 1100 C, and each system was directionally solidified in an alumina shell mold turbine shape to evaluate mold/metal reactivity. The gamma/gamma Mo system has good rupture resistance, transverse properties and processability, and is a high potential system for turbine blades. The gamma-beta system has good physical properties and oxidation resistance, and is a potential system for turbine vanes. The gamma-gamma system has good high temperature rupture resistance and requires further exploratory research.

  7. Microbially-influenced degradation of solidified/stabilized metal waste.

    PubMed

    Carmalin Sophia, A; Swaminathan, K; Sandhya, S

    2007-09-01

    In the present study, a refined microbially-influenced degradation method was used to evaluate the stability of a solidified synthetic waste containing chromium salt, cement and fly ash in two different proportions. The experimental samples showed evidence of microbial growth by leaching of sulfate. Chromium leached by Thiobacillus thiooxidans from the experimental samples 'C1' (10.26% CrCl3 .6H2O; 89.74% cement) and 'FC1' (10.26% CrCl3 .6H2O; 10% fly ash; 79.74% cement), after 30 days of exposure was 14.53 mg/g and 9.53 mg/g, respectively. The corresponding concentration of chromium in the leachate was 0.189 mg/l and 0.124 mg/l, respectively, which was lower than the toxicity characteristic leaching procedure (TCLP), regulatory limit (5 mg/l). Replacement of cement by 10% fly ash in FC1 restricted the leaching of chromium more effectively. Model equations based on two shrinking core models namely, acid dissolution and bulk diffusion model, were used to analyze the kinetics of microbial degradation. Of the two approaches, the bulk diffusion model fit the data better than the acid dissolution model as indicated by the correlation coefficients of >0.97. PMID:17107784

  8. Inclusion flotation-driven channel segregation in solidifying steels

    PubMed Central

    Li, Dianzhong; Chen, Xing-Qiu; Fu, Paixian; Ma, Xiaoping; Liu, Hongwei; Chen, Yun; Cao, Yanfei; Luan, Yikun; Li, Yiyi

    2014-01-01

    Channel segregation, which is featured by the strip-like shape with compositional variation in cast materials due to density contrast-induced flow during solidification, frequently causes the severe destruction of homogeneity and some fatal damage. An investigation of its mechanism sheds light on the understanding and control of the channel segregation formation in solidifying metals, such as steels. Until now, it still remains controversial what composes the density contrasts and, to what extent, how it affects channel segregation. Here we discover a new force of inclusion flotation that drives the occurrence of channel segregation. It originates from oxide-based inclusions (Al2O3/MnS) and their sufficient volume fraction-driven flotation becomes stronger than the traditionally recognized inter-dendritic thermosolutal buoyancy, inducing the destabilization of the mushy zone and dominating the formation of channels. This study uncovers the mystery of oxygen in steels, extends the classical macro-segregation theory and highlights a significant technological breakthrough to control macrosegregation. PMID:25422943

  9. A new technology for concentrating and solidifying liquid LLRW

    SciTech Connect

    Newell, N.; Osborn, M.W.; Carey, C.C.

    1995-12-31

    One of the unsolved problem areas of low level radioactive waste management is the radiolabeled material generated by life sciences research and clinical diagnostics. In hundreds of academic, biotechnology, and pharmaceutical institutions, there exists large amounts of both aqueous and organic solutions containing radioactively labeled nucleic acids, proteins, peptides, and their monomeric components. We have invented a generic slurry capable of binding all these compounds, thus making it possible to concentrate and solidify the radioactive molecules into a very small and lightweight material. The slurry can be contained in both large and small disposal plastic devices designed for the size of any particular operation. The savings in disposal costs and convenience of this procedure is a very attractive alternative to the present methods of long and short term storage. Additionally, the slurry can remove radiolabeled biological compounds from organic solvents, thus solving the major problem of {open_quotes}mixed{close_quotes} waste. We are now proceeding with the field application stage for the testing of these devices and anticipate widespread use of the process. We also are exploring the use of the slurry on other types of liquid low level radioactive waste.

  10. Gusev Rocks Solidified from Lava (Approximate True Color)

    NASA Technical Reports Server (NTRS)

    2006-01-01

    In recent weeks, as NASA's Mars Exploration Rover Spirit has driven through the basin south of 'Husband Hill,' it has been traversing mainly sand and dune deposits. This week, though, Spirit has been maneuvering along the edge of an arc-shaped feature called 'Lorre Ridge' and has encountered some spectacular examples of basaltic rocks with striking textures. This panoramic camera (Pancam) image shows a group of boulders informally named 'FuYi.' These basaltic rocks were formed by volcanic processes and may be a primary constituent of Lorre Ridge and other interesting landforms in the basin.

    Spirit first encountered basalts at its landing site two years ago, on a vast plain covered with solidified lava that appeared to have flowed across Gusev Crater. Later, basaltic rocks became rare as Spirit climbed Husband Hill. The basaltic rocks that Spirit is now seeing are interesting because they exhibit many small holes or vesicles, similar to some kinds of volcanic rocks on Earth. Vesicular rocks form when gas bubbles are trapped in lava flows and the rock solidifies around the bubbles. When the gas escapes, it leaves holes in the rock. The quantity of gas bubbles in rocks on Husband Hill varies considerably; some rocks have none and some, such as several here at FuYi, are downright frothy.

    The change in textures and the location of the basalts may be signs that Spirit is driving along the edge of a lava flow. This lava may be the same as the basalt blanketing the plains of Spirit's landing site, or it may be different. The large size and frothy nature of the boulders around Lorre Ridge might indicate that eruptions once took place at the edge of the lava flow, where the lava interacted with the rocks of the basin floor. Scientists hope to learn more as Spirit continues to investigate these rocks.

    As Earth approaches the Chinese New Year (The Year of the Dog), the Athena science team decided to use nicknames representing Chinese culture and geography

  11. Measurements of Mercury Released from Solidified/Stabilized Waste Forms

    SciTech Connect

    Mattus, C.H.

    2001-04-19

    This report covers work performed during FY 1999-2000 in support of treatment demonstrations conducted for the Mercury Working Group of the U.S. Department of Energy (DOE) Mixed Waste Focus Area. In order to comply with the requirements of the Resource Conservation and Recovery Act, as implemented by the U.S. Environmental Protection Agency (EPA), DOE must use one of these procedures for wastes containing mercury at levels above 260 ppm: a retorting/roasting treatment or an incineration treatment (if the wastes also contain organics). The recovered radioactively contaminated mercury must then be treated by an amalgamation process prior to disposal. The DOE Mixed Waste Focus Area and Mercury Working Group are working with the EPA to determine if some alternative processes could treat these types of waste directly, thereby avoiding for DOE the costly recovery step. They sponsored a demonstration in which commercial vendors applied their technologies for the treatment of two contaminated waste soils from Brookhaven National Laboratory. Each soil was contaminated with {approx}4500 ppm mercury; however, one soil had as a major radioelement americium-241, while the other contained mostly europium-152. The project described in this report addressed the need for data on the mercury vapor released by the solidified/stabilized mixed low-level mercury wastes generated during these demonstrations as well as the comparison between the untreated and treated soils. A related work began in FY 1998, with the measurement of the mercury released by amalgamated mercury, and the results were reported in ORNL/TM-13728. Four treatments were performed on these soils. The baseline was obtained by thermal treatment performed by SepraDyne Corp., and three forms of solidification/stabilization were employed: one using sulfur polymer cement (Brookhaven National Laboratory), one using portland cement [Allied Technology Group (ATG)], and a third using proprietary additives (Nuclear Fuel Services).

  12. Formation of mixed Al-Fe colloidal sorbent and dissolved-colloidal partitioning of Cu and Zn in the Cement Creek - Animas River Confluence, Silverton, Colorado

    USGS Publications Warehouse

    Schemel, L.E.; Kimball, B.A.; Runkel, R.L.; Cox, M.H.

    2007-01-01

    Transport and chemical transformations of dissolved and colloidal Al, Fe, Cu and Zn were studied by detailed sampling in the mixing zone downstream from the confluence of Cement Creek (pH 4.1) with the Animas River (pH 7.6). Complete mixing resulted in circumneutral pH in the downstream reach of the 1300 m study area. All four metals were transported through this mixing zone without significant losses to the streambed, and they exhibited transformations from dissolved to colloidal forms to varying degrees during the mixing process. Nearly all of the Al formed colloidal hydrous Al oxides (HAO) as pH increased (4.8-6.5), whereas colloidal hydrous Fe oxides (HFO) were supplied by Cement Creek as well as formed in the mixing zone primarily at higher pH (>6.5). The short travel time through the mixing zone (approx. 40 min) and pH limited the formation of HFO from dissolved Fe2+ supplied by Cement Creek. Although the proportions of HAO and HFO varied as the streams mixed, the colloidal sorbent typically was enriched in HAO relative to HFO by a factor of 1.5-2.1 (by mole) in the pH range where dissolved-to-colloidal partitioning of Cu and Zn was observed. Model simulations of sorption by HFO (alone) greatly underestimated the dissolved-to-colloidal partitioning of Zn. Previous studies have shown that HAO-HFO mixtures can sorb greater amounts of Zn than HFO alone, but the high Zn-to-sorbent ratio in this mixing zone could also account for greater partitioning. In contrast to Zn, comparisons with model simulations did not show that Cu sorption was greater than that for HFO alone, and also indicated that sorption was possibly less than what would be expected for a non-interactive mixture of these two sorbents. These field results for Cu, however, might be influenced by (organic) complexation or other factors in this natural system. Laboratory mixing experiments using natural source waters (upstream of the confluence) showed that the presence of HFO in the mixed sorbent

  13. Modeling creep behavior in a directionally solidified nickel base superalloy

    NASA Astrophysics Data System (ADS)

    Ibanez, Alejandro R.

    Directionally solidified (DS) nickel-base superalloys provide significant improvements relative to the limitations inherent to equiaxed materials in the areas of creep resistance, oxidation, and low and high cycle fatigue resistance. Since these materials are being pushed to the limits of their capability in gas turbine applications, accurate mathematical models are needed to predict the service lives of the hot-section components to prevent unscheduled outages due to sudden mechanical failures. The objectives of this study are to perform critical experiments and investigate the high temperature tensile, fracture toughness, creep deformation, creep rupture and creep crack growth behavior of DS GTD111 as well as to apply creep deformation, rupture and crack growth models that will enable the accurate representation of the life times of the DS GTD111 superalloy gas turbine components that are exposed to high temperatures under sustained tensile stresses. The applied models will be capable of accurately representing the creep deformation, rupture and crack growth behavior as a function of stress, time and temperature. The yield strength and fracture toughness behavior with temperature is governed by the gamma particles. The longitudinal direction showed higher ductility and strength than the transverse direction. The TL direction exhibited higher fracture toughness than the LT orientation because the crack follows a more tortuous path. The longitudinal direction showed higher creep ductility, lower minimum strain rates and longer creep rupture times than the transverse direction. The results in the transverse direction were similar to the ones for the equiaxed version of this superalloy. Two models for creep deformation have been evaluated. The power-law model includes a secondary and a tertiary creep term with the primary creep represented by a constant. A theta-projection model has also been evaluated and it appears to provide a more accurate representation of creep

  14. The Effects of Externally Solidified Product on Wave Celerity and Quality of Die Cast Products

    SciTech Connect

    Carroll Mobley; Yogeshwar Sahai; Jerry Brevick

    2003-10-10

    The cold chamber die casting process is used to produce essentially all the die cast aluminum products and about 50% of the die cast magnesium products made today. Modeling of the cold chamber die casting process and metallographic observations of cold chamber die cast products indicate that typically 5 to 20% of the shot weight is solidified in the shot sleeve before or during cavity filling. The protion of the resulting die casting which is solidified in the shot sleeve is referred to as externally solidified product, or, when identified as a casting defect, as cold flakes. This project was directed to extending the understanding of the effects of externally solidified product on the cold chamber die casting process and products to enable the production of defect-free die castings and reduce the energy associated with these products. The projected energy savings from controlling the fraction of externally solidified product in die cast components is 40 x 10 Btu through the year 2025.

  15. Constraints on silicates formation in the Si-Al-Fe system: Application to hard deposits in steam generators of PWR nuclear reactors

    NASA Astrophysics Data System (ADS)

    Berger, Gilles; Million-Picallion, Lisa; Lefevre, Grégory; Delaunay, Sophie

    2015-04-01

    Introduction: The hydrothermal crystallization of silicates phases in the Si-Al-Fe system may lead to industrial constraints that can be encountered in the nuclear industry in at least two contexts: the geological repository for nuclear wastes and the formation of hard sludges in the steam generator of the PWR nuclear plants. In the first situation, the chemical reactions between the Fe-canister and the surrounding clays have been extensively studied in laboratory [1-7] and pilot experiments [8]. These studies demonstrated that the high reactivity of metallic iron leads to the formation of Fe-silicates, berthierine like, in a wide range of temperature. By contrast, the formation of deposits in the steam generators of PWR plants, called hard sludges, is a newer and less studied issue which can affect the reactor performance. Experiments: We present here a preliminary set of experiments reproducing the formation of hard sludges under conditions representative of the steam generator of PWR power plant: 275°C, diluted solutions maintained at low potential by hydrazine addition and at alkaline pH by low concentrations of amines and ammoniac. Magnetite, a corrosion by-product of the secondary circuit, is the source of iron while aqueous Si and Al, the major impurities in this system, are supplied either as trace elements in the circulating solution or by addition of amorphous silica and alumina when considering confined zones. The fluid chemistry is monitored by sampling aliquots of the solution. Eh and pH are continuously measured by hydrothermal Cormet© electrodes implanted in a titanium hydrothermal reactor. The transformation, or not, of the solid fraction was examined post-mortem. These experiments evidenced the role of Al colloids as precursor of cements composed of kaolinite and boehmite, and the passivation of amorphous silica (becoming unreactive) likely by sorption of aqueous iron. But no Fe-bearing was formed by contrast to many published studies on the Fe

  16. Electrochemical and corrosion properties of YNi{sub 2.5}M{sub 0.5} (M = Ni, Al, Fe, Cr, Cu, Co, Mn) hybride-forming alloys

    SciTech Connect

    Korobov, I.I.; Vasina, S.Ya.; Petrii, O.A.

    1995-06-01

    Hydrogen sorption by electrode materials based on YNi{sub 2.5}M{sub 0.5} (M = Ni, Al, Fe, Cr, Co, Cu, Mn) intermetallic compounds (IMC) with Cu and PTFE binders is studied in 1 M NaOH solution. The obtained reversible electrochemical capacities correspond to YNi{sub 2.5}M{sub 0.5}H{sub 1.3-1.7} hybrides which are stable at room temperature and atmospheric pressure. The application of Cu binder allows one to more completely use the material sorption capacity and promotes both extraction and sorption of hydrogen by IMC.

  17. Effect of solidified structure on hot tear in Al-Cu alloy

    NASA Astrophysics Data System (ADS)

    Yoshida, Y.; Esaka, H.; Shinozuka, K.

    2015-06-01

    Hot tear is the one of the biggest problems of cast products of aluminum alloy. The effect of solidified structure on the hot tear has not been clear. Therefore, this study has been carried out to correlate solidified structure and hot tear. Al-2.0 wt% Cu alloy was cast at 750 °C in a moldcavity, which could intentionally form hot tear. To change solidified structure, some amount of refiner was added to the molten alloy. Length of hot tear decreased with increasing the amount of refiner. Further, the area of fine eutectic Al2Cu increased as amount of refiner increased. These may indicate that probability of healing increased in case of equiaxed structure. Therefore, the length of hot tear decreased with increasing the amount of refiner. great care should be taken in constructing both.

  18. Primary Dendrite Arm Spacings in Al-7Si Alloy Directionally Solidified on the International Space Station

    NASA Technical Reports Server (NTRS)

    Angart, Samuel; Lauer, Mark; Poirier, David; Tewari, Surendra; Rajamure, Ravi; Grugel, Richard

    2015-01-01

    Samples from directionally solidified Al- 7 wt. % Si have been analyzed for primary dendrite arm spacing (lambda) and radial macrosegregation. The alloy was directionally solidified (DS) aboard the ISS to determine the effect of mitigating convection on lambda and macrosegregation. Samples from terrestrial DS-experiments thermal histories are discussed for comparison. In some experiments, lambda was measured in microstructures that developed during the transition from one speed to another. To represent DS in the presence of no convection, the Hunt-Lu model was used to represent diffusion controlled growth under steady-state conditions. By sectioning cross-sections throughout the entire length of a solidified sample, lambda was measured and calculated using the model. During steady-state, there was reasonable agreement between the measured and calculated lambda's in the space-grown samples. In terrestrial samples, the differences between measured and calculated lambda's indicated that the dendritic growth was influenced by convection.

  19. Processing and Mechanical Properties of Directionally Solidified NiAl/NiAlTa Alloys

    NASA Technical Reports Server (NTRS)

    Johnson, D. R.; Oliver, B. F.; Noebe, R. D.; Whittenberger, J. D.

    1994-01-01

    Promising creep strengths were found for a directionally solidified NiAl-NiAlTa alloy when compared to other NiAl based intermetallics. The directionally solidified alloy had an off-eutectic composition that resulted in microstructures consisting of NiAl dendrites surrounded by aligned eutectic regions. The room temperature toughness of the two phase alloy was similar to that of polycrystalline NiAl even with the presence of the brittle Laves phase NiAlTa. Alloying additions that may improve the room temperature toughness by producing multiphase alloys are discussed.

  20. Results of compositional and microstructural analyses of solidified ingots. Ph.D. Thesis

    NASA Technical Reports Server (NTRS)

    Banan, Mohsen

    1991-01-01

    The results of compositional and microstructural analysis of solidified ingots are discussed. In the vibration section, the microstructural and compositional analysis of ingots solidified with and without vibration, the vibration induced dynamic acceleration measurements, and the macroscopic growth rate measurements using an interface demarcation technique are discussed. The Current induced Perturbation section includes the results of solidification of an ingot with alternating current pulses, the current interface demarcation in an alloy of In0.2Ga0.8SB, and in situ temperature measurements in the charges of GaSb and In0.2Ga0.8Sb during the passage of electric current.

  1. Evaluating Primary Dendrite Trunk Diameters in Directionally Solidified Al-Si Alloys

    NASA Technical Reports Server (NTRS)

    Grugel, R. N.; Tewari, S. N.; Poirier, D. R.

    2014-01-01

    The primary dendrite trunk diameters of Al-Si alloys that were directionally solidified over a range of processing conditions have been measured. These data are analyzed with a model based primarily on an assessment of secondary dendrite arm dissolution in the mushy zone. Good fit with the experimental data is seen and it is suggested that the primary dendrite trunk diameter is a useful metric that correlates well with the actual solidification processing parameters. These results are placed in context with the limited results from the aluminium - 7 wt. % silicon samples directionally solidified aboard the International Space Station as part of the MICAST project.

  2. 46 CFR 153.1108 - Heated prewash for solidifying NLS, high viscosity NLS and required prewashes of NLS whose...

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 46 Shipping 5 2012-10-01 2012-10-01 false Heated prewash for solidifying NLS, high viscosity NLS and required prewashes of NLS whose viscosity exceeds 25 mPa sec at 20 °C: Categories A, B, and C... Heated prewash for solidifying NLS, high viscosity NLS and required prewashes of NLS whose...

  3. 46 CFR 153.1108 - Heated prewash for solidifying NLS, high viscosity NLS and required prewashes of NLS whose...

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 46 Shipping 5 2011-10-01 2011-10-01 false Heated prewash for solidifying NLS, high viscosity NLS and required prewashes of NLS whose viscosity exceeds 25 mPa sec at 20 °C: Categories A, B, and C... Heated prewash for solidifying NLS, high viscosity NLS and required prewashes of NLS whose...

  4. 46 CFR 153.1108 - Heated prewash for solidifying NLS, high viscosity NLS and required prewashes of NLS whose...

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 46 Shipping 5 2014-10-01 2014-10-01 false Heated prewash for solidifying NLS, high viscosity NLS and required prewashes of NLS whose viscosity exceeds 25 mPa sec at 20 °C: Categories A, B, and C... Heated prewash for solidifying NLS, high viscosity NLS and required prewashes of NLS whose...

  5. 46 CFR 153.1108 - Heated prewash for solidifying NLS, high viscosity NLS and required prewashes of NLS whose...

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 46 Shipping 5 2013-10-01 2013-10-01 false Heated prewash for solidifying NLS, high viscosity NLS and required prewashes of NLS whose viscosity exceeds 25 mPa sec at 20 °C: Categories A, B, and C... Heated prewash for solidifying NLS, high viscosity NLS and required prewashes of NLS whose...

  6. 46 CFR 153.1108 - Heated prewash for solidifying NLS, high viscosity NLS and required prewashes of NLS whose...

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 46 Shipping 5 2010-10-01 2010-10-01 false Heated prewash for solidifying NLS, high viscosity NLS and required prewashes of NLS whose viscosity exceeds 25 mPa sec at 20 °C: Categories A, B, and C... Heated prewash for solidifying NLS, high viscosity NLS and required prewashes of NLS whose...

  7. Effect of drying-wetting cycles on leaching behavior of cement solidified lead-contaminated soil.

    PubMed

    Li, Jiang-Shan; Xue, Qiang; Wang, Ping; Li, Zhen-Ze; Liu, Lei

    2014-12-01

    Lead contaminated soil was treated by different concentration of ordinary Portland cement (OPC). Solidified cylindrical samples were dried at 40°C in oven for 48 h subsequent to 24h of immersing in different solution for one drying-wetting. 10 cycles were conducted on specimens. The changes in mass loss of specimens, as well as leaching concentration and pH of filtered leachates were studied after each cycle. Results indicated that drying-wetting cycles could accelerate the leaching and deterioration of solidified specimens. The cumulative leached lead with acetic acid (pH=2.88) in this study was 109, 83 and 71 mg respectively for solidified specimens of cement-to-dry soil (C/Sd) ratios 0.2, 0.3 and 0.4, compared to 37, 30, and 25mg for a semi-dynamic leaching test. With the increase of cycle times, the cumulative mass loss of specimens increased linearly, but pH of filtered leachates decreased. The leachability and deterioration of solidified specimens increased with acidity of solution. Increases of C/Sd clearly reduced the leachability and deterioration behavior. PMID:25433988

  8. Optimization of Gas Generation Testing of Contact-Handled Transuranic Solidified

    SciTech Connect

    Tamara Shokes; Kevin J. Liekhus; Vivian Bowman; Eric Schweinsberg

    2006-05-18

    The Contact-Handled Transuranic Waste Authorized methods for Payload Control (CH-TRAMPAC) requires that drums containing Waste Type IV (solidified organic waste) must be evaluated by gas generation testing (GGT) because a G-value, a measure of gas generation potential, has not been determined for Waste Type IV.

  9. Shear rupture of a directionally solidified eutectic gamma/gamma prime - alpha (Mo) alloy

    NASA Technical Reports Server (NTRS)

    Harf, F. H.

    1978-01-01

    Directionally solidified Mo alloys are evaluated to determine the shear rupture strength and to possibly improve it by microstructural and heat treatment variations. Bars of the alloy containing nominally 5.7% Al and 33.5% Mo by weight with balance Ni were directionally solidified at rates between 10 and 100 mm per hour in furnaces with thermal gradients at the liquid-solid interface of 250 or 100 C per cm. A limited number of longitudinal shear rupture tests were conducted at 760 C and 207 MPa in the as - solidified and in several heat treated conditions. It is shown that shear rupture failures are partly transgranular and that resistance to failure is prompted by good fiber alignment and a matrix structure consisting mainly of gamma prime. Well aligned as - solidified specimens sustained the shear stress for an average of 81 hours. A simulated coating heat treatment appeared to increase the transformation of gamma to gamma prime and raised the average shear life of aligned specimens to 111 hours. However, heat treatments at 1245 C and especially at 1190 C appeared to be detrimental by causing partial solutioning of the gamma prime, and reducing lives to 47 and 10 hours, respectively.

  10. Method of solidifying waste materials, such as radioactive or toxic materials, contained in aqueous solutions

    SciTech Connect

    Knieper, J.; May, K.; Printz, H.

    1984-07-24

    A method is disclosed of solidifying waste materials, such as radioactive or toxic materials, which are contained in aqueous solutions. To accomplish this solidification, an inorganic, non-metallic binding agent such as gypsum is intermixed with the aqueous solution and a substance such as pumice or ceramic tile which promotes the intermixing of the binding agent and the aqueous solution.

  11. On the Cu-Nb Phase Diagram and Solidified Microstructures

    NASA Technical Reports Server (NTRS)

    Li, D.; Robinson, M. B.; Rathz, T. J.; Williams, G.

    1998-01-01

    Container and containerless processing was employed to determine liquidus temperatures and to examine microstructural development in the Cu-Nb system. The Cu-Nb phase diagram of an S-shaped, near-horizontal liquidus, has been confirmed by both the temperature-time profiles and resultant microstructures with only Nb dendrites in a Cu matrix, which were obtained from crucible experiments under clean conditions. However, the microstructural pathways of Cu-Nb alloys are particularly sensitive to processing variables. By the addition of oxygen impurities or rapid solidification, droplet-shaped morphology was observed for some compositions, implying occurrence of a liquid-phase separation. The effects of impurities and cooling rates are analyzed in connection with a stable and metastable liquid miscibility gap, respectively.

  12. Effect of heat treatment on the fracture behaviour of directionally solidified (gamma/gamma-prime)-alpha alloy

    NASA Technical Reports Server (NTRS)

    Sriramamurthy, A. M.; Tewari, S. N.

    1987-01-01

    An investigation is conducted into the influence of various heat treatments on the work of fracture and its relation to microstructure for a directionally solidified Ni-33Mo-5.7Al (wt pct) (gamma/gamma-prime)-alpha alloy. The jagged crack propagation observed is due to delamination of the ligaments and associated plastic deformation. Fracture behavior is examined with respect to alloy microstructures and load-deflection curves. The four heat-treatment conditions considered are: (1) as-directionally solidified, (2) solutionized, (3) directionally solidified and thermally cycled, and (4) solutionized and thermally cycled.

  13. Effect of semiclassical molecular initial ground state configuration on the neutron spectra in the interactions of p+Al, Fe, and Zr at 1.2 GeV

    SciTech Connect

    Abdel-Waged, Khaled

    2005-04-01

    We studied the effect of the semiclassical molecular initial ground state configuration of the nucleus on the neutron spectra for p+Al, Fe, and Zr at 1.2 GeV by using an improved ultrarelativistic quantum molecular dynamics (ImUrQMD) model. Compared to the standard UrQMD version, it incorporates: (i) Pauli potential (ii) a medium modified NN{yields}N{delta} angular distribution, and (iii) a statistical multifragmentation decay model as an afterburner. It is shown that the slow evaporated, cascade, and quasielastic (inelastic) peaks of neutrons are all sensitive to different initialization procedures. Therefore, the implementation of a proper semiclassical ground state initialization in the ImUrQMD model is of importance for the description of all the neutron spectra in proton-induced reactions at intermediate energies ({approx_equal}1GeV)

  14. Electrical conductivity in directionally solidified lead-9 and -20 wt pct copper alloys

    NASA Technical Reports Server (NTRS)

    Kim, Shinwoo; Flanagan, W. F.; Lichter, B. D.; Grugel, R. N.

    1993-01-01

    Composites consisting of aligned copper dendrites in a lead matrix have been produced by directional solidification processing for potential application as grids in lead-acid batteries. To promote a uniform composite of aligned copper dendrites in a protective lead matrix, two alloy compositions, Pb-9 and -20 wt pct Cu, have been directionally solidified through a temperature gradient of 4.5 K/mm at constant growth velocities which ranged from 1 to 100 micron/s. With slow growth rates (below about 10 microns/s), the copper dendrites were generally columnar and continuous along the sample length; at higher velocities (above 60 microns/s), they assumed an intricate and equiaxed morphology. In accordance with copper content and growth rate, the electrical conductivity of the directionally solidified composites was found to be as much as a 2.5 times that of pure lead. The results are compared with that predicted by a model based on a geometrical dendrite.

  15. Method of casting articles of a bulk-solidifying amorphous alloy

    DOEpatents

    Lin, Xianghong; Johnson, William L.; Peker, Atakan

    1998-01-01

    A casting charge of a bulk-solidifying amorphous alloy is cast into a mold from a temperature greater than its crystallized melting temperature, and permitted to solidify to form an article. The oxygen content of the casting charge is limited to an operable level, as excessively high oxygen contents produce premature crystallization during the casting operation. During melting, the casting charge is preferably heated to a temperature above a threshold temperature to eliminate heterogeneous crystallization nucleation sites within the casting charge. The casting charge may be cast from above the threshold temperature, or it may be cooled to the casting temperature of more than the crystallized melting point but not more than the threshold temperature, optionally held at this temperature for a period of time, and thereafter cast.

  16. Validation of the solidifying soil process using laser-induced breakdown spectroscopy

    NASA Astrophysics Data System (ADS)

    Lin, Zhao-Xiang; Liu, Lin-Mei; Liu, Lu-Wen

    2016-09-01

    Although an Ionic Soil Stabilizer (ISS) has been widely used in landslide control, it is desirable to effectively monitor the stabilization process. With the application of laser-induced breakdown spectroscopy (LIBS), the ion contents of K, Ca, Na, Mg, Al, and Si in the permeable fluid are detected after the solidified soil samples have been permeated. The processes of the Ca ion exchange are analyzed at pressures of 2 and 3 atm, and it was determined that the cation exchanged faster as the pressure increased. The Ca ion exchanges were monitored for different stabilizer mixtures, and it was found that a ratio of 1:200 of ISS to soil is most effective. The investigated plasticity and liquidity indexes also showed that the 1:200 ratio delivers the best performance. The research work indicates that it is possible to evaluate the engineering performances of soil solidified by ISS in real time and online by LIBS.

  17. Microstructure of directionally solidified Ti-Fe eutectic alloy with low interstitial and high mechanical strength

    NASA Astrophysics Data System (ADS)

    Contieri, R. J.; Lopes, E. S. N.; Taquire de La Cruz, M.; Costa, A. M.; Afonso, C. R. M.; Caram, R.

    2011-10-01

    The performance of Ti alloys can be considerably enhanced by combining Ti and other elements, causing an eutectic transformation and thereby producing composites in situ from the liquid phase. This paper reports on the processing and characterization of a directionally solidified Ti-Fe eutectic alloy. Directional solidification at different growth rates was carried out in a setup that employs a water-cooled copper crucible combined with a voltaic electric arc moving through the sample. The results obtained show that a regular fiber-like eutectic structure was produced and the interphase spacing was found to be a function of the growth rate. Mechanical properties were measured using compression, microindentation and nanoindentation tests to determine the Vickers hardness, compressive strength and elastic modulus. Directionally solidified eutectic samples presented high values of compressive strength in the range of 1844-3000 MPa and ductility between 21.6 and 25.2%.

  18. Alloy and structural optimization of a directionally solidified lamellar eutectic alloy

    NASA Technical Reports Server (NTRS)

    Sheffler, K. D.

    1976-01-01

    Mechanical property characterization tests of a directionally solidified Ni-20 percent Cb-2.5 percent Al-6 percent Cr cellular eutectic turbine blade alloy demonstrated excellent long time creep stability and indicated intermediate temperature transverse tensile ductility and shear strength to be somewhat low for turbine blade applications. Alloy and structural optimization significantly improves these off-axis properties with no loss of longitudinal creep strength or stability. The optimized alloy-structure combination is a carbon modified Ni-20.1 percent Cb-2.5 percent Al-6.0 percent Cr-0.06 percent C composition processed under conditions producing plane front solidification and a fully-lamellar microstructure. With current processing technology, this alloy exhibits a creep-rupture advantage of 39 C over the best available nickel base superalloy, directionally solidified MAR M200+ Hf. While improved by about 20 percent, shear strength of the optimized alloy remains well below typical superalloy values.

  19. Method of casting articles of a bulk-solidifying amorphous alloy

    DOEpatents

    Lin, X.; Johnson, W.L.; Peker, A.

    1998-08-25

    A casting charge of a bulk-solidifying amorphous alloy is cast into a mold from a temperature greater than its crystallized melting temperature, and permitted to solidify to form an article. The oxygen content of the casting charge is limited to an operable level, as excessively high oxygen contents produce premature crystallization during the casting operation. During melting, the casting charge is preferably heated to a temperature above a threshold temperature to eliminate heterogeneous crystallization nucleation sites within the casting charge. The casting charge may be cast from above the threshold temperature, or it may be cooled to the casting temperature of more than the crystallized melting point but not more than the threshold temperature, optionally held at this temperature for a period of time, and thereafter cast. 8 figs.

  20. Interfacial Shear Strength of Cast and Directionally Solidified Nial-Sapphire Fiber Composites

    NASA Technical Reports Server (NTRS)

    Tewari, S. N.; Asthana, R.; Noebe, R. D.

    1993-01-01

    The feasibility of fabricating intermetallic NiAl-sapphire fiber composites by casting and zone directional solidification has been examined. The fiber-matrix interfacial shear strengths measured using a fiber push-out technique in both cast and directionally solidified composites are greater than the strengths reported for composites fabricated by powder cloth process using organic binders. Microscopic examination of fibers extracted from cast, directionally solidified (DS), and thermally cycled composites, and the high values of interfacial shear strengths suggest that the fiber-matrix interface does not degrade due to casting and directional solidification. Sapphire fibers do not pin grain boundaries during directional solidification, suggesting that this technique can be used to fabricate sapphire fiber reinforced NiAl composites with single crystal matrices.

  1. The effect of gravity level on the average primary dendritic spacing of a directionally solidified superalloy

    NASA Technical Reports Server (NTRS)

    Mccay, M. H.; Lee, J. E.; Curreri, P. A.

    1986-01-01

    The effect of alternating low (0.01 g) and high (1.8 g) gravity force on the primary spacings in the dendrite structure in a directionally solidified Ni-based superalloy (PWA 1480, containing 5 pct Co, 10 pct Cr, 4 pct W, 12 pct Ta, 5 pct Al, 1.5 pct Ti, and the balance Ni) was investigated using samples solidified in a directional solidification furnace aboard the NASA KC-135 aircraft that made a series of low-g parabolas. The cross-section slices for each growth rate were polished and etched with Kallings II, and the primary dendritic arm spacings were measured using the method of Jacobi and Schwerdtfeger (1976). The arm spacings were found to fluctuate with gravity force, increasing as the gravity level decreased, and growing finer as gravity increased.

  2. Functions and requirements document for interim store solidified high-level and transuranic waste

    SciTech Connect

    Smith-Fewell, M.A., Westinghouse Hanford

    1996-05-17

    The functions, requirements, interfaces, and architectures contained within the Functions and Requirements (F{ampersand}R) Document are based on the information currently contained within the TWRS Functions and Requirements database. The database also documents the set of technically defensible functions and requirements associated with the solidified waste interim storage mission.The F{ampersand}R Document provides a snapshot in time of the technical baseline for the project. The F{ampersand}R document is the product of functional analysis, requirements allocation and architectural structure definition. The technical baseline described in this document is traceable to the TWRS function 4.2.4.1, Interim Store Solidified Waste, and its related requirements, architecture, and interfaces.

  3. Diffusion welding of a directionally solidified gamma/gamma prime - delta eutectic alloy

    NASA Technical Reports Server (NTRS)

    Moore, T. J.

    1977-01-01

    Hot-press diffusion welding parameters were developed for a directionally solidified, gamma/gamma prime-delta eutectic alloy. Based on metallography, a good diffusion weld was achieved at 1100 C under 34.5 MPa (5 ksi) pressure for 1 hour. In addition, a dissimilar metal weld between gamma/gamma prime-delta and IN-100 was successfully made at 1100 C under 20.7 MPa (3 ksi) pressure for 1 hour.

  4. Structures of immiscible Al-In alloys solidified under microgravity conditions

    NASA Technical Reports Server (NTRS)

    Potard, C.

    1981-01-01

    Four samples of the immiscible Al-In system having monotectic and hypermonotectic compositions were solidified under microgravity during the NASA-SPAR IX flight of January 20th, 1981. The experimental thermal and physico-chemical conditions actually achieved have been analysed. Radiographic and metallographic observations of the samples show a non-regular dispersed primary phase inside the monotectic matrix. These observations are commented on the basis of capillarity and solidification aspects.

  5. Real-time X-ray transmission microscopy of solidifying Al-In alloys

    SciTech Connect

    Curreri, P.A.; Kaukler, W.F.

    1996-03-01

    Real-time observations of transparent analog materials have provided insight, yet the results of these observations are not necessarily representative of opaque metallic systems. In order to study the detailed dynamics of the solidification process, the authors develop the technologies needed for real-time X-ray microscopy of solidifying metallic systems, which has not previously been feasible with the necessary resolution, speed, and contrast. In initial studies of Al-In monotectic alloys unidirectionally solidified in an X-ray transparent furnace, in situ records of the evolution of interface morphologies, interfacial solute accumulation, and formation of the monotectic droplets were obtained for the first time: a radiomicrograph of Al-30In grown during aircraft parabolic maneuvers is presented, showing the volumetric phase distribution in this specimen. The benefits of using X-ray microscopy for postsolidification metallography include ease of specimen preparation, increased sensitivity, and three-dimensional analysis of phase distribution. Imaging of the solute boundary layer revealed that the isoconcentration lines are not parallel (as is often assumed) to the growth interface. Striations in the solidified crystal did not accurately decorate the interface position and shape. The monotectic composition alloy under some conditions grew in an uncoupled manner.

  6. Real-Time X-Ray Transmission Microscopy of Solidifying Al-In Alloys

    NASA Technical Reports Server (NTRS)

    Curreri, Peter A.; Kaukler, William F.

    1997-01-01

    Real-time observations of transparent analog materials have provided insight, yet the results of these observations are not necessarily representative of opaque metallic systems. In order to study the detailed dynamics of the solidification process, we develop the technologies needed for real-time X ray microscopy of solidifying metallic systems, which has not previously been feasible with the necessary resolution, speed, and contrast. In initial studies of Al-In monotectic alloys unidirectionally solidified in an X-ray transparent furnace, in situ records of the evolution of interface morphologies, interfacial solute accumulation, and formation of the monotectic droplets were obtained for the first time: A radiomicrograph of Al-30In grown during aircraft parabolic maneuvers is presented, showing the volumetric phase distribution in this specimen. The benefits of using X-ray microscopy for postsolidification metallography include ease of specimen preparation, increased sensitivity, and three-dimensional analysis of phase distribution. Imaging of the solute boundary layer revealed that the isoconcentration lines are not parallel (as is often assumed) to the growth interface. Striations in the solidified crystal did not accurately decorate the interface position and shape. The monotectic composition alloy under some conditions grew in an uncoupled manner.

  7. Real-Time X-Ray transmission microscopy of solidifying Al-In Alloys

    NASA Astrophysics Data System (ADS)

    Curreri, Peter A.; Kaukler, William F.

    1996-03-01

    Real-time observations of transparent analog materials have provided insight, yet the results of these observations are not necessarily representative of opaque metallic systems. In order to study the detailed dynamics of the solidification process, we develop the technologies needed for real-time Xray microscopy of solidifying metallic systems, which has not previously been feasible with the necessary resolution, speed, and contrast. In initial studies of Al-ln monotectic alloys unidirectionally solidified in an X-ray transparent furnace, in situ records of the evolution of interface morphologies, interfacial solute accumulation, and formation of the monotectic droplets were obtained for the first time: A radiomicrograph of Al-30In grown during aircraft parabolic maneuvers is presented, showing the volumetric phase distribution in this specimen. The benefits of using X-ray microscopy for postsolidification metallography include ease of specimen preparation, increased sensitivity, and three-dimensional analysis of phase distribution. Imaging of the solute boundary layer revealed that the isoconcentration lines are not parallel (as is often assumed) to the growth interface. Striations in the solidified crystal did not accurately decorate the interface position and shape. The monotectic composition alloy under some conditions grew in an uncoupled manner.

  8. Improvement of Cs leaching resistance of solidified radwastes with copper ferrocyanide (CFC)-vermiculite

    SciTech Connect

    Huang, C.T.; Wu, G. . Chemical Engineering Div.)

    1999-01-01

    Cesium removal from de-ionized water, seawater, and limewater using copper ferrocyanide (CFC) and porous media including silica gel, bentonite, vermiculite, and zeolite as adsorbents were investigated; CFC was incorporated with vermiculite to prepare a compound adsorbent for improving the Cs-leaching resistance of solidified borate radwastes. It was shown that the Cs-removal efficiency by CFC, defined as the percentage of cesium removed or adsorbed from solution, was largely affected by pHs of the solutions. Good removal efficiency occurred at pHs ranging from 3 to 12 with the best from 7 to 10. Vermiculite and zeolite were shown to have better removal power than silica gel and bentonite, and vermiculite was chosen to incorporate with CFC to make compound adsorbents because of its good compatibility with CFC floc. Compound adsorbents with different CFC contents were used as additives in the solidification of radioactive borate wastes for improving the cesium leaching resistance of the solidified products. Experimental results showed that the cesium leachability index measured following the method described in ANSI/ANS 16.1 increased from 7.96 to 9.76 by adding 0.25% of a compound adsorbent containing 20% CFC and 80% vermiculite. It indicated that the compound adsorbent is very useful for improving cesium-leaching resistance of the solidified borate wastes.

  9. Modeling leaching behavior of solidified wastes using back-propagation neural networks.

    PubMed

    Bayar, Senem; Demir, Ibrahim; Engin, Guleda Onkal

    2009-03-01

    In a previous study, treatment sludge obtained from a chemical industry, which contained potentially toxic heavy metals and organics, was characterized and solidified by solidification/stabilization (S/S). In this study, however, the prediction of leaching behavior of the sludge by linear regression method and neural networks (NNs) was discussed. NN analysis was used to construct models of leaching behavior as a function of mix composition (waste/binder ratio, W/B) using existing data from the previous study of cement-based S/S. The differences in leaching rate of each metal were also considered. The hazard characteristics of the waste were determined as defined in both Turkish and US EPA regulations, by means of Extraction Procedure Toxicity Test (EPTox) and DIN 38414-S4 Test. S/S studies were conducted using Portland cement to solidify the sludge containing high amount of Cr, Cu, Hg, Ni, Pb, and Zn. The W/B ratios of 36 specimens were kept between 0/100 and 40/100. The specimens were cured at room temperature for 7, 28, and 90 days. The heavy metal content of the extracts of each specimen was detected usually less than standard concentrations in EPTox and DIN 38414-S4 leaching procedures. By the use of NN, leaching behavior of the solidified wastes can be predicted and, therefore, optimum S/S technologies can be achieved. PMID:18068228

  10. Effect of tensile mean stress on fatigue behavior of single-crystal and directionally solidified superalloys

    NASA Technical Reports Server (NTRS)

    Kalluri, Sreeramesh; Mcgaw, Michael A.

