Science.gov

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. 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.

  19. 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.

  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. 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.

  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. 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.

  19. 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.

  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. 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.

  8. 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.

  9. 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.

  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. 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.

  17. 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.

  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. 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.

  20. 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

  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. 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.

  5. 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.

  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. 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.

  9. 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.

  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. 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.

  19. 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).

  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. 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.

  5. 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.

  6. 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.

  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. 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.

  6. 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.

  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. 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.

  5. 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.

  6. 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.

  7. 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.

  8. 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.

  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. 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.

  16. 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

  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. 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.

  19. 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.

  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. 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.

  3. 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

  4. 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.

  5. 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

  6. 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.

  7. 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.

  8. 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.

  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. 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.

  12. 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.

  13. 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.

  14. 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.

  15. 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})

  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. 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.

  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. 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.

  6. 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

  7. 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.

  8. 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.

  9. 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

  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. 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.

  18. 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.

  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. 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.

  1. 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.

  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. 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.

  8. 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

  9. 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.

  10. 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.

  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. 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.

  15. 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.

  16. 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.

  17. 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.

  18. 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.

  19. 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%.

  20. 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.

  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. 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.

  3. 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.

  4. 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.

  5. 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

  6. 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.

  7. 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.

  8. 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.

  9. 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.

  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.