Showing papers on "Alloy published in 1991"
TL;DR: In this paper, a double-phase alloy was proposed to improve the electrocatalytic activity of hydride forming intermetallic compounds of the ABs-type without making use of highly electrocalytic precious metals like Pd or Pt.
Abstract: A new class of materials is proposed to improve the electrocatalytic activity of hydride forming intermetallic compounds of the ABs-type without making use of highly electrocatalytic precious metals like Pd or Pt. These materials, denoted as ABe.5, consist of two different crystallographic phases: the bulk phase, still responsible for hydrogen storage, is formed by the corrosion-resistant multicomponent "standard alloy" based on LaNis; and a second phase, homogeneously decorating the surface of the bulk-phase particles, provides for the extremely fast electrochemical hydrogen reaction. The composition of the second-phase alloy is such that synergism in the electrocatalysis occurs. A simple metallurgical method of producing double-phase materials is described. Various analytical techniques such as EPMA and x-ray diffraction are employed to characterize the solids produced. It is shown that the kinetics of the charge-transfer reaction can be characterized electrochemically by the overall exchange current. In accordance with the Brewer-Engel theory, MoCo3 precipitates are found to be highly electrocatalytic, which is reflected in an increase of the overall exchange current from 190 mA. g-1 for the single-phase AB5 compound to 588 mA. g-L As a consequence very high discharge efficiencies are accomplished with these MoCo3-based powder electrodes, even under extreme conditions: at 0~ the efficiency is improved from 34 to 90%.
390 citations
TL;DR: In this paper, the authors show that room-temperature ductility can be improved dramatically by microalloying with iron, gallium or molybdenum, and the next challenge is to develop an alloy which has the required balance of ductility, toughness and strength.
Abstract: If their properties can be improved, nickel aluminide alloys offer significant payoffs in gas turbine engine applications. For these materials, excellent progress has been made toward understanding their mechanical behavior as well as improving their low-temperature ductility and high-temperature strength. For example, recent work shows that room-temperature ductility can be improved dramatically by microalloying with iron, gallium or molybdenum. The next challenge is to develop an alloy which has the required balance of ductility, toughness and strength. Development of design and test methodologies for components made out of low-ductility, anisotropic materials will also be required. While significant challenges remain, the continuing developments suggest that the prognosis for using NiAl alloys as high-temperature structural materials is good.
325 citations
Patent•
19 Jun 1991
TL;DR: In this paper, a green compact formed by compacting Al-contg. ferrite alloy powder to a prescribed shape is sintered in a nonoxidizing atmosphere and alumina is deposited on the surface of the resulting Sintered body by heat treatment in an atmosphere of oxidizing gas.
Abstract: PURPOSE:To obtain an alloy sintered body having high surface hardness and excellent wear resistance and hardly causing chipping and cracking by a method with suitability for mass production. CONSTITUTION:A green compact formed by compacting Al-contg. ferrite alloy powder to a prescribed shape is sintered in a nonoxidizing atmosphere and alumina is deposited on the surface of the resulting sintered body by heat treatment in an atmosphere of oxidizing gas.
301 citations
TL;DR: Serum concentration and urinary excretion of titanium, aluminum, and vanadium were measured for patients who had a well functioning cementless primary total hip replacement of one of two different designs, for patients Who had a loose total hip replacements that was to be revised, and for control subjects who had no implant.
Abstract: Serum concentration and urinary excretion of titanium, aluminum, and vanadium were measured for patients who had a well functioning cementless primary total hip replacement of one of two different designs, for patients who had a loose total hip replacement that was to be revised, and for control subjects who had no implant. Serum concentrations of titanium were elevated approximately twofold in the patients who had a loose implant, compared with the values for the control subjects. No major differences in terms of urine concentration of titanium, serum concentration of aluminum, or urine concentration of aluminum were observed among any of the groups that were studied. Concentrations of vanadium were uniformly low in all groups.
292 citations
TL;DR: In this article, a technique for fabricating metal matrix composites by the spontaneous (pressureless) infiltration of filler preforms with molten aluminium alloys is described, and the effects of processing variables, such as alloy chemistry, process temperature, and filler material, on the infiltration kinetics and resultant microstructures are discussed.
Abstract: A novel technique for fabricating metal matrix composites by the spontaneous (pressureless) infiltration of filler preforms with molten aluminium alloys is described. Numerous reinforcing materials, including Al2O3 and SiC of various configurations, such as particles, agglomerates, and fibres, have been incorporated as fillers. The effects of processing variables, such as alloy chemistry, process temperature, and filler material, on the infiltration kinetics and resultant microstructures are discussed. Comparisons with existing infiltration technology and preliminary composite properties are presented.