    1990-01-01

    Two nickel base superalloys, single crystal PWA 1480 and directionally solidified MAR-M 246 + Hf, were studied in view of the potential usage of the former and usage of the latter as blade materials for the turbomachinery of the space shuttle main engine. The baseline zero mean stress (ZMS) fatigue life (FL) behavior of these superalloys was established, and then the effect of tensile mean stress (TMS) on their FL behavior was characterized. At room temperature these superalloys have lower ductilities and higher strengths than most polycrystalline engineering alloys. The cycle stress-strain response was thus nominally elastic in most of the fatigue tests. Therefore, a stress range based FL prediction approach was used to characterize both the ZMS and TMS fatigue data. In the past, several researchers have developed methods to account for the detrimental effect of tensile mean stress on the FL for polycrystalline engineering alloys. However, the applicability of these methods to single crystal and directionally solidified superalloys has not been established. In this study, these methods were applied to characterize the TMS fatigue data of single crystal PWA 1480 and directionally solidified MAR-M 246 + Hf and were found to be unsatisfactory. Therefore, a method of accounting for the TMS effect on FL, that is based on a technique proposed by Heidmann and Manson was developed to characterize the TMS fatigue data of these superalloys. Details of this method and its relationship to the conventionally used mean stress methods in FL prediction are discussed.

  11. Composition of matter suitable for solidifying radioactive wastes, products based on said composition wherein radioactive wastes are solidified and process for obtaining said products

    SciTech Connect

    Arcuri, L.; Bertotti, E.; Carignani, G.; Cipriani, A.; Donato, A.; Grossi, G.

    1985-07-23

    A composition of matter suitable for solidifying radioactive wastes is formed of unsaturated polyester resins comprising a polyester (I) obtained polycondensing (a) maleic anhydride and/or maleic and/or fumaric acid, (b) isophthalic and/or terephthalic acid, (c) neopentylglycol, (d) optionally one or more conventional glycols, wherein the amount of (c) is at least 50% by moles, with respect to (c)+(d); another polyester (II) obtained polycondensing (a) maleic anhydride and/or maleic and/or fumaric acid, (b) isopropylidene-bis-(phenylene-oxypropanol-2), (c) optionally one or more conventional glycols, wherein the amount of (b) is at least 50% by moles with respect to (b)+(c); an ethylenically unsaturated monomer (III) capable of copolymerizing with (I) and (II); inhibitors, initiators, accelerators, glass fibers and other conventional additives and fillers the weight ratio of component (I) to (II) being from 100:0 to 20:80.

  12. Evolution of the dendritic morphology with the solidification velocity in rapidly solidified Al-4.5wt.%Cu droplets

    NASA Astrophysics Data System (ADS)

    Bedel, M.; Reinhart, G.; Gandin, Ch-A.; Bogno, A.-A.; Nguyen-Thi, H.; Henein, H.

    2015-06-01

    The microstructure morphology of Al-4.5wt.%Cu droplets formed by the Impulse Atomization technique is investigated. Three-dimensional reconstructions by synchrotron X- ray micro-tomography of several droplets reveal different morphologies in droplets of similar diameter and produced in the same batch. Moreover, microstructural features also indicate that the development of the dendrite arms occurs in some droplets along <111> crystallographic axes instead of the usual <100> directions observed in conventional casting for the same alloy. It has been observed that such an unusual growth direction of the dendrites is directly related to the solidification velocity. We underpin these results by carrying out comparisons with a solidification model. Predictions are used to discuss the change of dendrite growth direction, as well as the existence of a dendrite growth direction range for a given type of droplets. In addition, the effect of the droplet size and the cooling gas on the dendrite growth direction range observed experimentally is also investigated by using the model.

  13. Chemical characterization, leach, and adsorption studies of solidified low-level wastes

    SciTech Connect

    Walter, M.B.; Serne, R.J.; Jones, T.L.; McLaurine, S.B.

    1986-12-01

    Laboratory and field leaching experiments are beig conducted by Pacific Northwest Laboratory (PNL) to investigate the performance of solidified low-level nuclear waste in a typical, arid, near-surface disposal site. Under PNL's Special Waste Form Lysimeters-Arid Program, a field test facility was constructed to monitor the leaching of commercial solidified waste. Laboratory experiments were conducted to investigate the leaching and adsorption characteristics of the waste forms in contact with soil. Liquid radioactive wastes solidified in cement, vinyl ester-styrene, and bitumen were obtained from commercial boiling water and pressurized water reactors, and buried in a field leaching facility on the Hanford site in southeastern Washington State. Batch leaching, soil column adsorption, and soil/waste form column experiments were conducted in the laboratory, using small-scale cement waste forms and Hanford site ground water. The purpose of these experiments is to evaluate the ability of laboratory leaching tests to predict leaching under actual field conditions and to determine which mechanisms (i.e., diffusion, solubility, adsorption) actually control the concentration of radionuclides in the soil surrounding the waste form. Chemical and radionuclide analyses performed on samples collected from the field and laboratory experiments indicate strong adsorption of /sup 134,137/Cs and /sup 85/Sr onto the Hanford site sediment. Small amounts of /sup 60/Co are leached from the waste forms as very mobile species. Some /sup 60/Co migrated through the soil at the same rate as water. Chemical constituents present in the reactor waste streams also found at elevated levels in the field and laboratory leachates include sodium, sulfate, magnesium, and nitrate. Plausible solid phases that could be controlling some of the chemical and radionuclide concentrations in the leachate were identified using the MINTEQ geochemical computer code.

  14. Microstructure Analysis of Directionally Solidified Aluminum Alloy Aboard the International Space Station

    NASA Astrophysics Data System (ADS)

    Angart, Samuel Gilbert

    This thesis entails a detailed microstructure analysis of directionally solidified (DS) Al-7Si alloys processed in microgravity aboard the International Space Station and similar duplicate ground based experiments at Cleveland State University. In recent years, the European Space Agency (ESA) has conducted experiments on alloy solidification in microgravity. NASA and ESA have collaborated for three DS experiments with Al- 7 wt. % Si alloy, aboard the International Space Station (ISS) denoted as MICAST6, MICAST7 and MICAST12. The first two experiments were processed on the ISS in 2009 and 2010. MICAST12 was processed aboard the ISS in the spring of 2014; the resulting experimental results of MICAST12 are not discussed in this thesis. The primary goal of the thesis was to understand the effect of convection in primary dendrite arm spacings (PDAS) and radial macrosegregation within DS aluminum alloys. The MICAST experiments were processed with various solidification speeds and thermal gradients to produce alloy with differences in microstructure features. PDAS and radial macrosegregation were measured in the solidified ingot that developed during the transition from one solidification speed to another. To represent PDAS in DS alloy in the presence of no convection, the Hunt-Lu model was used to represent diffusion-controlled growth. By sectioning cross-sections throughout the entire length of solidified samples, PDAS was measured and calculated. The ground-based (1-g) experiments done at Cleveland State University CSU were also analyzed for comparison to the ISS experiments (0-g). During steady state in the microgravity environment, there was a reasonable agreement between the measured and calculated PDAS. In ground-based experiments, transverse sections exhibited obvious radial macrosegregation caused by thermosolutal convection resulting in a non-agreement with the Hunt-Lu model. Using a combination of image processing techniques and Electron Microprobe Analysis

  15. The influence of interfacial energies and gravitational levels on the directionally solidified structures in hypermonotectic alloys

    NASA Technical Reports Server (NTRS)

    Andrews, J. B.; Curreri, P. A.; Sandlin, A. C.

    1988-01-01

    Various Cu-Pb-Al alloys were directionally solidified under 1-g conditions and alternating high-g/low-g conditions (achieved using NSAS's KC-135 aircraft) as a means of studying the influence of interfacial energies and gravitational levels on the resulting microstructures. Directional solidification of low Al content alloys was found to result in samples with coarser more irregular microstructures than in alloys with high Al contents under all the gravity conditions considered. Structures are correlated with interfacial energies, growth rates, and gravitational levels.

  16. Growth-speed dependence of primary arm spacings in directionally solidified Pb-10 wt pct Sn

    NASA Technical Reports Server (NTRS)

    Chopra, M. A.; Tewari, S. N.

    1991-01-01

    The dependence of primary arm spacings on growth speed has been investigated for cellular and dendritic arrays in directionally solidified Pb-10 wt pct Sn. The spatial arrangements of cells and dendrites, as given by their coordination number, are not very different from each other. The primary arm spacing maxima and the cell-to-dendrite transition appear to be strongly influenced by the magnitude of the solute partition coefficient (k). The planar-to-cellular transition in Pb-Sn (k = 0.50) is supercritical as compared to the subcritical behavior reported in Al-Cu (k = 0.14) and succinonitrile-acetone (k = 0.1).

  17. Superconducting properties of Pb-Sn-In alloys directionally solidified aboard Skylab

    NASA Technical Reports Server (NTRS)

    Anderson, W. T., Jr.; Reger, J. L.

    1975-01-01

    Superconducting alloys of Pb-Sn-In were directionally solidified in the absence of gravity-induced convection and segregation by processing in a near weightless condition aboard Skylab. Lead-rich and tin-rich lamellar structures were obtained with both high and low G/R (temperature gradient/solidification rate) samples processed at 0-g and at 1-g in a ground-based laboratory. Thinner, higher density lamellae were found with the 0-g specimens. Magnetization curves at 4.2 K showed hysteresis effects with large areas under the curves indicating magnetic flux pinning by the normal state tin-rich phase.

  18. Macrosegregation During Steady-State Arrayed Growth of Dendrites in Directionally Solidified Pb-Sn Alloys

    NASA Technical Reports Server (NTRS)

    Tewari, S. N.; Shah, Rajesh

    1992-01-01

    The paper examines the growth parameter dependence of the longitudinal macrosegregation due to interdendritic thermosolutal convection during directional solidification of Pb-Sn alloys with a steady-state dendritic arrayed morphology. The experimentally observed longitudinal macrosegregation can be described by an empirical parameter, effective partition coefficient (kE), obtained from Cs = kEC0(1 - fs) super KI-1, where the original tin content is C0 and that corresponding to the fraction distance solidified (Fs) is Cs. Channel formation is strongly associated with the onset of thermosolutal convection in the interdendritic melt. The critical effective Rayleigh number for the onset of channel formation is about 0.07.

  19. A Directionally Solidified Iron-chromium-aluminum-tantalum Carbide Eutectic Alloy

    NASA Technical Reports Server (NTRS)

    Harf, F. H.

    1977-01-01

    A eutectic alloy, Fe-13.6CR-3.7Al+9TaC, was directionally solidified in a high gradient furnace, producing a microstructure of alined TaC fibers in an oxidation resistant alpha-iron matrix. Tensile and stress rupture properties, thermal cycling resistance, and microstructures were evaluated. The alloy displays at 1000 C an ultimate tensile strength of 58 MPa and a 100-hour rupture life at a stress of 21 MPa. Thermal cycling to 1100 C induces faceting in the TaC fibers.

  20. Mechanical behavior of the directionally solidified gamma/gamma prime - delta eutectic alloy

    NASA Technical Reports Server (NTRS)

    Barkalow, R. H.; Jackson, J. J.; Gell, M.; Leverant, G. R.

    1975-01-01

    The eutectic alloy Ni-20.0%Cb-2.5%Al-6.0%Cr was tested in short-term creep and long-term exposure to service conditions to assess its suitability for high temperature turbine blade applications. Long-time exposure showed the lamellar microstructure of the alloy to be exceptionally stable. Other properties tested were notch sensitivity, isothermal and thermomechanical fatigue strength, shear strength, and transverse ductility. It was shown that this alloy is superior to the best currently available directionally solidified superalloys over the temperature/stress conditions encountered in turbine airfoils.

  1. Directionally Solidified Aluminum - 7 wt% Silicon Alloys: Comparison of Earth and International Space Station Processed Samples

    NASA Technical Reports Server (NTRS)

    Grugel, Richard N,; Tewari, Surendra; Rajamure, R. S.; Erdman, Robert; Poirier, David

    2012-01-01

    Primary dendrite arm spacings of Al-7 wt% Si alloy directionally solidified in low gravity environment of space (MICAST-6 and MICAST-7: Thermal gradient approx. 19 to 26 K/cm, Growth speeds varying from 5 to 50 microns/s show good agreement with the Hunt-Lu model. Primary dendrite trunk diameters of the ISS processed samples show a good fit with a simple analytical model based on Kirkwood s approach, proposed here. Natural convection, a) decreases primary dendrite arm spacing. b) appears to increase primary dendrite trunk diameter.

  2. On the efficiency of laser ablation of photopolymerizing compositions in liquid and solidified states

    NASA Astrophysics Data System (ADS)

    Loktionov, E. Yu.; Protasov, Yu. S.; Protasov, Yu. Yu.; Telekh, V. D.

    2015-02-01

    The efficiency of laser ablation of photocuring compositions that are working substances of various laser-plasma facilities is investigated for the first time. A substantial difference in spectral-energetic laser ablation thresholds, specific mass consumption, momentum coupling coefficient, and conversion efficiency of the laser energy to the kinetic energy of gas-plasma flow for liquid and solidified phases is demonstrated. Application of this class of working media allows not only solving problems related to laser ablation of a target, transport, fine dosing, and obtaining long lifetime and reliability of laser-plasma-based technological setups, but also considerably broadens the range of their operational characteristics.

  3. Structure and Electrochemistry of LiNi1/3Co1/3-yMyMn1/3O2 (M=Ti, Al, Fe) Positive Electrode Materials

    SciTech Connect

    Wilcox, James; Patoux, Sebastien; Doeff, Marca

    2009-01-14

    A series of materials based on the LiNi1/3Co1/3-yMyMn1/3O2 (M = Ti,Al,Fe) system has been synthesized and examined structurally and electrochemically. It is found that the changes in electrochemical performance depend highly on the nature of the substituting atom and its effect on the crystal structure. Substitution with small amounts of Ti4+ (y = 1/12) leads to the formation of a high-capacity and high-rate positive electrode material. Iron substituted materials suffer from an increased antisite defect concentration and exhibit lower capacities and poor rate capabilities. Single-phase materials are found for LiNi1/3Co1/3-yAlyMn1/3O2 when y<_ 1/4 and all exhibit decreased capacities when cycled to 4.3 V. However, an increase in rate performance and cycle stability upon aluminum substitution is correlated with an improved lamellar structure.

  4. Proton and deuteron double differential cross sections at angles from 10 deg to 60 deg from Be, C, Al, Fe, Cu, Ge, W, and Pb under 558-MeV-proton irradiation

    NASA Technical Reports Server (NTRS)

    Beck, S. M.; Powell, C. A.

    1976-01-01

    The double differential cross sections for the production of protons and deuterons from targets of Be, C, Al, Fe, Cu, Ge, W, and Pb were obtained at laboratory angles of scatter of 10, 20, 30, 40, 50, and 60 degrees for 558-MeV incident protons. The position of the quasi-elastic peak, discernible in the cross sections up to approximately 40 degrees, corresponded closely to the theoretical predictions for proton-proton elastic scattering at 558 MeV. The mean ratio of deuteron to proton energy-integrated cross sections was 0.056 + or - 0.008. The dependence of energy-integrated cross sections for both protons and deuterons on target mass number A varied from A to the 1/3 power at 10 degrees to A to the 2/3 power above approximately 30 degrees. The ratio of energy-integrated deuteron cross sections for quasielastic processes to that for reactions yielding a deuteron-pi-meson pair was approximately 10 percent.

  5. Raman spectroscopic study of the mineral qingheiite Na2(Mn2+,Mg,Fe2+)2(Al,Fe3+)(PO4)3, a pegmatite phosphate mineral from Santa Ana pegmatite, Argentina.

    PubMed

    Frost, Ray L; Xi, Yunfei; Scholz, Ricardo; López, Andrés; Moreira, Caio; de Lena, Jorge Carvalho

    2013-10-01

    The pegmatite mineral qingheiite Na2(Mn(2+),Mg,Fe(2+))2(Al,Fe(3+))(PO4)3 has been studied by a combination of SEM and EMP, Raman and infrared spectroscopy. The studied sample was collected from the Santa Ana pegmatite, Argentina. The mineral occurs as a primary mineral in lithium bearing pegmatite, in association with beausite and lithiophilite. The Raman spectrum is characterized by a very sharp intense Raman band at 980 cm(-1) assigned to the PO4(3-) symmetric stretching mode. Multiple Raman bands are observed in the PO4(3-) antisymmetric stretching region, providing evidence for the existence of more than one phosphate unit in the structure of qingheiite and evidence for the reduction in symmetry of the phosphate units. This concept is affirmed by the number of bands in the ν4 and ν2 bending regions. No intensity was observed in the OH stretching region in the Raman spectrum but significant intensity is found in the infrared spectrum. Infrared bands are observed at 2917, 3195, 3414 and 3498 cm(-1) are assigned to water stretching vibrations. It is suggested that some water is coordinating the metal cations in the structure of qingheiite. PMID:23792288

  6. Polymorphism of the borophosphate anion in K(Fe,Al)[BP{sub 2}O{sub 8}(OH)] and Rb(Al, Fe)[BP{sub 2}O{sub 8}(OH)] crystal structures

    SciTech Connect

    Yakubovich, O. V.; Steele, I. M.; Dimitrova, O. V.

    2010-09-15

    The crystal structure of two borophosphates, Rb(Al,Fe)[BP{sub 2}O{sub 8}(OH)] (a = 9.381(6), b = 8.398(5), c = 9.579(6) A, {beta} = 102.605(10){sup o}, sp. gr. P2{sub 1}/c) and K(Fe,Al)[BP{sub 2}O{sub 8}(OH)] (a = 5.139(2), b = 8.065(4), c = 8.290(4)A, {alpha} = 86.841(8){sup o}, {beta} = 80.346(8){sup o}, {gamma} = 86.622(8){sup o}, sp. gr. P1-bar), obtained by hydrothermal synthesis in the AlCl{sub 3}: FeCl{sub 3}: K{sub 3}PO{sub 4}(Rb{sub 3}PO{sub 4}): B{sub 2}O{sub 3}: H{sub 2}O system has been established using X-ray diffraction (Bruker Smart diffractometer, T = 100 K). Hydrogen atoms are located and their coordinates and thermal parameters are refined. It is shown that the polymorphism of the [BP{sub 2}O{sub 8}(OH)]{sup 4-} borophosphate anion has a morphotropic nature and is related to the substitutions both in the cationic part of the structure and in the octahedral position of the anionic mixed framework. The synthesis of new isotypic triclinic compounds under hydrothermal conditions is predicted.

  7. A novel solidified floating organic drop microextraction method for preconcentration and determination of copper ions by flow injection flame atomic absorption spectrometry.

    PubMed

    Sahin, Ciğdem Arpa; Tokgöz, Ilknur

    2010-05-14

    A rapid, simple and cost effective solidified floating organic drop microextraction (SFODME) and flow injection flame atomic absorption spectrometric determination (FI-FAAS) method for copper was developed. In this method, a free microdrop of 1-undecanol containing 1,5-diphenyl carbazide (DPC) as the complexing agent was transferred to the surface of an aqueous sample including Cu(II) ions, while being agitated by a stirring bar in the bulk of the solution. Under the proper stirring conditions, the suspended microdrop can remain at the top-center position of the aqueous sample. After the completion of the extraction, the sample vial was cooled by placing it in a refrigerator for 10min. The solidified microdrop was then transferred into a conical vial, where it melted immediately and diluted to 300microL with ethanol. Finally, copper ions in 200microL of diluted solution were determined by FI-FAAS. Several factors affecting the microextraction efficiency, such as type of extraction solvent, pH, complexing agent concentration, extraction time, stirring rate, sample volume and temperature were investigated and optimized. Under optimized conditions for 100mL of solution, the preconcentration factor was 333 and the enrichment factor was 324. The limit of detection (3s) was 0.4ngmL(-1), the limit of quantification (10s) was 1.1ngmL(-1) and the relative standard deviation (RSD) for 10 replicate measurements of 10ngmL(-1) copper was 0.9%. The proposed method was successfully applied to the determination of copper in different water samples. PMID:20441870

  8. Shear rupture of a directionally solidified eutectic gamma/gamma-prime - alpha /Mo/ alloy. [for aircraft engine turbine blades

    NASA Technical Reports Server (NTRS)

    Harf, F. H.

    1978-01-01

    Directionally solidified gamma/gamma-prime - alpha (Mo) eutectic alloys are being evaluated for application as advanced aircraft engine turbine blades. Their excellent high-temperature strength is partly due to their directionally aligned microstructure. However, alloys with such directional structures may display low shear strength at 760 C, the operating temperature of advanced blade roots. The objective of this investigation was to determine the shear rupture strength of the gamma/gamma-prime - alpha eutectic alloy and possibly to improve it by microstructural and heat-treatment variations. Bars of gamma/gamma-prime - alpha alloy containing nominally 5.7% Al and 33.5% Mo by weight with balance Ni were directionally solidified at rates between 10 and 100 mm per hour. Materials were solidified in furnaces with thermal gradients at the liquid-solid interface of 250 or 100 C per cm. A limited number of longitudinal shear rupture tests were conducted at 760 C and 207 MPa in the as-solidified and in several heat-treated conditions. It was found that the shear rupture failures are partly transgranular and that resistance to failure is promoted by good fiber alignment and a matrix structure consisting mainly of gamma-prime. Well-aligned as-solidified specimens sustained the shear stress for an average of 81 hours, while cellular material failed in one hour or less.

  9. Investigation of magnetic properties and electronic structure of layered-structure borides AlT{sub 2}B{sub 2} (T=Fe, Mn, Cr) and AlFe{sub 2–x}Mn{sub x}B{sub 2}

    SciTech Connect

    Chai, Ping; Stoian, Sebastian A.; Tan, Xiaoyan; Dube, Paul A.; Shatruk, Michael

    2015-04-15

    The ternary phases AlT{sub 2}B{sub 2} (T=Fe, Mn, Cr) and quaternary phases AlFe{sub 2–x}Mn{sub x}B{sub 2} have been synthesized by arc-melting and characterized by powder X-ray diffraction, magnetic measurements, Mössbauer spectroscopy, and electronic band structure calculations. All the compounds adopt the AlFe{sub 2}B{sub 2}-type structure, in which infinite zigzag chains of B atoms are connected by Fe atoms into [Fe{sub 2}B{sub 2}] slabs that alternate with layers of Al atoms along the b axis. The magnetic measurements reveal that AlFe{sub 2}B{sub 2} is a ferromagnet with T{sub C}=282 K while AlMn{sub 2}B{sub 2} and AlCr{sub 2}B{sub 2} do not show magnetic ordering in the studied temperature range of 1.8–400 K. A systematic investigation of solid solutions AlFe{sub 2−x}Mn{sub x}B{sub 2} showed a non-linear change in the structural and magnetic behavior. The ferromagnetic ordering temperature is gradually decreased as the Mn content (x) increases. The Mössbauer spectra reveal the presence of non-magnetic (NM) and ferromagnetic (FM) spectral components in all Mn-containing samples, with the amount of NM fraction increasing as the Mn content increases. While for the AlFe{sub 2−x}Mn{sub x}B{sub 2} samples with x=0.0 and 0.4 the hyperfine splitting of the FM spectral component collapses at temperatures close to the Curie temperatures determined from the magnetic measurements, for the x=1.2 and 1.6 samples the FM fraction exhibits a sizable unquenched hyperfine splitting at room temperature, a finding that is inconsistent with the observed magnetic properties. Along with the increase in the amount of the NM fraction, this observation suggests formation of Fe-rich and Mn-rich regions in the structure of the solid solutions. Quantum-chemical calculations and crystal orbital Hamilton population analysis provide a clear explanation of the distinction in properties for this series of compounds and also reveal the importance of electronic factors in modifying the

  10. Properties of steel foundry electric arc furnace dust solidified/stabilized with Portland cement.

    PubMed

    Salihoglu, Guray; Pinarli, Vedat; Salihoglu, Nezih Kamil; Karaca, Gizem

    2007-10-01

    Electric arc furnace dust from steel production is generated in considerable amounts worldwide and needs to be treated as hazardous waste. The aim of this study was to investigate the properties of electric arc furnace dust solidified/stabilized by using Portland cement. Mortar and paste samples were prepared with varying waste-to-binder ratios between 0% and 90%. A comprehensive experimental program was designed including XRF characterization, setting time, unconfined compressive strength, and toxicity characteristics leaching procedure (TCLP), synthetic precipitation leaching procedure (SPLP), and acid neutralization capacity (ANC) tests. The results were evaluated in order to determine if the solidified /stabilized product can be disposed of at a landfill site with domestic waste or at a segregated landfill. The effect of using sand on S/S performance was also investigated. The results indicated that the solidification /stabilization process using PC helps the heavy metals to be bound in the cement matrix, but the TCLP leaching results exceeded the EPA landfilling limits. The SPLP leaching results conformed to the limits implying that the waste or S/S products can be disposed of at a segregated landfill; however the low ANC of the S/S products reveals that there may be leaching in the long-term. The sand used in the mortar samples adversely affected the S/S performance, causing higher heavy metal leaching levels, and lower pH levels in the leachate after the TCLP extraction than those measured in the leachate of the paste samples. PMID:17084503

  11. Microstructure refinement of commercial 7xxx aluminium alloys solidified by the electromagnetic vibration technique

    NASA Astrophysics Data System (ADS)

    Li, M.; Tamura, T.; Omura, N.; Murakami, Y.; Tada, S.

    2016-03-01

    This paper examines the microstructure refinement of commercial 7xxx aluminium alloys solidified by the electromagnetic vibration technique (EMV) as a function of vibration frequency, f. The microstructure evolution reveals that at the low frequency of f = 62.5 Hz, the solidified microstructure is coarse and with the increase of vibration frequency to f = 500 Hz, the grain size becomes the finest and further increase of frequency to f = 2000 Hz results in coarsening of microstructures. The refinement mechanism is clarified when considering the significant difference in electrical resistivities of the solid and the liquid in mushy zone, in which both phases coexist and subject to vibration. The frequency-dependent refinement behaviour is revealed when the displacement of the mobile solid and sluggish liquid is taken into account during solidification. In contrast to 3xxx aluminium alloys, no giant compounds have been discerned in the present 7xxx alloy regardless of the solidification condition. The formation of crystalline twin is briefly discussed when considering the vibration condition.

  12. Improvement of cesium leaching resistance of solidified borate wastes with copper-ferrocyanide-vermiculite adsorbent

    SciTech Connect

    Huang, C.T.; Wu, G.

    1996-09-01

    Removal of cesium from deionized water, sea water, and lime water with copper ferrocyanide (CFC) and porous media including silica gel, bentonite, vermiculite, and zeolite were investigated; CFC and vermiculite were incorporated to prepare a compound adsorbent which was used to improve the Cs-leaching resistance of solidified borate wastes. It was shown that the Cs-removal efficiency by CFC is largely affected by pHs of the solutions, good cesium removal occurs in pHs ranged from 3 to 12 and the best from 7 to 10; the effect of Cs concentration is significantly only from lime water for Cs > 10{sup {minus}6} M at high pH and is insignificant from other solutions. Vermiculite and zeolite were shown to have better removal efficiency than silica gel and bentonite, and vermiculite was chosen to incorporate with CFC to make compound adsorbents because of its good compatibility with CFC. Compound adsorbents with different CFC contents were used as additives in the solidification of borate radwaste for improving the cesium leaching resistance of waste forms. Experimental results showed that the measured, cesium leaching index following ANSI/ANS 16.1, was increased from 7.96 to 9.76 by adding 0.25% of a compound adsorbent containing 20% CFC and 80% vermiculite, which indicated that the CFC-vermiculite compound adsorbent is very useful for improving cesium leaching resistance of the solidified borate radwastes.

  13. Ti-modified niobium-silicide based directionally solidified in-situ composites

    SciTech Connect

    Bewlay, B.P.; Jackson, M.R.; Lipsitt, H.A.

    1997-12-31

    This paper examines microstructure-property relationships in high-temperature directionally solidified (DS) in-situ composites based on Nb silicides, such as Nb{sub 3}Si and Nb{sub 5}Si{sub 3}. These in-situ composites are based on the Nb{sub 3}Si-Nb binary eutectic, and are alloyed with Ti. They were prepared using cold crucible Czochralski crystal growth. Ternary Nb-Ti-Si alloys with Ti concentrations from 9 to 45%, and Si concentrations from 10 to 25%, were directionally solidified to generate aligned two- and three-phase composites containing a Nb solid solution with Nb{sub 3}Si and Nb{sub 5}Si{sub 3} silicides. Fracture toughness values generally greater than 10 MPa{radical}m were measured in these composites. For a given Si concentration, the fracture toughness of the Ti-containing composites was increased {approximately}6 MPa{radical}m over that of the binary alloy composites. The effects of Si concentration, and a range of Nb:Ti ratios, on microstructure, phase equilibria, and fracture toughness were examined.

  14. Comparisons of operating envelopes for contaminated soil stabilised/solidified with different cementitious binders.

    PubMed

    Kogbara, Reginald B; Al-Tabbaa, Abir; Stegemann, Julia A

    2014-03-01

    This work initiated the development of operating envelopes for stabilised/solidified contaminated soils. The operating envelopes define the range of operating variables for acceptable performance of the treated soils. The study employed a soil spiked with 3,000 mg/kg each of Cd, Cu, Pb, Ni and Zn, and 10,000 mg/kg of diesel. The binders used for treatment involved Portland cement (CEMI), pulverised fuel ash (PFA), ground granulated blast furnace slag (GGBS) and hydrated lime (hlime). The specific binder formulations were CEMI, CEMI/PFA = 1:4, CEMI/GGBS = 1:9 and hlime/GGBS = 1:4. The water contents employed ranged from 13 % to 21 % (dry weight), while binder dosages ranged from 5 % to 20 % (w/w). We monitored the stabilised/solidified soils for up to 84 days using different performance tests. The tests include unconfined compressive strength (UCS), hydraulic conductivity, acid neutralisation capacity (ANC) and pH-dependent leachability of contaminants. The water content range resulted in adequate workability of the mixes but had no significant effect on leachability of contaminants. We produced design charts, representing operating envelopes, from the results generated. The charts establish relationships between water content, binder dosage and UCS; and binder dosage, leachant pH and leachability of contaminants. The work also highlights the strengths and weaknesses of the different binder formulations. PMID:24243092

  15. Cryogenic EBSD reveals structure of directionally solidified ice–polymer composite

    SciTech Connect

    Donius, Amalie E.; Obbard, Rachel W.; Burger, Joan N.; Hunger, Philipp M.; Baker, Ian; Doherty, Roger D.; Wegst, Ulrike G.K.

    2014-07-01

    Despite considerable research efforts on directionally solidified or freeze-cast materials in recent years, little fundamental knowledge has been gained that links model with experiment. In this contribution, the cryogenic characterization of directionally solidified polymer solutions illustrates, how powerful cryo-scanning electron microscopy combined with electron backscatter diffraction is for the structural characterization of ice–polymer composite materials. Under controlled sublimation, the freeze-cast polymer scaffold structure is revealed and imaged with secondary electrons. Electron backscatter diffraction fabric analysis shows that the ice crystals, which template the polymer scaffold and create the lamellar structure, have a-axes oriented parallel to the direction of solidification and the c-axes perpendicular to it. These results indicate the great potential of both cryo-scanning electron microscopy and cryo-electron backscatter diffraction in gaining fundamental knowledge of structure–property–processing correlations. - Highlights: • Cryo-SEM of freeze-cast polymer solution reveals an ice-templated structure. • Cryo-EBSD reveals the ice crystal a-axis to parallel the solidification direction. • The honeycomb-like polymer phase favors columnar ridges only on one side. • Combining cryo-SEM with EBSD links solidification theory with experiment.

  16. The possibility for microbially influenced degradation of cement solidified low-level radioactive waste forms

    SciTech Connect

    Rogerss, R.D.; Hamilton, M.A.; McConnell, J.W.

    1993-12-31

    The Nuclear Regulatory Commission (NRC) regulations 10 CFR Part 61, {open_quotes}Licensing Requirements for Land Disposal of Radioactive Waste,{close_quotes} regulate the disposal of radioactive waste and provides, among other stipulations, that class B and C low-level radioactive waste (LLW) be stabilized. This is intended to ensure that solidified waste does not structurally degrade and cause subsidence in the disposal unit`s cover system. It is reasoned that deterioration of the waste form could adversely effect the stability of the burial site and lead to the release of radionuclides to the environment. Because of its apparent structural integrity, cement has been widely used as a binder to solidify LLW. However, the resulting preparations called pozzolanic cements are susceptible to failure due to the actions of stress and environment. This paper presents data from the literature that document the significance of biologically mediated chemical attack on concrete, in general. Concrete is susceptible to aggressive reaction with acids (both mineral and organic) of natural and antrhopogenic origin. If persistent, such reactions ultimately lead to structural failure. Groups of microorganisms have been identified that are capable of metabolically coverting organic and inorganic substrates into organic and mineral acids.

  17. Characterization of mc-Si directionally solidified in travelling magnetic fields

    NASA Astrophysics Data System (ADS)

    Kiessling, F.-M.; Büllesfeld, F.; Dropka, N.; Frank-Rotsch, Ch.; Müller, M.; Rudolph, P.

    2012-12-01

    Solar-grade boron doped silicon has been directionally solidified in a vertical gradient freeze-type furnace equipped with KRISTMAG®-heaters to study the influence of travelling magnetic fields (TMFs) on the ingot quality. As-grown silicon ingots of 22×22×13 cm3 in volume were cut vertically and analysed. Information was obtained on the curvature of the melt-solid interface, the grain size distribution, the content of SiC and Si3N4 particles and the electrical activity of defects. TMFs were used to enhance melt stirring and to control the growth interface shape. Primarily inclusion-free ingots were solidified with grains of several centimetres in size. Minority carrier lifetimes of τ=20-30 μs were measured on polished surfaces of cuts from as-grown ingots. The concentrations of carbon, oxygen and nitrogen were determined by FTIR spectroscopy to (3-4)×1017 atoms/cm3, (2-3)×1017 atoms/cm3 and (0.6-2)×1015 atoms/cm3, respectively. Mean etch pit densities were evaluated on vertical cuts as low as (2-3)×103 cm-2.

  18. Effect of tensile mean stress on fatigue behavior of single-crystal and directionally solidified superalloys

    NASA Technical Reports Server (NTRS)

    Kalluri, Sreeramesh; Mcgaw, Michael A.

    1992-01-01

    Two nickel base superalloys, single crystal PWA 1480 and directionally solidified MAR-M 246 + Hf, were studied in view of the potential usage of the former and usage of the latter as blade materials for the turbomachinery of the Space Shuttle main engine. The baseline zero mean stress (ZMS) fatigue life (FL) behavior of these superalloys was established, and then the effect of tensile mean stress (TMS) on their FL behavior was characterized. A stress range based FL prediction approach was used to characterize both the ZMS and TMS fatigue data. In the past, several researchers have developed methods to account for the detrimental effect of tensile mean stress on the FL for polycrystalline engineering alloys. These methods were applied to characterize the TMS fatigue data of single crystal PWA 1480 and directionally solidified MAR-M 246 + Hf and were found to be unsatisfactory. Therefore, a method of accounting for the TMS effect on FL, that is based on a technique proposed by Heidmann and Manson was developed to characterize the TMS fatigue data of these superalloys. Details of this method and its relationship to the conventionally used mean stress methods in FL prediction are discussed.

  19. Increased corrosion resistance of the AZ80 magnesium alloy by rapid solidification.

    PubMed

    Aghion, E; Jan, L; Meshi, L; Goldman, J

    2015-11-01

    Magnesium (Mg) and Mg-alloys are being considered as implantable biometals. Despite their excellent biocompatibility and good mechanical properties, their rapid corrosion is a major impediment precluding their widespread acceptance as implantable biomaterials. Here, we investigate the potential for rapid solidification to increase the corrosion resistance of Mg alloys. To this end, the effect of rapid solidification on the environmental and stress corrosion behavior of the AZ80 Mg alloy vs. its conventionally cast counterpart was evaluated in simulated physiological electrolytes. The microstructural characteristics were examined by optical microscopy, SEM, TEM, and X-ray diffraction analysis. The corrosion behavior was evaluated by immersion, salt spraying, and potentiodynamic polarization. Stress corrosion resistance was assessed by Slow Strain Rate Testing. The results indicate that the corrosion resistance of rapidly solidified ribbons is significantly improved relative to the conventional cast alloy due to the increased Al content dissolved in the α-Mg matrix and the correspondingly reduced presence of the β-phase (Mg17 Al12 ). Unfortunately, extrusion consolidated solidified ribbons exhibited a substantial reduction in the environmental performance and stress corrosion resistance. This was mainly attributed to the detrimental effect of the extrusion process, which enriched the iron impurities and increased the internal stresses by imposing a higher dislocation density. In terms of immersion tests, the average corrosion rate of the rapidly solidified ribbons was <0.4 mm/year compared with ∼2 mm/year for the conventionally cast alloy and 26 mm/year for the rapidly solidified extruded ribbons. PMID:25491147

  20. Effects of FIB milling and pre-straining on the microstructure of directionally solidified Mo pillars: a Laue diffraction analysis

    SciTech Connect

    Zimmermann, Julien; Van Petegem, S.; Bei, Hongbin; Grolimund, D.; George, Easo P; Van Swygenhoven, H.

    2010-01-01

    White beam Laue micro-diffraction was performed on directionally solidified, single-crystal Mo pillars in the as-grown state, after focused ion beam (FIB) milling and after pre-straining. The Laue diffraction peaks from the as-grown pillars are very sharp and show no broadening, similar to those from single-crystal Si wafers. Significant broadening and streaking of the peaks occurred after FIB milling and pre-straining, indicative of the damage these treatments induce in the nearly perfect crystal structure of the directionally solidified Mo pillars.

  1. Effects of Rapid Solidification Process and 0.1 wt.% Pr Addition on Properties of Sn-9Zn Alloy and Cu/Solder/Cu Joints

    NASA Astrophysics Data System (ADS)

    Zhao, Guoji; Jing, Yanxia; Sheng, Guangmin; Chen, Jianhua

    2016-04-01

    Effects of 0.1 wt.% Pr addition and rapid solidification process on Sn-9Zn solder alloy were investigated. Solder characteristics of the as-solidified and rapidly solidified Sn-9Zn-0.1Pr alloys were analyzed in comparison with those of the as-solidified Sn-9Zn alloy. Mechanical properties and interfacial microstructure of solder/Cu joints obtained using these solders were comparatively studied. By comparison with the as-solidified Sn-9Zn alloy, the wettability of the solder was obviously improved with 0.1 wt.% Pr addition, and the melting behavior of the solder was promoted due to the rapid solidification process. The corrosion resistance of Sn-9Zn-0.1Pr alloy was improved due to the refined microstructure resulting from 0.1 wt.% Pr addition and rapid solidification. The growth of IMCs at the interface of Sn-9Zn-0.1Pr/Cu joints was depressed in some degree. Rapid solidification process promoted the interfacial reaction during soldering and improved the bonding strength of joints.

  2. Effects of Rapid Solidification Process and 0.1 wt.% Pr Addition on Properties of Sn-9Zn Alloy and Cu/Solder/Cu Joints

    NASA Astrophysics Data System (ADS)

    Zhao, Guoji; Jing, Yanxia; Sheng, Guangmin; Chen, Jianhua

    2016-05-01

    Effects of 0.1 wt.% Pr addition and rapid solidification process on Sn-9Zn solder alloy were investigated. Solder characteristics of the as-solidified and rapidly solidified Sn-9Zn-0.1Pr alloys were analyzed in comparison with those of the as-solidified Sn-9Zn alloy. Mechanical properties and interfacial microstructure of solder/Cu joints obtained using these solders were comparatively studied. By comparison with the as-solidified Sn-9Zn alloy, the wettability of the solder was obviously improved with 0.1 wt.% Pr addition, and the melting behavior of the solder was promoted due to the rapid solidification process. The corrosion resistance of Sn-9Zn-0.1Pr alloy was improved due to the refined microstructure resulting from 0.1 wt.% Pr addition and rapid solidification. The growth of IMCs at the interface of Sn-9Zn-0.1Pr/Cu joints was depressed in some degree. Rapid solidification process promoted the interfacial reaction during soldering and improved the bonding strength of joints.

  3. Annual report on the development and characterization of solidified forms for nuclear wastes, 1979

    SciTech Connect

    Chick, L.A.; McVay, G.L.; Mellinger, G.B.; Roberts, F.P.

    1980-12-01

    Development and characterization of solidified nuclear waste forms is a major continuing effort at Pacific Northwest Laboratory. Contributions from seven programs directed at understanding chemical composition, process conditions, and long-term behaviors of various nuclear waste forms are included in this report. The major findings of the report are included in extended figure captions that can be read as brief technical summaries of the research, with additional information included in a traditional narrative format. Waste form development proceeded on crystalline and glass materials for high-level and transuranic (TRU) wastes. Leaching studies emphasized new areas of research aimed at more basic understanding of waste form/aqueous solution interactions. Phase behavior and thermal effects research included studies on crystal phases in defense and TRU waste glasses and on liquid-liquid phase separation in borosilicate waste glasses. Radiation damage effects in crystals and glasses from alpha decay and from transmutation are reported.

  4. Dendrite characteristics in directionally solidified Pb-8 pct Au and Pb-3 pct Pd alloys

    NASA Technical Reports Server (NTRS)

    Tewari, S. N.

    1986-01-01

    An investigation of Pb-8 pct Au and Pb-3 pct Pd alloy specimens which have been partially directionally solidified and then quenched is performed in order to characterize their dendritic microstructural details and solute composition profiles. A controlled sectioning technique is employed to measure dendrite tip radii. It is found that most of the observed behavior is predicted quite well by a modification of the Burden and Hunt (1974) model proposed by Laxmanan (1984), in addition to the models based on the marginal stability approach. Results indicate that quantitative comparison of the primary arm spacing measurements can not form the basis of distinguishing among the various dendrite growth models in a positive temperature gradient.

  5. Side branch morphology and coarsening in directionally solidified Pb-8.4 at. pct Au

    NASA Technical Reports Server (NTRS)

    Tewari, S. N.; Lee, David; Nesarikar, V. V.

    1989-01-01

    The scaling relationships among the morphological features associated with the formation of perturbations (side branches) in the intercellular regions of a directionally solidified Pg-8.4 at. pct Au alloy were investigated. It is shown that the ratio between the initial side-branch spacing near dendrite tips, lambda-2, and the dendrite-tip radius, r(t), equals 2 to 2.5. The ratio between the distance from the dendrite tip to the location of the first side branch formation, lambda(p), and the t(r) equals 8 to 10. It was found that the model proposed by Kirkwood (1985) for the secondary dendrite arm coarsening shows a very good quantitative fit to the experimentally observed secondary arm coarsening kinetics during directional solidification.

  6. Particle Engulfment and Pushing By Solidifying Interfaces - Recent Theoretical and Experimental Developments

    NASA Technical Reports Server (NTRS)

    Stefanescu, D. M.; Catalina, A. V.; Juretzko, Frank R.; Sen, Subhayu; Curreri, P. A.

    2003-01-01

    The objective of the work on Particle Engulfment and Pushing by Solidifying Interfaces (PEP) include: 1) to obtain fundamental understanding of the physics of particle pushing and engulfment, 2) to develop mathematical models to describe the phenomenon, and 3) to perform critical experiments in the microgravity environment of space to provide benchmark data for model validation. Successful completion of this project will yield vital information relevant to a diverse area of terrestrial applications. With PEP being a long term research effort, this report will focus on advances in the theoretical treatment of the solid/liquid interface interaction with an approaching particle, experimental validation of some aspects of the developed models, and the experimental design aspects of future experiments to be performed on board the International Space Station.

  7. On oscillatory microstructure during cellular growth of directionally solidified Sn–36at.%Ni peritectic alloy

    NASA Astrophysics Data System (ADS)

    Peng, Peng; Li, Xinzhong; Li, Jiangong; Su, Yanqing; Guo, Jingjie

    2016-04-01

    An oscillatory microstructure has been observed during deep-cellular growth of directionally solidified Sn–36at.%Ni hyperperitectic alloy containing intermetallic compounds with narrow solubility range. This oscillatory microstructure with a dimension of tens of micrometers has been observed for the first time. The morphology of this wave-like oscillatory structure is similar to secondary dendrite arms, and can be observed only in some local positions of the sample. Through analysis such as successive sectioning of the sample, it can be concluded that this oscillatory microstructure is caused by oscillatory convection of the mushy zone during solidification. And the influence of convection on this oscillatory microstructure was characterized through comparison between experimental and calculations results on the wavelength. Besides, the change in morphology of this oscillatory microstructure has been proved to be caused by peritectic transformation during solidification. Furthermore, the melt concentration increases continuously during solidification of intermetallic compounds with narrow solubility range, which helps formation of this oscillatory microstructure.

  8. Studies of directionally solidified eutectic Bi/MnBi at low growth velocities

    NASA Technical Reports Server (NTRS)

    Pirich, R. G.

    1984-01-01

    The (lambda-squared)(V) deviation for diffusion-only rod eutectic growth, where lambda is the interrod spacing and V is the growth velocity, was studied at growth velocities less than 5 cm/h in directionally solidified eutectic Bi-Mn (Bi/MnBi). At lower growth velocities, (V less than 0.5 cm/h) morphological instability occurred which resulted in nonaligned, irregularly dispersed MnBi fibers. The (lambda-squared)(V) relation was experimentally determined over a range of growth velocities between 0.1 and 50 cm/h, thermal gradients in the liquid at the liquid-solid interface that varied from 40 to 120 C/cm and solidification orientation with respect to the direction of gravity. Naturally induced, convective instabilities are suggested as a possible growth velocity limit for cooperative growth in the Bi-Mn and related alloy systems.

  9. Low-cost directionally-solidified turbine blades, volume 2. [TFE731-3 turbofan engine

    NASA Technical Reports Server (NTRS)

    Dennis, R. E.; Hoppin, G. S., III; Hurst, L. G.

    1979-01-01

    An endothermically heated technology was used to manufacture low cost, directionally solidified, uncooled nickel-alloy blades for the TFE731-3 turbofan engine. The MAR-M 247 and MER-M 100+Hf blades were finish processed through heat treatment, machining, and coating operations prior to 150 hour engine tests consisting of the following sequences: (1) 50 hours of simulated cruise cycling (high fatigue evaluation); (2) 50 hours at the maximum continuous power rating (stress rupture endurance (low cycle fatigue). None of the blades visually showed any detrimental effects from the test. This was verified by post test metallurgical evaluation. The specific fuel consumption was reduced by 2.4% with the uncooled blades.

  10. Effect of Microstructure on Creep in Directionally Solidified NiAl-31Cr-3Mo

    NASA Technical Reports Server (NTRS)

    Whittenberger, J. Daniel; Raj, S. V.; Locci, I. E.

    2001-01-01

    The 1200 to 1400 K slow strain rate characteristics of the directionally solidified (DS) eutectic Ni-33Al-31Cr-3 Mo have been determined as a function of growth rate. While differences in the light optical level microstructure were observed in alloys grown at rates ranging from 7.6 to 508 mm/h, compression testing indicated that all had essentially the same strength. The exception was Ni-33 Al-31Cr-3Mo DS at 25.4 mm/h which was slightly stronger than the other growth velocities; no microstructural reason could be found for this improvement. Comparison of the approximately 1300 K properties revealed that four different DS NiAl-34(Cr,Mo) alloys have a similar creep resistance which suggests that there is a common, but yet unknown, strengthening mechanism.

  11. Microstructure-property relationships in directionally solidified single crystal nickel-base superalloys

    NASA Technical Reports Server (NTRS)

    Mackay, R. A.; Nathal, M. V.

    1986-01-01

    Some of the microstructural features which influence the creep properties of directionally solidified and single crystal nickel-base superalloys are discussed. Gamma precipitate size and morphology, gamma-gamma lattice mismatch, phase instability, alloy composition, and processing variations are among the factors considered. Recent experimental results are reviewed and related to the operative deformation mechanisms and to the corresponding mechanical properties. Special emphasis is placed on the creep behavior of single crystal superalloys at high temperatures, where directional gamma coarsening is prominent, and at lower temperatures, where gamma coarsening rates are significantly reduced. It can be seen that very subtle changes in microstructural features can have profound effects on the subsequent properties of these materials.

  12. Structure and creep rupture properties of directionally solidified eutectic gamma/gamma-prime-alpha alloy

    NASA Technical Reports Server (NTRS)

    Whittenberger, J. D.; Wirth, G.

    1982-01-01

    A simple ternary gamma/gamma-prime-alpha alloy of nominal composition (wt-%) Ni-32Mo-6Al has been directionally solidified at 17 mm/h and tested in creep rupture at 1073, 1173, and 1273 K. A uniform microstructure consisting of square-shaped Mo fibers in a gamma + gamma-prime matrix was found despite some variation in the molybdenum and aluminum concentrations along the growth direction. Although the steady-state creep rate is well described by the normal stress temperature equation, the stress exponent (12) and the activation energy (580 kJ/mol) are high. The rupture behavior is best characterized by the Larson-Miller parameter where the constant equals 20.

  13. Solidified liquid layer model expands the application fields of quartz crystal microbalance.

    PubMed

    Fu, Long; Chen, Yanyan; Ma, Hongwei

    2012-05-14

    The application of a quartz crystal microbalance (QCM) in liquid is hindered by the complexity of data analysis. Recently, a "solidified liquid layer" (SLL) model has been proposed to simplify the data analysis. Here, missing evidence to support the SLL model is provided: 1) the SLL model is responsive to the density change of the liquid environment, 2) thickness values from the SLL model (T(SLL) ) are in agreement with values measured by ellipsometry. The SLL model predicts that a 0.18 nm change of T(SLL) will lead to a 1 Hz signal, which is the resolution that most commercial QCMs could easily achieve. Using the SLL model, Au-S bond breakage has been successful. Biosensor applications are also being designed according to the SLL model. It is believed that with these results, the SLL model will bring QCM back to the radar screen of scientists. PMID:22492463

  14. Effect of Microstructure on Creep in Directionally Solidified NiAl-31Cr-3Mo

    NASA Technical Reports Server (NTRS)

    Whittenberger, J. D.; Raj, S. V.; Locci, I. E.

    2001-01-01

    The 1200 to 1400 K slow strain rate characteristics of the directionally solidified (DS) eutectic Ni-33Al-31Cr-3 Mo have been determined as a function of growth rate. While differences in the light optical level microstructure were observed in alloys grown at rates ranging from 7.6 to 508 mm/h, compression testing indicated that all had essentially the same strength. The exception was Ni-33Al-31Cr-3Mo DS at 25.4 mm/h which was slightly stronger than the other growth velocities; no microstructural reason could be found for this improvement. Comparison of the approx. 1300 K properties revealed that four different DS NiAl-34(Cr,Mo) alloys have a similar creep resistance which suggests that there is a common, but yet unknown, strengthening mechanism.

  15. The microstructure of dislocation clusters in industrial directionally solidified multicrystalline silicon

    SciTech Connect

    Kivambe, Maulid M.; Stokkan, Gaute; Ervik, Torunn; Lohne, Otto; Ryningen, Birgit

    2011-09-15

    The microstructure of commonly occurring dislocation patterns in industrial directionally solidified multicrystalline silicon has been systematically studied by light microscopy, electron backscatter diffraction, and transmission electron microscopy. The work has been focused on dislocation clusters on wafers near the top of cast blocks. In near {l_brace}111{r_brace} grain surface, dislocation arrays parallel to {l_brace}110{r_brace} plane traces are lying in parallel rows of {l_brace}111{r_brace} planes inclined to the surface, in mainly <112>30 deg. orientation. The dislocation configuration suggests that the microstructure may result from a recovery process. The dislocations formed during crystal growth and cooling have undergone transformations at high temperature in order to achieve low energy configurations for minimization of dislocation and crystal energy.

  16. On the Detection of Creep Damage in a Directionally Solidified Nickel Base Superalloy Using Nonlinear Ultrasound

    NASA Astrophysics Data System (ADS)

    Kang, Jidong; Qu, Jianmin; Saxena, Ashok; Jacobs, Larry

    2004-02-01

    A limited experimental study was conducted to investigate the feasibility of using nonlinear ultrasonic technique for assessing the remaining creep life of a directionally solidified (DS) nickel base superalloy. Specimens of this alloy were subjected to creep testing at different stress levels. Creep tests were periodically interrupted at different creep life fractions to conduct transmission ultrasonic tests to explore if a correlation exists between the higher order harmonics and the accumulated creep damage in the samples. A strong and unique correlation was found between the third order harmonic of the transmitted wave and the exhausted creep life fraction. Preliminary data also show an equally strong correlation between plastic deformation accumulated during monotonic loading and the second harmonic of the transmitted ultrasonic wave while no correlation was found between plastic strain and the third order harmonic. Thus, the nonlinear ultrasonic technique can potentially distinguish between damage due to plastic deformation and creep deformation.

  17. High temperature oxidation resistant coatings for the directionally solidified Ni-Nb-Cr-Al eutectic superalloy

    NASA Technical Reports Server (NTRS)

    Strangman, T. E.; Ulion, N. E.; Felten, E. J.

    1977-01-01

    Protective coatings required for the Ni-Nb-Cr-Al directionally solidified eutectic superalloy were developed and evaluated on the basis of oxidation resistance, diffusional stability, thermal fatigue, and creep resistance. NiCrAlY+Pt and NiCrAlY physical vapor-deposition coating systems exhibited the best combination of properties. Burner-rig testing indicated that the useful life of a 127-micron-thick NiCrAlY+Pt coating exceeds 1000 h at 1366 K. Eutectic-alloy creep lives at 1311 K and a stress of 151.7 MN/sq m were greater for NiCrAlY+Pt-coated specimens than for uncoated specimens by a factor of two.

  18. 1300 K Compressive Properties of Directionally Solidified Ni-33Al-33Cr-1Mo

    NASA Technical Reports Server (NTRS)

    Whittenberger, J. Daniel; Raj, S. V.; Locci, Ivan E.

    2000-01-01

    The Ni-33Al-33Cr-1Mo eutectic has been directionally solidified by a modified Bridgeman technique at growth rates ranging from 7.6 to 508 mm/h to produce grain/cellular microstructures, containing alternating plates of NiAl and Cr alloyed with Mo. The grains had sharp boundaries for slower growth rates (< 12.7 mm/h), while faster growth rates (> 25.4 mm/h) lead to cells bounded by intercellular regions. Compressive testing at 1300 K indicated that alloys DS'ed at rates between 25.4 to 254 mm/h possessed the best strengths which exceed that for the as-cast alloy.

  19. Quasicrystallinity Studies on Conventionally Solidified Aluminum-Technetium and Aluminum-Uranium Based Alloys

    NASA Astrophysics Data System (ADS)

    Athanasiou, N. S.

    We present quasicrystallinity investigations on conventionally solidified binary Al-Tc, ternary Al-Tc-M (M = Mn, Ni, Cu, Ru, Rh, Pd, Re, Ir, Pt), Al-Cu-U, as well as quaternary Al-Cu-Ru-U alloys. By conventional cooling (dT/dt≈103 to 102 Ksec-1) crystalline phases were formed in all the systems, except for Al-Tc-Ir system, where only icosahedral quasicrystalline phases were found. A new large (1-1.5 mm in size) icosahedral (F-type structure) quasicrystal with a pentaprismatic growth morphology was obtained in the sample with the nominal composition Al77.6Tc10Ir12.4. The characterization of the quasicrystalline state was examined by X-ray diffractometry, scanning electron microscopy (SEM) and energy-dispersive X-ray microanalysis (EDXA).

  20. A model for the filling of cold cavities with solidifying, semi-crystalline polymers

    SciTech Connect

    Papathanasiou, T D; Guell, D C

    1992-01-01

    A model for the filling stage of injection molding that includes wall solidification and crystallisation was used to investigate the interaction between solidification and pressure drop during the filling of a rectangular plate with high-density polyethylene. We find that wall solidification affects the pressure drop in a complex way, reflecting the interplay between reduction in the area available for flow and thermal insulation of the still-molten polymer. Development of crystallinity on the surface of the part is also modelled under conditions of uniform and spatially varying cooling. Results indicate that nonuniform cooling can results in complex crystallinity distributions which are determined by thermal history of solidified polymer, duration of filling stage and by exact dependence of crystallisation kinetics on temperature.

  1. Radial macrosegregation and dendrite clustering in directionally solidified Al-7Si and Al-19Cu alloys

    NASA Astrophysics Data System (ADS)

    Ghods, M.; Johnson, L.; Lauer, M.; Grugel, R. N.; Tewari, S. N.; Poirier, D. R.

    2016-05-01

    Hypoeutectic Al-7 wt% Si and Al-19 wt% Cu alloys were directionally solidified upward in a Bridgman furnace through a range of constant growth speeds and thermal gradients. Though processing is thermo-solutally stable, flow initiated by gravity-independent advection at, slightly leading, central dendrites moves rejected solute out ahead and across the advancing interface. Here any lagging dendrites are further suppressed which promotes a curved solid-liquid interface and the eventual dendrite "clustering" seen in transverse sections (dendrite "steepling" in longitudinal orientations) as well as extensive radial macrosegregation. Both aluminum alloys showed considerable macrosegregation at the low growth speeds (10 and 30 μm s-1) but not at higher speed (72 μm s-1). Distribution of the fraction eutectic-constituent on transverse sections was determined in order to quantitatively describe radial macrosegregation. The convective mechanisms leading to dendrite-steepling were elucidated with numerical simulations, and their results compared with the experimental observations.

  2. Secondary and tertiary dendrite arm spacing relationships in directionally solidified Al-Si alloys

    NASA Technical Reports Server (NTRS)

    Grugel, R. N.

    1993-01-01

    Secondary, lambda sub 2, and tertiary, lambda sub 3, dendrite arm spacings have been measured from Al-Si alloys which were directionally solidified as functions of growth velocity, V, temperature gradient, G, and composition, Co. Both lambda sub 2 and lambda sub 3 decreased as the imposed growth velocity and silicon concentrations were increased, and for each function a systematic variance in the rate was seen. Complications with measuring secondary arm spacings are shown and it was found that the tertiary arm data agree much better with coarsening theory, the implication being that lambda sub 3, when measurable, is a more representative and reliable measure of the solidification history than lambda sub 2.

  3. Microstructure and property of directionally solidified Ni-Si hypereutectic alloy

    NASA Astrophysics Data System (ADS)

    Cui, Chunjuan; Tian, Lulu; Zhang, Jun; Yu, Shengnan; Liu, Lin; Fu, Hengzhi

    2016-03-01

    This paper investigates the influence of the solidification rate on the microstructure, solid/liquid interface, and micro-hardness of the directionally solidified Ni-Si hypereutectic alloy. Microstructure of the Ni-Si hypereutectic alloy is refined with the increase of the solidification rate. The Ni-Si hypereutectic composite is mainly composed of α-Ni matrix, Ni-Ni3Si eutectic phase, and metastable Ni31Si12 phase. The solid/liquid interface always keeps planar interface no matter how high the solidification rate is increased. This is proved by the calculation in terms of M-S interface stability criterion. Moreover, the Ni-Si hypereutectic composites present higher micro-hardness as compared with that of the pure Ni3Si compound. This is caused by the formation of the metastable Ni31Si12 phase and NiSi phase during the directional solidification process.

  4. The effect of structure on tensile properties of directionally solidified Zn-based alloys

    NASA Astrophysics Data System (ADS)

    Ares, A. E.; Schvezov, C. E.

    2011-03-01

    The main objective of this study was to measure thermal (cooling rates, temperature gradients and velocities of the liquidus and solidus isotherms), structural (grain size and primary and secondary dendritic arm spacings) and tensile parameters (maximum tensile strength (MTS), yield strength (YS) and ultimate tensile strength (UTS)) in zinc-aluminum (ZA) hypoeutectic (Zn-3 wt%Al) and hypereutectic (Zn-10 wt%Al, Zn-15 wt%Al, Zn-20 wt%Al, Zn-30 wt%Al, Zn-37 wt%Al and Zn-50 wt%Al) alloys directionally solidified, which present columnar, equiaxed and columnar-to-equiaxed transition (CET) structures. The different types of structures were analyzed with optical and Scanning Electron Microscopy (SEM). Correlations between temperature gradient, cooling rate, local solidification time, grain size and dendritic spacings and tensile tests parameters are presented and discussed. The results show the influence of concentration, microstructural arrangement and thermal conditions on the mechanical properties during the solidification process.

  5. Growth parameters for aligned microstructures in directionally solidified aluminum-bismuth monotectic

    NASA Technical Reports Server (NTRS)

    Parr, R. A.; Johnston, M. H.

    1978-01-01

    Microstructures are shown for directionally solidified Al-3.4 wt pct Bi alloys with 0.2 wt pct Fe and 0.6 wt pct Fe additions. The third element causes the LI/SI + LII growth interface to become cellular. The bismuth forms at the cell nodes, appearing either as uniformly spaced arrays of spheres in the case of 0.2 wt pct Fe, or as an irregular network in the case of 0.6 wt pct Fe. Changes in the growth conditions which are known to control cellular structure are seen to have a similar effect on the bismuth spacing, with the cross sectional spacing varying as the inverse of G (Temperature gradient) x R(Growth rate).

  6. Simultaneous temperature and concentration measurement in front of solidifying monotectic systems using the two wavelength holographic technique

    NASA Technical Reports Server (NTRS)

    Ecker, A.; Alexander, J. Iwan D.; Frazier, D. O.

    1987-01-01

    A holographic technique for the simultaneous measurement of temperature and concentration in solidifying transparent model alloy systems was developed. Its application to the study of the interactions between the temperature, concentration, and fluid flow fields in such systems at 1 g and micro-g conditions is discussed.

  7. Simultaneous temperature and concentration measurement in front of solidifying monotectic systems using the two wavelength holographic technique

    NASA Astrophysics Data System (ADS)

    Ecker, A.; Alexander, J. Iwan D.; Frazier, D. O.

    1987-02-01

    A holographic technique for the simultaneous measurement of temperature and concentration in solidifying transparent model alloy systems was developed. Its application to the study of the interactions between the temperature, concentration, and fluid flow fields in such systems at 1 g and micro-g conditions is discussed.

  8. A Laboratory Screening Study On The Use Of Solidifiers As A Response Tool To Remove Crude Oil Slicks On Seawater

    EPA Science Inventory

    The effectiveness of five solidifiers to remove Prudhoe Bay crude oil from artificial seawater in the laboratory was determined by ultraviolet-visible spectroscopy (UV-VIS) and gas chromatography/mass spectrometry (GC/MS). The performance of the solidifers was determined by US-V...

  9. Investigation on the application of steel slag-fly ash-phosphogypsum solidified material as road base material.

    PubMed

    Shen, Weiguo; Zhou, Mingkai; Ma, Wei; Hu, Jinqiang; Cai, Zhi

    2009-05-15

    The aim of the present work is to prepare a new type of steel slag-fly ash-phosphogypsum solidified material totally composed with solid wastes to be utilized as road base material. The mix formula of this material was optimized, the solidified material with optimal mix formula (fly ash/steel slag=1:1, phosphogypsum dosage=2.5%) results in highest strength. The strength development, resilience modulus and splitting strength of this material were studied comparing with some typical road base materials, the 28- and 360-day strength of this material can reach 8MPa and 12MPa, respectively, its resilience modulus reaches 1987MPa and splitting strength reaches 0.82MPa, it has higher early strength than lime-fly ash and lime-soil road base material, its long-term strength is much higher than cement stabilized granular materials, the solidified material has best water stability among those road base materials, it can be engineered as road base material with competitive properties. The strength formation mechanism of this solidified material is discussed also. PMID:18801617

  10. Solidifying agent and processing of blood used for the larval diet affect screwworm (Diptera: Calliphoridae) life-history parameters

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The current artificial diet for mass rearing screwworm, Cochliomyia hominivorax, (Coquerel) (Diptera: Calliphoridae) larvae is a semi-solid medium consisting of dry whole bovine blood, poultry egg powder and a milk substitute mixed with a bulking and solidifying agent and water. To reduce the mass r...

  11. Long and short-term performance of a stabilized/solidified electric arc furnace dust.

    PubMed

    Pereira, C Fernández; Galiano, Y Luna; Rodríguez-Piñero, M A; Parapar, J Vale

    2007-09-30

    The application of class F fly ash, cement and lime to the Stabilization/Solidification (S/S) of electric arc furnace dust containing hazardous metals such as Zn, Pb, Cd, and Cr is described. The aim of the study was to determine the influence of the setting conditions during the S/S treatment and to know the behaviour of an aged solidified and stabilized waste. In order to determine the efficiency attained by the S/S process, USEPA TCLP, and other leaching tests have been accomplished. In addition, the compressive strength of the solidified waste at different times has been determined. In order to study the influence of the environmental conditions in which setting occurs, experiments were carried out with samples of the same composition, under different setting conditions: laboratory environment, stove at a temperature of 40-60 degrees C and setting in a hermetically sealed plastic bag at room temperature. All the samples were subjected to the TCLP test at 28 days, and the metal content of the resulting leachates was analysed. The results show that in some cases the setting conditions of the mixtures have a noticeable influence on the characteristics of the leachate. The evolution with time of some S/S solids, one month after their manufacture and more than 9 years after that has also been evaluated, by means of their leaching behaviour. The results obtained in this work have shown, in all the laboratory cured samples that the leachate pH decrease in the course of time, and consequently the leaching behaviour is in general worse. This could be due to the carbonation of the S/S solid and the subsequent loss of alkalinity. PMID:17459579

  12. Surface free energy of polypropylene and polycarbonate solidifying at different solid surfaces

    NASA Astrophysics Data System (ADS)

    Chibowski, Emil; Terpilowski, Konrad

    2009-12-01

    Advancing and receding contact angles of water, formamide, glycerol and diiodomethane were measured on polypropylene (PP) and polycarbonate (PC) sample surfaces which solidified at Teflon, glass or stainless steel as matrix surfaces. Then from the contact angle hystereses (CAH) the apparent free energies γstot of the surfaces were evaluated. The original PP surface is practically nonpolar, possessing small electron donor interaction ( γs-=1.91 mJ/m), as determined from the advancing contact angles of these liquids. It may result from impurities of the polymerization process. However, it increases up to 8-10 mJ/m 2 for PP surfaces contacted with the solids. The PC surfaces both original and modified show practically the same γs-=6.56.7 mJ/m. No electron acceptor interaction is found on the surfaces. The γstot of modified PP and PC surfaces depend on the kind of probe liquid and contacted solid surface. The modified PP γstot values determined from CAH of polar liquids are greater than that of original surface and they increase in the sequence: Teflon, glass, stainless steel surface, at which they solidified. No clear dependence is observed between γstot and dielectric constant or dipole moment of the polar probe liquids. The changes in γstot of the polymer surfaces are due to the polymer nature and changes in its surface structure caused by the structure and force field of the contacting solid. It has been confirmed by AFM images.

  13. Pollutants leaching behaviour from solidified wastes: a selection of adapted various models.

    PubMed

    Moszkowicz, P; Sanchez, F; Barna, R; Méhu, J

    1998-07-01

    Leaching tests are essential in the environmental assessment of stabilized wastes. Research programmes were conducted on their interpretation in order to develop tools for the evaluation of long term release of pollutants contained in solidified wastes. Models for the leaching of porous materials are discussed in this paper according to the specificity of the chemical species (i.e. transport model with total dissolution of species-diffusional model; transport model with progressive dissolution of species due to limitation of solubility-shrinking core model; and the model coupling transport and chemical phenomena). The leaching behaviour of pollutants (i.e. lead) solidified in a cement matrix was studied under different chemical conditions. Results have shown that the release of species whose solubilities depend on the physico-chemical conditions, and especially the pH (e.g. amphoteric metals), is governed by the solubility of the species in the pore water at local conditions and by the pH evolution within the matrix. A coupled dissolution/diffusion model was developed to describe the release of chemically complex species contained in a porous medium in contact with water. Leaching tests of cement matrices and artificial porous matrices containing calcium hydroxide and pollutants were conducted in order to validate the coupled dissolution/diffusion model. A good assessment of the retention of some pollutants contained in cement matrices could then be obtained by the association of two tests: solubilization of the pollutants related to the chemical context (pH) under steady state conditions and monolithic long term dynamic leaching tests in order to characterize the evolution of the chemical context (pH) and consequently the release of pollutants. The objective is to integrate this approach in the standardization process (CEN TC 292- WG 6, in progress). PMID:18967159

  14. Advanced powder metallurgy aluminum alloys via rapid solidification technology, phase 2

    NASA Technical Reports Server (NTRS)

    Ray, Ranjan; Jha, Sunil C.

    1987-01-01

    Marko's rapid solidification technology was applied to processing high strength aluminum alloys. Four classes of alloys, namely, Al-Li based (class 1), 2124 type (class 2), high temperature Al-Fe-Mo (class 3), and PM X7091 type (class 4) alloy, were produced as melt-spun ribbons. The ribbons were pulverized, cold compacted, hot-degassed, and consolidated through single or double stage extrusion. The mechanical properties of all four classes of alloys were measured at room and elevated temperatures and their microstructures were investigated optically and through electron microscopy. The microstructure of class 1 Al-Li-Mg alloy was predominantly unrecrystallized due to Zr addition. Yield strengths to the order of 50 Ksi were obtained, but tensile elongation in most cases remained below 2 percent. The class 2 alloys were modified composition of 2124 aluminum alloy, through addition of 0.6 weight percent Zr and 1 weight percent Ni. Nickel addition gave rise to a fine dispersion of intermetallic particles resisting coarsening during elevated temperature exposure. The class 2 alloy showed good combination of tensile strength and ductility and retained high strength after 1000 hour exposure at 177 C. The class 3 Al-Fe-Mo alloy showed high strength and good ductility both at room and high temperatures. The yield and tensile strength of class 4 alloy exceeded those of the commercial 7075 aluminum alloy.

  15. Rapid Prototyping

    NASA Technical Reports Server (NTRS)

    1999-01-01

    Javelin, a Lone Peak Engineering Inc. Company has introduced the SteamRoller(TM) System as a commercial product. The system was designed by Javelin during a Phase II NASA funded small commercial product. The purpose of the invention was to allow automated-feed of flexible ceramic tapes to the Laminated Object Manufacturing rapid prototyping equipment. The ceramic material that Javelin was working with during the Phase II project is silicon nitride. This engineered ceramic material is of interest for space-based component.

  16. Low Strain Rate Deformation of Directionally Solidified Alloys, and the Earth's Inner Core

    NASA Astrophysics Data System (ADS)

    Bergman, M. I.; Karato, S.

    2009-05-01

    The elastic anisotropy of the Earth's inner core (IC) is likely due to a lattice preferred orientation (LPO) of Fe crystals, though there is debate about the stable phase of Fe under inner core conditions. The cause of the LPO is likely due to either solidification or deformation, though it seems increasingly likely that no one explanation may suffice to understand the complex IC structure that seismologists are beginning to reveal. We have begun experiments to understand the high temperature deformation mechanism, recovery, and recrystallization of directionally solidified alloys. We start with directionally solidified, 3 weight percent Sn-Zn castings that have the columnar, dendritic structure that has been proposed for the IC. Zn is hexagonal close- packed (hcp), a probable phase of Fe in the IC. Hcp dendrites assume a platelet morphology. Typical grain sizes in our castings are 5 mm in the short dimension, with .4 mm platelet spacings. We then heat a slice of a casting to a high homologous temperature (greater than .95), at which the interdendritic Sn-rich phase melts, but the primary Zn-rich phase remains solid. While held at this temperature, we subject the slice to torsion at constant strain rate, while measuring the torque to infer the stress. We examine each slice before and after deformation for changes in crystalline orientation, microstructure (morphology and grain size), and chemical variations. So far we have obtained order one strains at low strain rates (2 x 10-6 1/s), which for fine-grained (.1 mm), pure Zn is near the boundary between diffusional flow and recrystallization. Inferring the stress during deformation (as of this writing we know only the maximum normalized stress is less than 10-5 Pa) and observing changes in microstructure and LPO will hopefully yield the deformation mechanism of these coarse-grained, dendritic alloys, as well as the lengthscale (grain size or dendritic spacing) relevant to deformation. As a control, we anneal (no

  17. Characterizing the physical properties of solidified PEG, an analog for basaltic lava crust

    NASA Astrophysics Data System (ADS)

    Soule, S. A.; Cashman, K.; Rust, A.

    2001-12-01

    The crust of a basaltic lava flow provides significant resistance to flow and is an important indicator of lava flow dynamics. Analog studies using polyethylene glycol (PEG), such as those by Fink and Griffiths (1990) and Griffiths and Fink (1992), are a useful means to determine the conditions under which different crustal morphologies are produced. To accurately apply the results of these studies to natural systems, we must understand how to scale between basaltic lava and its analog, PEG. The long-term goal of our study is to characterize the physical properties of both materials for the purpose of developing scaling relationships. We have designed a set of experiments to determine the strength and viscosity of solidified PEG. We measure the ductile deformation and failure of PEG under tension and in simple shear. Experiments are conducted with either constant stress or constant strain rate and at a range of temperatures (5 to 25 \\deg C). Tension experiments are conducted on hourglass-shaped PEG casts with failure occurring at the midpoint of the hourglass. Tension is produced by hanging weight (constant stress) or by pulling with a DC servo motor (constant strain rate). Simple shear experiments are conducted by turning a gear frozen into a sheet of PEG. A thinned ring of crust centered around the gear controls the failure location. From constant stress experiments, we measure pre-failure ductile deformation of the PEG to determine its viscosity. Constant strain rate experiments allow us to determine the dependence of PEG strength on strain rate. To determine the physical properties of basaltic crust we are building a furnace capable of melting large quantities of basalt and conducting experiments at high temperature. The experiments conducted on PEG will aid in the design of similar experiments on lava. The results of this study will have applications beyond scaling between analog models and natural systems. The presence or absence of a continuous flow crust

  18. Comparative Investigation of the Downward and Upward Directionally Solidified Single-Crystal Blades of Superalloy CMSX-4

    NASA Astrophysics Data System (ADS)

    Wang, Fu; Ma, Dexin; Bogner, Samuel; Bührig-Polaczek, Andreas

    2016-05-01

    Single-crystal blades of Ni-base superalloys CMSX-4 have been directionally solidified using the downward directional solidification (DWDS) process. The possible benefits of the process were comparatively evaluated with respect to the Bridgman process' results. The DWDS process exhibits good capabilities for casting the single-crystal components. The thermal gradients of this process are approximately seven times higher than those of the Bridgman process. It provides more advantages for solidifying the single-crystal superalloy blades by reducing the casting defects, refining the microstructure, decreasing the size of the γ/ γ' eutectic pools, refining the γ' precipitates, alleviating the degree of the microsegregation, and minimizing the size and volume fraction of the micropores.

  19. Measurements of Mercury Released From Solidified/Stabilized Waste Forms-FY2002

    SciTech Connect

    Mattus, C.H.

    2003-02-17

    This report covers work performed during FY 2002 in support of treatment demonstrations conducted for the U.S. Department of Energy (DOE) Mixed Waste Focus Area (MWFA) Mercury Working Group. To comply with the requirements of the Resource Conservation and Recovery Act, as implemented by the U.S. Environmental Protection Agency (EPA), DOE must use one of the following procedures for mixed low-level radioactive wastes containing mercury at levels above 260 ppm: a retorting/roasting treatment or (if the wastes also contain organics) an incineration treatment. The recovered radioactively contaminated mercury must then be treated by an amalgamation process prior to disposal. The DOE MWFA Mercury Working Group is working with EPA to determine whether some alternative processes could be used to treat these types of waste directly, thereby avoiding a costly recovery step for DOE. In previous years, demonstrations were performed in which commercial vendors applied their technologies for the treatment of radiologically contaminated elemental mercury as well as radiologically contaminated and mercury-contaminated waste soils from Brookhaven National Laboratory. The test results for mercury release in the headspace were reported in two reports, ''Measurements of Mercury Released from Amalgams and Sulfide Compounds'' (ORNL/TM-13728) and ''Measurements of Mercury Released from Solidified/Stabilized Waste Forms'' (ORNL/TM-2001/17). The current work did not use a real waste; a surrogate sludge had been prepared and used in the testing in an effort to understand the consequences of mercury speciation on mercury release.

  20. The influence of interfacial energies and gravitational levels on the directionally solidified structures in hypermonotectic alloys

    NASA Astrophysics Data System (ADS)

    Sandlin, A. C.; Andrews, J. B.; Curreri, P. A.

    1988-11-01

    Several Cu-Pb-Al alloys were directionally solidified under one-g conditions and alternating high-g/low-g conditions in order to determine the influence of interfacial energies and gravitational levels on the resulting microstructures. The low-g conditions were obtained through use of NASA's KC-135 aircraft. In the Cu-Pb-Al system, changes in the Al content are known to result in variations in the interfacial energy relationships between the phases. Theory predicts that this should lead to a transition from an irregular to a regular, aligned microstructure in monotectic composition alloys. Four different hypermonotectic alloy compositions were used in this study in order to vary systematically the interfacial energies between the phases. Preliminary results indicate microstructural variations between control and flight samples and samples processed at different rates under both one-g and high-g/low-g conditions. In addition, directional solidification of low Al content alloys resulted in samples with coarse, irregular microstructures, as compared to finer, more aligned microstructures in alloys with high Al contents. This was seen in samples processed under both one-g and high-g/low-g conditions. The resulting structures have been related to interfacial energies, growth rates, and gravitational levels.

  1. Evaluating Local Primary Dendrite Arm Spacing Characterization Techniques Using Synthetic Directionally Solidified Dendritic Microstructures

    NASA Astrophysics Data System (ADS)

    Tschopp, Mark A.; Miller, Jonathan D.; Oppedal, Andrew L.; Solanki, Kiran N.

    2015-10-01

    Microstructure characterization continues to play an important bridge to understanding why particular processing routes or parameters affect the properties of materials. This statement certainly holds true in the case of directionally solidified dendritic microstructures, where characterizing the primary dendrite arm spacing is vital to developing the process-structure-property relationships that can lead to the design and optimization of processing routes for defined properties. In this work, four series of simulations were used to examine the capability of a few Voronoi-based techniques to capture local microstructure statistics (primary dendrite arm spacing and coordination number) in controlled (synthetically generated) microstructures. These simulations used both cubic and hexagonal microstructures with varying degrees of disorder (noise) to study the effects of length scale, base microstructure, microstructure variability, and technique parameters on the local PDAS distribution, local coordination number distribution, bulk PDAS, and bulk coordination number. The Voronoi tesselation technique with a polygon-side-length criterion correctly characterized the known synthetic microstructures. By systematically studying the different techniques for quantifying local primary dendrite arm spacings, we have evaluated their capability to capture this important microstructure feature in different dendritic microstructures, which can be an important step for experimentally correlating with both processing and properties in single crystal nickel-based superalloys.

  2. Microsegregation in directionally solidified Pb-8.4 at. pct Au alloy

    NASA Technical Reports Server (NTRS)

    Tewari, S. N.

    1988-01-01

    The dependence of microsegregation behavior on growth rate and thermal gradient has been examined in a Pb-8.4 at. pct Au alloy material partially directionally solidified and quenched. The composition of the quenched 'liquid' at the dendrite tip (Ct), that of the eutectic-like solid phase freezing from the interdendritic liquid at the base of dendrite (Cse), the volume fraction of this eutectic-like region (fe), and solute profiles in the interdendritic quenched liquid and ahead of the dendrite have been measured. Two dendritic growth models for solidification of a binary alloy melt in a positive thermal gradient at the liquid-solid interface, one for dendrites with 'minimum undercooled dendrite tip' and the other for an Ivantsov type of dendrite with 'marginally stable tip', have been examined for a quantitative comparison with measured values of Ct, Cse, and fe. Convection in the melt, possibly due to horizontal density gradients, is found to be a serious limitation for theoretical understanding of the observed experimental behavior and meaningful comparison of theories.

  3. Primary arm spacing in directionally solidified Pb-10 wt pct Sn alloys

    NASA Technical Reports Server (NTRS)

    Chopra, M. A.; Tewari, S. N.

    1990-01-01

    The dependence of primary arm spacings on growth speed was investigated for cellular and dendritic arrays in Pb-10 wt percent Sn samples directionally solidified under a constant positive thermal gradient in the melt. The gradient of constitutional supercooling was varied from almost zero (near the break-down of the planar liquid-solid interface at small growth speeds, cellular morphology) to near unity (large growth speeds, dendritic morphology). The spatial arrangements of cells and dendrites, as given by their coordination number, are not very different from each other. It appears that primary arm spacing maxima and the cell to dendrite transition are strongly influenced by the magnitude of the solute partition coefficient. The planar to cellular bifurction is supercritical in Pb-Sn which has a high partition coefficient, as compared to the subcritical behavior reported in Al-Cu and succinonitrile-acetone, both of which have low partition coefficients. The primary arm spacing model due to Hunt agrees with the experimentally observed trend for the whole growth regime. There is a good quantitative agreement at higher grdients of supercooling. However, the model overpredicts the primary arm spacings at low gradients of constitutional supercooling.

  4. Prediction of waste leaching from solidified low-level radioactive waste

    NASA Astrophysics Data System (ADS)

    Tahboub, Alaeddin Borhan

    In 1983 a research program called Special Waste-Form Lysimeter Arid (SWLA) was initiated at Hanford Lysimeter testing facility near Richland, Washington to evaluate radionuclide release from solidified Low-Level Radioactive waste from underground burial facilities. The goal of this research is to help interpret experimental results from the Hanford site and formulate recommendations regarding source-term modeling for Low- Level waste forms. The specific objective is to test the diffusion source-term models based on ANS/ANSI 16.1 (ANS, 1986) laboratory leach test. The project uses the SWMS_2d model to predict the leaching of 137Cs, 90Sr, 60Co, and 3H radio nuclides from the waste form contained in Hanford lysimeters. Effective diffusion coefficients (De's) as measured by the above standard test were obtained from published literature for each nuclide. These De's together with the published soil properties and environmental conditions at the Hanford site are the model input. The source term modeling results are compared to the measured lysimeter data. Results showed that, the model is able to predict release of 3H. The model was not able to predict the release of 60Co from the waste form, which indicate that there are other processes rather than diffusion involved. The effective diffusion coefficient from ANS/ANSI 16.1 test can be used only for non reactive radionuclides like 3H (tritium).

  5. Particle Engulfment and Pushing by Solidifying Interfaces. Pt. 2; Micro-Gravity Experiments and Theoretical Analysis

    NASA Technical Reports Server (NTRS)

    Stefanescu, Doru M.; Juretzko, Frank R.; Dhindaw, Brij K.; Catalina, Adrian; Sen, Subhayu; Curreri, Peter A.

    1998-01-01

    Results of the directional solidification experiments on Particle Engulfment and Pushing by Solidifying Interfaces (PEP) conducted on the space shuttle Columbia during the Life and Microgravity Science Mission are reported. Two pure aluminum (99.999%) 9 mm cylindrical rods, loaded with about 2 vol.% 500 micrometers diameter zirconia particles were melted and resolidified in the microgravity (microg) environment of the shuttle. One sample was processed at step-wise increased solidification velocity, while the other at step-wise decreased velocity. It was found that a pushing-to-engulfment transition (PET) occurred in the velocity range of 0.5 to 1 micrometers. This is smaller than the ground PET velocity of 1.9 to 2.4 micrometers. This demonstrates that natural convection increases the critical velocity. A previously proposed analytical model for PEP was further developed. A major effort to identify and produce data for the surface energy of various interfaces required for calculation was undertaken. The predicted critical velocity for PET was of 0.775 micrometers/s.

  6. Mechanical, electrical, and thermal properties of the directionally solidified Bi-Zn-Al ternary eutectic alloy

    NASA Astrophysics Data System (ADS)

    Şahin, M.; Çadırlı, E.

    2014-10-01

    A Bi-2.0Zn-0.2Al (wt%) ternary eutectic alloy was prepared using a vacuum melting furnace and a casting furnace. The samples were directionally solidified upwards at a constant growth rate ( V = 18.4 μm/s) under different temperature gradients ( G = 1.15-3.44 K/mm) and at a constant temperature gradient ( G = 2.66 K/mm) under different growth rates ( V = 8.3-500 μm/s) in a Bridgman-type directional solidification furnace. The dependence of microstructure parameter ( λ) on the solidification parameters ( G and V) and that of the microhardness (Hv) on the microstructure and solidification parameters were investigated. The resistivity ( ρ) measurements of the studied alloy were performed using the standard four-point-probe method, and the temperature coefficient of resistivity ( α) was calculated from the ρ- T curve. The enthalpy (Δ H) and the specific heat ( C p ) values were determined by differential scanning calorimetry analysis. In addition, the thermal conductivities of samples, obtained using the Wiedemann-Franz and Smith-Palmer equations, were compared with the experimental results. The results revealed that, the thermal conductivity values obtained using the Wiedemann-Franz and Smith-Palmer equations for the Bi-2.0Zn-0.2Al (wt%) alloy are in the range of 5.2-6.5 W/Km and 15.2-16.4 W/Km, respectively.