277 citations
TL;DR: The mechanism and kinetics of the hydrogen evolution reaction were studied in on nickel-zinc alloy electrodes prepared by electrodeposition at controlled potential as discussed by the authors, and it was found that the reaction proceeds via the Volmer-Heyrovsky mechanism.
Abstract: The mechanism and kinetics of the hydrogen evolution reaction were studied in on nickel‐zinc alloy electrodes prepared by electrodeposition at controlled potential A series of electrodes containing 70 to 28% Ni was prepared Before the measurements, zinc was leached in alkaline solution Using the ac impedance technique, it was found that the reaction proceeds via the Volmer‐Heyrovsky mechanism, and the kinetic parameters of the process were determined With a decrease in the nickel content, the electrode becomes more active, and an increase in the real surface area is observed The surface morphology was studied using SEM and optical microscopy
251 citations
TL;DR: In this paper, the authors studied the oxidation kinetics of copper thin films at temperatures below 200 °C in air and found that the amorphous Cu65Ti35 alloy film is more oxidation resistant than the crystalline phase.
Abstract: The oxidation kinetics of copper thin films have been studied at temperatures below 200 °C in air. The protection of copper from oxidation can be achieved by alloying copper film with Ti, Pd, Cr, or Al. The influence of the composition and microstructure to the oxidation rate has been studied. The compounds Cu3Ti, Cu3Pd, and CuAl2 are stable in the oxidation ambient. The formation of Cr‐oxide, which is a passive oxide, explains the inhibition of oxidation on Cu‐Cr films. Compared with the crystalline phase, the amorphous Cu65Ti35 alloy film is more oxidation resistant. A TiN layer with oxygen incorporated is more effective in preventing copper oxidation than a TiN layer without oxygen incorporated. A passivating Si3N4 layer on copper thin films can prevent copper oxidation effectively at 350 °C in oxygen ambient.
249 citations
TL;DR: The metastable alloy is seen to evolve from a spin glass at low Co concentrations to a reentrant spin glass with evidence for both ferromagnetic and spin-glass ordering, and finally to a ferromagnet for xg0.40.
Abstract: Crystalline ${\mathrm{Co}}_{\mathit{x}}$${\mathrm{Cu}}_{1\mathrm{\ensuremath{-}}\mathit{x}}$ alloys, which cannot be obtained by equilibrium methods, have been fabricated by magnetron sputtering. The magnetic properties of the alloys, whose structure remains single-phase fcc up to x=0.80, is studied over the entire range of compositions. As in the case of other random magnetic systems such as Fe-Au, the metastable alloy is seen to evolve from a spin glass at low Co concentrations to a reentrant spin glass with evidence for both ferromagnetic and spin-glass ordering, and finally to a ferromagnet for xg0.40. A magnetic phase diagram for fcc Co-Cu is proposed.
242 citations
TL;DR: In this article, the results reported in this paper indicate further possibilities for the development of powerful new electrocatalysts for the reduction of,,, or, for the purpose of reducing to,, or.
Abstract: Many Cu alloys have been studied for electrocatalytic activity of reduction in aqueous solution. Anomalously low overpotentials with highly selective Cu alloy catalysts have been seen for the reduction of to, , or . Cu‐Ni alloys produce and selectively at reversible potentials and Cu‐Sn and Cu‐Pb produce and with an enhanced reaction rate at the reversible potentials of formation. Other alloy catalysts such as Cu‐Zn, Cu‐Cd, or Cu‐Ag also exhibit behaviors distinct from those of the elemental metals. The results reported here indicate further possibilities for the development of powerful new electrocatalysts for the reduction of .
187 citations
TL;DR: In this paper, an attempt to improve ductility of NiAl (B2)-base alloys has been made by the addition of alloying elements and the control of microstructure.
Abstract: An attempt to improve ductility of NiAl (B2)-base alloys has been made by the addition of alloying elements and the control of microstructure. It has been found that a small amount of fccγ phase formed by the addition of Fe, Co, and Cr has a drastic effect not only on the hot workability but also on the tensile ductility at room temperature. The enhancement in ductility is mainly due to the modification of Β-phase grains by the coexistence ofγ phase. The effect of alloying elements on the hot forming ability is strongly related to the phase equilibria and partition behavior amongγ,γ′ (L12 structure), and Β phases in the Ni-Al-X alloy systems. The ductility-enhancement method shows promise for expanding the practical application of nickel aluminide.