  7. Method Developed for Quantitative Analysis of Inclusions in Solidified Aluminum Ingots

    NASA Astrophysics Data System (ADS)

    Jaradeh, Majed M.; Carlberg, Torbjorn

    2011-02-01

    A deep-etching method was used to determine inclusions in solidified direct chill cast aluminum ingots. The technique was developed to allow easy quantification of the amount and size distribution of inclusions over billet lengths and cross sections. A pressure filtration (Prefil) test also was used to verify molten alloy cleanliness during casting, and the results of these measurements then were compared. The amount and distribution of nonmetallic inclusions were analyzed, as determined using a NaOH deep-etching method over billet lengths and cross sections. A higher inclusion count was observed at both billet ends, with more inclusions located nearer the billet section centerline. Furthermore, the inclusion density in the radial direction at every distance along the billet length was distributed inhomogeneously. Differences were observed between Prefil samples taken at different casting stages. The Prefil curves and metallographic analysis of Prefil residue obtained from melt samples, at an early casting stage or before degassing, indicate more oxides than in a melt sample taken under steady-state casting conditions. A reasonable correlation was established between the number of inclusions in the molten alloy (measured using Prefil and LiMCA) and the etch pits on deep-etched surfaces of billet cross sections.

  8. Primary arm spacing in directionally solidified Pb-10 wt percent Sn alloys

    NASA Technical Reports Server (NTRS)

    Chopra, M. A.; Tewari, S. N.

    1990-01-01

    The dependence of primary arm spacings on growth speed was investigated for cellular and dendritic arrays in Pb-10 wt percent Sn samples directionally solidified under a constant positive thermal gradient in the melt. The gradient of constitutional supercooling was varied from almost zero (near the break-down of the planar liquid-solid interface at small growth speeds, cellular morphology) to near unity (large growth speeds, dendritic morphology). The spatial arrangements of cells and dendrites, as given by their coordination number, are not very different from each other. It appears that primary arm spacing maxima and the cell to dendrite transition are strongly influenced by the magnitude of the solute partition coefficient. The planar to cellular bifurcation is supercritical in Pb-Sn which has a high partition coefficient, as compared to the subcritical behavior reported in Al-Cu and succinonitrile-acetone, both of which have low partition coefficients. The primary arm spacing model due to Hunt agrees with the experimentally observed trend for the whole growth regime. There is a good quantitative agreement at higher gradients of supercooling. However, the model overpredicts the primary arm spacings at low gradients of constitutional supercooling.

  9. Static leaching of solidified/stabilized hazardous waste from the Solidtech process

    SciTech Connect

    Bisson, D.L.; Jackson, D.R.; Williams, K.R. ); Grube, W.E. )

    1991-10-01

    WILT, ANS 16.1 the TCLP leach tests were performed on solidified/stabilized (s/s) wastes treated by Solidtech, Inc. of Houston, Texas as part of a US EPA SITE demonstration project conducted in December 1988 at the Imperial Oil Company/Champion Chemical Company Superfund site in Morganville, New Jersey. All three leaching tests performed on the s/s wastes indicated that the primary contaminants of concern (lead and PCBs) were not leachable. The ANS 16.1 static leach test for the s/s wastes provided diffusion coefficients (D{sub e}) for Al, Ca and Na that were comparable to those obtained from the WILT test. However, plots of the ANS 16.1 data indicated that wetting of the samples confounded the static leaching process. The large column WILT D{sub e} was used to estimate that less than 0.8 {mu}g/cm{sup 2} lead would leach from a one-cubic yard block of s/s waste in contact with groundwater over a 60-month leaching period. This corresponds to concentrations less than 10 {mu}g/L lead in the water contacting the block of s/s waste.

  10. On oscillatory microstructure during cellular growth of directionally solidified Sn–36at.%Ni peritectic alloy

    PubMed Central

    Peng, Peng; Li, Xinzhong; Li, Jiangong; Su, Yanqing; Guo, Jingjie

    2016-01-01

    An oscillatory microstructure has been observed during deep-cellular growth of directionally solidified Sn–36at.%Ni hyperperitectic alloy containing intermetallic compounds with narrow solubility range. This oscillatory microstructure with a dimension of tens of micrometers has been observed for the first time. The morphology of this wave-like oscillatory structure is similar to secondary dendrite arms, and can be observed only in some local positions of the sample. Through analysis such as successive sectioning of the sample, it can be concluded that this oscillatory microstructure is caused by oscillatory convection of the mushy zone during solidification. And the influence of convection on this oscillatory microstructure was characterized through comparison between experimental and calculations results on the wavelength. Besides, the change in morphology of this oscillatory microstructure has been proved to be caused by peritectic transformation during solidification. Furthermore, the melt concentration increases continuously during solidification of intermetallic compounds with narrow solubility range, which helps formation of this oscillatory microstructure. PMID:27066761

  11. Thermal fatigue and oxidation data of superalloys including directionally solidified eutectics

    NASA Technical Reports Server (NTRS)

    Hill, V. L.; Humphreys, V. E.

    1977-01-01

    Thermal fatigue and oxidation data were obtained on 61 specimens, representing 15 discrete alloy compositions or fabricating techniques and three coating systems. Conventionally fabricated alloys included V57, MM 200, Rene 77, Rene 125, MM 246, MM 509, IN-738, IN-792 + Hf, and MM 200 + Hf. The directionally solidified alloys were MM 200, MM 200 single crystal, MM 200 bicrystal, cellular gamma/gamma' - delta) and lamellar gamma/gamma' - delta. The coatings systems included NiCrAlY on IN-738, In-792 + Hf, MM 200 DS, MM 200 DS single crystal, and cellular gamma/gamma' - delta and NiCrAlY/Pt on lamellar gamma/gamma' - delta. Crack initiation survival rates were recorded for all alloys, with and without coatings. All uncoated alloys, except MM 509, exhibited significant oxidation weight loss in 75,000 to 15,000 cycles. MM 509 specimens had weight losses only slightly higher than coated specimens through 7,500 cycles. All coated specimens had low weight loss.

  12. A Numerical Model of the Temperature Field of the Cast and Solidified Ceramic Material

    SciTech Connect

    Kavicka, Frantisek; Sekanina, Bohumil; Stransky, Karel; Stetina, Josef; Dobrovska, Jana

    2010-06-15

    Corundo-baddeleyit material (CBM)--EUCOR--is a heat- and wear-resistant material even at extreme temperatures. This article introduces a numerical model of solidification and cooling of this material in a non-metallic mould. The model is capable of determining the total solidification time of the casting and also the place of the casting which solidifies last. Furthermore, it is possible to calculate the temperature gradient in any point and time, and also determine the local solidification time and the solidification interval of any point. The local solidification time is one of the input parameters for the cooperating model of chemical heterogeneity. This second model and its application on samples of EUCOR prove that the applied method of measurement of chemical heterogeneity provides detailed quantitative information on the material structure and makes it possible to analyse the solidification process. The analysis of this process entails statistical processing of the results of the measurements of the heterogeneity of the components of EUCOR and performs correlation of individual components during solidification. The crystallisation process seems to be very complicated, where the macro- and microscopic segregations differ significantly. The verification of both numerical models was conducted on a real cast 350x200x400 mm block.

  13. Microstructural stability of directionally solidified eutectic NiAl-Mo under static and thermal cycling conditions

    SciTech Connect

    Kush, M.T.; Holmes, J.W.; Gibala, R.

    1997-12-31

    The quasi-binary eutectic NiAl-9% Mo with faceted molybdenum fibers was subjected to both thermal annealing conditions and to annealing under thermal cycling conditions to determine the microstructural stability of this alloy. The static temperature tests were run at 0.85T{sub M}--0.97T{sub M} in an argon gas atmosphere. The thermal cycling tests were performed between temperatures of 700 C and 1,200 C by induction heating disk-shaped specimens in an argon gas atmosphere using time-temperature heating and cooling profiles to approximate potential engine applications. To quantify microstructural changes, the fiber size and size distribution and number of fibers per unit area were measured as a function of time at temperature. The overall results demonstrate that the directionally solidified eutectic NiAl-9Mo subjected to thermal fatigue conditions exhibits cell boundary coarsening and large shape changes, whereas the microstructure under static stress-free annealing is stable.

  14. Thermal Parameters and Microstructural Development in Directionally Solidified Zn-Rich Zn-Mg Alloys

    NASA Astrophysics Data System (ADS)

    Vida, Talita A.; Freitas, Emmanuelle S.; Brito, Crystopher; Cheung, Noé; Arenas, Maria A.; Conde, Ana; De Damborenea, Juan; Garcia, Amauri

    2016-06-01

    Transient directional solidification experiments have been carried out with Zn-Mg hypoeutectic alloys under an extensive range of cooling rates with a view to analyzing the evolution of microstructure. It is shown that the microstructure is formed by a Zn-rich matrix of different morphologies and competitive eutectic mixtures (Zn-Zn11Mg2 and Zn-Zn2Mg). For 0.3 wt-pct Mg and 0.5 wt-pct Mg alloys, the Zn-rich matrix is shown to be characterized by high-cooling rates plate-like cells (cooling rates >9.5 and 24 K/s, respectively), followed by a granular-dendritic morphological transition for lower cooling rates. In contrast, a directionally solidified Zn1.2 wt-pct Mg alloy casting is shown to have the Zn-rich matrix formed only by dendritic equiaxed grains. Experimental growth laws are proposed relating the plate-like cellular interphase, the secondary dendritic arm spacing, and the eutectic interphase spacings to solidification thermal parameters, i.e., cooling rate and growth rate. The experimental law for the growth of secondary dendritic spacings under unsteady-state solidifications is also shown to encompass results of hypoeutectic Zn-Mg alloys subjected to steady-state Bridgman growth.

  15. Formation of (Bi,Pb)-2223 phase during solidifying and sintering

    SciTech Connect

    Lu, X.Y.; Nagata, A.; Kamada, S.

    1997-06-01

    High-temperature microstructures and the formation of (Bi,Pb)-2223 phase were examined in Bi{sub 1.84}Pb{sub 0.34}Sr{sub 1.91}Ca{sub 2.03}Cu{sub 3.06}O{sub x} during solidifying and sintering by high temperature optical microscope, XRD, SEM, EDS and AC susceptibility measurement. During solidification, firstly, the needle-like phase (Sr{sub x}Ca{sub 1{minus}x}){sub 2}CuO{sub 3} began to crystallize at about 930{degrees}C, secondly, the (Sr{sub x}Ca{sub 1{minus}x}) CuO{sub 2} with rectangular shape began to crystallize around 890 {degrees}C, and finally the plate-like 2212 phase began to form by the peritectic reaction of the two (Sr,Ca)-Cu-O compounds and liquid phase below 870{degrees}C. The 2223 phase and Sr{sub 6}Pb{sub 2}O{sub 9} were transformed slowly by the solid state reaction of the 2212 phase and residual (Sr,Ca)-Cu-O compounds in a long time sitering (> 18 h) at 840{degrees} C after solidification.

  16. Particle Engulfment and Pushing by Solidifying Interfaces: USMP-4 One Year Report

    NASA Technical Reports Server (NTRS)

    Stefanescu, D. M.; Juretzko, F. R.; Catalina, A. V.; Sen, S.; Curreri, P.; Schmitt, C.

    1999-01-01

    The experiment Particle Pushing and Engulfment by Solidifying Interfaces (PEP) was conducted during the USMP-4 (United States Microgravity Payload-4) mission on board the shuttle Columbia in November 1997. This experiment has its place within the framework of a long-term scientific effort to understand the physics of particle pushing. The first flight experiment of this kind was performed with a metal matrix composite on board STS-78 in the summer of 1996. The use of opaque matrices limits the evaluation to pre-and post-flight comparison of particle locations within the sample. By using transparent matrices the interaction of one or multiple particles with an advancing solid/liquid (SL) interface can be studied in-situ. If this observation can then directly be transmitted from the orbiter to the scientists by video down-link, a real-time execution of the experiment is possible in a micro-gravity environment. Part of this experiment was an extensive training of the payload specialists to perform the experiment in orbit. This was further enhanced by the availability of video down-link and direct communication with the astronauts. Even though the PEP experiment is aimed at understanding the interaction of a liquid/solid interface with insoluble particles and thus is fundamental in scope, the prospective applications are not. Possible applications range from improved metal matrix composites to understanding and preventing frost heaving affecting roads.

  17. On oscillatory microstructure during cellular growth of directionally solidified Sn-36at.%Ni peritectic alloy.

    PubMed

    Peng, Peng; Li, Xinzhong; Li, Jiangong; Su, Yanqing; Guo, Jingjie

    2016-01-01

    An oscillatory microstructure has been observed during deep-cellular growth of directionally solidified Sn-36at.%Ni hyperperitectic alloy containing intermetallic compounds with narrow solubility range. This oscillatory microstructure with a dimension of tens of micrometers has been observed for the first time. The morphology of this wave-like oscillatory structure is similar to secondary dendrite arms, and can be observed only in some local positions of the sample. Through analysis such as successive sectioning of the sample, it can be concluded that this oscillatory microstructure is caused by oscillatory convection of the mushy zone during solidification. And the influence of convection on this oscillatory microstructure was characterized through comparison between experimental and calculations results on the wavelength. Besides, the change in morphology of this oscillatory microstructure has been proved to be caused by peritectic transformation during solidification. Furthermore, the melt concentration increases continuously during solidification of intermetallic compounds with narrow solubility range, which helps formation of this oscillatory microstructure. PMID:27066761

  18. Perfect cellular eutectic growth in directionally solidified NiAl-Cr(Mo) hypereutectic alloy

    NASA Astrophysics Data System (ADS)

    Shang, Zhao; Shen, Jun; Zhang, Jianfei; Wang, Lei; Fu, Hengzhi

    2012-09-01

    Cellular eutectic microstructures with fully lamellar morphology were observed in the directionally solidified Ni-31Al-32Cr-6Mo (at%) hypereutectic alloy at withdrawal rates of 15, 25 and 50 μm/s, but the morphologies of cellular microstructures did not change consecutively with increasing withdrawal rate. The growth interfaces were deep cellular at withdrawal rates of 15 and 50 μm/s, but it changed to be shallow cellular at rate of 25 μm/s. The reason is that the interface undercooling comes to minimum at the middle rate of 25 μm/s. If the interface undercooling decreases, the tendency of constitutional undercooling will be weaken. The small constitutional undercooling will increase the interface stability, so that the interface morphology changes from deep cellular to shallow cellular. The shallow cellular growth interface led to a perfect cellular eutectic microstructure, which was analogous to the planar eutectic microstructure. In this case, the widths of the intercellular regions were narrowest, no coarse or irregular plates existed at the cell boundaries, and the thicknesses of the lamellae were almost uniform. The properties of the alloy may be markedly improved.

  19. Thermal Parameters and Microstructural Development in Directionally Solidified Zn-Rich Zn-Mg Alloys

    NASA Astrophysics Data System (ADS)

    Vida, Talita A.; Freitas, Emmanuelle S.; Brito, Crystopher; Cheung, Noé; Arenas, Maria A.; Conde, Ana; De Damborenea, Juan; Garcia, Amauri

    2016-04-01

    Transient directional solidification experiments have been carried out with Zn-Mg hypoeutectic alloys under an extensive range of cooling rates with a view to analyzing the evolution of microstructure. It is shown that the microstructure is formed by a Zn-rich matrix of different morphologies and competitive eutectic mixtures (Zn-Zn11Mg2 and Zn-Zn2Mg). For 0.3 wt-pct Mg and 0.5 wt-pct Mg alloys, the Zn-rich matrix is shown to be characterized by high-cooling rates plate-like cells (cooling rates >9.5 and 24 K/s, respectively), followed by a granular-dendritic morphological transition for lower cooling rates. In contrast, a directionally solidified Zn1.2 wt-pct Mg alloy casting is shown to have the Zn-rich matrix formed only by dendritic equiaxed grains. Experimental growth laws are proposed relating the plate-like cellular interphase, the secondary dendritic arm spacing, and the eutectic interphase spacings to solidification thermal parameters, i.e., cooling rate and growth rate. The experimental law for the growth of secondary dendritic spacings under unsteady-state solidifications is also shown to encompass results of hypoeutectic Zn-Mg alloys subjected to steady-state Bridgman growth.

  20. Deformation and fracture of a directionally solidified NiAl-28Cr-6Mo eutectic alloy

    NASA Technical Reports Server (NTRS)

    Chen, X. F.; Johnson, D. R.; Noebe, R. D.; Oliver, B. F.

    1995-01-01

    A directionally solidified alloy based on the NiAl-(Cr, Mo) eutectic was examined by transmission and scanning electron microscopy to characterize the microstructure and room temperature deformation and fracture behavior. The microstructure consisted of a lamellar morphology with a group of zone axes (111) growth direction for both the NiAl and (Cr, Mo) phases. The interphase boundary between the eutectic phases was semicoherent and composed of a well-defined dislocation network. In addition, a fine array of coherent NiAl precipitates was dispersed throughout the (Cr, Mo) phase. The eutectic morphology was stable at 1300 K with only coarsening of the NiAl precipitates occurring after heat treatment for 1.8 ks (500 h). Fracture of the aligned eutectic is characterized primarily by a crack bridging/renucleation mechanism and is controlled by the strength of the semicoherent interface between the two phases. However, contributions to the toughness of the eutectic may arise from plastic deformation of the NiAl phase and the geometry associated with the fracture surface.

  1. Leaching mechanisms of solidified low-level waste. The literature survey

    SciTech Connect

    Dougherty, D.; Colombo, P.

    1985-06-01

    A literature survey on leaching mechanisms, available mathematical models and factors that affect leaching from solidified low-level radioactive waste (LLW) was compiled. Physicochemical mechanisms identified include diffusion, dissolution, ion exchange, corrosion and surface effects. Diffusion was generally considered to be the predominant mechanism in LLW leachability. However, this hierarchy of importance has been strongly questioned for waste forms containing soluble salts and has been shown to be invalid for waste forms incorporating sorbents which control the release of radionuclides by ion exchange. Leaching behavior was modeled both mathematically for curve fitting to leaching data and by consideration of physical and chemical interactions within and between solidification agents, waste materials and additives, if any. Physicochemical analyses of bitumen and polymer solidification agents have considered them to be inert encapsulants with limited water permeability. All of the mathematical models are derived from solutions to the diffusion equation. Other mechanistic processes are included as additional terms in the equation. No comprehensive evaluations of mathematical models for LLW based on curve fitting to data were found in the literature. Factors that affect leaching have been categorized as system factors, leachant factors and waste form factors. System factors include temperature, pressure, radiation, time and the ratio of waste form area to leachant volume. Leachant factors include pH, Eh, flow or replacement frequency and composition while waste form factors include composition, surface condition, porosity and surface area to volume ratio. Information from the literature is reported for each of these factors. 75 refs., 2 figs., 4 tabs.

  2. In-situ formation of solidified hydrogen thin-membrane targets using a pulse tube cryocooler

    NASA Astrophysics Data System (ADS)

    Astbury, S.; Bedacht, S.; Brummitt, P.; Carroll, D.; Clarke, R.; Crisp, S.; Hernandez-Gomez, C.; Holligan, P.; Hook, S.; Merchan, J. S.; Neely, D.; Ortner, A.; Rathbone, D.; Rice, P.; Schaumann, G.; Scott, G.; Spindloe, C.; Spurdle, S.; Tebartz, A.; Tomlinson, S.; Wagner, F.; Borghesi, M.; Roth, M.; Tolley, M. K.

    2016-04-01

    An account is given of the Central Laser Facility's work to produce a cryogenic hydrogen targetry system using a pulse tube cryocooler. Due to the increasing demand for low Z thin laser targets, CLF (in collaboration with TUD) have been developing a system which allows the production of solid hydrogen membranes by engineering a design which can achieve this remotely; enabling the gas injection, condensation and solidification of hydrogen without compromising the vacuum of the target chamber. A dynamic sealing mechanism was integrated which allows targets to be grown and then remotely exposed to open vacuum for laser interaction. Further research was conducted on the survivability of the cryogenic targets which concluded that a warm gas effect causes temperature spiking when exposing the solidified hydrogen to the outer vacuum. This effect was shown to be mitigated by improving the pumping capacity of the environment and reducing the minimum temperature obtainable on the target mount. This was achieved by developing a two-stage radiation shield encased with superinsulating blanketing; reducing the base temperature from 14 ± 0.5 K to 7.2 ± 0.2 K about the coldhead as well as improving temperature control stability following the installation of a high-performance temperature controller and sensor apparatus. The system was delivered experimentally and in July 2014 the first laser shots were taken upon hydrogen targets in the Vulcan TAP facility.

  3. Genetic evidence in the mouse solidifies the calcium hypothesis of myofiber death in muscular dystrophy.

    PubMed

    Burr, A R; Molkentin, J D

    2015-09-01

    Muscular dystrophy (MD) refers to a clinically and genetically heterogeneous group of degenerative muscle disorders characterized by progressive muscle wasting and often premature death. Although the primary defect underlying most forms of MD typically results from a loss of sarcolemmal integrity, the secondary molecular mechanisms leading to muscle degeneration and myofiber necrosis is debated. One hypothesis suggests that elevated or dysregulated cytosolic calcium is the common transducing event, resulting in myofiber necrosis in MD. Previous measurements of resting calcium levels in myofibers from dystrophic animal models or humans produced equivocal results. However, recent studies in genetically altered mouse models have largely solidified the calcium hypothesis of MD, such that models with artificially elevated calcium in skeletal muscle manifest fulminant dystrophic-like disease, whereas models with enhanced calcium clearance or inhibited calcium influx are resistant to myofiber death and MD. Here, we will review the field and the recent cadre of data from genetically altered mouse models, which we propose have collectively mostly proven the hypothesis that calcium is the primary effector of myofiber necrosis in MD. This new consensus on calcium should guide future selection of drugs to be evaluated in clinical trials as well as gene therapy-based approaches. PMID:26088163

  4. Microstructural Development of Directionally Solidified Hg(1-x)Zn(x)Se Alloys

    NASA Technical Reports Server (NTRS)

    Cobb, S. D.; Szofran, F. F.; Jones, K. S.; Lehoczky, S. L.

    1999-01-01

    Hg(1-x)Zn(x)Se alloys have been studied as an alternative to Hg(1-x)Cd(x)Te for the detection of electromagnetic radiation, because the shorter ZnSe and HgSe bonds have been predicted to improve lattice stability. Several ingots with x = 0.1 were directionally solidified using a modified Bridgman-Stockbarger method; one was grown in an applied magnetic field, which greatly reduced radial compositional variations. A method was developed to reduce wetting. This, combined with the convex liquid-solid interface shape, produced boules that were single crystalline after growing about 3.5 cm. Observed surface features indicated ampoule wetting was eliminated using a graphite getter. Microstructural characteristics were greatly improved over HgCdTe alloys. In six boules, a total of only one twin was observed. A method for polishing and producing dislocation etch pits was developed for these alloys, revealing dislocation etch pit densities one to two orders of magnitude less than HgTe-based alloys. A kink in the thermal profile during processing of one boule generated more dislocations than did lattice mismatch due to compositional variations. This alloy has improved microstructural properties and resistance to dislocation formation compared with similar II-VI alloys.

  5. Massive, solidified bone in the wing of a volant courting bird

    PubMed Central

    Bostwick, Kimberly S.; Riccio, Mark L.; Humphries, Julian M.

    2012-01-01

    One pervasive morphological feature of tetrapods is the pipe-like, often marrow-filled, structure of the limb or long bones. This ‘hollow’ form maximizes flexural strength and stiffness with the minimum amount of bony material, and is exemplified by truly hollow (air-filled), or pneumatic, humeri in many modern birds. High-resolution microCT scans of the wings of two male club-winged manakins (Machaeropterus deliciosus) uncovered a notable exception to the hollow-tube rule in terrestrial vertebrates; males exhibited solidified ulnae more than three times the volume of birds of comparable body size, with significantly higher tissue mineral densities. The humeri exhibited similar (but less extreme) modifications. Each of the observed osteological modifications increases the overall mass of the bone, running counter to pervasive weight-reducing optimizations for flight in birds. The club-winged manakin is named for a pair of unique wing feathers found in adult males; these enlarged feathers attach directly to the ulna and resonate to produce a distinctive sound used in courtship displays. Given that the observed modifications probably assist in sound production, the club-winged manakin represents a case in which sexual selection by female choice has generated an ecologically ‘costly’ forelimb morphology, unique in being specialized for sound production at a presumed cost in flight efficiency. PMID:22696286

  6. Elastic and attenuation anisotropy in directionally solidified (hcp) zinc, and the seismic anisotropy in the Earth's inner core

    NASA Astrophysics Data System (ADS)

    Bergman, Michael I.; Giersch, Louis; Hinczewski, Michael; Izzo, Valerie

    2000-01-01

    The inner core of the Earth has been interpreted as being elastically anisotropic, with the direction parallel to the rotation axis fast. There are also observations that north-south rays exhibit greater amplitude reduction and more complex waveforms. In previous work, we found that directionally solidified, polycrystalline, tin (Sn)-rich alloys exhibit a solidification texturing that is measurable ultrasonically, and suggested that such texturing might be a cause for the observed seismic elastic anisotropy. Here, we find that zinc (Zn)-rich alloys also exhibit a measurable elastic anisotropy that is due to a preferred growth direction. We confirm the grain orientation by back-reflection X-ray diffraction. Zn solidifies as a hexagonal closest-packed (hcp) metal, albeit one with a c/ a ratio greater than the ideal, unlike hcp iron (Fe), and is 60% elastically anisotropic. We also find that the columnar dendritic grains that grow with a preferred orientation during directional solidification result in anisotropic scattering off grain boundaries, yielding an anisotropic apparent attenuation. In addition, we present results for directionally solidified 100% Zn, which exhibits qualitative differences in both the elastic and attenuation anisotropy from Zn alloys. The laboratory results can be interpreted as a cause for both the seismic elastic and attenuation anisotropy if the cooling near the inner core has more nearly cylindrical than spherical symmetry.

  7. Microstructural development of rapid solidification in Al-Si powder

    SciTech Connect

    Jin, F.

    1995-11-01

    The microstructure and the gradient of microstructure that forms in rapidly solidificated powder were investigated for different sized particles. High pressure gas atomization solidification process has been used to produce a series of Al-Si alloys powders between 0.2 {mu}m to 150 {mu}m diameter at the eutectic composition (12.6 wt pct Si). This processing technique provides powders of different sizes which solidify under different conditions (i.e. interface velocity and interface undercooling), and thus give different microstructures inside the powders. The large size powder shows dendritic and eutectic microstructures. As the powder size becomes smaller, the predominant morphology changes from eutectic to dendritic to cellular. Microstructures were quantitatively characterized by using optical microscope and SEM techniques. The variation in eutectic spacing within the powders were measured and compared with the theoretical model to obtain interface undercooling, and growth rate during the solidification of a given droplet. Also, nucleation temperature, which controls microstructures in rapidly solidified fine powders, was estimated. A microstructural map which correlates the microstructure with particle size and processing parameters is developed.

  8. Experimental Studies of the Interaction Between a Parallel Shear Flow and a Directionally-Solidifying Front

    NASA Technical Reports Server (NTRS)

    Zhang, Meng; Maxworthy, Tony

    1999-01-01

    It has long been recognized that flow in the melt can have a profound influence on the dynamics of a solidifying interface and hence the quality of the solid material. In particular, flow affects the heat and mass transfer, and causes spatial and temporal variations in the flow and melt composition. This results in a crystal with nonuniform physical properties. Flow can be generated by buoyancy, expansion or contraction upon phase change, and thermo-soluto capillary effects. In general, these flows can not be avoided and can have an adverse effect on the stability of the crystal structures. This motivates crystal growth experiments in a microgravity environment, where buoyancy-driven convection is significantly suppressed. However, transient accelerations (g-jitter) caused by the acceleration of the spacecraft can affect the melt, while convection generated from the effects other than buoyancy remain important. Rather than bemoan the presence of convection as a source of interfacial instability, Hurle in the 1960s suggested that flow in the melt, either forced or natural convection, might be used to stabilize the interface. Delves considered the imposition of both a parabolic velocity profile and a Blasius boundary layer flow over the interface. He concluded that fast stirring could stabilize the interface to perturbations whose wave vector is in the direction of the fluid velocity. Forth and Wheeler considered the effect of the asymptotic suction boundary layer profile. They showed that the effect of the shear flow was to generate travelling waves parallel to the flow with a speed proportional to the Reynolds number. There have been few quantitative, experimental works reporting on the coupling effect of fluid flow and morphological instabilities. Huang studied plane Couette flow over cells and dendrites. It was found that this flow could greatly enhance the planar stability and even induce the cell-planar transition. A rotating impeller was buried inside the

  9. Modeling of zinc solubility in stabilized/solidified electric arc furnace dust.

    PubMed

    Fernández-Olmo, Ignacio; Lasa, Cristina; Irabien, Angel

    2007-06-18

    Equilibrium models which attempt for the influence of pH on the solubility of metals can improve the dynamic leaching models developed to describe the long-term behavior of waste-derived forms. In addition, such models can be used to predict the concentration of metals in equilibrium leaching tests at a given pH. The aim of this work is to model the equilibrium concentration of Zn from untreated and stabilized/solidified (S/S) electric arc furnace dust (EAFD) using experimental data obtained from a pH-dependence leaching test (acid neutralization capacity, ANC). EAFD is a hazardous waste generated in electric arc furnace steel factories; it contains significant amounts of heavy metals such as Zn, Pb, Cr or Cd. EAFD from a local factory was characterized by X-ray fluorescence (XRF), acid digestion and X-ray diffraction (XRD). Zn and Fe were the main components while the XRD analysis revealed that zincite, zinc ferrite and hematite were the main crystalline phases. Different cement/EAFD formulations ranging from 7 to 20% dry weight of cement were prepared and subjected to the ANC leaching test. An amphoteric behavior of Zn was found from the pH dependence test. To model this behavior, the geochemical model Visual MINTEQ (VMINTEQ) was used. In addition to the geochemical model, an empirical model based on the dissolution of Zn in the acidic zone and the re-dissolution of zinc compounds in the alkaline zone was considered showing a similar prediction than that obtained with VMINTEQ. This empirical model seems to be more appropriate when the metal speciation is unknown, or when if known, the theoretical solid phases included in the database of VMINTEQ do not allow to describe the experimental data. PMID:17324503

  10. The relationship of microstructure to fracture and corrosion behavior of a directionally solidified superalloy

    NASA Astrophysics Data System (ADS)

    Trexler, Matthew D.

    GTD-111 DS is a directionally solidified superalloy currently used in turbine engines. To accurately predict the life of engine components it is essential to examine and characterize the microstructural evolution of the material and its effects on material properties. The as-cast microstructure of GTD-111 is highly inhomogeneous as a result of coring. The current post-casting heat treatments do not effectively eliminate the inhomogeneity. This inhomogeneity affects properties including tensile strength, fracture toughness, fracture path, and corrosion behavior, primarily in terms of the number of grains per specimen. The goal of this work was to link microstructural features to these properties. Quantitative fractography was used to determine that the path of cracks during failure of tensile specimens is influenced by the presence of carbides, which are located in the interdendritic regions of the material as dictated by segregation. The solvus temperature of the precipitate phase, Ni3(Al, Ti), was determined to be 1200°C using traditional metallography, differential thermal analysis, and dilatometry. A heat-treatment was designed to homogenize the microstructure for tensile testing that isolates the carbide by dissolving all of the "eutectic" Ni3(Al, Ti) precipitate phase, which is also found in the interdendritic areas. High temperature oxidation/sulfidation tests were conducted to investigate the corrosion processes involved when GTD-111 DS is utilized in steam and gas combustion turbine engines. The kinetics of corrosion in both oxidizing and sulfidizing atmospheres were determined using thermogravimetric analysis. Additionally, metallography of these samples after TGA revealed a correlation between the presence of grain boundaries and sulfur attack, which led to catastrophic failure of the material under stress-free conditions in a sulfur bearing environment. In summary, this work correlates the inhomogeneous microstructure of GTD-111 DS to tensile fracture

  11. Pyrolysis Autoclave Technology Demonstration Program for Treatment of DOE Solidified Organic Wastes

    SciTech Connect

    Roesener, W.S.; Mason, J.B.; Ryan, K.; Bryson, S.; Eldredge, H.B.

    2006-07-01

    In the summer of 2005, MSE Technologies Applications, Inc. (MSE) and THOR Treatment Technologies, LLC (TTT) conducted a demonstration test of the Thermal Organic Reduction (THOR{sup sm}) in-drum pyrolysis autoclave system under contract to the Department of Energy. The purpose of the test was to demonstrate that the THOR{sup sm} pyrolysis autoclave system could successfully treat solidified organic waste to remove organics from the waste drums. The target waste was created at Rocky Flats and currently resides at the Radioactive Waste Management Complex (RWMC) at the Idaho National Laboratory (INL). Removing the organics from these drums would allow them to be shipped to the Waste Isolation Pilot Plant for disposal. Two drums of simulated organic setup waste were successfully treated. The simulated waste was virtually identical to the expected waste except for the absence of radioactive components. The simulated waste included carbon tetrachloride, trichloroethylene, perchloroethylene, Texaco Regal oil, and other organics mixed with calcium silicate and Portland cement stabilization agents. The two-stage process consisted of the THOR{sup sm} electrically heated pyrolysis autoclave followed by the MSE off gas treatment system. The treatment resulted in a final waste composition that meets the requirements for WIPP transportation and disposal. There were no detectable volatile organic compounds in the treated solid residues. The destruction and removal efficiency (DRE) for total organics in the two drums ranged from >99.999% to >99.9999%. The operation of the process proved to be easily controllable using the pyrolysis autoclave heaters. Complete treatment of a fully loaded surrogate waste drum including heat-up and cooldown took place over a two-day period. This paper discusses the results of the successful pyrolysis autoclave demonstration testing. (authors)

  12. Time-dependent performance of soil mix technology stabilized/solidified contaminated site soils.

    PubMed

    Wang, Fei; Wang, Hailing; Al-Tabbaa, Abir

    2015-04-01

    This paper presents the strength and leaching performance of stabilized/solidified organic and inorganic contaminated site soil as a function of time and the effectiveness of modified clays applied in this project. Field trials of deep soil mixing application of stabilization/solidification (S/S) were performed at a site in Castleford in 2011. A number of binders and addictives were applied in this project including Portland cement (PC), ground granulated blastfurnace slag (GGBS), pulverised fuel ash (PFA), MgO and modified clays. Field trial samples were subjected to unconfined compressive strength (UCS), BS CN 12457 batch leaching test and the extraction of total organics at 28 days and 1.5 years after treatment. The results of UCS test show that the average strength values of mixes increased from 0-3250 kPa at 28 days to 250-4250 kPa at 1.5 years curing time. The BS EN 12457 leachate concentrations of all metals were well below their drinking water standard, except Ni in some mixes exceed its drinking water standard at 0.02 mg/l, suggesting that due to varied nature of binders, not all of them have the same efficiency in treating contaminated soil. The average leachate concentrations of total organics were in the range of 20-160 mg/l at 28 days after treatment and reduced to 18-140 mg/l at 1.5 years. In addition, organo clay (OC)/inorgano-organo clay (IOC) slurries used in this field trial were found to have a negative effect on the strength development, but were very effective in immobilizing heavy metals. The study also illustrates that the surfactants used to modify bentonite in this field trail were not suitable for the major organic pollutants exist in the site soil in this project. PMID:25603299

  13. Solidified structure and leaching properties of metallurgical wastewater treatment sludge after solidification/stabilization process.

    PubMed

    Radovanović, Dragana Đ; Kamberović, Željko J; Korać, Marija S; Rogan, Jelena R

    2016-01-01

    The presented study investigates solidification/stabilization process of hazardous heavy metals/arsenic sludge, generated after the treatment of the wastewater from a primary copper smelter. Fly ash and fly ash with addition of hydrated lime and Portland composite cement were studied as potential binders. The effectiveness of the process was evaluated by unconfined compressive strength (UCS) testing, leaching tests (EN 12457-4 and TCLP) and acid neutralization capacity (ANC) test. It was found that introduction of cement into the systems increased the UCS, led to reduced leaching of Cu, Ni and Zn, but had a negative effect on the ANC. Gradual addition of lime resulted in decreased UCS, significant reduction of metals leaching and high ANC, due to the excess of lime that remained unreacted in pozzolanic reaction. Stabilization of more than 99% of heavy metals and 90% of arsenic has been achieved. All the samples had UCS above required value for safe disposal. In addition to standard leaching tests, solidificates were exposed to atmospheric conditions during one year in order to determine the actual leaching level of metals in real environment. It can be concluded that the EN 12457-4 test is more similar to the real environmental conditions, while the TCLP test highly exaggerates the leaching of metals. The paper also presents results of differential acid neutralization (d-AN) analysis compared with mineralogical study done by scanning electron microscopy and X-ray diffraction analysis. The d-AN coupled with Eh-pH (Pourbaix) diagrams were proven to be a new effective method for analysis of amorphous solidified structure. PMID:26457922

  14. Simulation and experiment for oxygen-enriched combustion engine using liquid oxygen to solidify CO2

    NASA Astrophysics Data System (ADS)

    Liu, Yongfeng; Jia, Xiaoshe; Pei, Pucheng; Lu, Yong; Yi, Li; Shi, Yan

    2016-01-01

    For capturing and recycling of CO2 in the internal combustion engine, Rankle cycle engine can reduce the exhaust pollutants effectively under the condition of ensuring the engine thermal efficiency by using the techniques of spraying water in the cylinder and optimizing the ignition advance angle. However, due to the water spray nozzle need to be installed on the cylinder, which increases the cylinder head design difficulty and makes the combustion conditions become more complicated. In this paper, a new method is presented to carry out the closing inlet and exhaust system for internal combustion engines. The proposed new method uses liquid oxygen to solidify part of cooled CO2 from exhaust system into dry ice and the liquid oxygen turns into gas oxygen which is sent to inlet system. The other part of CO2 is sent to inlet system and mixed with oxygen, which can reduce the oxygen-enriched combustion detonation tendency and make combustion stable. Computing grid of the IP52FMI single-cylinder four-stroke gasoline-engine is established according to the actual shape of the combustion chamber using KIVA-3V program. The effects of exhaust gas recirculation (EGR) rate are analyzed on the temperatures, the pressures and the instantaneous heat release rates when the EGR rate is more than 8%. The possibility of enclosing intake and exhaust system for engine is verified. The carbon dioxide trapping device is designed and the IP52FMI engine is transformed and the CO2 capture experiment is carried out. The experimental results show that when the EGR rate is 36% for the optimum EGR rate. When the liquid oxygen of 35.80-437.40 g is imported into the device and last 1-20 min, respectively, 21.50-701.30 g dry ice is obtained. This research proposes a new design method which can capture CO2 for vehicular internal combustion engine.

  15. Comparison of rapid methods for chemical analysis of milligram samples of ultrafine clays.

    USGS Publications Warehouse

    Rettig, S.L.; Marinenko, J.W.; Khoury, H.N.; Jones, B.F.

    1983-01-01

    Two rapid methods for the decomposition and chemical analysis of clays were adapted for use with 20-40mg size samples, typical amounts of ultrafine products (< 0.5 micrometer diameter) obtained from modern separation methods for clay minrals. The results of these methods were compared with those of 'classical' rock analyses. The two methods consisted of mixed lithium metaborate fusion and heated decomposition with HF in a closed vessel. The latter technique was modified to include subsequent evaporation with concentrated H2SO4 and re-solution in HCl, which reduced the interference of the fluoride ion in the determination of Al, Fe, Ca, Mg, Na, and K.-from Authors

  16. Advanced powder metallurgy aluminum alloys via rapid solidification technology

    NASA Technical Reports Server (NTRS)

    Ray, R.

    1984-01-01

    Aluminum alloys containing 10 to 11.5 wt. pct. of iron and 1.5 to 3 wt. pct. of chromium using the technique of rapid solidification powder metallurgy were studied. Alloys were prepared as thin ribbons (.002 inch thick) rapidly solidified at uniform rate of 10(6) C/second by the melt spinning process. The melt spun ribbons were pulverized into powders (-60 to 400 mesh) by a rotating hammer mill. The powders were consolidated by hot extrusion at a high reduction ratio of 50:1. The powder extrusion temperature was varied to determine the range of desirable processing conditions necessary to yield useful properties. Powders and consolidated alloys were characterized by SEM and optical metallography. The consolidated alloys were evaluated for (1) thermal stability, (2) tensile properties in the range, room temperature to 450 F, and (3) notch toughness in the range, room temperature to 450 F.

  17. Synthesis and properties of A{sub 6}B{sub 2}(OH){sub 16}Cl{sub 2}.4H{sub 2}O (A = Mg, Ni, Zn, Co, Mn and B = Al, Fe) materials for environmental applications

    SciTech Connect

    Dias, Anderson; Cunha, Lumena; Vieira, Andiara C.

    2011-09-15

    Highlights: {yields} A{sub 6}B{sub 2}(OH){sub 16}Cl{sub 2}.4H{sub 2}O (A = Mg, Ni, Zn, Co, Mn and B = Al, Fe) materials were synthesized. {yields} Chemical synthesis produced different levels of crystallinity and ordering degree. {yields} Structural investigation by Raman scattering revealed a complex band structure. {yields} A strong correlation between band structure and ionic radius was determined. -- Abstract: Double layered hydroxide materials of composition A{sub 6}B{sub 2}(OH){sub 16}Cl{sub 2}.4H{sub 2}O (A = Mg, Ni, Zn, Co, Mn and B = Al, Fe) were synthesized by chemical precipitation at 60 {sup o}C. Different levels of crystallinity and ordering degree were observed depending upon the chemical environment or the combination between divalent and trivalent cations. The results from high-resolution transmission electron microscopy revealed that nanostructured layered samples were obtained with interplanar spacing compatible with previous literature. Raman scattering was employed to investigate the complex band structure observed, particularly the lattice vibrations at lower frequencies, which is intimately correlated to the cationic radius of both divalent and trivalent ions. The results showed that strongly coordinated water and chloride ions besides highly structured hydroxide layers have a direct influence on the stability of the hydrotalcites. It was observed that transition and decomposition temperatures varied largely for different chemical compositions.

  18. Rapid weight loss

    MedlinePlus

    ... loss-rapid weight loss; Overweight-rapid weight loss; Obesity-rapid weight loss; Diet-rapid weight loss ... for people who have health problems because of obesity. For these people, losing a lot of weight ...

  19. Drug release and permeation studies of nanosuspensions based on solidified reverse micellar solutions (SRMS).

    PubMed

    Friedrich, I; Reichl, S; Müller-Goymann, C C

    2005-11-23

    Solidified reverse micellar solutions (SRMS), i.e. mixtures of lecithin and triglycerides, offer high solubilisation capacities for different types of drugs in contrast to simple triglyceride systems [Friedrich, I., Müller-Goymann, C.C., 2003. Characterisation of SRMS and production development of SRMS-based nanosuspensions. Eur. J. Pharm. Biopharm. 56, 111-119]. Nanosuspensions based on SRMS were prepared by homogenisation close to the melting point of the SRMS matrix. In a first step the SRMS matrices of 1:1 (w/w) ratios of lecithin and triglycerides were loaded with 17beta-estradiol-hemihydrate (EST), hydrocortisone (HC) or pilocarpine base (PB), respectively, and subsequently ground in liquid nitrogen to minimise drug diffusion later on. The powder was then dispersed in a polysorbate 80 solution using high pressure homogenisation. The drug loading capacities of the nanosuspensions were very high in the case of poorly water-soluble EST (99% of total 0.1%, w/w, EST) and HC (97% of total 0.5%, w/w, HC) but not sufficient with the more hydrophilic PB (37-40% of total 1.0%, w/w, PB). These findings suggest SRMS-based nanosuspensions to be promising aqueous drug carrier systems for poorly soluble drugs like EST and HC. Furthermore, in vitro drug permeation from the different drug-loaded nanosuspensions was performed across human cornea construct (HCC) as an organotypical cell culture model. PB permeation did not differ from the nanosuspension and an aqueous solution whereas the permeation coefficients of HC-loaded nanosuspensions were reduced in comparison to aqueous and oily solutions of HC. However, the permeated amount was higher from the nanosuspensions due to a much lower HC concentration in the solution than that in the nanosuspension (solution 0.02%, w/w, versus nanosuspension 0.5%, w/w). The high drug load of the nanoparticles provides prolonged HC release. Permeated amounts of EST were reduced in comparison to HC and only detectable with an ELISA technique

  20. Crack initiation modeling of a directionally-solidified nickel-base superalloy

    NASA Astrophysics Data System (ADS)

    Gordon, Ali Page

    Combustion gas turbine components designed for application in electric power generation equipment are subject to periodic replacement as a result of cracking, damage, and mechanical property degeneration that render them unsafe for continued operation. In view of the significant costs associated with inspecting, servicing, and replacing damaged components, there has been much interest in developing models that not only predict service life, but also estimate the evolved microstructural state of the material. This thesis explains manifestations of microstructural damage mechanisms that facilitate fatigue crack nucleation in a newly-developed directionally-solidified (DS) Ni-base superalloy components exposed to elevated temperatures and high stresses. In this study, models were developed and validated for damage and life prediction using DS GTD-111 as the subject material. This material, proprietary to General Electric Energy, has a chemical composition and grain structure designed to withstand creep damage occurring in the first and second stage blades of gas-powered turbines. The service conditions in these components, which generally exceed 600°C, facilitate the onset of one or more damage mechanisms related to fatigue, creep, or environment. The study was divided into an empirical phase, which consisted of experimentally simulating service conditions in fatigue specimens, and a modeling phase, which entailed numerically simulating the stress-strain response of the material. Experiments have been carried out to simulate a variety of thermal, mechanical, and environmental operating conditions endured by longitudinally (L) and transversely (T) oriented DS GTD-111. Both in-phase and out-of-phase thermo-mechanical fatigue tests were conducted. In some cases, tests in extreme environments/temperatures were needed to isolate one or at most two of the mechanisms causing damage. Microstructural examinations were carried out via SEM and optical microscopy. A continuum

  1. Use of rotation to suppress thermosolutal convection in directionally solidified binary alloys

    NASA Technical Reports Server (NTRS)

    Pearlstein, Arne J.

    1994-01-01

    Effects of rotation on onset of convection during plane-front directional solidification of Pb-Sn and the pseudobinary system mercury cadmium telluride (Hg(1-x)Cd(x)Te), and on dendritic solidification of Pb-Sn have been studied by means of linear stability analysis. Incorporating Coriolis and centrifugal accelerations into the momentum equation of Coriell et al., we find that under realistic processing conditions, a large degree of stabilization can be achieved using modest rotation rates for both Pb-Sn and mercury cadmium telluride. At a growth velocity of 5 micron/sec and nominal liquid-side temperature gradient of 200 K/cm in Pb-Sn, rotation at 500 rpm results in a hundredfold increase in the critical Sn concentration. Large increases in the maximum allowable growth velocity at fixed melt composition are also attainable with modest rotation rates. The effect is amplified under conditions of reduced gravitational acceleration. For Hg(1-x)Cd(x)Te, we have also studied the nonrotating case. The key differences are due to the existence of a composition range for Hg(1-x)Cd(x)Te in which the melt density has a local maximum as a function of temperature. When the melt solidifies by cooling from below, the liquid density may initially increase with distance above the interface, before ultimately decreasing as the melt temperature increases above the value at which the local density maximum occurs. In contrast to the Pb-Sn case where density depends monotonically on temperature and composition, for Hg(1-x)Cd(x)Te there exists a critical value of the growth velocity above which plane-front solidification is unstable for all bulk CdTe mole fractions. Again, rotation leads to significant inhibition of onset. We identify the predicted stabilization with the Taylor-Proudman mechanism by which rotation inhibits thermal convection in a single-component fluid heated from below. In a binary liquid undergoing solidification, rotation inhibits the onset of buoyancy

  2. Effect of a transverse magnetic field on solidification structure in directionally solidified Al-Cu-Ag ternary alloys

    NASA Astrophysics Data System (ADS)

    Guan, Guang; Du, Dafan; Fautrelle, Yves; Moreau, Rene; Ren, Zhongming; Li, Xi

    2015-07-01

    The effect of a transverse magnetic field on solidification structure in directionally solidified Al-Cu-Ag ternary alloys was investigated experimentally. The results show that the application of the transverse magnetic field significantly modified the solidification structures. Indeed, the magnetic field caused the formation of macrosegregation and the transformation of the liquid/solid interface from cellular to planar. Moreover, it was found that the magnetic field refined the eutectic cell and decreased the mushy zone length. This may be attributed to the thermoelectric magnetic convection between eutectic cells.

  3. Reuse of cement-solidified municipal incinerator fly ash in cement mortars: physico-mechanical and leaching characteristics.

    PubMed

    Cinquepalmi, Maria Anna; Mangialardi, Teresa; Panei, Liliana; Paolini, Antonio Evangelista; Piga, Luigi

    2008-03-01

    The reuse of cement-solidified Municipal Solid Waste Incinerator (MSWI) fly ash (solidified/stabilised (S/S) product) as an artificial aggregate in Portland cement mortars was investigated. The S/S product consisted of a mixture of 48 wt.% washed MSWI fly ash, 20 wt.% Portland cement and 32 wt.% water, aged for 365 days at 20 degrees C and 100% RH. Cement mortars (water/cement weight ratio=0.62) were made with Portland cement, S/S product and natural sand at three replacement levels of sand with S/S product (0%, 10% and 50% by mass). After 28 days of curing at 20 degrees C and 100% RH, the mortar specimens were characterised for their physico-mechanical (porosity, compressive strength) and leaching behaviour. No retardation in strength development, relatively high compressive strengths (up to 36 N/mm2) and low leaching rates of heavy metals (Cr, Cu, Pb and Zn) were always recorded. The leaching data from sequential leach tests on monolithic specimens were successfully elaborated with a pseudo-diffusional model including a chemical retardation factor related to the partial dissolution of contaminant. PMID:17658684

  4. Nial and Nial-Based Composites Directionally Solidified by a Containerless Zone Process. Ph.D. Thesis

    NASA Technical Reports Server (NTRS)

    Joslin, Steven M.

    1995-01-01

    A containerless electromagnetically levitated zone (CELZ) process has been used to directionally solidify NiAl and NiAl-based composites. The CELZ processing results in single crystal NiAl (HP-NiAl) having higher purity than commercially pure NiAl grown by a modified Bridgman process (CP-NiAl). The mechanical properties, specifically fracture toughness and creep strength, of the HP-NiAl are superior to binary CP-NiAl and are used as a base-line for comparison with the composite materials subsequently studied. Two-phase composite materials (NiAl-based eutectic alloys) show improvement in room temperature fracture toughness and 1200 to 1400 K creep strength over that of binary HP-NiAl. Metallic phase reinforcements produce the greatest improvement in fracture toughness, while intermetallic reinforcement produces the largest improvement in high temperature strength. Three-phase eutectic alloys and composite materials were identified and directionally solidified with the intent to combine the improvements observed in the two-phase alloys into one alloy. The room temperature fracture toughness and high temperature strength (in air) serve as the basis for comparison between all of the alloys. Finally, the composite materials are discussed in terms of dominant fracture mechanism observed by fractography.

  5. Cold Heat Release Characteristics of Solidified Oil Droplet-Water Solution Latent Heat Emulsion by Air Bubbles

    NASA Astrophysics Data System (ADS)

    Inaba, Hideo; Morita, Shin-Ichi

    The present work investigates the cold heat-release characteristics of the solidified oil droplets (tetradecane, C14H30, freezing point 278.9 K)/water solution emulsion as a latent heat-storage material having a low melting point. An air bubbles-emulsion direct-contact heat exchange method is selected for the cold heat-results from the solidified oil droplet-emulsion layer. This type of direct-contact method results in the high thermal efficiency. The diameter of air bubbles in the emulsion increases as compared with that in the pure water. The air bubbles blown from a nozzle show a strong mixing behavior during rising in the emulsion. The temperature effectiveness, the sensible heat release time and the latent heat release time have been measured as experimental parameters. The useful nondimensional emulsion level equations for these parameters have been derived in terms of the nondimensional emalsion level expressed the emulsion layer dimensions, Reynolds number for air flow, Stefan number and heat capacity ratio.

  6. Leach studies on cement-solidified ion exchange resins from decontamination processes at operating nuclear power stations

    SciTech Connect

    McIsaac, C.V.; Akers, D.W.; McConnell, J.W.; Morcos, N.

    1992-08-01

    The effects of varying pH and leachant compositions on the physical stability and leachability of radionuclides and chelating agents were determined for cement-solidified decontamination ion-exchange resin wastes collected from two operating commercial light water reactors. Small scale waste-form specimens were collected during waste solidifications performed at the Brunswick Steam Electric Plant Unit 1 and at the James A. FitzPatrick Nuclear Power Station. The collected specimens were leach tested, and their compressive strength was measured in accordance with the Nuclear Regulatory Commission`s ``Technical Position on Waste Form`` (Revision 1), from the Low-Level Waste Management Branch. Leachates from these studies were analyzed for radionuclides, selected transition metals, and chelating agents to assess the leachability of these waste form constituents. Leachants used for the study were deionized water, simulated seawater, and groundwater compositions similar to those found at Barnwell, South Carolina and Hanford, Washington. Results of this study indicate that initial leachant pH does not affect leachate pH or releases from cement-solidified decontamination ion-exchange resin waste forms. However, differences in leachant composition and the presence of chelating agents may affect the releases of radionuclides and chelating agents. In addition, results from this study indicate that the cumulative releases of radionuclides and chelating agents observed for forms that disintegrated were similar to those for forms that maintained their general physical integrity.

  7. Leach studies on cement-solidified ion exchange resins from decontamination processes at operating nuclear power stations

    SciTech Connect

    McIsaac, C.V.; Akers, D.W.; McConnell, J.W.; Morcos, N.

    1992-01-01

    The effects of varying pH and leachant compositions on the physical stability and leachability of radionuclides and chelating agents were determined for cement-solidified decontamination ion-exchange resin wastes collected from two operating commercial light water reactors. Small scale waste-form specimens were collected during waste solidifications performed at the Brunswick Steam Electric Plant Unit 1 and at the James A. FitzPatrick Nuclear Power Station. The collected specimens were leach tested, and their compressive strength was measured in accordance with the Nuclear Regulatory Commission's Technical Position on Waste Form'' (Revision 1), from the Low-Level Waste Management Branch. Leachates from these studies were analyzed for radionuclides, selected transition metals, and chelating agents to assess the leachability of these waste form constituents. Leachants used for the study were deionized water, simulated seawater, and groundwater compositions similar to those found at Barnwell, South Carolina and Hanford, Washington. Results of this study indicate that initial leachant pH does not affect leachate pH or releases from cement-solidified decontamination ion-exchange resin waste forms. However, differences in leachant composition and the presence of chelating agents may affect the releases of radionuclides and chelating agents. In addition, results from this study indicate that the cumulative releases of radionuclides and chelating agents observed for forms that disintegrated were similar to those for forms that maintained their general physical integrity.

  8. Evaluation of sulfidic mine tailings solidified/stabilized with cement kiln dust and fly ash to control acid mine drainage

    SciTech Connect

    Nehdi, M.; Tariq, A.

    2008-11-15

    In the present research, industrial byproducts, namely, cement kiln dust (CKD) and Class C fly ash (FAC) have been used as candidate materials along with the partial addition of sulfate-resistant cement (SRC) in the Stabilization/solidification of polymetallic sulfidic mine tailings (MT). The effectiveness of S/S was assessed by comparing laboratory experimental values obtained from unconfined compressive strength, hydraulic conductivity and leaching propensity tests of S/S samples with regulatory standards for safe surface disposal of such wastes. Despite general regulatory compliance of compressive strength and hydraulic conductivity, some solidified/stabilized-cured matrices were found unable to provide the required immobilization of pollutants. Solidified/stabilized and 90-day cured mine tailings specimens made with composite binders containing (10% CKD + 10% FAC), (5% SRC + 15% FAC) and (5% SRC + 5% CKD + 10% FAC) significantly impaired the solubility of all contaminants investigated and proved successful in fixing metals within the matrix, in addition to achieving adequate unconfined compressive strength and hydraulic conductivity values, thus satisfying USEPA regulations. Laboratory investigations revealed that, for polymetallic mining waste, leachate concentrations are the most critical factor in assessing the effectiveness of S/S technology.

  9. Directionally Solidified NiAl-Based Alloys Studied for Improved Elevated-Temperature Strength and Room-Temperature Fracture Toughness

    NASA Technical Reports Server (NTRS)

    Whittenberger, J. Daniel; Raj, Sai V.; Locci, Ivan E.; Salem, Jonathan A.

    2000-01-01

    Efforts are underway to replace superalloys used in the hot sections of gas turbine engines with materials possessing better mechanical and physical properties. Alloys based on the intermetallic NiAl have demonstrated potential; however, they generally suffer from low fracture resistance (toughness) at room temperature and from poor strength at elevated temperatures. Directional solidification of NiAl alloyed with both Cr and Mo has yielded materials with useful toughness and elevated-temperature strength values. The intermetallic alloy NiAl has been proposed as an advanced material to extend the maximum operational temperature of gas turbine engines by several hundred degrees centigrade. This intermetallic alloy displays a lower density (approximately 30-percent less) and a higher thermal conductivity (4 to 8 times greater) than conventional superalloys as well as good high-temperature oxidation resistance. Unfortunately, unalloyed NiAl has poor elevated temperature strength (approximately 50 MPa at 1027 C) and low room-temperature fracture toughness (about 5 MPa). Directionally solidified NiAl eutectic alloys are known to possess a combination of high elevated-temperature strength and good room-temperature fracture toughness. Research has demonstrated that a NiAl matrix containing a uniform distribution of very thin Cr plates alloyed with Mo possessed both increased fracture toughness and elevated-temperature creep strength. Although attractive properties were obtained, these alloys were formed at low growth rates (greater than 19 mm/hr), which are considered to be economically unviable. Hence, an investigation was warranted of the strength and toughness behavior of NiAl-(Cr,Mo) directionally solidified at faster growth rates. If the mechanical properties did not deteriorate with increased growth rates, directional solidification could offer an economical means to produce NiAl-based alloys commercially for gas turbine engines. An investigation at the NASA Glenn

  10. Flow-induced morphological instabilities due to temporally-modulated stagnation-point flow. [in single crystals growth by directionally-solidifying interface

    NASA Technical Reports Server (NTRS)

    Merchant, G. J.; Davis, S. H.

    1989-01-01

    The influence of periodically-modulated planar stagnation-point flow on the morphological stability of a directionally-solidifying interface is presently considered with a view to the effect of unsteady nonparallel flows on single-crystal growth. The modeling of the system assumes that the viscous boundary layer thickness is much greater than that of the solute boundary layer, and that the modulation frequency is much smaller than the strength of plane stagnation-point flow. The solidifying interface is either stabilized or destabilized depending on the ratio of the period of modulation to the solute-diffusion time.

  11. Rapid shallow breathing

    MedlinePlus

    Tachypnea; Breathing - rapid and shallow; Fast shallow breathing; Respiratory rate - rapid and shallow ... Shallow, rapid breathing has many possible medical causes, including: Asthma Blood clot in an artery in the lung Choking Chronic obstructive ...

  12. Undercooled and rapidly quenched Ni-Mo alloys

    NASA Technical Reports Server (NTRS)

    Tewari, S. N.; Glasgow, T. K.

    1986-01-01

    Hypoeutectic, eutectic, and hypereutectic nickel-molybdenum alloys were rapidly solidified by both bulk undercooling and melt spinning techniques. Alloys were undercooled in both electromagnetic levitation and differential thermal analysis equipment. The rate of recalescence depended upon the degree of initial undercooling and the nature (faceted or nonfaceted) of the primary nucleating phase. Alloy melts were observed to undercool more in the presence of primary Beta (NiMo intermetallic) phase than in gamma (fcc solid solution) phase. Melt spinning resulted in an extension of molybdenum solid solubility in gamma nickel, from 28 to 37.5 at % Mo. Although the microstructures observed by undercooling and melt spinning were similar the microsegregation pattern across the gamma dendries was different. The range of microstructures evolved was analyzed in terms of the nature of the primary phase to nucleate, its subsequent dendritic growth, coarsening and fragmentation, and final solidification of interfenderitic liquid.

  13. Undercooled and rapidly quenched Ni-Mo alloys

    NASA Technical Reports Server (NTRS)

    Tewari, S. N.; Glasgow, T. K.

    1987-01-01

    Hypoeutectic, eutectic, and hypereutectic nickel-molybdenum alloys were rapidly solidified by both bulk undercooling and melt spinning techniques. Alloys were undercooled in both electromagnetic levitation and differential thermal analysis equipment. The rate of recalescence depended upon the degree of initial undercooling and the nature (faceted or nonfaceted) of the primary nucleating phase. Alloy melts were observed to undercool more in the presence of primary Beta (NiMo intermetallic) phase than in gamma (fcc solid solution) phase. Melt spinning resulted in an extension of molybdenum solid solubility in gamma nickel, from 28 to 37.5 at. pct Mo. Although the microstructures observed by undercooling and melt spinning were similar, the microsegregation pattern across the gamma dendries was different. The range of microstructures evolved was analyzed in terms of the nature of the primary phase to nucleate, its subsequent dendritic growth, coarsening and fragmentation, and final solidification of interfenderitic liquid.

  14. The convective liquidus in a solidifying magma chamber - A fluid dynamic investigation

    NASA Technical Reports Server (NTRS)

    Brandeis, Genevieve; Marsh, Bruce D.

    1989-01-01

    An experimental study of the solidification of a layer of paraffin cooled from above is reported. When the fluid is superheated, convection sets in at the beginning of cooling but rapidly decreases in intensity. Once the layer has lost its superheat, convection ceases and further cooling is by conduction. The interior temperature then remains constant until encountered by the upper crust. The convective liquidus is defined as the temperature threshold below which convection is very weak or nonexistent. In natural basaltic systems the convective liquidus, although strictly unknown, may be very close to the true liquidus. Rapid convection may therefore not be a dominant process during the crystallization of many magmna chambers; instead, convection is part of an overall intimate balance between phase equilibria, crystal growth, and heat transfer.

  15. Growth kinetics of gamma-prime precipitates in a directionally solidified eutectic, gamma/gamma-prime-delta

    NASA Technical Reports Server (NTRS)

    Tewari, S. N.

    1976-01-01

    A directionally solidified eutectic alloy (DSEA), of those viewed as potential candidates for the next generation of aircraft gas turbine blade materials, is studied for the gamma-prime growth kinetics, in the system Ni-Nb-Cr-Al, specifically: Ni-20 w/o Nb-6 w/o Cr-2.5 w/o Al gamma/gamma-prime-delta DSEA. Heat treatment, polishing and etching, and preparation for electron micrography are described, and the size distribution of gamma-prime phase following various anneals is plotted, along with gamma-prime growth kinetics in this specific DSEA, and the cube of gamma-prime particle size vs anneal time. Activation energies and coarsening kinetics are studied.

  16. Dynamic evolution process of multilayer core-shell microstructures within containerlessly solidifying Fe(50)Sn(50) immiscible alloy.

    PubMed

    Wang, W L; Wu, Y H; Li, L H; Geng, D L; Wei, B

    2016-03-01

    Multilayer core-shell structures are frequently formed in polymers and alloys when temperature and concentration fields are well symmetrical spatially. Here we report that two- to five-layer core-shell microstructures were the dominant structural morphology of a binary Fe(50)Sn(50) immiscible alloy solidified under the containerless and microgravity states within a drop tube. Three dimensional phase field simulation reveals that both the uniformly dispersive structure and the multilayer core-shells are the various metastable and transitional states of the liquid phase separation process. Only the two-layer core-shell is the most stable microstructure with the lowest chemical potential. Because of the suppression of Stokes motion, solutal Marangoni migration becomes important to drive the evolution of core-shell structures. PMID:27078410

  17. Dynamic evolution process of multilayer core-shell microstructures within containerlessly solidifying F e50S n50 immiscible alloy

    NASA Astrophysics Data System (ADS)

    Wang, W. L.; Wu, Y. H.; Li, L. H.; Geng, D. L.; Wei, B.

    2016-03-01

    Multilayer core-shell structures are frequently formed in polymers and alloys when temperature and concentration fields are well symmetrical spatially. Here we report that two- to five-layer core-shell microstructures were the dominant structural morphology of a binary F e50S n50 immiscible alloy solidified under the containerless and microgravity states within a drop tube. Three dimensional phase field simulation reveals that both the uniformly dispersive structure and the multilayer core-shells are the various metastable and transitional states of the liquid phase separation process. Only the two-layer core-shell is the most stable microstructure with the lowest chemical potential. Because of the suppression of Stokes motion, solutal Marangoni migration becomes important to drive the evolution of core-shell structures.

  18. Influence of Growth Rate on Microstructural Length Scales in Directionally Solidified NiAl-Mo Hypo-Eutectic Alloy

    NASA Astrophysics Data System (ADS)

    Zhang, Jianfei; Ma, Xuewei; Ren, Huiping; Chen, Lin; Jin, Zili; Li, Zhenliang; Shen, Jun

    2016-01-01

    In this article, the Ni-46.1Al-7.8Mo (at.%) alloy was directionally solidified at different growth rates ranging from 15 μm/s to 1000 μm/s under a constant temperature gradient (334 K/cm). The dependence of microstructural length scales on the growth rate was investigated. The results show that, with the growth rate increasing, the primary dendritic arm spacings (PDAS) and secondary dendritic arm spacings (SDAS) decreased. There exists a large distribution range in PDAS under directional solidification conditions at a constant temperature gradient. The average PDAS and SDAS as a function of growth rate can be given as λ1 = 848.8967 V-0.4509 and λ2 = 64.2196 V-0.4140, respectively. In addition, a comparison of our results with the current theoretical models and previous experimental results has also been made.

  19. Directionally solidified Eu doped CaF2/Li3AlF6 eutectic scintillator for neutron detection

    NASA Astrophysics Data System (ADS)

    Kamada, Kei; Hishinuma, Kousuke; Kurosawa, Shunsuke; Shoji, Yasuhiro; Pejchal, Jan; Ohashi, Yuji; Yokota, Yuui; Yoshikawa, Akira

    2015-12-01

    Eu doped CaF2/Li3AlF6 eutectics were grown by μ-PD method. The directionally solidified eutectic with well-aligned 600 nm diameter Eu:CaF2 scintillator fibers surrounded with Li3AlF6 was prepared. The grown eutectics showed an emission peak at 422 nm ascribed to Eu2+ 4f-5d transition from Eu:CaF2 scintillation fiber. Li concentration in the Eu:CaF2-Li3AlF6 eutectic is around 0.038 mol/cm3,which is two times higher than that of LiCaAlF6 single crystal (0.016 mol/cm3). The light yield of Eu:CaF2-Li3AlF6 eutectic was around 7000 ph/neutron. The decay time was about 550 ns (89%) and 1450 ns (11%).

  20. Development and Evaluation of Directionally-Solidified NiAl/(CR,MO)-Based Eutectic Alloys for Airfoil Applications

    NASA Technical Reports Server (NTRS)

    Raj, S. V.; Locci, I. E.; Whittenberger, J. D.

    2001-01-01

    The results of recent efforts to develop directionally-solidified alloys based on the Ni-33Al-31Cr-3Mo eutectic composition are discussed. These developmental efforts included studying the effects of macroalloying and growth rates on microstructure formation as well as the elevated temperature compressive and tensile properties of these alloys. These observations revealed that contrary to conventional opinion, the cellular microstructure was stronger and tougher than the planar eutectic microstructure due to a microstructural refinement of the cell size and interlamellar spacing. The high temperature strengths of these alloys are compared with those of commercial superalloys and advanced NiAl single crystals. The implications of this research on airfoil manufacturing and applications are discussed.

  1. Effect of Growth Rate and Composition on the Eutectic Spacing in the Directionally Solidified NiAl-Mo Eutectic Alloys

    NASA Astrophysics Data System (ADS)

    Zhang, JianFei; Shen, Jun; Ren, HuiPing; Yang, JiChun; Chen, Lin; Jin, ZiLi; Li, ZhenLiang; Zhao, XueLing

    2015-08-01

    A series of stoichiometric NiAl alloys contain four different concentrations of Mo (7.8, 9, 13, 16 at.%) were directionally solidified in the Bridgman-type directional solidification furnace for four different growth rates ( V = 1.5-6 μm/s) in a constant temperature gradient ( G = 334 K/cm). the microstructures of the alloys produced with the different growth rates at a constant temperature gradient tended to form fully fibrous structures. The fiber spacings λ were measured from transverse section of the specimen. The variation of λ with respect to growth rate ( V) and composition ( C 0) were determined by linear regression analysis. It has been found that λ decreases with the increasing values of V and C 0. The results are compared with theoretical models and previous experimental published data.

  2. Evaluation of dendrite morphology using fractal dimension and dimensionless perimeter in unidirectionally solidified Al-Si Alloys

    NASA Astrophysics Data System (ADS)

    Ohsasa, K.; Natsume, Y.; Sekiya, T.; Hatayama, T.

    2015-06-01

    The dendrite morphology of unidirectionally solidified Al-Si alloys was evaluated by measuring the fractal dimension and dimensionless perimeter of dendrites. In an unidirectional solidification experiment, columnar crystals grew from a bottom chill and columnar to equiaxed transition (CET) occurred at the upper part of an ingot. Then, equiaxed crystals were formed at the top of the ingot. Different dendrite morphology was observed in longitudinal, transverse and oblique sections, however, the fractal dimension or dimensionless perimiter of the dendrites in the sections with same local solidification time showed same values, and continuously decreased with increase in the local solidification time through columnar, CET and equiaxed regions. It can be considered that the fractal dimension and dimensionless perimiter of dendrites are controlled by local solidification time and irrespective of dendrite morphology. This result demonstrated the potential of the fractal dimension and dimensionless perimiter as a parameter for estimating local solidification time of an ingot in which the measurement of SDAS is difficult.

  3. Shipment and Disposal of Solidified Organic Waste (Waste Type IV) to the Waste Isolation Pilot Plant (WIPP)

    SciTech Connect

    D'Amico, E. L; Edmiston, D. R.; O'Leary, G. A.; Rivera, M. A.; Steward, D. M.

    2006-07-01

    In April of 2005, the last shipment of transuranic (TRU) waste from the Rocky Flats Environmental Technology Site to the WIPP was completed. With the completion of this shipment, all transuranic waste generated and stored at Rocky Flats was successfully removed from the site and shipped to and disposed of at the WIPP. Some of the last waste to be shipped and disposed of at the WIPP was waste consisting of solidified organic liquids that is identified as Waste Type IV in the Contact-Handled Transuranic Waste Authorized Methods for Payload Control (CH-TRAMPAC) document. Waste Type IV waste typically has a composition, and associated characteristics, that make it significantly more difficult to ship and dispose of than other Waste Types, especially with respect to gas generation. This paper provides an overview of the experience gained at Rocky Flats for management, transportation and disposal of Type IV waste at WIPP, particularly with respect to gas generation testing. (authors)

  4. Fatigue crack propagation behaviour of unidirectionally solidified gamma/gamma-prime-delta eutectic alloys. [Ni-Nb-Al alloys

    NASA Technical Reports Server (NTRS)

    Bretz, P. E.; Hertzberg, R. W.

    1979-01-01

    Fatigue crack propagation studies were carried out on unidirectionally solidified gamma/gamma-prime-delta (Ni-Nb-Al) alloys over an aluminum content range of 1.5-2.5% by weight. The variation of Al content of as-grown alloys did not significantly affect the crack growth behavior of these eutectic composites. The results indicate that the addition of Al to the eutectic dramatically improved the FCP behavior. The gamma/gamma-prime-delta alloy exhibited crack growth rates for a given stress intensity range that are an order of magnitude lower than those for the gamma-delta alloy. It is suggested that this difference in FCP behavior can be explained on the basis of stacking fault energy considerations. Extensive delaminations at the crack tip were also revealed, which contributed to the superior fatigue response. Delamination was predominantly intergranular in nature.

  5. Evaluation of the MICAST #2-12 AI-7wt%Si Sample Directionally Solidified Aboard the International Space Station

    NASA Technical Reports Server (NTRS)

    Tewari, Surendra N.; Ghods, Masoud; Angart, Samuel G.; Lauer, Mark; Grugel, Richard N.; Poirier, David R.

    2016-01-01

    The US team of the European led "MIcrostructure Formation in CASTing of Technical Alloys under Diffusive and Magnetically Controlled Convective Conditions" (MICAST) program recently received a third Aluminum - 7wt% silicon alloy that was processed in the microgravity environment aboard the International Space Station. The sample, designated MICAST#2-12, was directionally solidified in the Solidification with Quench Furnace (SQF) at a constant rate of 40micometers/s through an imposed temperature gradient of 31K/cm. Procedures taken to evaluate the state of the sample prior to sectioning for metallographic analysis are reviewed and rational for measuring the microstructural constituents, in particular the primary dendrite arm spacing (Lambda (sub1)), is given. The data are presented, put in context with the earlier samples, and evaluated in view of a relevant theoretical model.

  6. Fatigue crack growth rates and fracture toughness of rapidly solidified Al-8. 5 pct Fe-1. 2 pct V-1. 7 pct Si alloys

    SciTech Connect

    Hariprasad, S.; Sastry, S.M.L.; Jerina, K.L. . Mechanical Engineering Dept.); Lederich, R.J. )

    1994-05-01

    The room-temperature fatigue crack growth rates (FCGR) and fracture toughness were evaluated for different crack plane Orientations of an Al-8.5 pct Fe-1.2 pct V-1.7 pct Si alloy produced by planar flow casting (PFC) and atomized melt deposition (AMD) processes. For the alloy produced by the PFC process, properties were determined in six different orientations, including the short transverse directions S-T and S-L. Diffusion bonding and adhesive bonding methods were used to prepare specimens for determining FCGR and fracture toughness in the short transverse direction. Interparticle boundaries control fracture properties in the alloy produced by PFC. Fracture toughness of the PFC alloy varies from 13.4 MPa[radical][bar m] to 30.8 MPa[radical][bar m], depending on the orientation of the crack plane relative to the interparticle boundaries. Fatigue crack growth resistance and fracture toughness are greater in the L-T, L-S, and T-S directions than in the T-L, S-T, and S-L orientations. The alloy produced by AMD does not exhibit anisotropy in fracture toughness and fatigue crack growth resistance in the as-deposited condition or in the extruded condition. The fracture toughness varies from 17.2 MPa[radical][bar m] to 18.5 MPa[radical][bar m] for the as-deposited condition and from 19.8 MPa[radical][bar m] to 21.0 MPa[radical][bar m] for the extruded condition. Fracture properties are controlled by intrinsic factors in the alloy produced by AMD. Fatigue crack growth rates of the AMD alloy are comparable to those of the PFC alloy in the L-T orientation. The crack propagation modes were studied by optical metallographic examination of crack-microstructure interactions and scanning electron microscopy of the fracture surfaces.

  7. The effect of anti-phase domain size on the ductility of a rapidly solidified Ni3Al-Cr alloy

    NASA Technical Reports Server (NTRS)

    Carro, G.; Bertero, G. A.; Wittig, J. E.; Flanagan, W. F.

    1989-01-01

    Tensile tests on splat-quenched Ni3Al-Cr alloys showed a sharp decrease in ductility with long-time annealing. The growth of the initially very-fine-size anti-phase domains showed a tenuous correlation with ductility up to a critical size, where ductility was lost. The grain size was relatively unaffected by these annealing treatments, but the grain-boundary curvature decreased, implying less toughness. An important observation was that, for the longest annealing time, a chromium-rich precipitate formed, which the data indicate could be a boride. Miniaturized tensile tests were performed on samples which were all obtained from the same splat-quenched foil, and the various domain sizes were controlled by subsequent annealing treatments.

  8. Fatigue crack growth rates and fracture toughness of rapidly solidified Al-8.5 pct Fe-1.2 pct V-1.7 pct Si alloys

    NASA Astrophysics Data System (ADS)

    Hariprasad, S.; Sastry, S. M. L.; Jerina, K. L.; Lederich, R. J.

    1994-05-01

    The room-temperature fatigue crack growth rates (FCGR) and fracture toughness were evaluated for different crack plane orientations of an Al-8.5 Pct Fe-1.2 Pct V-1.7 Pct Si alloy produced by planar flow casting (PFC) and atomized melt deposition (AMD) processes. For the alloy produced by the PFC process, properties were determined in six different orientations, including the short transverse directions S-T and S-L. Diffusion bonding and adhesive bonding methods were used to prepare specimens for determining FCGR and fracture toughness in the short transverse direction. Interparticle boundaries control fracture properties in the alloy produced by PFC. Fracture toughness of the PFC alloy varies from 13.4 MPa√m to 30.8 MPa√m, depending on the orientation of the crack plane relative to the interparticle boundaries. Fatigue crack growth resistance and fracture toughness are greater in the L-T, L-S, and T-S directions than in the T-L, S-T, and S-L orientations. The alloy produced by AMD does not exhibit anisotropy in fracture toughness and fatigue crack growth resistance in the as-deposited condition or in the extruded condition. The fracture toughness varies from 17.2 MPa√m to 18.5 MPa√m for the as-deposited condition and from 19.8 MPa√m to 21.0 MPa√m for the extruded condition. Fracture properties are controlled by intrinsic factors in the alloy produced by AMD. Fatigue crack growth rates of the AMD alloy are comparable to those of the PFC alloy in the L-T orientation. The crack propagation modes were studied by optical metallographic examination of crack-microstructure interactions and scanning electron microscopy of the fracture surfaces.

  9. Immobilization and leaching characteristics of arsenic from cement and/or lime solidified/stabilized spent adsorbent containing arsenic.

    PubMed

    Kundu, Sanghamitra; Gupta, A K

    2008-05-01

    Solidification/stabilization (S/S) of hazardous iron oxide coated cement (IOCC) spent adsorbent containing arsenic (As(III)) was investigated in the present study. Cement and lime-based S/S effectiveness was evaluated by performing semi-dynamic leach tests. The S/S effectiveness was evaluated by measuring effective diffusion coefficients (D(e)) and leachability indices (LX). It was found that though cement or lime alone were efficient in preventing arsenic leaching (D(e) being in range of 10(-10) to 10(-12) for all the matrices) from the solidified matrices, the best combination for arsenic containment in the matrix was obtained when a mixture of cement and lime was used. The LX values for all the matrices were higher than 10, suggesting that the S/S treated arsenic sludge are acceptable for "controlled utilization". Calcite formation along with precipitation and conversion into non-soluble forms (calcium arsenite, calcium hydrogen arsenate hydrates, calcium hydrogen arsenates, etc.) were found to be the responsible mechanism for low leaching of arsenic from the solidified/stabilized samples. A linear relationship between cumulative fraction (CFR) of arsenic leached and square root of leach time (R(2) ranging from 0.90 to 0.94) suggested that the diffusion is the responsible mechanism for arsenic leaching. Thus, cement and lime show effective containment of the As(III) within the matrix thus indicating S/S by cement and lime, which is also a low-cost option, as a suitable management option for the toxic As(III) sludge. PMID:17913352

  10. The effects of artificial ageing on the leaching behaviour of heavy metals in stabilized/solidified industrial sludge.

    PubMed

    Keskes, M; Choura, M; Rouis, J

    2009-12-01

    The use of a hydraulic binder for the treatment of mineral-based industrial wastes, containing heavy metals, by the chemical fixation and solidification (CFS) technique has raised serious questions regarding the prediction of the behaviour of these pollutants in the obtained solid matrix. It seems necessary, for this reason, to study the behaviour of these metals in response to leaching in order to evaluate their chemical speciation within the solidified sludge over the medium and long-terms. Within the framework of the current research, we applied the CFS technique to metallic hydroxide sludge, produced by the electrotyping surface treatment industry, by using Portland artificial cement (PAC). Compaction at the paste phase of this treated sludge resulted in up to 35% enhancement of the retention of pollutants, mainly trivalent chromium, in a cementing matrix, as compared with the classical technique that uses a simple vibration of sludge at the paste phase. The implemented process led to an improvement in the compactness of the sludge, and thus assured a better retention of heavy metals in response to the leaching of this treated sludge. The evaluation of the chemical properties of the materials obtained after an artificial ageing process using humidity variation cycles and thermal chocks also revealed a significant improvement in the retention capacity of heavy metals in the solidified sludge, which was mainly favoured by the development of carbonation. In fact, the release of the heavy metals from the above mentioned treated sludge was reduced by 58% for zinc and 51% for trivalent chromium after the artificial ageing process. PMID:20088205

  11. Solidifying agent and processing of blood used for the larval diet affect screwworm (Diptera: Calliphoridae) life-history parameters.

    PubMed

    Chaudhury, M F; Skoda, S R; Sagel, A

    2011-06-01

    Spray-dried whole bovine blood and a sodium polyacrylate polymer gel as a bulking and solidifying agent are among the constituents of the current larval diet for mass rearing screwworm, Cochliomyia hominivorax (Coquerel) (Diptera: Calliphoridae). Locally available, inexpensive dietary materials could reduce rearing cost and address an uncertain commercial supply of spray-dried blood. We compared efficacy of diet prepared from fresh bovine blood after decoagulation with sodium citrate or ethylenediaminetetraacetic acid (EDTA) or after mechanical defibrination, with the diet containing spray-dried blood using either gel or cellulose fiber as the bulking and solidifying agent. Several life-history parameters were compared among insects reared on each of the blood and bulking agent diets combination. Diets containing citrated blood yielded the lightest larval and pupal weights and fewest pupae. EDTA-treated blood with the gel also caused reductions. EDTA-treated blood with fiber yielded screwworms that were heavier and more numerous than those from the diet with citrated blood but lighter than those from the control diet using spray-dried blood. A reduction in percentage of adults emerging from pupae occurred from diets with both bulking agents using citrated blood and the diet using EDTA mixed with the gel bulking agent. As a group, the cellulose-fiber diets performed better than the gel diets. Larval diet did not affect adult longevity, weight of the eggs deposited by the females that emerged or subsequent egg hatch. Parameter measurements of insects from both defibrinated blood diets were similar to those from the spray-dried blood diets, indicating that fresh, defibrinated bovine blood can successfully replace the dry blood in the screwworm rearing medium. PMID:21735935

  12. Annealing of directionally solidified alloys revisited: No loss of solidification texture in Earth’s inner core

    NASA Astrophysics Data System (ADS)

    Al-Khatatbeh, Yahya; Bergman, Michael I.; Lewis, Daniel J.; Mason, Zachary; Zhu, Laura; Rosenstock, Sarita

    2013-10-01

    Bergman et al. (2010) found experimental evidence for recrystallization and loss of solidification texture during annealing of directionally solidified hexagonal close-packed (hcp) Zn-rich Sn alloys. They suggested that this could support the model of Alboussiere et al. (2010) and Monnereau et al. (2010), in which the Earth’s inner core translates convectively eastwards with enhanced solidification in the western hemisphere and melting in the eastern, because as inner core material translates eastwards and anneals it might lose texture, as inferred seismically. The 2010 study hypothesized that the alloys recrystallized rather than coarsened via diffusion due to the very low solubility of Sn in the Zn-rich phase. This study tests this hypothesis by annealing directionally solidified hcp Zn-rich Al alloys, in which there is greater solubility. Indeed, we find the Zn-rich Al alloys coarsen without recrystallization or fundamental change in texture. However, in contrast to the 2010 study the current study also did not find recrystallization in Zn-rich Sn alloys. This might tend to support models such as those by Cormier (2007) and Aubert et al. (2008) where long term mantle control over fluid flow near the base of the outer core might result in a weaker solidification texture in the eastern hemisphere. Although we do believe the results of the previous study are valid because they were repeatable at that time, it shows that there is something subtle that we cannot yet account for, and it remains unclear whether there is loss of solidification texture due to annealing of Earth’s inner core.

  13. Characterization of Hypereutectic Al-Si Powders Solidified under Far-From Equilibrium Conditions

    SciTech Connect

    Y.E. Kalay; L.S. Chumbley; I.E. Anderson; R.E. Napolitano

    2007-07-01

    The rapid solidification microstructure of gas-atomized Al-Si powders of 15, 18, 25, and 50 wt pct Si were examined using scanning electron microscopy (SEM) and transmission electron microscopy (TEM). In order of increasing particle size, the powders exhibited microcellular Al, cellular/dendritic Al, eutectic Al, and primary Si growth morphologies. Interface velocity and undercooling were estimated from measured eutectic spacing based on the Trivedi-Magnin-Kurz (TMK) model, permitting a direct comparison with theoretical predictions of solidification morphology. Based on our observations, additional conditions for high-undercooling morphological transitions are proposed as an extension of coupled-zone predictions.

  14. PUBLISHER'S NOTE: Rapid Communications Rapid Communications

    NASA Astrophysics Data System (ADS)

    Miller, Tom

    2009-09-01

    As part of a general review of Superconductor Science and Technology, we have been examining the scope for Rapid Communications (RAPs). We recognize these articles make up an important part of the journal representing the latest state-of-the-art research in superconductivity. To reflect this, we have devised a new scope for this article type: 'Rapid Communications. The journal offers open access to outstanding short articles (no longer than 5 journal pages or 4500 words including figures) reporting new and timely developments in superconductivity and its applications. These articles should report very substantial new advances in superconductivity to the readers of Superconductor Science and Technology, but are not expected to meet any requirement of 'general interest'. RAPs will be processed quickly (average receipt to online publication for RAPs is around 60 days) and are permanently free to read in the electronic journal. Authors submitting a RAP should provide reasons why the work is urgent and requires rapid publication. Each RAP will be assessed for suitability by our Reviews and Rapid Communications Editor before full peer review takes place.' The essential points are: They should report very substantial new advances in superconductivity and its application; They must be no longer than 5 journal pages long (approx. 4500 words); Average publication time for a Rapid Communication is 60 days; They are free to read. As mentioned in the previous publisher's announcement (2009 Supercond. Sci. Technol. 22 010101), each submitted Rapid Communication must come with a letter justifying why it should be prioritized over regular papers and will be pre-assessed by our Reviews and Rapid Communications Editor. In addition, we will work with the authors of any Rapid Communication to promote and raise the visibility of the work presented in it. We will be making further changes to the journal in the near future and we write to you accordingly. Thank you for your kind

  15. Ligandless, ion pair-based and ultrasound assisted emulsification solidified floating organic drop microextraction for simultaneous preconcentration of ultra-trace amounts of gold and thallium and determination by GFAAS.

    PubMed

    Fazelirad, Hamid; Taher, Mohammad Ali

    2013-01-15

    In the present work, a new, simple and efficient method for simultaneous preconcentration of ultra-trace amounts of gold and thallium is developed using an ion pair based-ultrasound assisted emulsification-solidified floating organic drop microextraction procedure before graphite furnace atomic absorption spectrometry determination. This methodology was used to preconcentrate the ion pairs formed between AuCl(4)(-) and TlCl(4)(-) and [C(23)H(42)]N(+) in a microliter-range volume of 1-undecanol. Several factors affecting the microextraction efficiency, such as HCl volume, type and volume of extraction solvent, sonication time, sample volume, temperature, ionic strength and [C(23)H(42)]NCl volume were investigated and optimized. Under the optimized conditions, the enrichment factor of 441 and 443 and calibration graphs of 2.2-89 and 22.2-667 ng L(-1) for gold and thallium were obtained, respectively. The intra- and inter-day precision of ± 4.4 and ± 4.9% for Au and ± 4.8 and ± 5.4% for Tl were obtained. The detection limit was 0.66 ng L(-1) for Au and 4.67 ng L(-1) for Tl. The results show that the liquid-liquid pretreatment using ion pair forming, is sensitive, rapid, simple and safe method for the simultaneous preconcentration of gold and thallium. The method was successfully applied for determination of gold and thallium in natural water and hair samples. PMID:23200402

  16. A novel extraction method for β-carotene and other carotenoids in fruit juices using air-assisted, low-density solvent-based liquid-liquid microextraction and solidified floating organic droplets.

    PubMed

    Sricharoen, Phitchan; Limchoowong, Nunticha; Techawongstien, Suchila; Chanthai, Saksit

    2016-07-15

    Green extraction using air-assisted, low-density solvent-based liquid-liquid microextraction and solidified floating organic droplets (AA-LDS-LLME-SFOD) prior to spectrophotometry was successfully applied for quantitation of carotenoids in fruit juices. Under optimal conditions, β-carotene could be quantified with a linear response up to a concentration of 60 μg mL(-1). The procedure was performed in a microcentrifuge tube with 40 μL of 1-dodecanol as the extraction solvent and a 1.0 mL juice sample containing 8% NaCl under seven extraction cycles of air pumping by syringe. This method was validated based on linearity (0.2-30 μg mL(-1), R(2) 0.998), limit of detection (0.04 μg mL(-1)) and limit of quantification (0.13 μg mL(-1)). The precision, expressed as the relative standard deviation (RSD) of the calibration curve slope (n=12), for inter-day and intra-day analysis was 4.85% and 7.92%, respectively. Recovery of β-carotene was in the range of 93.6-101.5%. The newly proposed method is simple, rapid and environmentally friendly, particularly as a useful screening test for food analysis. PMID:26948629

  17. Laser rapid manufacturing of special pattern Inco 718 nickel-based alloy component

    NASA Astrophysics Data System (ADS)

    Zhong, Minlin; Yang, Lin; Liu, Wenjin; Huang, Ting; He, Jingjiang

    2005-01-01

    Laser rapid manufacturing based on laser cladding is a novel layer additive manufacturing technology, which can be well used for producing specific material, geometry and properties components normally unavailable or very costly by conventional methods. This paper presents a project research work on laser rapid manufacturing of special pattern Inco 718 nickel based alloy component with special pattern for aeronautical application. The required pattern Inco 718 nickel based alloy component was manufactured directly by laser deposition with optimized parameters: laser power: 800W, laser beam diameter: 0.8 mm, scanning speed: 0.5 m/min, powder feeding rate: 3g/min; The basic microstructure of laser deposited sample is directionally solidified columnar structure, with metallurgical bound to the substrate. Laser deposited component has good metallurgical and compositional and hardness homogeneity. The average hardness is about Hv0.2 440. The tensile strength of the laser deposited Inco 718 sample is respectively 121 and 116 kgf/mm2 at room temperature and at 650°C, which are a little bit less than the data of forged Inco 718 plate 142 and 127 kgf/mm2 due to its directional solidified columnar structure perpendicular to the tensile test force.

  18. Curvature effects in rapid alloy solidification

    NASA Astrophysics Data System (ADS)

    Conti, Massimo

    2001-04-01

    The growth of a cylindrical or spherical crystal into its undercooled melt is a process whose description is complicated by the lack of a stationary regime. A simple approach to the problem, justified for low growth rates and widely used in the past for both pure substances and alloy solidification, is based on a quasistatic approximation which assumes an instantaneous adaptation of the diffusional field to the interface configuration. For alloy solidification, assuming isothermal conditions and local interface equilibrium, this simplified model predicts a diffusion controlled growth, with the radius of the crystal increasing asymptotically as ~t1/2. However, as pointed out by recent investigations, thermal diffusion and nonequilibrium effects enter as essential ingredients in rapid alloy solidification. In the present paper we use the phase-field model to simulate the cylindrical and spherical growth of a solid germ into a supersaturated alloy melt. The problem is treated in its full time-dependent characteristics, accounting for nonequilibrium effects as well as for the rejection of both heat and solute away from the advancing front. We observe a complex behavior and a rich variety of dynamic regimes: in different regions of parameter space the growth rate is limited by diffusion (either thermal or chemical) or is kinetic controlled. Traversing the boundaries which limit these regions, the process undergoes sharp transitions which leave a trace in the solidified alloy. For realistic values of the Lewis number, thermal effects drive the process into a a diffusive regime, in which the rate limiting mechanism is the rejection of solute.

  19. Dentritic morphology and microsegregation in directionally solidified superalloy, PWA-1480, single crystal: Effect of gravity; center director's discretionary fund report

    NASA Technical Reports Server (NTRS)

    Tewari, S. N.; Kumar, M. Vijaya; Lee, J. E.; Curreri, P. A.

    1990-01-01

    Primary dendrite spacings, secondary dendrite spacings, and microsegregation have been examined in PWA-1480 single crystal specimens which were directionally solidified during parabolic maneuvers on the KC-135 aircraft. Experimentally observed growth rate and thermal gradient dependence of primary dendrite spacings are in good agreement with predictions from dendrite growth models for binary alloys. Secondary dendrite coarsening kinetics show a reasonable fit with the predictions from an analytical model proposed by Kirkwood for a binary alloy. The partition coefficients of tantalum, titanium, and aluminum are observed to be less than unity, while that for tungsten and cobalt are greater than unity. This is qualitatively similar to the nickel base binaries. Microsegregation profiles experimentally observed for PWA-1480 superalloy show a good fit with Bower, Brody, and Flemings model developed for binary alloys. Transitions in gravity levels do not appear to affect primary dendrite spacings. A trend of decreased secondary arm spacings with transition from high gravity to the low gravity period was observed at a growth speed of 0.023 cm s(exp -1). However, definite conclusions can only be drawn by experiments at lower growth speeds which make it possible to examine the side-branch coarsening kinetics over a longer duration. Such experiments, not possible due to the insufficient low-gravity time of the KC-135, may be carried out in the low-gravity environment of space.

  20. Changes in speciation and leaching behaviors of heavy metals in dredged sediment solidified/stabilized with various materials.

    PubMed

    Bao, Jianping; Wang, Liang; Xiao, Man

    2016-05-01

    Solidification/stabilization (S/S) of sediments is frequently used to treat contaminants in dredged sediments. In this study, sediment collected from the Pearl River Delta (China) was solidified/stabilized with three different kinds of functional materials: cement, lime and bentonite. Lime primarily acted via induced increases in pH, while cements stabilization occurred through their silicate-based systems and the main function of bentonite was adsorption. The speciation and leaching behaviors of specific heavy metals before and after S/S were analyzed and the results showed that the residual speciation of Cd, Cr, Ni, Pb and Zn increased in all treatments except for Cu, as the exchangeable speciation, carbonate-bound speciation and Fe-Mn-oxide-bound speciation of Cu (all of which could be stabilized) were less than 2 % of the total amount. Pb leaching only decreased when pH increased, while the mobility of Cr and Ni only decreased in response to the silicate-based systems. The leached portion of the Fe-Mn-oxide-bound speciation followed the order Zn > Cu > Ni/Cd > Pb > Cr. The leached portion of organic-matter-bound species was less than 4 % for Cd, Cr, Ni and Pb, but 35.1 % and 20.6 % for Cu and Zn, respectively. PMID:26846241

  1. Long-term leaching behavior of phenol in cement/activated-carbon solidified/stabilized hazardous waste.

    PubMed

    Liu, Jianguo; Nie, Xiaoqin; Zeng, Xianwei; Su, Zhaoji

    2013-01-30

    The long-term leaching behavior of phenol in solidified/stabilized (S/S) hazardous wastes cured for 28 d with different amounts of activated carbon (AC) was investigated using synthetic inorganic acid (H(2)SO(4):HNO(3) = 2:1, pH = 3.2), acetic acid buffer (HAc/NaAc, pH = 4.93), and deionized water as leachants to simulate the leaching of phenol in three exposure scenarios: acid-precipitation, co-disposal, and neutral-precipitation. Phenol immobilization was enhanced by AC adsorption and impaired by the growth of micropores with increasing amount of AC; thus the optimal added amount of AC to be to added S/S wastes was 2%. The leaching behavior of phenol in co-disposal scenario was unpredictable due to inadequate ionization of HAc in the HAc-NaAc buffer solution. The findings indicated that S/S products should be disposed of in hazardous waste landfills rather than municipal solid waste landfills. PMID:23270892

  2. Influence of growth direction on the microstructure of unidirectionally solidified Cu Pb monotectic alloy using zone-melt technique

    NASA Astrophysics Data System (ADS)

    Aoi, Ichiro; Ishino, Makoto; Yoshida, Makoto; Fukunaga, Hideharu; Nakae, Hideo

    2001-02-01

    The influence of growth direction on the monotectic structure of the Cu-Pb alloy is studied. In order to examine the influence under a 1 g environment, both the upward (opposite to the direction of gravity) and downward (the direction of gravity) unidirectional solidifications (UDS) are carried out. In the case of the upward UDS, a banded structure, which consists of Pb-rich and Cu-rich layers, is observed. The L 2 droplets pile up in front of the solid/liquid interface. On the other hand, in the downward UDS, the irregularly shaped L 2 phase uniformly disperses in the specimen and no banded structure is found. The gravity macrosegregation of the L 2 liquid is observed at the bottom of the molten alloy in the downward solidified specimen. This is caused by the difference in the density between the L 1 and L 2 phases. Furthermore, a mechanism for the formation of a banded structure is suggested. This mechanism suggests that the coalesced L 2 phase covers the solid/liquid interface by producing a Pb-rich layer that permits an increase in the undercooling of the L 1/L 2 interface compared to the monotectic temperature. As nucleation of the α-Cu phase occurs on the Pb-rich layer, the coexisting three phases are then restored. The temperature at the growth front is also returned to the monotectic temperature. The repetition mentioned above will result in the banded structure found in the upward UDS.

  3. On morphologies, microsegregation, and mechanical behavior of directionally solidified cobalt-base superalloy at medium cooling rate

    NASA Astrophysics Data System (ADS)

    Chu, Shuangjie; Li, Jianguo; Liu, Zhongyuan; Shi, Zhengxing; Fu, Hengzhi

    1994-03-01

    A newly developed experimental setup that can provide a temperature gradient of 1300 K/cm has been used in the research of the morphologies, microsegregation, and mechanical behavior of directionally solidified cobalt-base superalloy (known as K10 in PR China) at medium cooling rates from 38 to 60 K/s. Experimental results show that the primary and secondary dendrite spacings of K10 become less than one-fifth and one-eighth, respectively, of those obtainable with a conventional 100 K/cm temperature gradient and a cooling rate below 1 K/s: the carbides are directionally arrayed and the carbides’ morphology changes from islands of general cast state into worms; microsegregation is almost completely eliminated; the mechanical properties, as can be expected, are greatly superior to those obtainable with 100 K/cm temperature gradient; at 1073 K, creep-rupture strength increases from 167 to 196 MPa; endurance life is raised from 10 to 30 hours; the reduction in area increases from 12 to 52 pct; and the specific elongation increases from 17 to 46 pct. And with the increase of cooling rate, there are always corresponding improvements of mechanical properties of K10. Otherwise, the fractography of superfine columnar structure samples is high-toughness transgranular fracture, with cracks originating at the edge of carbides.

  4. Thermal-expansion behavior of a directionally solidified NiAl-Mo composite investigated by neutron diffraction and dilatometry

    SciTech Connect

    Bei, H.; George, E.P.; Brown, D.W.; Pharr, G.M.; Choo, H.; Porter, W.D.; Bourke, M.A.M.

    2005-06-15

    The thermal expansion of directionally solidified NiAl-Mo eutectic alloys consisting of nanoscale Mo fibers embedded in a NiAl matrix was analyzed by neutron diffraction and dilatometry. From room temperature to 800 deg. C, perpendicular to the fiber direction, the NiAl and Mo phases expand independently with average coefficients of thermal expansion (CTEs) of 16.0x10{sup -6} deg. C{sup -1} and 5.8x10{sup -6} deg. C{sup -1}, respectively. Parallel to the fiber direction, they coexpand up to 650 deg. C with an average CTE of 12.8x10{sup -6} deg. C{sup -1}, but above this temperature the Mo fibers expand more than the NiAl matrix. This anomalous behavior is the result of the load transfer to the Mo fibers when the NiAl matrix softens. The average CTE of the composite parallel to the fiber direction was determined by dilatometry to be 13.0x10{sup -6} deg. C{sup -1}, which is approximately 11% lower than the value predicted by a simple rule of mixtures using the CTEs of the constituent phases.

  5. Development of two rhenium- containing superalloys for single- crystal blade and directionally solidified vane applications in advanced turbine engines

    NASA Astrophysics Data System (ADS)

    Harris, K.; Erickson, G. L.; Sikkenga, S. L.; Brentnall, W. D.; Aurrecoechea, J. M.; Kubarych, K. G.

    1993-08-01

    A team approach involving several turbine engine companies using the concepts of simultaneous engi-neering has been used to successfully develop CMSX-4 ® alloy for turbine blade applications. CMSX-4 al-loy is a second-generation, single-crystal cast nickel-base superalloy containing 3% Re and approximately 70% volume fraction of γ. The high level of balanced properties determined by labora-tory evaluation has been confirmed during field testing of the Solarγ Mars T-14000 industrial gas turbine with CMSX-4 single-crystal (SX) blades in both the coated and bare condition. A similar collaborative ap-proach has resulted in the successful development of CM 186 LCγ alloy for complex, directionally solidi-fied (DS) columnar grain vane segments. CM 186 LC alloy is a second-generation DS columnar grain cast nickel-base superalloy containing 3% Re and approximately 65% volume fraction of γ. Excellent com-ponent producibility and quality is demonstrated. Turbine engine testing is scheduled to commence by the end of 1993.

  6. Effect of Growth Rate on the Microstructure and Microhardness in a Directionally Solidified Al-Zn-Mg Alloy

    NASA Astrophysics Data System (ADS)

    Acer, Emine; Çadırlı, Emin; Erol, Harun; Gündüz, Mehmet

    2016-06-01

    The Al-5.5Zn-2.5Mg (wt pct) ternary alloy was prepared using a vacuum melting furnace and a casting furnace. Five samples were directionally solidified upwards at a constant temperature gradient ( G = 5.5 K/mm) under different growth rates ( V = 8.3-165 μm/s) in a Bridgman-type directional solidification furnace. The primary dendrite arm spacing, λ 1, secondary dendrite arm spacing, λ 2, and microhardness, HV, of the samples were measured. The effects of V on λ 1, λ 2 and HV properties of the Al-Zn-Mg alloy were studied by microstructure analysis and mechanical characterization. Microstructure characterization of the alloys was carried out using optical microscopy, scanning electron microscopy, wavelength-dispersive X-ray fluorescence spectrometry, and energy dispersive X-ray spectroscopy. From the experimental results, it is found that the λ 1, λ 2 values decrease, but HV values increase with the increase in V, and HV values decrease with the increase in λ 1 and λ 2. Dependencies of dendritic spacing and microhardness on the growth rate were determined using linear regression analysis. The growth rate, microstructure, and Hall-Petch-type relationships obtained in this work have been compared with the results of previous studies.

  7. Microstructural characterization of Ti-44Al-11Nb in the chill-cast and directionally solidified configurations

    SciTech Connect

    Halladay, T.R.

    1998-12-01

    The microstructural evolution in chill-cast and directionally solidified Ti-44Al-11Nb (at.%) was studied by x-ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM) methods. From this data, the microstructural distribution and formation sequences of various phases like Al3Ti, TiAl, and Ti3Al were established. The elemental and phase distributions were determined by TEM with energy dispersive x-ray spectroscopy (EDX) and spectrum imaging. Both casting techniques produced the same phases, (Al3Ti, TiAl, and Ti3Al with some Nb in solid solution), but the microstructural distribution was markedly different. The chill-casting technique resulted in a coarser microstructure, with large gamma crystals and duplex regions of either (gamma + alpha2) or (gamma + Al3Ti) interspersed throughout the alloy. The directional solidification technique resulted in a much more uniform microstructure with fine lamellar grains in a dendritic macrostructure. Both casting techniques showed enrichment of niobium in interdendritic regions.

  8. Magnetic and metallurgical properties of directionally solidified eutectic Bi/MnBi composites - The effects of annealing. [in low gravity

    NASA Technical Reports Server (NTRS)

    Pirich, R. G.; Larson, D. J., Jr.

    1979-01-01

    Eutectic Bi/MnBi (97.8 a/o Bi) samples have been plane-front directionally solidified. The resultant microstructures consist of elongated, aligned particles of MnBi dispersed in a Bi-matrix. Magnetization as a function of temperature (4.2 to 300 K) and applied field (up to 220 kG) has been used to evaluate solidification parameters and magnetic properties. At room temperature, in addition to the diamagnetic contribution of Bi, one finds a superposition of the ferromagnetic, low temperature (LTP) MnBi phase and paramagnetic phases. At cryogenic temperatures, one of the room temperature paramagnetic phases is ferromagnetic with an intrinsic coercivity of 120 kOe while the other remains paramagnetic for low fields and orders ferromagnetically at high fields in a complicated way. Annealing of as-grown samples was found to produce significant changes in magnetic properties. The origins of the paramagnetic phases and their relation to the mechanisms which control the coercive field of the hard magnetic LTP MnBi phase are discussed.

  9. Temperature-dependent phase-specific deformation mechanisms in a directionally solidified NiAl-Cr(Mo) lamellar composite

    DOE PAGESBeta

    Yu, Dunji; An, Ke; Chen, Xu; Bei, Hongbin

    2015-10-09

    Phase-specific thermal expansion and mechanical deformation behaviors of a directionally solidified NiAl–Cr(Mo) lamellar in situ composite were investigated by using real-time in situ neutron diffraction during compression at elevated temperatures up to 800 °C. Tensile and compressive thermal residual stresses were found to exist in the NiAl phase and Crss (solid solution) phase, respectively. Then, based on the evolution of lattice spacings and phase stresses, the phase-specific deformation behavior was analyzed qualitatively and quantitatively. Moreover, estimates of phase stresses were derived by Hooke's law on the basis of a simple method for the determination of stress-free lattice spacing in inmore » situ composites. During compressive loading, the NiAl phase yields earlier than the Crss phase. The Crss phase carries much higher stress than the NiAl phase, and displays consistent strain hardening at all temperatures. The NiAl phase exhibits strain hardening at relatively low temperatures and softening at high temperatures. During unloading, the NiAl phase yields in tension whereas the Crss phase unloads elastically. Additionally, post-test microstructural observations show phase-through cracks at room temperature, micro cracks along phase interfaces at 600 °C and intact lamellae kinks at 800 °C, which is due to the increasing deformability of both phases as temperature rises.« less

  10. Hydrodynamic alignment and assembly of nano-fibrillated cellulose in the laminar extensional flow: Effects of solidifying agents

    NASA Astrophysics Data System (ADS)

    Mittal, Nitesh; Lundell, Fredrik; Soderberg, Daniel

    2015-11-01

    There are several fiber production technologies that are based on wet-spinning processes. Many such processes rely on the transformation of a liquid solution into a solid filament. The kinetics of solidification depends largely on the diffusion of the solvents, additives and polymer molecules, which make such systems quite complex and differ from a system to another as a function of the specific chemical, physical and structural features of the used material components. Moreover, tuning the orientation of the polymers in the liquid suspensions makes it further possible to control their structure, which in turn can lead to materials having improved properties. By keeping in mind the facts mentioned above, the aim of the current study is to utilize benefits of a flow focusing approach to align carboxymethylated cellulose nanofibrils (CNF), as a colloidal dispersion, with the help of a laminar elongational flow-field followed by the solidification using different solidifying agents or molecules (with dissimilar diffusion behavior based on their size and charges) to synthesize fibers with enhanced mechanical properties. CNF are charged elongated particles obtained from woods with diameter of 4-10 nm and length of 1-1.5 μm, and they are completely biodegradable.

  11. Room-temperature deformation behavior of a directionally solidified {beta} (B2)-(Ni-Fe-Al) intermetallic alloy

    SciTech Connect

    Misra, A.; Kim, J.T.; Gibala, R.

    1997-01-01

    The room-temperature mechanical behavior of a directionally solidified columnar-grained, single-phase {beta} (B2)-(Ni-20 at. pct Fe-30 At. pct Al) intermetallic alloy deformed along the hard {l_angle}001{r_angle} direction has been characterized. The 0.2 pct offset compressive yield stress was found to be comparable to that of {l_angle}001{r_angle} single crystals of stoichiometric NiAl. The dislocation substructure consisted of a preponderance of long, straight a{l_angle}111{r_angle} screw dislocations on {l_brace}112{r_brace} planes, with cross-slip on {l_brace}123{r_brace} and {l_brace}110{r_brace} planes. The superpartials were not resolved by weak-beam imaging conditions, indicating that the antiphase boundary (APB) energy of NiAl is not reduced significantly by the Fe addition. The dislocation substructure was analyzed as a function of strain and compared to the dislocation substructure in {l_angle}001{r_angle} NiAl and body-centered cubic (bcc) metals deformed at low homologous temperatures. The debris left behind by a{l_angle}111{r_angle} screw dislocations consisted of prismatic edge dipole loops 5 to 25 nm in diameter.

  12. Determination of molybdenum in plants by vortex-assisted emulsification solidified floating organic drop microextraction and flame atomic absorption spectrometry

    NASA Astrophysics Data System (ADS)

    Oviedo, Jenny A.; Fialho, Lucimar L.; Nóbrega, Joaquim A.

    2013-08-01

    A fast and sensitive procedure for extraction and preconcentration of molybdenum in plant samples based on solidified floating organic drop microextraction combined with flame atomic absorption spectrometry and discrete nebulization was developed. 8-Hydroxyquinoline (8-HQ) was used as complexing agent. The experimental conditions established were: 0.5% m v- 1 of 8-HQ, 60 μL of 1-undecanol as the extractant phase, 2 min vortex extraction time, centrifugation for 2 min at 2000 rpm, 10 min into an ice bath and discrete nebulization by introducing 200 μL of solution. The calibration curve was linear from 0.02 to 4.0 mg L- 1 with a limit of detection of 4.9 μg L- 1 and an enhancement factor of 67. The relative standard deviations for ten replicate measurements of 0.05 and 1.0 mg L- 1 Mo were 6.0 and 14.5%, respectively. The developed procedure was applied for determining molybdenum in corn samples and accuracy was proved using certified reference materials.

  13. APS TBC performance on directionally-solidified superalloy substrates with HVOF NiCoCrAlYHfSi bond coatings

    DOE PAGESBeta

    Lance, Michael J.; Unocic, Kinga A.; Haynes, James A.; Pint, Bruce A.

    2015-09-04

    Directionally-solidified (DS) superalloy components with advanced thermal barrier coatings (TBC) to lower the metal operating temperature have the potential to replace more expensive single crystal superalloys for large land-based turbines. In order to assess relative TBC performance, furnace cyclic testing was used with superalloys 1483, X4 and Hf-rich DS 247 substrates and high velocity oxygen fuel (HVOF)-NiCoCrAlYHfSi bond coatings at 1100 °C with 1-h cycles in air with 10% H2O. With these coating and test conditions, there was no statistically-significant effect of substrate alloy on the average lifetime of the air plasma sprayed (APS) yttria-stabilized zirconia (YSZ) top coatings onmore » small coupons. Using photo-stimulated luminescence piezospectroscopy maps at regular cycling intervals, the residual compressive stress in the α-Al2O3 scale underneath the YSZ top coating and on a bare bond coating was similar for all three substrates and delaminations occurred at roughly the same rate and frequency. As a result, x-ray fluorescence (XRF) measurements collected from the bare bond coating surface revealed higher Ti interdiffusion occurring with the 1483 substrate, which contained the highest Ti content.« less

  14. APS TBC performance on directionally-solidified superalloy substrates with HVOF NiCoCrAlYHfSi bond coatings

    SciTech Connect

    Lance, Michael J.; Unocic, Kinga A.; Haynes, James A.; Pint, Bruce A.

    2015-09-04

    Directionally-solidified (DS) superalloy components with advanced thermal barrier coatings (TBC) to lower the metal operating temperature have the potential to replace more expensive single crystal superalloys for large land-based turbines. In order to assess relative TBC performance, furnace cyclic testing was used with superalloys 1483, X4 and Hf-rich DS 247 substrates and high velocity oxygen fuel (HVOF)-NiCoCrAlYHfSi bond coatings at 1100 °C with 1-h cycles in air with 10% H2O. With these coating and test conditions, there was no statistically-significant effect of substrate alloy on the average lifetime of the air plasma sprayed (APS) yttria-stabilized zirconia (YSZ) top coatings on small coupons. Using photo-stimulated luminescence piezospectroscopy maps at regular cycling intervals, the residual compressive stress in the α-Al2O3 scale underneath the YSZ top coating and on a bare bond coating was similar for all three substrates and delaminations occurred at roughly the same rate and frequency. As a result, x-ray fluorescence (XRF) measurements collected from the bare bond coating surface revealed higher Ti interdiffusion occurring with the 1483 substrate, which contained the highest Ti content.

  15. Effects of rhenium alloying on the microstructures and mechanical properties of directionally solidified NiAl-Mo eutectic alloy

    SciTech Connect

    Misra, A.; Wu, Z.L.; Gibala, R.

    1997-12-31

    Low ductility of the reinforcing bcc metal phase at room temperature and weak interfaces can limit the intrinsic toughness and ductility of NiAl-bcc metal eutectic composites. The potential of rhenium (Re) addition, which is known to solid solution soften and lower the ductile-to-brittle transition temperature of various bcc metals, to enhance the ductility and toughness of a directionally solidified NiAl-9 at.% Mo eutectic alloy was investigated. Re partitioned to the bcc metal phase and formed a substitutional solid solution. The interface morphology was changed from a faceted to a non-faceted one. Re alloying caused softening of the Mo fibers, and as a result NiAl-Mo(Re) alloys were softer in compression and flexure and had {approximately}20% higher fracture toughness values as compared to the transverse orientation toughness of NiAl-9Mo alloy. The toughness of the NiAl-Mo(Re) alloys was lower than the longitudinal orientation toughness of the NiAl-9Mo alloy due to the poor alignment of the Mo(Re) phase with the growth direction. The toughening mechanisms have been evaluated and schemes for processing NiAl-Mo(Re) alloys for higher toughness in the longitudinal orientation are suggested. The role of the residual interstitial impurities and partitioning of Ni and Al to Mo fibers on the mechanical properties are highlighted.

  16. Detachment of secondary dendrite arm in a directionally solidified Sn-Ni peritectic alloy under deceleration growth condition

    NASA Astrophysics Data System (ADS)

    Peng, Peng; Li, Xinzhong; Li, Jiangong; Su, Yanqing; Guo, Jingjie; Fu, Hengzhi

    2016-06-01

    In order to better understand the detachment mechanism of secondary dendrite arm during peritectic solidification, the detachment of secondary dendrite arm from the primary dendrite arms in directionally solidified Sn-36at.%Ni peritectic alloys is investigated at different deceleration rates. Extensive detachment of secondary dendrite arms from primary stem is observed below peritectic reaction temperature TP. And an analytical model is established to characterize the detachment process in terms of the secondary dendrite arm spacing λ2, the root radius of detached arms and the specific surface area (SV) of dendrites. It is found that the detachment mechanism is caused by not only curvature difference between the tips and roots of secondary branches, but also that between the thicker secondary branches and the thinner ones. Besides, this detachment process is significantly accelerated by the temperature gradient zone melting (TGZM) effect during peritectic solidification. It is demonstrated that the reaction constant (f) which is used to characterize the kinetics of peritectic reaction is crucial for the determination of the detachment process. The value of f not only changes with growth rate but also with solidification time at a given deceleration rate. In conclusion, these findings help the better understanding of the detachment mechanism.

  17. Detachment of secondary dendrite arm in a directionally solidified Sn-Ni peritectic alloy under deceleration growth condition

    PubMed Central

    Peng, Peng; Li, Xinzhong; Li, Jiangong; Su, Yanqing; Guo, Jingjie; Fu, Hengzhi

    2016-01-01

    In order to better understand the detachment mechanism of secondary dendrite arm during peritectic solidification, the detachment of secondary dendrite arm from the primary dendrite arms in directionally solidified Sn-36at.%Ni peritectic alloys is investigated at different deceleration rates. Extensive detachment of secondary dendrite arms from primary stem is observed below peritectic reaction temperature TP. And an analytical model is established to characterize the detachment process in terms of the secondary dendrite arm spacing λ2, the root radius of detached arms and the specific surface area (SV) of dendrites. It is found that the detachment mechanism is caused by not only curvature difference between the tips and roots of secondary branches, but also that between the thicker secondary branches and the thinner ones. Besides, this detachment process is significantly accelerated by the temperature gradient zone melting (TGZM) effect during peritectic solidification. It is demonstrated that the reaction constant (f) which is used to characterize the kinetics of peritectic reaction is crucial for the determination of the detachment process. The value of f not only changes with growth rate but also with solidification time at a given deceleration rate. In conclusion, these findings help the better understanding of the detachment mechanism. PMID:27270334

  18. Temperature-dependent phase-specific deformation mechanisms in a directionally solidified NiAl-Cr(Mo) lamellar composite

    SciTech Connect

    Yu, Dunji; An, Ke; Chen, Xu; Bei, Hongbin

    2015-10-09

    Phase-specific thermal expansion and mechanical deformation behaviors of a directionally solidified NiAl–Cr(Mo) lamellar in situ composite were investigated by using real-time in situ neutron diffraction during compression at elevated temperatures up to 800 °C. Tensile and compressive thermal residual stresses were found to exist in the NiAl phase and Crss (solid solution) phase, respectively. Then, based on the evolution of lattice spacings and phase stresses, the phase-specific deformation behavior was analyzed qualitatively and quantitatively. Moreover, estimates of phase stresses were derived by Hooke's law on the basis of a simple method for the determination of stress-free lattice spacing in in situ composites. During compressive loading, the NiAl phase yields earlier than the Crss phase. The Crss phase carries much higher stress than the NiAl phase, and displays consistent strain hardening at all temperatures. The NiAl phase exhibits strain hardening at relatively low temperatures and softening at high temperatures. During unloading, the NiAl phase yields in tension whereas the Crss phase unloads elastically. Additionally, post-test microstructural observations show phase-through cracks at room temperature, micro cracks along phase interfaces at 600 °C and intact lamellae kinks at 800 °C, which is due to the increasing deformability of both phases as temperature rises.

  19. Orientation Selection and Microstructural Evolution in Directionally Solidified Tb0.3Dy0.7Fe1.95

    NASA Astrophysics Data System (ADS)

    Palit, Mithun; Banumathy, S.; Singh, A. K.; Pandian, S.; Chattopadhyay, Kamanio

    2016-04-01

    Tb0.3Dy0.7Fe1.95 alloy was directionally solidified by using a modified Bridgman technique at a wide range of growth rates of 5 to 100 cm/h. The directionally grown samples exhibited plane front solidification morphology up to a growth rate of 90 cm/h. Typical island banding feature was observed closer to the chilled end, which eventually gave rise to irregular peritectic coupled growth (PCG). The PCG gained prominence with an increase in the growth rate. The texture study revealed formation of strong <311> texture in a lower growth rate regime, <110> and "rotated <110>" in an intermediate growth regime, and <112> in a higher growth rate regime. In-depth analysis of the atomic configuration of a solid-liquid interface revealed that the growth texture is influenced by the kinetics of atomic attachment to the solid-liquid interface, which is intimately related to a planar packing fraction and an atomic stacking sequence of the interfacial plane. The mechanism proposed in this article is novel and will be useful in addressing the orientation selection mechanism of topologically closed packed intermetallic systems. The samples grown at a higher growth rate exhibit larger magnetostriction ( λ) and dλ/dH owing to the absence of pro-peritectic (Tb,Dy)Fe3 and formation of <112> texture, which lies closer to the easy magnetization direction (EMD).

  20. Detachment of secondary dendrite arm in a directionally solidified Sn-Ni peritectic alloy under deceleration growth condition.

    PubMed

    Peng, Peng; Li, Xinzhong; Li, Jiangong; Su, Yanqing; Guo, Jingjie; Fu, Hengzhi

    2016-01-01

    In order to better understand the detachment mechanism of secondary dendrite arm during peritectic solidification, the detachment of secondary dendrite arm from the primary dendrite arms in directionally solidified Sn-36at.%Ni peritectic alloys is investigated at different deceleration rates. Extensive detachment of secondary dendrite arms from primary stem is observed below peritectic reaction temperature TP. And an analytical model is established to characterize the detachment process in terms of the secondary dendrite arm spacing λ2, the root radius of detached arms and the specific surface area (SV) of dendrites. It is found that the detachment mechanism is caused by not only curvature difference between the tips and roots of secondary branches, but also that between the thicker secondary branches and the thinner ones. Besides, this detachment process is significantly accelerated by the temperature gradient zone melting (TGZM) effect during peritectic solidification. It is demonstrated that the reaction constant (f) which is used to characterize the kinetics of peritectic reaction is crucial for the determination of the detachment process. The value of f not only changes with growth rate but also with solidification time at a given deceleration rate. In conclusion, these findings help the better understanding of the detachment mechanism. PMID:27270334

  1. Quasi-dynamic leaching characteristics of polychlorinated dibenzo-p-dioxins and dibenzofurans from raw and solidified waste incineration residues.

    PubMed

    Hsi, Hsing-Cheng; Wang, Lin-Chi; Yu, Tsung-Hsien; Chang-Chien, Guo-Ping

    2008-03-01

    Quasi-dynamic leaching characteristics of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) from raw and solidified air pollution control (APC) residues were examined via a nine-time multiple leaching test. The effect of injected activated carbon in the APC residues on the PCDD/F leachability was also evaluated. When humic acid solution was used as a leachant, the leaching concentrations of PCDD/Fs fluctuated between the first and the fifth leaching, followed by a gradual increase and then suddenly reached maximum values at the leaching sequences around seventh and eighth. This significant enhancement in PCDD/F leachability was mainly due to an increase in the release of highly chlorinated PCDD/Fs. Leaching of PCDD/Fs with n-hexane was, in contrast, primarily caused by the partitioning of hydrophobic PCDD/Fs between the APC residue surface and the liquid phase of n-hexane. Consequently, the largest leaching concentrations for n-hexane tests achieved at the first leaching, followed by a decrease and reached plateaus. Solidification/stabilization (S/S) decreased the PCDD/F leachability up to the fifth leaching by the use of humic acid solution. However, S/S increased the PCDD/F leaching concentrations and rates with n-hexane. The activated carbon in APC residues significantly inhibited the release of PCDD/F with n-hexane. The inhibiting effect provided by activated carbon was, however, less significant by the use of humic acid solution. PMID:18028984

  2. High rate of N2 fixation by East Siberian cryophilic soil bacteria as determined by measuring acetylene reduction in nitrogen-poor medium solidified with gellan gum.

    PubMed

    Hara, Shintaro; Hashidoko, Yasuyuki; Desyatkin, Roman V; Hatano, Ryusuke; Tahara, Satoshi

    2009-05-01

    For evaluating N(2) fixation of diazotrophic bacteria, nitrogen-poor liquid media supplemented with at least 0.5% sugar and 0.2% agar are widely used for acetylene reduction assays. In such a soft gel medium, however, many N(2)-fixing soil bacteria generally show only trace acetylene reduction activity. Here, we report that use of a N(2) fixation medium solidified with gellan gum instead of agar promoted growth of some gellan-preferring soil bacteria. In a soft gel medium solidified with 0.3% gellan gum under appropriate culture conditions, bacterial microbiota from boreal forest bed soils and some free-living N(2)-fixing soil bacteria isolated from the microbiota exhibited 10- to 200-fold-higher acetylene reduction than those cultured in 0.2% agar medium. To determine the N(2) fixation-activating mechanism of gellan gum medium, qualitative differences in the colony-forming bacterial components from tested soil microbiota were investigated in plate cultures solidified with either agar or gellan gum for use with modified Winogradsky's medium. On 1.5% agar plates, apparently cryophilic bacterial microbiota showed strictly distinguishable microbiota according to the depth of soil in samples from an eastern Siberian Taiga forest bed. Some pure cultures of proteobacteria, such as Pseudomonas fluorescens and Burkholderia xenovorans, showed remarkable acetylene reduction. On plates solidified with 1.0% gellan gum, some soil bacteria, including Luteibacter sp., Janthinobacterium sp., Paenibacillus sp., and Arthrobacter sp., uniquely grew that had not grown in the presence of the same inoculants on agar plates. In contrast, Pseudomonas spp. and Burkholderia spp. were apparent only as minor colonies on the gellan gum plates. Moreover, only gellan gum plates allowed some bacteria, particularly those isolated from the shallow organic soil layer, to actively swarm. In consequence, gellan gum is a useful gel matrix to bring out growth potential capabilities of many soil

  3. The effect of thermal cycling on the structure and properties of a Co, Cr, Ni-TaC directionally solidified eutectic composite

    NASA Technical Reports Server (NTRS)

    Dunlevey, F. M.; Wallace, J. F.

    1973-01-01

    The effect of thermal cycling on the structure and properties of a cobalt, chromium, nickel, tantalum carbide directionally solidified eutectic composite is reported. It was determined that the stress rupture properties of the alloy were decreased by the thermal cycling. The loss in stress rupture properties varied with the number of cycles with the loss in properties after about 200 cycles being relatively high. The formation of serrations and the resulting changes in the mechanical properties of the material are discussed.

  4. Dispersion strengthening of precipitation hardened Al-Cu-Mg alloys prepared by rapid solidification and mechanical alloying

    NASA Technical Reports Server (NTRS)

    Gilman, P. S.; Sankaran, K. K.

    1988-01-01

    Several Al-4Cu-1Mg-1.5Fe-0.75Ce alloys have been processed from either rapidly solidified or mechanically alloyed powder using various vacuum degassing parameters and consolidation techniques. Strengthening by the fine subgrains, grains, and the dispersoids individually or in combination is more effective when the alloys contain shearable precipitates; consequently, the strength of the alloys is higher in the naturally aged rather than the artificially aged condition. The strengths of the mechanically alloyed variants are greater than those produced from prealloyed powder. Properties and microstructural features of these dispersion strengthened alloys are discussed in regards to their processing histories.

  5. Rapid-solidification processing and powder metallurgy of al alloys. Final technical report, 15 April 1982-15 April 1985

    SciTech Connect

    Fraser, H.L.

    1986-10-29

    Regarding work on the development of microstructure during rapid solidification, three areas were addressed. The first of these involved a determination of the mechanism of formation of the so-called zones A and B in hypereutectic Al-transition metal alloys. The second area of work involving the development of microstructure concerns submerged phase transformations. In a study of Al-Be hypereutectic alloys, it was determined that solidification proceeded by a set of phase transformations that may be described by a monotectic reaction. The third area of study concerning microstructural development involves quasi-crystalline Al alloys. In fact, work done in this program has concentrated on the potentially beneficial aspects of quasi-crystalline phases in the microstructure of Al alloys. Work on the consolidation of particulate was concentrated on the use of conventional techniques (.e. extrusion) and novel processes (i.e. dynamic compaction). An estimate of the mechanical properties of rapidly solidified Al alloys was obtained. As explained above, the effect of extrusion is to cause decomposition of the rapidly solidified microstructure. A comparison was made, using the alloy Al-8Fe-2Mo, between the tensile properties of the decomposed microstructure (.e. extruded) and subscale test specimens produced by laser surface melting, consisting entirely of zone A.

  6. Magnetic anisotropy in rapidly quenched amorphous glass-coated nanowires

    NASA Astrophysics Data System (ADS)

    Óvári, T.-A.; Rotărescu, C.; Atițoaie, A.; Corodeanu, S.; Lupu, N.; Chiriac, H.

    2016-07-01

    Results on the roles played by the magnetoelastic and magnetostatic anisotropy terms in the magnetic behavior of glass-coated magnetostrictive amorphous nanowires prepared by means of rapid solidification are reported. Their contributions have been analyzed both experimentally, through hysteresis loop measurements, and theoretically, using micromagnetic simulations. All the investigated samples exhibit a magnetically bistable behavior, characterized by a single-step magnetization reversal when the applied field reaches a critical threshold value, called switching field. The combined interpretation of the experimental and theoretical data allows one to understand the effect of the magnetoelastic term on the value of the switching field, on one hand, and the effect of the magnetostatic term on the nucleation mechanism on the other, both with an essential impact on the characteristics of the nanowires' magnetic bistability. The results are crucial for understanding the basic magnetic properties of these novel rapidly solidified ultrathin magnetic wires, as well as for tailoring their properties according to the specific requirements of various sensing applications.

  7. Modeling rapidly rotating stars

    NASA Astrophysics Data System (ADS)

    Rieutord, M.

    2006-06-01

    We review the quest of modeling rapidly rotating stars during the past 40 years and detail the challenges to be taken up by models facing new data from interferometry, seismology, spectroscopy... We then present the progress of the ESTER project aimed at giving a physically self-consistent model for the structure and evolution of rapidly rotating stars.

  8. Solid lipid micro-dispersions (SLMs) based on PEGylated solidified reverse micellar solutions (SRMS): a novel carrier system for gentamicin.

    PubMed

    Kenechukwu, Franklin C; Momoh, Mumuni A; Nnamani, Petra O; Attama, Anthony A

    2015-01-01

    The purpose of this study was to formulate and evaluate novel PEGylated solidified reverse micellar solutions (SRMS)-based solid lipid microparticles (SLMs) for improved delivery of gentamicin. Lipid matrix (SRMS) [consisting of 15% w/w Phospholipon® 90G (P90G) in 35% w/w dika wax (Irvingia gabonensis) was formulated and characterized by differential scanning calorimetry (DSC). SLMs were formulated by melt-emulsification using the SRMS, PEG 4000 and gentamicin (1.0, 2.0, 3.0% w/w), and their physicochemical as well as pharmacokinetic parameters determined. In vitro permeation of gentamicin from the SLMs through artificial membrane (0.22 μm pore size) was carried out using Franz's cell and phosphate-buffered saline (PBS, pH 7.4) as acceptor medium, while bioevaluation was performed using clinical isolates of Pseudomonas aeruginosa and Staphylococcus aureus. Stable and irregularly-shaped gentamicin-loaded SLMs of size range 34.49 ± 2.56 to 53.52 ± 3.09 µm were obtained. The SLMs showed sustained drug permeation and exhibited time-dependent and capacity-limited bioactivity. Overall, SLMs containing 2% w/w SRMS, 3% w/w gentamicin and PEG 4000 entrapped the highest amount of drug, gave highest IZD against the test organisms and highest permeation flux (5.239 μg/cm(2).min) and permeation coefficient (1.781 × 10(-6)cm/min) within 420 min, while pure gentamicin gave the least. Preliminary in vivo pharmacokinetic studies also showed an AUC-24 of 1507 µg/h/ml for the optimized formulation, while that of oral drug solution was 678 µg/h/ml. This showed a 2.2-fold increase in the systemic bioavailability of gentamicin from the optimized formulation. PEGylated SRMS-based SLMs prepared with heterolipid from Irvingia gabonensis would likely offer a reliable delivery system for gentamicin. PMID:24724962

  9. Interconnection of thermal parameters, microstructure and mechanical properties in directionally solidified Sn–Sb lead-free solder alloys

    SciTech Connect

    Dias, Marcelino; Costa, Thiago; Rocha, Otávio; Spinelli, José E.; Cheung, Noé; Garcia, Amauri

    2015-08-15

    Considerable effort is being made to develop lead-free solders for assembling in environmental-conscious electronics, due to the inherent toxicity of Pb. The search for substitute alloys of Pb–Sn solders has increased in order to comply with different soldering purposes. The solder must not only meet the expected levels of electrical performance but may also have appropriate mechanical strength, with the absence of cracks in the solder joints. The Sn–Sb alloy system has a range of compositions that can be potentially included in the class of high temperature solders. This study aims to establish interrelations of solidification thermal parameters, microstructure and mechanical properties of Sn–Sb alloys (2 wt.%Sb and 5.5 wt.%Sb) samples, which were directionally solidified under cooling rates similar to those of reflow procedures in industrial practice. A complete high-cooling rate cellular growth is shown to be associated with the Sn–2.0 wt.%Sb alloy and a reverse dendrite-to-cell transition is observed for the Sn–5.5 wt.%Sb alloy. Strength and ductility of the Sn–2.0 wt.%Sb alloy are shown not to be affected by the cellular spacing. On the other hand, a considerable variation in these properties is associated with the cellular region of the Sn–5.5 wt.%Sb alloy casting. - Graphical abstract: Display Omitted - Highlights: • The microstructure of the Sn–2 wt.%Sb alloy is characterized by high-cooling rates cells. • Reverse dendrite > cell transition occurs for Sn–5.5 wt.%Sb alloy: cells prevail for cooling rates > 1.2 K/s. • Sn–5.5 wt.%Sb alloy: the dendritic region occurs for cooling rates < 0.9 K/s. • Sn–5.5 wt.%Sb alloy: tensile properties are improved with decreasing cellular spacing.

  10. Observations of Al, Fe and Ca(+) in Mercury's Exosphere

    NASA Technical Reports Server (NTRS)

    Bida, Thomas A.; Killen, Rosemary M.

    2011-01-01

    We report 5-(sigma) tangent column detections of Al and Fe, and strict 3-(sigma) tangent column upper limits for Ca(+) in Mercury's exosphere obtained using the HIRES spectrometer on the Keck I telescope. These are the first direct detections of Al and Fe in Mercury's exosphere. Our Ca(-) observation is consistent with that reported by The Mercury Atmospheric and Surface Composition Spectrometer (MASCS) on the MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) spacecraft.

  11. Rapid Airplane Parametric Input Design (RAPID)

    NASA Technical Reports Server (NTRS)

    Smith, Robert E.

    1995-01-01

    RAPID is a methodology and software system to define a class of airplane configurations and directly evaluate surface grids, volume grids, and grid sensitivity on and about the configurations. A distinguishing characteristic which separates RAPID from other airplane surface modellers is that the output grids and grid sensitivity are directly applicable in CFD analysis. A small set of design parameters and grid control parameters govern the process which is incorporated into interactive software for 'real time' visual analysis and into batch software for the application of optimization technology. The computed surface grids and volume grids are suitable for a wide range of Computational Fluid Dynamics (CFD) simulation. The general airplane configuration has wing, fuselage, horizontal tail, and vertical tail components. The double-delta wing and tail components are manifested by solving a fourth order partial differential equation (PDE) subject to Dirichlet and Neumann boundary conditions. The design parameters are incorporated into the boundary conditions and therefore govern the shapes of the surfaces. The PDE solution yields a smooth transition between boundaries. Surface grids suitable for CFD calculation are created by establishing an H-type topology about the configuration and incorporating grid spacing functions in the PDE equation for the lifting components and the fuselage definition equations. User specified grid parameters govern the location and degree of grid concentration. A two-block volume grid about a configuration is calculated using the Control Point Form (CPF) technique. The interactive software, which runs on Silicon Graphics IRIS workstations, allows design parameters to be continuously varied and the resulting surface grid to be observed in real time. The batch software computes both the surface and volume grids and also computes the sensitivity of the output grid with respect to the input design parameters by applying the precompiler tool

  12. Rapidly Progressive Dementia

    PubMed Central

    Geschwind, Michael D.; Shu, Huidy; Haman, Aissa; Sejvar, James J.; Miller, Bruce L.

    2009-01-01

    In contrast with more common dementing conditions that typically develop over years, rapidly progressive dementias can develop subacutely over months, weeks, or even days and be quickly fatal. Because many rapidly progressive dementias are treatable, it is paramount to evaluate and diagnose these patients quickly. This review summarizes recent advances in the understanding of the major categories of RPD and outlines efficient approaches to the diagnosis of the various neurodegenerative, toxic-metabolic, infectious, autoimmune, neoplastic, and other conditions that may progress rapidly. PMID:18668637

  13. Effects of the Growth Rate on Microstructures and Room Temperature Mechanical Properties of Directionally Solidified Mg-5.2Zn Alloy

    NASA Astrophysics Data System (ADS)

    Liu, Shaojun; Yang, Guangyu; Xiao, Lei; Luo, Shifeng; Jie, Wanqi

    2016-06-01

    Effects of the growth rate on the microstructures and room temperature mechanical properties of Mg-5.2Zn alloy were investigated using Bridgman method at a constant temperature gradient 30 K/mm with different growth rates (v = 10 ~ 100 μm/s). The microstructure of directionally solidified Mg-5.2Zn alloy is composed of dendrite primary α(Mg) phase and interdendritic α(Mg) + Mg7Zn3 eutectic, which agrees well with the predicted microstructure using Scheil model. The morphology of the primary α(Mg) phase transforms from cellular, to cellular-dendritic, and then to dendritic with the increase of growth rate from 10 μm/s to 100 μm/s. According to the Kurz-Fisher model, the approximate criterion growth rate for cellular/dendrite transition is determined to be about 12.7 μm/s, which just lies in the experimental result interval. Using non-linear fitting analysis, λ 1 (the primary dendrite arm spacing) and λ 2 (secondary dendrite arm spacing) were found to be dependent on v (growth rate) in the form of λ 1 = 8.6964 × 10-6 v -0.23983, λ 2 = 1.7703 × 10-6 v -0.34161, which is in good agreement with the calculated values by the Trivedi model and Kattamis-Flemings model, respectively. Furthermore, tensile test shows that the directional solidified experimental Mg-5.2Zn alloy shows higher strength than the non-directional solidified alloy under the same cooling rate. The dendritic structure shows higher strength than the cellular structure due to the fact that brittle interdendrite eutectic was refined in dendritic structures.

  14. Characterization of dislocation structures and deformation mechanisms in as-grown and deformed directionally solidified NiAl–Mo composites

    SciTech Connect

    Kwon, J.; Bowers, M. L.; Brandes, M. C.; McCreary, V.; Robertson, Ian M.; Phani, P. Sudaharshan; Bei, H.; Gao, Y. F.; Pharr, George M.; George, Easo P.; Mills, M. J.

    2015-02-26

    In this paper, directionally solidified (DS) NiAl–Mo eutectic composites were strained to plastic strain values ranging from 0% to 12% to investigate the origin of the previously observed stochastic versus deterministic mechanical behaviors of Mo-alloy micropillars in terms of the development of dislocation structures at different pre-strain levels. The DS composites consist of long, [1 0 0] single-crystal Mo-alloy fibers with approximately square cross-sections embedded in a [1 0 0] single-crystal NiAl matrix. Scanning transmission electron microscopy (STEM) and computational stress state analysis were conducted for the current study. STEM of the as-grown samples (without pre-straining) reveal no dislocations in the investigated Mo-alloy fibers. In the NiAl matrix, on the other hand, a(1 0 0)-type dislocations exist in two orthogonal orientations: along the [1 0 0] Mo fiber axis, and wrapped around the fiber axis. They presumably form to accommodate the different thermal contractions of the two phases during cool down after eutectic solidification. At intermediate pre-strain levels (4–8%), a/2(1 1 1)-type dislocations are present in the Mo-alloy fibers and the pre-existing dislocations in the NiAl matrix seem to be swept toward the interphase boundary. Some of the dislocations in the Mo-alloy fibers appear to be transformed from a(1 0 0)-type dislocations present in the NiAl matrix. Subsequently, the transformed dislocations in the fibers propagate through the NiAl matrix as a(1 1 1) dislocations and aid in initiating additional slip bands in adjacent fibers. Thereafter, co-deformation presumably occurs by (1 1 1) slip in both phases. With a further increase in the pre-strain level (>10%), multiple a/2(1 1 1)-type dislocations are observed in many locations in the Mo-alloy fibers. Interactions between these systems upon subsequent deformation could lead to stable junctions and persistent dislocation sources. Finally, the transition from stochastic to

  15. Characterization of dislocation structures and deformation mechanisms in as-grown and deformed directionally solidified NiAl–Mo composites

    DOE PAGESBeta

    Kwon, J.; Bowers, M. L.; Brandes, M. C.; McCreary, V.; Robertson, Ian M.; Phani, P. Sudaharshan; Bei, H.; Gao, Y. F.; Pharr, George M.; George, Easo P.; et al

    2015-02-26

    In this paper, directionally solidified (DS) NiAl–Mo eutectic composites were strained to plastic strain values ranging from 0% to 12% to investigate the origin of the previously observed stochastic versus deterministic mechanical behaviors of Mo-alloy micropillars in terms of the development of dislocation structures at different pre-strain levels. The DS composites consist of long, [1 0 0] single-crystal Mo-alloy fibers with approximately square cross-sections embedded in a [1 0 0] single-crystal NiAl matrix. Scanning transmission electron microscopy (STEM) and computational stress state analysis were conducted for the current study. STEM of the as-grown samples (without pre-straining) reveal no dislocations inmore » the investigated Mo-alloy fibers. In the NiAl matrix, on the other hand, a(1 0 0)-type dislocations exist in two orthogonal orientations: along the [1 0 0] Mo fiber axis, and wrapped around the fiber axis. They presumably form to accommodate the different thermal contractions of the two phases during cool down after eutectic solidification. At intermediate pre-strain levels (4–8%), a/2(1 1 1)-type dislocations are present in the Mo-alloy fibers and the pre-existing dislocations in the NiAl matrix seem to be swept toward the interphase boundary. Some of the dislocations in the Mo-alloy fibers appear to be transformed from a(1 0 0)-type dislocations present in the NiAl matrix. Subsequently, the transformed dislocations in the fibers propagate through the NiAl matrix as a(1 1 1) dislocations and aid in initiating additional slip bands in adjacent fibers. Thereafter, co-deformation presumably occurs by (1 1 1) slip in both phases. With a further increase in the pre-strain level (>10%), multiple a/2(1 1 1)-type dislocations are observed in many locations in the Mo-alloy fibers. Interactions between these systems upon subsequent deformation could lead to stable junctions and persistent dislocation sources. Finally, the transition from stochastic to

  16. Microstructural development and mechanical properties of a near-eutectic directionally solidified Sn–Bi solder alloy

    SciTech Connect

    Silva, Bismarck Luiz; Reinhart, Guillaume; Nguyen-Thi, Henri; Mangelinck-Noël, Nathalie; Garcia, Amauri; Spinelli, José Eduardo

    2015-09-15

    Sn–Bi solders may be applied for electronic applications where low-temperature soldering is required, i.e., sensitive components, step soldering and soldering LEDs. In spite of their potential to cover such applications, the mechanical response of soldered joints of Sn–Bi alloys in some cases does not meet the strength requirements due to inappropriate resulting microstructures. Hence, careful examination and control of as-soldered microstructures become necessary with a view to pre-programming reliable final properties. The present study aims to investigate the effects of solidification thermal parameters (growth rate — V{sub L} and cooling rate — T-dot{sub L}) on the microstructure of the Sn–52 wt.%Bi solder solidified under unsteady-state conditions. Samples were obtained by upward directional solidification (DS), followed by characterization through metallography and scanning electron microscopy (SEM). The microstructures are shown to be formed by Sn-rich dendrites decorated with Bi precipitates surrounded by a complex regular eutectic mixture, with alternated Bi-rich and Sn-rich phases. Experimental correlations of primary (λ{sub 1}), secondary (λ{sub 2}), tertiary (λ{sub 3}) dendritic and eutectic spacings (λ{sub coarse} and λ{sub fine}) with cooling rate and growth rate are established. Two ranges of lamellar eutectic sizes were determined, described by two experimental equations λ = 1.1 V{sub L}{sup −1/2} and λ = 0.67 V{sub L}{sup −1/2}. The onset of tertiary branches within the dendritic array along the Sn–52 wt.%Bi alloy DS casting is shown to occur for cooling rates lower than 1.5 °C/s. - Highlights: • The Sn–52 wt.%Bi solder was shown to have two eutectic sizes. • The fishbone eutectic is preferably located adjacent to the Bi-rich lamellar phases. • The onset of tertiary dendritic branches in Sn–Bi is associated with T-dot{sub L} < 1.5 °C/s. • Higher eutectic fraction and λ{sub 3} provoked a reverse increase in

  17. Rapid road repair vehicle

    DOEpatents

    Mara, Leo M.

    1999-01-01

    Disclosed are improvments to a rapid road repair vehicle comprising an improved cleaning device arrangement, two dispensing arrays for filling defects more rapidly and efficiently, an array of pre-heaters to heat the road way surface in order to help the repair material better bond to the repaired surface, a means for detecting, measuring, and computing the number, location and volume of each of the detected surface imperfection, and a computer means schema for controlling the operation of the plurality of vehicle subsystems. The improved vehicle is, therefore, better able to perform its intended function of filling surface imperfections while moving over those surfaces at near normal traffic speeds.

  18. Rapid small lot manufacturing

    SciTech Connect

    Harrigan, R.W.

    1998-05-09

    The direct connection of information, captured in forms such as CAD databases, to the factory floor is enabling a revolution in manufacturing. Rapid response to very dynamic market conditions is becoming the norm rather than the exception. In order to provide economical rapid fabrication of small numbers of variable products, one must design with manufacturing constraints in mind. In addition, flexible manufacturing systems must be programmed automatically to reduce the time for product change over in the factory and eliminate human errors. Sensor based machine control is needed to adapt idealized, model based machine programs to uncontrolled variables such as the condition of raw materials and fabrication tolerances.

  19. Ultra-flexible framework breathing in response to dehydration in liskeardite, [(Al,Fe){sub 16}(AsO{sub 4}){sub 9}(OH){sub 21}(H{sub 2}O){sub 11}]·26H{sub 2}O, a natural open-framework compound

    SciTech Connect

    Grey, Ian. E.; Brand, Helen E.A.; Rumsey, Michael S.; Gozukara, Yesim

    2015-08-15

    Dehydration of the natural open-framework compound, liskeardite, [(Al,Fe){sub 16}(AsO{sub 4}){sub 9}(OH){sub 21}(H{sub 2}O){sub 11}]·26H{sub 2}O, is accompanied by a change in the sign of the thermal expansion from positive to negative above room temperature, and at ~100 °C the structure undergoes a dramatic 2D contraction by co-operative rotation of heteropolyhedral columns that constitute the framework walls. Monoclinic liskeardite, I112 with a≈b≈24.7 Å, c ≈7.8 Å and β≈90° is transformed to a tetragonal phase, I-4 with a≈20.6 Å, c ≈7.7 Å. The associated 30% decrease in volume is unprecedented in inorganic microporous compounds. The flexibility of the contraction is related to the double-hinged nature of the column rotations about [001]. Octahedra in adjacent columns are interconnected by corner-sharing with the two pairs of anions forming opposing edges of AsO{sub 4} tetrahedra, so a double-hinged rotation mechanism operates. Thermal analysis and mass spectroscopic results for liskeardite show that the phase transition at ~100 °C is related to removal of the channel water. The tetragonal phase shows exceptionally large NTE behaviour. Over the temperature range 148–178 the NTE along a and b is close to linear with a magnitude of the order of −900×10{sup −6} °C{sup −1}. The contraction along the channel direction is smaller but still appreciable at −200×10{sup −6} °C{sup −1}. - Graphical abstract: Structure of the collapsed liskeardite framework, formed on dehydration above 100 °C. - Highlights: • The thermal expansion of the mineral liskeardite changes + to − above ambient. • Dehydration at 100 °C results in a record reversible 30% volume reduction. • In situ synchrotron XRD has led to a structural model for the dehydrated phase. • Framework breathing flexibility is attributed to a double-hinge rotation mechanism. • The dehydrated phase shows unprecedented -ve expansion for inorganic materials.

  20. Rapid Cycling and Its Treatment

    MedlinePlus

    ... may be rapid, ultra-rapid or ultradian cycling. Biological rhythm disturbances: This theory proposes that people with rapid cycling have daily biological rhythms that are out of sync with typical “ ...

  1. Influence of the static high magnetic field on the liquid-liquid phase separation during solidifying the hyper-monotectic alloys

    NASA Astrophysics Data System (ADS)

    Wang, J.; Zhong, Y. B.; Fautrelle, Y.; Zheng, T. X.; Li, F.; Ren, Z. M.; Debray, F.

    2013-09-01

    Magnetic in-situ quenching refers to fixing and quenching the sample at a static high magnetic field (SHMF) up to 18 T; it has been achieved by a specially designed facility. Zn-7wt%Bi and Zn-10wt%Bi hyper-monotectic melts were quenched under different magnetic flux densities to investigate the influence of SHMF on the liquid-liquid phase separation process in solidifying hyper-monotectic alloys. Because this separation is mainly caused by the growth of minority phase droplets (Bi droplets in the present study), and such growth is attributed to the diffusion of Bi element and the coalescence between the droplets, the influence of SHMF on the growth of Bi droplets was analyzed. Results show that the imposed SHMF prevented the formation of layered structure in the Zn-10wt%Bi alloy and refined the Bi particles in the Zn-7wt%Bi alloy, which indicates that the SHMF retarded the liquid-liquid phase separation during solidifying the hyper-monotectic alloys. Indeed, the two motions of droplets in determining the coalescence, Marangoni migration and Stocks sedimentation, were slowed down by the applied SHMF. Analytical estimations of the magnitude of such damping effect have been made and show that the 18 T SHMF could reduce the speed of Stokes sedimentation and Marangoni migration of the minority phase droplets by about 95.5 % and 62.4 %, respectively.

  2. Effect of pH on the release of radionuclides and chelating agents from cement-solidified decontamination ion-exchange resins collected from operating nuclear power stations

    SciTech Connect

    McIsaac, C.V.; Akers, D.W.; McConnell, J.W. )

    1991-06-01

    Data are presented on the physical stability and leachability of radionuclides and chelating agents from cement-solidified decontamination ion-exchange resin wastes collected from two operating commercial light water reactors. Small-scale waste--form specimens collected during solidifications performed at the Brunswick Steam Electric Plant Unit 1 and at the James A. FitzPatrick Nuclear Power Station were leach-tested and subjected to compressive strength testing in accordance with the Nuclear Regulatory Commission's Technical Position on Waste Form'' (Revision 1). Samples of untreated resin waste collected from each solidification vessel before the solidification process were analyzed for concentrations of radionuclides, selected transition metals, and chelating agents to determine the quantities of these chemicals in the waste-form specimens. The chelating agents included oxalic, citric, and picolinic acids. In order to determine the effect of leachant chemical composition and pH on the stability and leachability of the waste forms, waste-form specimens were leached in various leachants. Results of this study indicate that differences in pH do not affect releases from cement-solidified decontamination ion-exchange resin waste forms, but that differences in leachant chemistry and the presence of chelating agents may affect the releases of radionuclides and chelating agents. Also, this study indicates that the cumulative releases of radionuclides and chelating agents are similar for waste- form specimens that decomposed and those that retained their general physical form. 36 refs., 60 figs., 28 tabs.

  3. Interconnection between microstructure and microhardness of directionally solidified binary Al-6wt.%Cu and multicomponent Al-6wt.%Cu-8wt.%Si alloys.

    PubMed

    Vasconcelos, Angela J; Kikuchi, Rafael H; Barros, André S; Costa, Thiago A; Dias, Marcelino; Moreira, Antonio L; Silva, Adrina P; Rocha, Otávio L

    2016-05-31

    An experimental study has been carried out to evaluate the microstructural and microhardness evolution on the directionally solidified binary Al-Cu and multicomponent Al-Cu-Si alloys and the influence of Si alloying. For this purpose specimens of Al-6wt.%Cu and Al-6wt.%Cu-8wt.%Si alloys were prepared and directionally solidified under transient conditions of heat extraction. A water-cooled horizontal directional solidification device was applied. A comprehensive characterization is performed including experimental dendrite tip growth rates (VL) and cooling rates (TR) by measuring Vickers microhardness (HV), optical microscopy and scanning electron microscopy with microanalysis performed by energy dispersive spectrometry (SEM-EDS). The results show, for both studied alloys, the increasing of TR and VL reduced the primary dendrite arm spacing (l1) increasing the microhardness. Furthermore, the incorporation of Si in Al-6wt.%Cu alloy to form the Al-6wt.%Cu-8wt.%Si alloy influenced significantly the microstructure and consequently the microhardness but did not affect the primary dendritic growth law. An analysis on the formation of the columnar to equiaxed transition (CET) is also performed and the results show that the occurrence of CET is not sharp, i.e., the CET in both cases occurs in a zone rather than in a parallel plane to the chill wall, where both columnar and equiaxed grains are be able to exist. PMID:27254454

  4. Design requirements document for the interim store phase I solidified high-level waste function 4.2.4.1.2

    SciTech Connect

    Calmus, R.B.

    1996-09-30

    The U.S. Department of Energy (DOE) has embarked upon a course to acquire Hanford site.t,,nk waste tr:atment and immobilization services using privatized facilities. This plan contains a two-phased approach. Phase I is a ``proof-of-principle/commercial demonstration-scale`` effort and Phase II is a full-scale production effort. In accordance with the planned approach, interim storage and disposal of various products from privatized facilities are to be DOE furnished. The path forward adopted for Phase I solidified high-level waste (HLW) interim storage entails use of Vaut 2 and 3 in the Hanford Site Spent Nuclear Fuels Canister Storage Building (CSB), to be located in the Hanford Site 200 East Area. This design requirements document establishes the functions, with associated requirements, allocated to the Phase I solidified HLW interim storage system. These requirements will be used as the basis for conceptual design of the CSB and supporting systems. This document will also provide the basis for preparation of a performance specification for design and construction activities necessary to achieve the overall project mission.

  5. Compression and immersion tests and leaching of radionuclides, stable metals, and chelating agents from cement-solidified decontamination waste collected from nuclear power stations

    SciTech Connect

    Akers, D.W.; Kraft, N.C.; Mandler, J.W.

    1994-06-01

    A study was performed for the Nuclear Regulatory Commission (NRC) to evaluate structural stability and leachability of radionuclides, stable metals, and chelating agents from cement-solidified decontamination ion-exchange resin wastes collected from seven commercial boiling water reactors and one pressurized water reactor. The decontamination methods used at the reactors were the Can-Decon, AP/Citrox, Dow NS-1, and LOMI processes. Samples of untreated resin waste and solidified waste forms were subjected to immersion and compressive strength testing. Some waste-form samples were leach-tested using simulated groundwaters and simulated seawater for comparison with the deionized water tests that are normally performed to assess waste-form leachability. This report presents the results of these tests and assesses the effects of the various decontamination methods, waste form formulations, leachant chemical compositions, and pH of the leachant on the structural stability and leachability of the waste forms. Results indicate that releases from intact and degraded waste forms are similar and that the behavior of some radionuclides such as {sup 55}Fe, {sup 60}Co, and {sup 99}Tc were similar. In addition, the leachability indexes are greater than 6.0, which meets the requirement in the NRC`s ``Technical Position on Waste Form,`` Revision 1.

  6. Determination of the Solid/Liquid Interface Shape and Resultant Radial Homogeneity in Directionally Solidified Hg(0.89)Mn(0.11)Te

    NASA Technical Reports Server (NTRS)

    Price, M. W.; Scripa, R. N.; Lehoczky, S. L.; Szofran, F. R.; Hanson, B.

    1999-01-01

    Directional solidification and interrupted directional solidification experiments were used to determine tile shape of the solid/liquid interface and the resultant radial homogeneity in Hg(0.89)Mg(0.11)Te. For directionally solidified samples solidified at a rate of 0.09 microns/sec in a thermal gradient of 83 C/cm, a maximum of 0.006 molar percent MnTe radial variation across the Hg0.89)Mn(0.11)Te boules at specific locations was determined using an FTIR technique. This FTIR evaluation of the radial homogeneity also indicated an asymmetrical, convex interface shape during solidification. The asymmetrical, convex shape of the growth interface was confirmed by interrupted directional solidification experiments. These were performed under the same growth conditions as the normally completed directional solidification experiments except that the samples were quenched before the final growth transient was reached. In these experiments, etching and scanning X-ray fluorescence were used to reveal the shape of the solid/liquid interface. Microprobe analysis of composition gradients across the interface was used to confirm the authors' previous work in evaluating the segregation coefficient of Hg(0.89)Mn(0.11)Te alloy. Microprobe analysis of the interface region of the interrupted growth sample revealed a dendritic structure containing secondary and tertiary dendritic arms.

  7. Release of radionuclides and chelating agents from cement-solidified decontamination low-level radioactive waste collected from the Peach Bottom Atomic Power Station Unit 3

    SciTech Connect

    Akers, D.W.; Kraft, N.C.; Mandler, J.W.

    1994-03-01

    As part of a study being performed for the Nuclear Regulatory Commission (NRC), small-scale waste-form specimens were collected during a low oxidation-state transition-metal ion (LOMI)-nitric permanganate (NP)-LOMI solidification performed in October 1989 at the Peach Bottom Atomic Power Station Unit 3. The purpose of this program was to evaluate the performance of cement-solidified decontamination waste to meet the low-level waste stability requirements defined in the NRC`s ``Technical Position on Waste Form,`` Revision 1. The samples were acquired and tested because little data have been obtained on the physical stability of actual cement-solidified decontamination ion-exchange resin waste forms and on the leachability of radionuclides and chelating agents from those waste forms. The Peach Bottom waste-form specimens were subjected to compressive strength, immersion, and leach testing in accordance with the NRC`s ``Technical Position on Waste Form,`` Revision 1. Results of this study indicate that the specimens withstood the compression tests (>500 psi) before and after immersion testing and leaching, and that the leachability indexes for all radionuclides, including {sup 14}C, {sup 99}{Tc}, and {sup 129}I, are well above the leachability index requirement of 6.0, required by the NRC`s ``Technical Position on Waste Form,`` Revision 1.

  8. Navigate the Digital Rapids

    ERIC Educational Resources Information Center

    Lindsay, Julie; Davis, Vicki

    2010-01-01

    How can teachers teach digital citizenship when the digital landscape is changing so rapidly? How can teachers teach proper online social interactions when the students are outside their classroom and thus outside their control? Will encouraging students to engage in global collaborative environments land teachers in hot water? These are the…

  9. Rapid Prototyping in PVS

    NASA Technical Reports Server (NTRS)

    Munoz, Cesar A.; Butler, Ricky (Technical Monitor)

    2003-01-01

    PVSio is a conservative extension to the PVS prelude library that provides basic input/output capabilities to the PVS ground evaluator. It supports rapid prototyping in PVS by enhancing the specification language with built-in constructs for string manipulation, floating point arithmetic, and input/output operations.

  10. AFRPL Rapid Indexing System.

    ERIC Educational Resources Information Center

    Beltran, Alfred A.

    A modified Keyword Out of Context (KWOC) system was developed to gain rapid control over more than 8,000 scattered, unindexed documents. This was the first step in providing the technical information support required by Air Force Rocket Propulsion Laboratory scientists and engineers. Implementation of the KWOC system, computer routines, and…

  11. Rapid road repair vehicle

    DOEpatents

    Mara, Leo M.

    1998-01-01

    Disclosed is a rapid road repair vehicle capable of moving over a surface to be repaired at near normal posted traffic speeds to scan for and find an the high rate of speed, imperfections in the pavement surface, prepare the surface imperfection for repair by air pressure and vacuum cleaning, applying a correct amount of the correct patching material to effect the repair, smooth the resulting repaired surface, and catalog the location and quality of the repairs for maintenance records of the road surface. The rapid road repair vehicle can repair surface imperfections at lower cost, improved quality, at a higher rate of speed than was was heretofor possible, with significantly reduced exposure to safety and health hazards associated with this kind of road repair activities in the past.

  12. Rapid road repair vehicle

    DOEpatents

    Mara, L.M.

    1998-05-05

    Disclosed is a rapid road repair vehicle capable of moving over a surface to be repaired at near normal posted traffic speeds to scan for and find at the high rate of speed, imperfections in the pavement surface, prepare the surface imperfection for repair by air pressure and vacuum cleaning, applying a correct amount of the correct patching material to effect the repair, smooth the resulting repaired surface, and catalog the location and quality of the repairs for maintenance records of the road surface. The rapid road repair vehicle can repair surface imperfections at lower cost, improved quality, at a higher rate of speed than was not heretofor possible, with significantly reduced exposure to safety and health hazards associated with this kind of road repair activities in the past. 2 figs.

  13. Rapid climate change

    SciTech Connect

    Morantine, M.C.

    1995-12-31

    Interactions between insolation changes due to orbital parameter variations, carbon dioxide concentration variations, the rate of deep water formation in the North Atlantic and the evolution of the northern hemisphere ice sheets during the most recent glacial cycle will be investigated. In order to investigate this period, a climate model is being developed to evaluate the physical mechanisms thought to be most significant during this period. The description of the model sub-components will be presented. The more one knows about the interactions between the sub-components of the climate system during periods of documented rapid climate change, the better equipped one will be to make rational decisions on issues related to impacts on the environment. This will be an effort to gauge the feedback processes thought to be instrumental in rapid climate shifts documented in the past, and their potential to influence the current climate. 53 refs.

  14. Rapidly refuelable fuel cell

    DOEpatents

    Joy, R.W.

    1982-09-20

    A rapidly refuelable dual cell of an electrochemical type is described wherein a single anode cooperates with two cathodes and wherein the anode has a fixed position and the cathodes are urged toward opposite faces of the anodes at constant and uniform force. The associated cathodes are automatically retractable to permit the consumed anode remains to be removed from the housing and a new anode inserted between the two cathodes.

  15. Rapid Detection of Pathogens

    SciTech Connect

    David Perlin

    2005-08-14

    Pathogen identification is a crucial first defense against bioterrorism. A major emphasis of our national biodefense strategy is to establish fast, accurate and sensitive assays for diagnosis of infectious diseases agents. Such assays will ensure early and appropriate treatment of infected patients. Rapid diagnostics can also support infection control measures, which monitor and limit the spread of infectious diseases agents. Many select agents are highly transmissible in the early stages of disease, and it is critical to identify infected patients and limit the risk to the remainder of the population and to stem potential panic in the general population. Nucleic acid-based molecular approaches for identification overcome many of the deficiencies associated with conventional culture methods by exploiting both large- and small-scale genomic differences between organisms. PCR-based amplification of highly conserved ribosomal RNA (rRNA) genes, intergenic sequences, and specific toxin genes is currently the most reliable approach for bacterial, fungal and many viral pathogenic agents. When combined with fluorescence-based oligonucleotide detection systems, this approach provides real-time, quantitative, high fidelity analysis capable of single nucleotide allelic discrimination (4). These probe systems offer rapid turn around time (<2 h) and are suitable for high throughput, automated multiplex operations that are critical for clinical diagnostic laboratories. In this pilot program, we have used molecular beacon technology invented at the Public health Research Institute to develop a new generation of molecular probes to rapidly detect important agents of infectious diseases. We have also developed protocols to rapidly extract nucleic acids from a variety of clinical specimen including and blood and tissue to for detection in the molecular assays. This work represented a cooperative research development program between the Kramer-Tyagi/Perlin labs on probe development

  16. Rapidly Progressive Dementia

    PubMed Central

    Geschwind, Michael D.

    2016-01-01

    Purpose of Review This article presents a practical and informative approach to the evaluation of a patient with a rapidly progressive dementia (RPD). Recent Findings Prion diseases are the prototypical causes of RPD, but reversible causes of RPD might mimic prion disease and should always be considered in a differential diagnosis. Aside from prion diseases, the most common causes of RPD are atypical presentations of other neurodegenerative disorders, curable disorders including autoimmune encephalopathies, as well as some infections, and neoplasms. Numerous recent case reports suggest dural arterial venous fistulas sometimes cause RPDs. Summary RPDs, in which patients typically develop dementia over weeks to months, require an alternative differential than the slowly progressive dementias that occur over a few years. Because of their rapid decline, patients with RPDs necessitate urgent evaluation and often require an extensive workup, typically with multiple tests being sent or performed concurrently. Jakob-Creutzfeldt disease, perhaps the prototypical RPD, is often the first diagnosis many neurologists consider when treating a patient with rapid cognitive decline. Many conditions other than prion disease, however, including numerous reversible or curable conditions, can present as an RPD. This chapter discusses some of the major etiologies for RPDs and offers an algorithm for diagnosis. PMID:27042906

  17. Rapid frequency scan EPR.

    PubMed

    Tseitlin, Mark; Rinard, George A; Quine, Richard W; Eaton, Sandra S; Eaton, Gareth R

    2011-08-01

    In rapid frequency scan EPR with triangular scans, sufficient time must be allowed to insure that the magnetization in the x, y plane decays to baseline at the end of the scan, which typically is about 5T(2) after the spins are excited. To permit relaxation of signals excited toward the extremes of the scan the total scan time required may be much longer than 5T(2). However, with periodic, saw-tooth excitation, the slow-scan EPR spectrum can be recovered by Fourier deconvolution of data recorded with a total scan period of 5T(2), even if some spins are excited later in the scan. This scan time is similar to polyphase excitation methods. The peak power required for either polyphase excitation or rapid frequency scans is substantially smaller than for pulsed EPR. The use of an arbitrary waveform generator (AWG) and cross loop resonator facilitated implementation of the rapid frequency scan experiments reported here. The use of constant continuous low B(1), periodic excitation waveform, and constant external magnetic field is similar to polyphase excitation, but could be implemented without the AWG that is required for polyphase excitation. PMID:21664848

  18. Rapid Frequency Scan EPR

    PubMed Central

    Tseitlin, Mark; Rinard, George A.; Quine, Richard W.; Eaton, Sandra S.; Eaton, Gareth R.

    2011-01-01

    In rapid frequency scan EPR with triangular scans, sufficient time must be allowed to insure that the magnetization in the x,y plane decays to baseline at the end of the scan, which typically is about 5 T2 after the spins are excited. To permit relaxation of signals excited toward the extremes of the scan the total scan time required may be much longer than 5 T2. However, with periodic, saw-tooth excitation, the slow-scan EPR spectrum can be recovered by Fourier deconvolution of data recorded with a total scan period of 5 T2, even if some spins are excited later in the scan. This scan time is similar to polyphase excitation methods. The peak power required for either polyphase excitation or rapid frequency scans is substantially smaller than for pulsed EPR. The use of an arbitrary waveform generator (AWG) and cross loop resonator facilitated implementation of the rapid frequency scan experiments reported here. The use of constant continuous low B1, periodic excitation waveform, and constant external magnetic field is similar to polyphase excitation, but could be implemented without the AWG that is required for polyphase excitation. PMID:21664848

  19. Rapid adhesive bonding concepts

    NASA Technical Reports Server (NTRS)

    Stein, B. A.; Tyeryar, J. R.; Hodges, W. T.

    1984-01-01

    Adhesive bonding in the aerospace industry typically utilizes autoclaves or presses which have considerable thermal mass. As a consequence, the rates of heatup and cooldown of the bonded parts are limited and the total time and cost of the bonding process is often relatively high. Many of the adhesives themselves do not inherently require long processing times. Bonding could be performed rapidly if the heat was concentrated in the bond lines or at least in the adherends. Rapid adhesive bonding concepts were developed to utilize induction heating techniques to provide heat directly to the bond line and/or adherends without heating the entire structure, supports, and fixtures of a bonding assembly. Bonding times for specimens are cut by a factor of 10 to 100 compared to standard press bonding. The development of rapid adhesive bonding for lap shear specimens (per ASTM D1003 and D3163), for aerospace panel bonding, and for field repair needs of metallic and advanced fiber reinforced polymeric matrix composite structures are reviewed.

  20. Right-Rapid-Rough

    NASA Technical Reports Server (NTRS)

    Lawrence, Craig

    2003-01-01

    IDEO (pronounced 'eye-dee-oh') is an international design, engineering, and innovation firm that has developed thousands of products and services for clients across a wide range of industries. Its process and culture attracted the attention of academics, businesses, and journalists around the world, and are the subject of a bestselling book, The Art of Innovation by Tom Kelley. One of the keys to IDEO's success is its use of prototyping as a tool for rapid innovation. This story covers some of IDEO's projects, and gives reasons for why they were successful.

  1. Rapidly Progressing Chagas Cardiomyopathy.

    PubMed

    Hollowed, John; McCullough, Matthew; Sanchez, Daniel; Traina, Mahmoud; Hernandez, Salvador; Murillo, Efrain

    2016-04-01

    Chagas disease, caused by the parasiteTrypanosoma cruzi, can cause a potentially life-threatening cardiomyopathy in approximately 10-40% of afflicted individuals. The decline in cardiac function characteristically progresses over the course of many years. We report a case of Chagas disease in which the patient experienced an atypical rapid deterioration to severe cardiomyopathy over the course of 16 months. This case argues the need for increased routine surveillance for patients with confirmedT. cruziinfection, who are determined to be at high-risk for worsening cardiomyopathy. PMID:26856912

  2. Rapid and Quiet Drill

    NASA Technical Reports Server (NTRS)

    Sherrit, Stewart; Badescu, Mircea; Bar-Cohen, Yoseph; Chang, Zensheu; Bao, Xiaoqi

    2007-01-01

    This describes aspects of the rapid and quiet drill (RAQD), which is a prototype apparatus for drilling concrete or bricks. The design and basic principle of operation of the RAQD overlap, in several respects, with those of ultrasonic/ sonic drilling and coring apparatuses described in a number of previous NASA Tech Briefs articles. The main difference is that whereas the actuation scheme of the prior apparatuses is partly ultrasonic and partly sonic, the actuation scheme of the RAQD is purely ultrasonic. Hence, even though the RAQD generates considerable sound, it is characterized as quiet because most or all of the sound is above the frequency range of human hearing.

  3. Rapid prototype and test

    SciTech Connect

    Gregory, D.L.; Hansche, B.D.

    1996-06-01

    In order to support advanced manufacturing, Sandia has acquired the capability to produce plastic prototypes using stereolithography. Currently, these prototypes are used mainly to verify part geometry and ``fit and form`` checks. This project investigates methods for rapidly testing these plastic prototypes, and inferring from prototype test data actual metal part performance and behavior. Performances examined include static load/stress response, and structural dynamic (modal) and vibration behavior. The integration of advanced non-contacting measurement techniques including scanning laser velocimetry, laser holography, and thermoelasticity into testing of these prototypes is described. Photoelastic properties of the epoxy prototypes to reveal full field stress/strain fields are also explored.

  4. Development of a Fluid-Particle Model in Simulating the Motion of External Solidified Crystals and the Evolution of Defect Bands in High-Pressure Die Casting

    NASA Astrophysics Data System (ADS)

    Bi, Cheng; Xiong, Shoumei; Li, Xiaobo; Guo, Zhipeng

    2016-04-01

    A numerical fluid-particle model was developed to simulate the motion of external solidified crystals (ESCs) in the melt during the filling process of high-pressure die casting (HPDC). Simulation results on a tensile bar casting with two types of ingates (semi-circle and circle) revealed that for a long time scale the ESCs tended to distribute in a ring pattern around the specimen center, whereas for a short time scale the ESC distribution changed constantly from the ring pattern to either the center pattern or the ring-center pattern. It was proposed that the defect bands would form at these areas where two solidification fronts met (where solidification shrinkage occurred), including one originating from the skin layer of the specimen and the other from the ESC region. Accordingly, three types of defect band patterns, which were commonly observed in HPDC experiment, could be successfully simulated and explained using this model.

  5. Effect of swaging on the 1000 C compressive slow plastic flow characteristics of the directionally solidified eutectic alloy gamma/gamma prime-alpha

    NASA Technical Reports Server (NTRS)

    Whittenberger, J. D.; Wirth, G.

    1983-01-01

    Swaging between 750 and 1050 C has been investigated as a means to introduce work into the directionally solidified eutectic alloy gamma/gamma prime-alpha (Ni-32.3 wt percent Mo-6.3 wt percent Al) and increase the elevated temperature creep strength. The 1000 C slow plastic compressive flow stress-strain rate properties in air of as-grown, annealed, and worked nominally 10 and 25 percent materials have been determined. Swaging did not improve the slow plastic behavior. In fact large reductions tended to degrade the strength and produced a change in the deformation mechanism from uniform flow to one involving intense slip band formation. Comparison of 1000 C tensile and compressive strength-strain rate data reveals that deformation is independent of the stress state.

  6. Stability of several oxide dispersion strengthened alloys and a directionally solidified gamma/gamma prime-alpha eutectic alloy in a thermal gradient

    NASA Technical Reports Server (NTRS)

    Staniek, G.; Whittenberger, J. D.

    1980-01-01

    Thermal gradient testing of three oxide dispersion strengthened alloys (two Ni-base alloys, MA 754 and MA 6000 E, and the Fe-base MA 956) and the directionally solidified eutectic alloy, gamma/gamma prime-alpha, have been conducted. Experiments were carried out with maximum temperatures up to 1200 C and thermal gradients on the order of 100 C/mm. The oxide dispersion strengthened alloys were difficult to test because the thermal stresses promoted crack nucleation and growth; thus the ability of these alloys to maintain a thermal gradient may be limited. The stability of individual fibers in gamma/gamma prime-alpha was excellent; however, microstructural changes were observed in the vicinity of grain boundaries. Similar structures were also observed in isothermally annealed material; therefore thermal gradients do not affect the microstructure of gamma/gamma prime-alpha in any significant manner.

  7. Experimental investigation of influence of acid rain on leaching and hydraulic characteristics of cement-based solidified/stabilized lead contaminated clay.

    PubMed

    Du, Yan-Jun; Jiang, Ning-Jun; Shen, Shui-Long; Jin, Fei

    2012-07-30

    Remediation of contaminated lands in China urban areas is of great concern. Degradation of construction facilities caused by acid rain is a serious environmental pollution issue in China. This paper presents an investigation of the effects of acid rain on leaching and hydraulic properties of cement-based solidified/stabilized lead contaminated soil. Laboratory tests including infiltration test and soaking test are conducted. It is found that the soil hydraulic conductivity decreases with increase in the pore volume of flow of permeant liquids (acid rain and distilled water). The decreasing rate in the case of the acid rain is lower than that in the case of the distilled water. The soaking test results show that pH and the presence of sulfate ions of acid rain have considerable influence on the leached concentrations and leaching rate of calcium. PMID:22614025

  8. Evaluation of Primary Dendrite Arm Spacings from Aluminum-7wt% Silicon alloys Directionally Solidified aboard the International Space Station - Comparison with Theory

    NASA Technical Reports Server (NTRS)

    Angart, Samuel; Lauer, Mark; Poirier, David; Tewari, Surendra; Rajamure, Ravi; Grugel, Richard

    2015-01-01

    Aluminum – 7wt% silicon alloys were directionally solidified in the microgravity environment aboard the International Space Station as part of the “MIcrostructure Formation in CASTing of Technical Alloys under Diffusive and Magnetically Controlled Convective Conditions” (MICAST) European led program. Cross-sections of the sample during periods of steady-state growth were metallographically prepared from which the primary dendrite arm spacing (lambda 1) was measured. These spacings were found to be in reasonable agreement with the Hunt-Lu model which assumes a diffusion-controlled, convectionless, environment during controlled solidification. Deviation from the model was found and is attributed to gravity-independent thermocapillary convection where, over short distances, the liquid appears to have separated from the crucible wall.

  9. Effect of Growth Rate on Elevated Temperature Plastic Flow and Room Temperature Fracture Toughness of Directionally Solidified NiAl-31Cr-3Mo

    NASA Technical Reports Server (NTRS)

    Whittenberger, J. Daniel; Raj, S. V.; Locci, I. E.; Salem, J. A.

    1999-01-01

    The eutectic system Ni-33Al-31Cr-3Mo was directionally solidified at rates ranging from 7.6 to 508 mm/h. Samples were examined for microstructure and alloy chemistry, compression tested at 1200 and 1300 K, and subjected to room temperature fracture toughness measurements. Lamellar eutectic grains were formed at 12.7 mm/h; however cellular structures with a radial eutectic pattern developed at faster growth rates. Elevated temperature compression testing between 10(exp -4) to 10(exp -7)/s did not reveal an optimum growth condition, nor did any single growth condition result in a significant fracture toughness advantage. The mechanical behavior, taken together, suggests that Ni-33Al-31Cr-3Mo grown at rates from 25.4 to 254 mm/h will have nominally equivalent properties.

  10. Effects of Minor Alloying Additions on the Microstructure, Toughness, and Creep Strength of Directionally Solidified NiAl-31Cr-3Mo

    NASA Technical Reports Server (NTRS)

    Whittenberger, J. D.; Raj, S. V.; Locci, I. E.; Salem, J. A.

    2001-01-01

    A study of the effects of small (0.25 to 1.0 at%) fifth element additions to the structure and mechanical properties of directionally solidified (DS) NiAl-31Cr-3Mo has been undertaken. Essentially all the additions changed the as-DS'ed microstructure from lamellar eutectic grains to cells and, in some cases, introduced NiAl dendrites and/or third phases. In general the alloying additions did not improve strength or toughness over that possessed by the base composition; only Hf and, perhaps Ti, gave a minor increase in elevated temperature creep resistance. The lack of improvement in creep properties is probably due to inability to precipitation harden NiAl.

  11. Microstructure Investigation of Directionally Solidified NiAl-Cr(Mo)- xDy ( x = 0, 0.1 wt.%) Hypereutectic Alloys at Different Withdrawal Rates

    NASA Astrophysics Data System (ADS)

    Wang, Lei; Shen, Jun; Shang, Zhao; Zhang, Jian-Fei; Du, Yu-Jun; Fu, Heng-Zhi

    2013-11-01

    The microstructures of directionally solidified Ni-31Al-32Cr-6Mo (at.%)- xDy ( x = 0, 0.1 wt.%) hypereutectic alloys were studied at different withdrawal rates. The results show that the microstructure changes from the planar eutectic to the cellular eutectic and the volume fraction of the primary Cr(Mo) dendrites decreases for the Dy-free alloy with the withdrawal rate varying from 6 μm/s to 30 μm/s. The addition of 0.1 wt.% Dy promotes the planar-to-cellular transition. Moreover, the white Dy-containing phase does not form in the alloy for the planar interface growth (6 μm/s), but it can occur in the boundary of eutectic cells for the cellular interface growth (30 μm/s). A sketchy model of the planar and cellular growth is supposed to interpret it.

  12. The Effect of Long-Term Thermal Exposure on the Microstructure and Stress Rupture Property of a Directionally Solidified Ni-Based Superalloy

    NASA Astrophysics Data System (ADS)

    Jiang, X. W.; Wang, D.; Xie, G.; Li, H.; Lou, L. H.; Zhang, J.

    2014-09-01

    Microstructural degradation and microstructure-property relationship during long-term thermal exposure in a directionally solidified Ni-based superalloy are systematically studied. The coarsening kinetics of γ' precipitation conforms well to the LSW model during the long-term thermal exposure. The detailed time dependence of MC decomposition during the long-term thermal exposure is revealed. Grain boundary coarsening was mainly facilitated by γ' and M23C6 precipitates coarsening in GBs region, and the GB coarsening kinetics conforms well to the JMAK theory. During different stages of the thermal exposure, dominant factors for the decrease of stress-rupture lifetime vary due to the evolution of multiple microstructures (γ' coarsening, MC decomposition, and grain boundary coarsening).

  13. The Effect of Long-Term Thermal Exposure on the Microstructure and Stress Rupture Property of a Directionally Solidified Ni-Based Superalloy

    NASA Astrophysics Data System (ADS)

    Jiang, X. W.; Wang, D.; Xie, G.; Li, H.; Lou, L. H.; Zhang, J.

    2014-12-01

    Microstructural degradation and microstructure-property relationship during long-term thermal exposure in a directionally solidified Ni-based superalloy are systematically studied. The coarsening kinetics of γ' precipitation conforms well to the LSW model during the long-term thermal exposure. The detailed time dependence of MC decomposition during the long-term thermal exposure is revealed. Grain boundary coarsening was mainly facilitated by γ' and M23C6 precipitates coarsening in GBs region, and the GB coarsening kinetics conforms well to the JMAK theory. During different stages of the thermal exposure, dominant factors for the decrease of stress-rupture lifetime vary due to the evolution of multiple microstructures ( γ' coarsening, MC decomposition, and grain boundary coarsening).

  14. Partial melting of a Pb-Sn mushy layer due to heating from above, and implications for regional melting of Earth's directionally solidified inner core

    NASA Astrophysics Data System (ADS)

    Yu, James; Bergman, Michael I.; Huguet, Ludovic; Alboussiere, Thierry

    2015-09-01

    Superimposed on the radial solidification of Earth's inner core may be hemispherical and/or regional patches of melting at the inner-outer core boundary. Little work has been carried out on partial melting of a dendritic mushy layer due to heating from above. Here we study directional solidification, annealing, and partial melting from above of Pb-rich Sn alloy ingots. We find that partial melting from above results in convection in the mushy layer, with dense, melted Pb sinking and resolidifying at a lower height, yielding a different density profile than for those ingots that are just directionally solidified, irrespective of annealing. Partial melting from above causes a greater density deeper down and a corresponding steeper density decrease nearer the top. There is also a change in microstructure. These observations may be in accordance with inferences of east-west and perhaps smaller-scale variations in seismic properties near the top of the inner core.

  15. Effects of Microalloying on the Microstructures and Mechanical Properties of Directionally Solidified Ni-33(at.%)Al-31Cr-3Mo Eutectic Alloys Investigated

    NASA Technical Reports Server (NTRS)

    Whittenberger, J. Daniel; Raj, Sai V.; Locci, Ivan E.; Salem, Jonathan A.

    2002-01-01

    Despite nickel aluminide (NiAl) alloys' attractive combination of oxidation and thermophysical properties, their development as replacements for superalloy airfoils in gas turbine engines has been largely limited by difficulties in developing alloys with an optimum combination of elevated-temperature creep resistance and room-temperature fracture toughness. Alternatively, research has focused on developing directionally solidified NiAl-based in situ eutectic composites composed of NiAl and (Cr,Mo) phases in order to obtain a desirable combination of properties a systematic investigation was undertaken at the NASA Glenn Research Center to examine the effects of small additions of 11 alloying elements (Co, Cu, Fe, Hf, Mn, Nb, Re, Si, Ta, Ti, and Zr) in amounts varying from 0.25 to 1.0 at.% on the elevated-temperature strength and room-temperature fracture toughness of directionally solidified Ni-33Al-31Cr-3Mo eutectic alloy. The alloys were grown at 12.7 mm/hr, where the unalloyed eutectic base alloy exhibited a planar eutectic microstructure. The different microstructures that formed because of these fifth-element additions are included in the table. The additions of these elements even in small amounts resulted in the formation of cellular microstructures, and in some cases, dendrites and third phases were observed. Most of these elemental additions did not improve either the elevated-temperature strength or the room-temperature fracture toughness over that of the base alloy. However, small improvements in the compression strength were observed between 1200 and 1400 K when 0.5 at.% Hf and 0.25 at.% Ti were added to the base alloy. The results of this study suggest that the microalloying of Ni-33Al-31Cr-3Mo will not significantly improve either its elevatedtemperature strength or its room-temperature fracture toughness. Thus, any improvements in these properties must be acquired by changing the processing conditions.

  16. Microstructural Characterization of a Directionally-Solidified Ni-33 (at. %)Al-31Cr-3Mo Eutectic Alloy as a Function of Withdrawal Rate

    NASA Technical Reports Server (NTRS)

    Raj, S. V.; Locci, I. E.; Whittenberger, J. D.; Salem, J. A.

    2000-01-01

    The Ni-33 (at. %)Al-3lCr-3Mo eutectic alloy was directionally-solidified (DS) at different rates, V(sub I), varying between 2.5 to 508 mm/ h. Detailed qualitative and quantitative metallographic and chemical analyses were conducted on the directionally-solidified rods. The microstructures consisted of eutectic colonies with parallel lamellar NiAl/(Cr,Mo) plates for solidification rates at and below 12.7 mm/ h. Cellular eutectic microstructures were observed at higher solidification rates, where the plates exhibited a radial pattern. The microstructures were demonstrated to be fairly uniform throughout a 100 mm length of the DS zone by quantitative metallography. The average cell size, bar-d, decreased with increasing growth rate to a value of 125 microns at 508 mm/ h according to the relation bar-d (microns) approx. = 465 V(sup -0.22, sub I), where V(sub I) is in mm/ h. Both the average NiAl plate thickness, bar-Delta(sub NiAl), and the interlamellar spacing, bar-lambda, were observed to be constant for V(sub I) less than or = 50.8 mm/ h but decreased with increasing growth rate above this value as 0.93 bar-Delta(sub NiAl)(microns) = 61.2 V(sup -0.93, sub I) and bar-lambda (microns) = 47.7 V(sup -0.64, sub I), respectively. The present results are detailed on a microstructural map. Keywords Optical microscopy, microstructure, compounds intermetallic, directional solidification

  17. Prediction of cracks in continuously cast steel beam blank through fully coupled analysis of fluid flow, heat transfer, and deformation behavior of a solidifying shell

    SciTech Connect

    Lee, J.E.; Yeo, T.J.; Oh, K.H.; Yoon, J.K.; Yoon, U.S.

    2000-01-01

    A mathematical model has been developed for the prediction of cracks in the continuously cast steel beam blank through the fully coupled analysis of fluid flow, heat transfer, and deformation behavior of a solidifying shell. Fluid flow and heat transfer in the strand mold were analyzed with a three-dimensional (3-D) finite-volume method (FVM). For the complex geometry of the beam blank, a body-fitted coordinate (BFC) system was employed, Thermo-elastic-plastic deformation behavior in the strand was analyzed using the finite-element method (FEM) based on the two-dimensional (2-D) slice model. The thermal fields of the strand calculated with the FVM were used in the analysis of the deformation behavior of the strand. Through the iterative analysis of the fluid flow, heat-transfer, and deformation behavior, the coupling parameter of the heat-transfer coefficient between the strand and the mold was obtained. In order to describe the thermophysical properties and thermomechanical behavior of steel in the mushy zone, the microsegregation of solute elements was assessed. Consequently, some characteristic temperatures of steel as well as variations of phase fractions with temperature were determined. The probability of cracking in the strand, originating form an interdendritic liquid film, was quantified as a crack susceptibility coefficient. Recirculating flows were developed in the web and flange-tip regions. The development of a solidifying shell in the flange-center region was retarded by the inlet flow from a submerged entry nozzle (SEN). An air gap was formed mainly near the flange-tip corner. Surface cracks in the web and fillet regions and internal cracks in the flange-tip region were predicted.

  18. Development of a solidified self-microemulsifying drug delivery system (S-SMEDDS) for atorvastatin calcium with improved dissolution and bioavailability.

    PubMed

    Yeom, Dong Woo; Son, Ho Yong; Kim, Jin Han; Kim, Sung Rae; Lee, Sang Gon; Song, She Hyon; Chae, Bo Ram; Choi, Young Wook

    2016-06-15

    To improve the dissolution and oral bioavailability (BA) of atorvastatin calcium (ATV), we previously introduced an optimized self-microemulsifying drug delivery system (SMEDDS) using Capmul(®) MCM (oil), Tween(®) 20 (surfactant), and tetraglycol (cosurfactant). In this study, various solid carriers were employed to develop a solidified SMEDDS (S-SMEDDS): mannitol (M) and lactose (L) as water-soluble carriers, and Sylysia(®) 350 (S) and Aerosil(®) 200 (A) as water-insoluble carriers. Maximum solidifying capacities (SCmax) of water-insoluble carriers were significantly greater than those of water-soluble carriers were. The resultant powders were free flowing with an angle of repose <40° and Carr's index 5-20%, regardless of the solid carrier types. S-SMEDDS with mannitol (S(M)-SMEDDS) or lactose (S(L)-SMEDDS) had a smaller droplet size and greater dissolution than S-SMEDDS with Sylysia(®) 350 (S(S)-SMEDDS) or Aerosil(®) 200 (S(A)-SMEDDS). Following oral administration of various formulations to rats at a dose equivalent to 25mg/kg of ATV, plasma drug levels were measured by LC-MS/MS. The relative BAs (RBAs) of SMEDDS, S(M)-SMEDDS, and S(S)-SMEDDS were 345%, 216%, and 160%, respectively, compared to that of ATV suspension. Additionally, at a reduced dose of ATV equivalent to 5mg/kg, the RBAs of S(M)-SMEDDS and S(S)-SMEDDS compared to that of SMEDDS were 101% and 65%, respectively. These results suggest that S(M)-SEMDDS offers great potential for the development of solid dosage forms with improved oral absorption of drugs with poor water solubility. PMID:27125455

  19. Rapid mineralocorticoid receptor trafficking.

    PubMed

    Gekle, M; Bretschneider, M; Meinel, S; Ruhs, S; Grossmann, C

    2014-03-01

    The mineralocorticoid receptor (MR) is a ligand-dependent transcription factor that physiologically regulates water-electrolyte homeostasis and controls blood pressure. The MR can also elicit inflammatory and remodeling processes in the cardiovascular system and the kidneys, which require the presence of additional pathological factors like for example nitrosative stress. However, the underlying molecular mechanism(s) for pathophysiological MR effects remain(s) elusive. The inactive MR is located in the cytosol associated with chaperone molecules including HSP90. After ligand binding, the MR monomer rapidly translocates into the nucleus while still being associated to HSP90 and after dissociation from HSP90 binds to hormone-response-elements called glucocorticoid response elements (GREs) as a dimer. There are indications that rapid MR trafficking is modulated in the presence of high salt, oxidative or nitrosative stress, hypothetically by induction or posttranslational modifications. Additionally, glucocorticoids and the enzyme 11beta hydroxysteroid dehydrogenase may also influence MR activation. Because MR trafficking and its modulation by micro-milieu factors influence MR cellular localization, it is not only relevant for genomic but also for nongenomic MR effects. PMID:24252381

  20. Rapid Decisions From Experience

    PubMed Central

    Zeigenfuse, Matthew D.; Pleskac, Timothy J.; Liu, Taosheng

    2014-01-01

    In many everyday decisions, people quickly integrate noisy samples of information to form a preference among alternatives that offer uncertain rewards. Here, we investigated this decision process using the Flash Gambling Task (FGT), in which participants made a series of choices between a certain payoff and an uncertain alternative that produced a normal distribution of payoffs. For each choice, participants experienced the distribution of payoffs via rapid samples updated every 50 ms. We show that people can make these rapid decisions from experience and that the decision process is consistent with a sequential sampling process. Results also reveal a dissociation between these preferential decisions and equivalent perceptual decisions where participants had to determine which alternatives contained more dots on average. To account for this dissociation, we developed a sequential sampling rank-dependent utility model, which showed that participants in the FGT attended more to larger potential payoffs than participants in the perceptual task despite being given equivalent information. We discuss the implications of these findings in terms of computational models of preferential choice and a more complete understanding of experience-based decision making. PMID:24549141

  1. Rapid response manufacturing (RRM)

    SciTech Connect

    Cain, W.D.; Waddell, W.L.

    1997-02-18

    US industry is fighting to maintain its competitive edge in the global market place. Today markets fluctuate rapidly. Companies, to survive, have to be able to respond with quick-to-market, improved, high quality, cost efficient products. The way products are developed and brought to market can be improved and made more efficient through the proper incorporation of emerging technologies. The RRM project was established to leverage the expertise and resources of US private industries and federal agencies to develop, integrate, and deploy new technologies that meet critical needs for effective product realization. The RRM program addressed a needed change in the US Manufacturing infrastructure that will ensure US competitiveness in world market typified by mass customization. This project provided the effort needed to define, develop and establish a customizable infrastructure for rapid response product development design and manufacturing. A major project achievement was the development of a broad-based framework for automating and integrating the product and process design and manufacturing activities involved with machined parts. This was accomplished by coordinating and extending the application of feature-based product modeling, knowledge-based systems, integrated data management, and direct manufacturing technologies in a cooperative integrated computing environment. Key technological advancements include a product model that integrates product and process data in a consistent, minimally redundant manner, an advanced computer-aided engineering environment, knowledge-based software aids for design and process planning, and new production technologies to make products directly from design application software.

  2. The measurement of 129I for the cement and the paraffin solidified low and intermediate level wastes (LILWs), spent resin or evaporated bottom from the pressurized water reactor (PWR) nuclear power plants.

    PubMed

    Park, S D; Kim, J S; Han, S H; Ha, Y K; Song, K S; Jee, K Y

    2009-09-01

    In this paper a relatively simple and low cost analysis procedure to apply to a routine analysis of (129)I in low and intermediate level radioactive wastes (LILWs), cement and paraffin solidified evaporated bottom and spent resin, which are produced from nuclear power plants (NPPs), pressurized water reactors (PWR), is presented. The (129)I is separated from other nuclides in LILWs using an anion exchange adsorption and solvent extraction by controlling the oxidation and reduction state and is then precipitated as silver iodide for counting the beta activity with a low background gas proportional counter (GPC). The counting efficiency of GPC was varied from 4% to 8% and it was reversely proportional to the weight of AgI by a self absorption of the beta activity. Compared to a higher pH, the chemical recovery of iodide as AgI was lowered at pH 4. It was found that the chemical recovery of iodide for the cement powder showed a lower trend by increasing the cement powder weight, but it was not affected for the paraffin sample. In this experiment, the overall chemical recovery yield of the cement and paraffin solidified LILW samples and the average weight of them were 67+/-3% and 5.43+/-0.53 g, 70+/-7% and 10.40+/-1.60 g, respectively. And the minimum detectable activity (MDA) of (129)I for the cement and paraffin solidified LILW samples was calculated as 0.070 and 0.036 Bq/g, respectively. Among the analyzed cement solidified LILW samples, (129)I activity concentration of four samples was slightly higher than the MDA and their ranges were 0.076-0.114 Bq/g. Also of the analyzed paraffin solidified LILW samples, five samples contained a little higher (129)I activity concentration than the MDA and their ranges were 0.036-0.107 Bq/g. PMID:19297180

  3. Rapid shallow breathing index.

    PubMed

    Karthika, Manjush; Al Enezi, Farhan A; Pillai, Lalitha V; Arabi, Yaseen M

    2016-01-01

    Predicting successful liberation of patients from mechanical ventilation has been a focus of interest to clinicians practicing in intensive care. Various weaning indices have been investigated to identify an optimal weaning window. Among them, the rapid shallow breathing index (RSBI) has gained wide use due to its simple technique and avoidance of calculation of complex pulmonary mechanics. Since its first description, several modifications have been suggested, such as the serial measurements and the rate of change of RSBI, to further improve its predictive value. The objective of this paper is to review the utility of RSBI in predicting weaning success. In addition, the use of RSBI in specific patient populations and the reported modifications of RSBI technique that attempt to improve the utility of RSBI are also reviewed. PMID:27512505

  4. rapidMCR

    SciTech Connect

    2011-11-04

    rapidMCR is a user friendly software package that includes automatic preprocessing, analysis, and viewing of hyperspectral image data sets. Currently, this software package specifically preprocesses and analyzes hyperspectral fluorescence image data sets that have been created on Sandia hyperspectral imaging microscopes; however, this software can be modified to include spectroscopic image data sets from other (non-Sandia developed) instruments as well. This software relies on using prior information about the spectroscopic image data sets by conducting a rigorous characterization of the instrument. By characterizing the instrument for noise and artifacts, we can implement our algorithms to account for the effects specific to a particular instrument. This allows us to automate the data preprocessing while improving the analysis results.

  5. rapidMCR

    Energy Science and Technology Software Center (ESTSC)

    2011-11-04

    rapidMCR is a user friendly software package that includes automatic preprocessing, analysis, and viewing of hyperspectral image data sets. Currently, this software package specifically preprocesses and analyzes hyperspectral fluorescence image data sets that have been created on Sandia hyperspectral imaging microscopes; however, this software can be modified to include spectroscopic image data sets from other (non-Sandia developed) instruments as well. This software relies on using prior information about the spectroscopic image data sets by conductingmore » a rigorous characterization of the instrument. By characterizing the instrument for noise and artifacts, we can implement our algorithms to account for the effects specific to a particular instrument. This allows us to automate the data preprocessing while improving the analysis results.« less

  6. Solid state rapid thermocycling

    SciTech Connect

    Beer, Neil Reginald; Spadaccini, Christopher

    2014-05-13

    The rapid thermal cycling of a material is targeted. A solid state heat exchanger with a first well and second well is coupled to a power module. A thermoelectric element is coupled to the first well, the second well, and the power module, is configured to transfer thermal energy from the first well to the second well when current from the power module flows through the thermoelectric element in a first direction, and is configured to transfer thermal energy from the second well to the first well when current from the power module flows through the thermoelectric element in a second direction. A controller may be coupled to the thermoelectric elements, and may switch the direction of current flowing through the thermoelectric element in response to a determination by sensors coupled to the wells that the amount of thermal energy in the wells falls below or exceeds a pre-determined threshold.

  7. Rapid Polymer Sequencer

    NASA Technical Reports Server (NTRS)

    Stolc, Viktor (Inventor); Brock, Mathew W. (Inventor)

    2011-01-01

    Method and system for rapid and accurate determination of each of a sequence of unknown polymer components, such as nucleic acid components. A self-assembling monolayer of a selected substance is optionally provided on an interior surface of a pipette tip, and the interior surface is immersed in a selected liquid. A selected electrical field is impressed in a longitudinal or transverse direction at the tip, a polymer sequence is passed through the tip, and a change in an electrical current signal is measured as each polymer component passes through the tip. Each measured change in electrical current signals is compared with a database of reference signals, with each reference signal identified with a polymer component, to identify the unknown polymer component. The tip preferably has a pore inner diameter of no more than about 40 nm and is prepared by heating and pulling a very small section of a glass tubing.

  8. Rapid mercury assays

    SciTech Connect

    Szurdoki, S.; Kido, H.; Hammock, B.D.

    1996-10-01

    We have developed rapid assays with the potential of detecting mercury in environmental samples. our methods combine the simple ELISA-format with the selective, high affinity complexation of mercuric ions by sulfur-containing ligands. The first assay is based on a sandwich chelate formed by a protein-bound ligand immobilized on the wells of a microliter plate, mercuric ion of the analyzed sample, and another ligand conjugated to a reporter enzyme. The second assay involves competition between mercuric ions and an organomercury-conjugate to bind to a chelating conjugate. Several sulfur containing chelators (e.g., dithiocarbamates) and organomercurials linked to macromolecular carriers have been investigated in these assay formats. The assays detect mercuric ions in ppb/high ppt concentrations with high selectivity.

  9. Rapid shallow breathing index

    PubMed Central

    Karthika, Manjush; Al Enezi, Farhan A.; Pillai, Lalitha V.; Arabi, Yaseen M.

    2016-01-01

    Predicting successful liberation of patients from mechanical ventilation has been a focus of interest to clinicians practicing in intensive care. Various weaning indices have been investigated to identify an optimal weaning window. Among them, the rapid shallow breathing index (RSBI) has gained wide use due to its simple technique and avoidance of calculation of complex pulmonary mechanics. Since its first description, several modifications have been suggested, such as the serial measurements and the rate of change of RSBI, to further improve its predictive value. The objective of this paper is to review the utility of RSBI in predicting weaning success. In addition, the use of RSBI in specific patient populations and the reported modifications of RSBI technique that attempt to improve the utility of RSBI are also reviewed. PMID:27512505

  10. Rapid geophysical surveyor

    SciTech Connect

    Roybal, L.G.; Carpenter, G.S.; Josten, N.E.

    1993-01-01

    The Rapid Geophysical Surveyor (RGS) is a system designed to rapidly and economically collect closely-spaced geophysical data used for characterization of Department of Energy (DOE) waste sites. Geophysical surveys of waste sites are an important first step in the remediation and closure of these sites; especially older sties where historical records are inaccurate and survey benchmarks have changed due to refinements in coordinate controls and datum changes. Closely-spaced data are required to adequately differentiate pits, trenches, and soil vault rows whose edges may be only a few feet from each other. A prototype vehicle designed to collect magnetic field data was built at the Idaho national Engineering Laboratory (INEL) during the summer of 1992. The RGS was one of several projects funded by the Buried Waste Integrated Demonstration (BWID) program. This vehicle was demonstrated at the Subsurface Disposal Area (SDA) within the Radioactive Waste Management Complex (RWMC) on the INEL in September of 1992. Magnetic data were collected over two areas in the SDA, with a total survey area of about 1.7 acres. Data were collected at a nominal density of 2 1/2 inches along survey lines spaced 1 foot apart. Over 350,000 data points were collected over a 6 day period corresponding to about 185 man-days using conventional ground survey techniques. This report documents the design and demonstration of the RGS concept including the presentation of magnetic data collected at the SDA. The surveys were able to show pit and trench boundaries and determine details of their spatial orientation never before achieved.

  11. Rapid geophysical surveyor

    SciTech Connect

    Roybal, L.G.; Carpenter, G.S.; Josten, N.E.

    1993-07-01

    The Rapid Geophysical Surveyor (RGS) is a system designed to rapidly and economically collect closely-spaced geophysical data used for characterization of Department of Energy (DOE) waste sites. Geophysical surveys of waste sites are an important first step in the remediation and closure of these sites; especially older sties where historical records are inaccurate and survey benchmarks have changed due to refinements in coordinate controls and datum changes. Closely-spaced data are required to adequately differentiate pits, trenches, and soil vault rows whose edges may be only a few feet from each other. A prototype vehicle designed to collect magnetic field data was built at the Idaho national Engineering Laboratory (INEL) during the summer of 1992. The RGS was one of several projects funded by the Buried Waste Integrated Demonstration (BWID) program. This vehicle was demonstrated at the Subsurface Disposal Area (SDA) within the Radioactive Waste Management Complex (RWMC) on the INEL in September of 1992. Magnetic data were collected over two areas in the SDA, with a total survey area of about 1.7 acres. Data were collected at a nominal density of 2 1/2 inches along survey lines spaced 1 foot apart. Over 350,000 data points were collected over a 6 day period corresponding to about 185 man-days using conventional ground survey techniques. This report documents the design and demonstration of the RGS concept including the presentation of magnetic data collected at the SDA. The surveys were able to show pit and trench boundaries and determine details of their spatial orientation never before achieved.

  12. Advances in rapid prototyping

    SciTech Connect

    Atwood, C.L.; McCarty, G.D.; Pardo, B.T.; Bryce, E.A.

    1993-12-31

    Recent advances in stereolithography and selective laser sintering have had a significant impact on the overall quality of parts produced using these rapid prototyping processes. The development and implementation of 3D System`s QuickCast{trademark} resin and software for building investment casting patterns have proven to be major steps toward fabricating highly accurate patterns with very good surface finishes. Sandia uses patterns generated from rapid prototyping processes to reduce the cycle time and cost of fabricating prototype parts in support of a Sandia National Laboratories managed program called FASTCAST. As participants in the Beta test program for QuickCast{trademark} resin and software, they experienced a steep learning curve and were able to build accurate parts in a short period of time. It is now possible, using this technology, to produce highly accurate prototype parts as well as acceptable firs article and small lots size production parts. They use the Selective Laser Sintering (SLS) process to fabricate prototype wax patterns for investment casting. DTM Corporation recently introduced the use of their polycarbonate material for fabricating investment casting patterns. The polycarbonate material is processed significantly faster, with improved strength, dimensional stability, and without a support structure during the build process. Sandia is currently changing from investment casting wax to polycarbonate for the fabrication of investment casting patterns using the SLS process. This presentation will focus on the successes with these new materials from the standpoints of application, accuracy, surface finish, and post processing. Also presented will be examples of parts manufactured by these processes.

  13. Fracture toughness and fatigue crack growth in rapidly quenched Nb-Cr-Ti in situ composites

    SciTech Connect

    Chan, K.S.; Davidson, D.L.; Anton, D.L.

    1997-09-01

    In situ composites based on the Nb-Cr-Ti ternary system were processed by rapid solidification in order to reduce the size of the reinforcing intermetallic phase. Two-phase microstructures with small Cr{sub 2}Nb particles in a Nb(Cr, Ti) solid solution alloy matrix were produced for several compositions that previous work showed to produce high toughness composites in cast materials. The fracture and fatigue behaviors of these composites were characterized at ambient temperature. The results indicate that the fracture resistance increases with a decreasing volume of Cr{sub 2}Nb particles. Fracture toughnesses of the rapidly solidified materials with their smaller particle sizes were lower than for conventionally processed composites with larger particles of the intermetallic compound. The fatigue crack growth rate curves exhibit steep slopes and a low critical stress intensity factor at fracture. The lack of fracture and fatigue resistance is attributed to the continguity of the intermetallic particles and the absence of plastic flow in the Nb solid solution matrix. The matrix alloy appears to be embrittled by (1) the rapid solidification processing that prevented plastic relaxation of residual stresses, (2) a high oxygen content, and (3) the constraint caused by the hard Cr{sub 2}Nb particles.

  14. The Rapid Transient Surveyor

    NASA Astrophysics Data System (ADS)

    Baranec, Christoph; Tonry, John; Wright, Shelley; Tully, R. Brent; Lu, Jessica R.; Takamiya, Marianne Y.; Hunter, Lisa

    2016-01-01

    The next decade of astronomy will be dominated by large area surveys (see the detailed discussion in the Astro-2010 Decadal survey and NRC's recent OIR System Report). Ground-based optical transient surveys, e.g., LSST, ZTF and ATLAS and space-based exoplanet, supernova, and lensing surveys such as TESS and WFIRST will join the Gaia all-sky astrometric survey in producing a flood of data that will enable leaps in our understanding of the universe. There is a critical need for further characterization of these discoveries through high angular resolution images, deeper images, spectra, or observations at different cadences or periods than the main surveys. Such follow-up characterization must be well matched to the particular surveys, and requires sufficient additional observing resources and time to cover the extensive number of targets.We describe plans for the Rapid Transient Surveyor (RTS), a permanently mounted, rapid-response, high-cadence facility for follow-up characterization of transient objects on the U. of Hawai'i 2.2-m telescope on Maunakea. RTS will comprise an improved robotic laser adaptive optics system, based on the prototype Robo-AO system (formerly at the Palomar 1.5-m and now at the Kitt Peak 2.2-m telescope), with simultaneous visible and near-infrared imagers as well as a near-infrared integral field spectrograph (R~100, λ = 850 - 1830 nm, 0.15″ spaxels, 8.7″×6.0″ FoV). RTS will achieve an acuity of ~0.07″ in visible wavelengths and < 0.16″ in the near infrared leading to an increase of the infrared point-source sensitivity against the sky background by a factor of ~9, crucial for efficient near-infrared spectroscopy.RTS will allow us to map the dark matter distribution in the z < 0.1 local universe with ten times better accuracy and precision than previous experiments. ATLAS will discover several thousand SNIae per year, measuring SNIa peak brightness, and decline rates, while RTS will measure reddening by dust, confirm SN type and

  15. Rapid Evaporation of microbubbles

    NASA Astrophysics Data System (ADS)

    Gautam, Jitendra; Esmaeeli, Asghar

    2008-11-01

    When a liquid is heated to a temperature far above its boiling point, it evaporates abruptly. Boiling of liquid at high temperatures can be explosive and destructive, and poses a potential hazard for a host of industrial processes. Explosive boiling may occur if a cold and volatile liquid is brought into contact with a hot and non-volatile liquid, or if a liquid is superheated or depressurized rapidly. Such possibilities are realized, for example, in the depressurization of low boiling point liquefied natural gas (LNG) in the pipelines or storage tanks as a result of a leak. While boiling of highly heated liquids can be destructive at macroscale, the (nearly) instantaneous pace of the process and the release of large amount of kinetic energy make the phenomena extremely attractive at microscale where it is possible to utilize the released energy to derive micromechanical systems. For instance, there is currently a growing interest in micro-explosion of liquid for generation of micro bubbles for actuation purposes. The aim of the current study is to gain a fundamental understanding of the subject using direct numerical simulations. In particular, we seek to investigate the boundary between stable and unstable nucleus growth in terms of the degree of liquid superheat and to compare the dynamics of unstable and stable growth.

  16. Rapid Polymer Sequencer

    NASA Technical Reports Server (NTRS)

    Stolc, Viktor (Inventor); Brock, Matthew W (Inventor)

    2013-01-01

    Method and system for rapid and accurate determination of each of a sequence of unknown polymer components, such as nucleic acid components. A self-assembling monolayer of a selected substance is optionally provided on an interior surface of a pipette tip, and the interior surface is immersed in a selected liquid. A selected electrical field is impressed in a longitudinal direction, or in a transverse direction, in the tip region, a polymer sequence is passed through the tip region, and a change in an electrical current signal is measured as each polymer component passes through the tip region. Each of the measured changes in electrical current signals is compared with a database of reference electrical change signals, with each reference signal corresponding to an identified polymer component, to identify the unknown polymer component with a reference polymer component. The nanopore preferably has a pore inner diameter of no more than about 40 nm and is prepared by heating and pulling a very small section of a glass tubing.

  17. Problems of rapid growth.

    PubMed

    Kim, T D

    1980-01-01

    South Korea's export-oriented development strategy has achieved a remarkable growth record, but it has also brought 2 different problems: 1) since the country's exports accounted for about 1% of total world export volume, the 1st world has become fearful about Korea's aggressive export drive; and 2) the fact that exports account for over 30% of its total gross national product (GNP) exposes the vulnerability of South Korea's economy itself. South Korea continues to be a poor nation, although it is rated as 1 of the most rapidly growing middle income economies. A World Bank 1978 report shows Korea to be 28th of 58 middle income countries in terms of per capita GNP in 1976. Of 11 newly industrializing countries (NIC), 5 in the European continent are more advanced than the others. A recent emphasis on the basic human needs approach has tended to downgrade the concept of GNP. Korea has only an abundant labor force and is without any natural resources. Consequently, Korea utilized an export-oriented development strategy. Oil requirements are met with imports, and almost all raw materials to be processed into exportable products must be imported. To pay import bills Korea must export and earn foreign exchange. It must be emphasized that foreign trade must always be 2-way traffic. In order to export more to middle income countries like Korea, the countries of the 1st world need to ease their protectionist measures against imports from developing countries. PMID:12336527

  18. Preparation and characterization of Al2O3/Y3Al5O12/ZrO2 ternary hypoeutectic in situ composites by laser rapid solidification

    NASA Astrophysics Data System (ADS)

    Su, Haijun; Zhang, Jun; Tian, Junjie; Liu, Lin; Fu, Hengzhi

    2008-07-01

    The directionally solidified oxide eutectic in situ composite is one of the most promising high-temperature structural materials in oxidizing environments. Pore-free rods and plates of ternary Al2O3/Y3Al5O12 (YAG)/ZrO2 hypoeutectic in situ composites with hypoeutectic composition (71 mol % Al2O3, 17 mol % Y2O3, and 12 mol % ZrO2) are prepared rapidly by the laser zone remelting technique. The hypoeutectic growth and microstructure characteristic of grown crystals are studied using the scanning electron microscopy, x-ray diffraction, and energy dispersive spectroscopy, aiming to understand well the rapid solidification behavior of the ternary oxide system of Al2O3-Y2O3-ZrO2. The rapidly solidified Al2O3/YAG/ZrO2 hypoeutectic shows a refined, interpenetrating, and irregular lamellar structure with a reticular distribution of coarse Al2O3 and yttrium aluminum garnet (YAG) and smaller ZrO2 phases. The fine ZrO2 phases are partially embedded at the Al2O3/YAG interfaces. Moreover, the typical dendrite microstructure similar to the metallic solidification is also observed. The formation of two kinds of microstructures is mainly attributed to the rapid growth during the laser zone remelting and constitutional supercooling. The Al2O3 and YAG phases grow in a typical faceted manner, and the ZrO2 phase presents a weak-faceted growth. The size of the interphase spacing obtained decreases rapidly in increasing the laser scanning rate. The fundamental investigations on the irregular growth mechanisms of the hypoeutectic are suggestive to the comprehension of the complex solidification behavior of the ternary oxide systems.

  19. Rapid mixing kinetic techniques.

    PubMed

    Martin, Stephen R; Schilstra, Maria J

    2013-01-01

    Almost all of the elementary steps in a biochemical reaction scheme are either unimolecular or bimolecular processes that frequently occur on sub-second, often sub-millisecond, time scales. The traditional approach in kinetic studies is to mix two or more reagents and monitor the changes in concentrations with time. Conventional spectrophotometers cannot generally be used to study reactions that are complete within less than about 20 s, as it takes that amount of time to manually mix the reagents and activate the instrument. Rapid mixing techniques, which generally achieve mixing in less than 2 ms, overcome this limitation. This chapter is concerned with the use of these techniques in the study of reactions which reach equilibrium; the application of these methods to the study of enzyme kinetics is described in several excellent texts (Cornish-Bowden, Fundamentals of enzyme kinetics. Portland Press, 1995; Gutfreund, Kinetics for the life sciences. Receptors, transmitters and catalysis. Cambridge University Press, 1995).There are various ways to monitor changes in concentration of reactants, intermediates and products after mixing, but the most common way is to use changes in optical signals (absorbance or fluorescence) which often accompany reactions. Although absorbance can sometimes be used, fluorescence is often preferred because of its greater sensitivity, particularly in monitoring conformational changes. Such methods are continuous with good time resolution but they seldom permit the direct determination of the concentrations of individual species. Alternatively, samples may be taken from the reaction volume, mixed with a chemical quenching agent to stop the reaction, and their contents assessed by techniques such as HPLC. These methods can directly determine the concentrations of different species, but are discontinuous and have a limited time resolution. PMID:23729251

  20. Characterization of solidified radioactive waste and container due to the incorporation of high density polyethylene granules and powder in mortar matrices

    SciTech Connect

    Peric, A.D.

    1999-07-01

    Powder and granules of the high density polyethylene (PEHD) were used to prepare mortar based matrices for immobilization of radioactive waste materials containing {sup 137}Cs, as well as containers for solidified radioactive waste form. Seven types of matrices, differ due to the percentage of granules and filler material added, were investigated. PEHD powder and granules were added to mortar matrix preparations with the objective of improving physico-chemical characteristics of the radwaste-mortar matrix mixtures, in particular the leach-rate of the immobilized radionuclide, as well as mechanical characteristics either of mortar matrix and container. In this paper, only mechanical strength aspect of the investigated mortar and concrete container formulations, is presented. The equivalent diameter of the PEHD granules used was 2.0 mm. PEHD granules were used to replace 100 volume percent of stone granules, sifted size of 2.0 mm, normally used in the matrix preparation, in order to decrease the porosity and density of the mortar matrix and to avoid segregation of the stone particles at the bottom of the immobilized radioactive waste cylindrical form. PEHD powder, particle size of 250 micrometer, was added as filler to the mortar formulation, replacing 5, 8 and 10 wt% of the total cement weight in matrix formulation and 15 and 18 wt% of the total cement weight in container formulation. Cured samples were investigated on mechanical strength, using 150 MPa hydraulic press, in order to determine influence of added polyethylene granules and powder on samples resistance to mechanical forces that solidified waste materials and concrete containers may experience at the disposal site. Results of performed investigations have shown that samples prepared with polyethylene granules, replacing 100 wt% of the stone granules, have almost twice as much mechanical strength than samples prepared with stone aggregate. Samples prepared with PEHD granules and powder have mechanical