169 citations
TL;DR: In this paper, the Raman spectrum of green rust is given for the first time, and the pitting seems to be associated with the presence of Mo4+ in this inner layer, but in passive conditions the film contains FeMoO4.
TL;DR: In this paper, a nanocrystalline Ni-P alloy with 9 nm crystallites was synthesized by means of crystallization from amorphous alloys, and the structure and grain sizes of the alloy were examined using x-ray diffraction, transmission electron microscopy, and high resolution electron microscope.
Abstract: A new method to prepare nanocrystalline alloys was developed by means of crystallization from amorphous alloys. By using this method, a Ni-P alloy with 9 nm crystallites was synthesized. The structure and grain sizes of the alloy were examined by means of x-ray diffraction, transmission electron microscopy, and high resolution electron microscopy. Specific heat capacity and thermal expansion coefficient of the nanocrystalline Ni-P alloy prepared by this method were found to be greater than those of the coarse-grained crystalline alloy by 12.3% and 56.2%, respectively. A new micromechanism for nanometer-sized crystallites formation is discussed.
TL;DR: In this article, the growth of alumina scales on a conventional wrought alloy Fe-20Cr-5Al and on an yttria containing ODS alloy of similar base composition were investigated.
TL;DR: In this article, the role of back reflectors in enhancing the absorption of weakly absorbing, long-wavelength light has been investigated as applied to amorphous silicon alloy solar cells.
Abstract: The role of back reflectors in enhancing the absorption of weakly absorbing, long‐wavelength light has been investigated as applied to amorphous silicon alloy solar cells. The reflectance and scattering properties of various types of back reflectors have been studied. The performance of p‐i‐n amorphous silicon alloy solar cells deposited on different back reflectors has been analyzed. The studies elucidate the role of back reflectors in improving the short‐circuit current density and thereby the efficiency of the cell.
TL;DR: Commercial alloys used in this study exhibited more complex and less predictable release behavior than did the simpler ternary alloy systems used by previous investigators, and it is believed that the use of commercial preparations is necessary for their in vivo behavior to be modeled.
Abstract: Ten dental casting alloys were tested for alloy-element release into cell-culture medium, and this release was related to alloy composition, alloy microstructure, and alloy cytotoxicity (previously determined). Cell-culture medium was analyzed for alloy elements by flame atomic absorption. Concentrations of elements in the medium were normalized by dividing them by their atomic abundance in the alloy, giving element medium-alloy ratios (EMA ratios). Results showed that Au, In, and Pd generally did not dissolve into the medium, but that Ag, Cd, Cu, Ga, Ni, and Zn frequently dissolved. Comparison of EMA ratios for Ag, Cu, and Zn showed that each element retained a behavioral identity in diverse metallurgical environments, but that these environments influenced the release behavior to some degree. Some EMA ratios in multiphase alloys were greater than those in solid solutions, and EMA ratios showed great diversity within all the alloys. Nominal composition seemed to be of little value in the prediction of me...
TL;DR: Carbides of composition R 2 Fe 17 C x (x ≈2; R = Y, Sm) are formed by reaction of a powder of the 2:17 parent alloy in a hydrocarbon gas (methane, acetylene, butane) at around 550°C as discussed by the authors.
TL;DR: In this article, a model of a random binary iron-chromium alloy was proposed to explain the passivity of stainless steels and it was shown that if the chromium content is above a certain threshold (the percolation limit), then the dissolution will proceed for a while and then stop.
Abstract: PITTING corrosion—the localized dissolution of a passivated (oxide-covered) metal in the presence of a solution of certain anionic species—is a major cause of failure of metal structures. The breakdown of extremely thin (∼1 nm thick), highly stable passivating layers typically occurs in a sporadic, localized and stochastic fashion1,2, rather than as a catastrophic, global process. Using a model of a random binary iron–chromium alloy, we have shown previously3–6 that experimental observations of passivity of stainless steels can be explained by assuming that it is controlled by the selective dissolution of iron7. Thus if the chromium content is above a certain threshold (the percolation limit8), clusters of iron are finite and dissolution will proceed for a while and then stop. Oxidation of surface chromium atoms to form Cr—O—Cr linkages then creates a passive state in which the entire surface is covered with such a layer3,5. Here we show that, by adding to this model the further assumption that there is a small but finite dissolution rate for surface chromium atoms, one obtains a mechanism for the triggering of pitting corrosion of stainless steels that is consistent with experimental studies.
TL;DR: In this article, the authors investigated possible explanations for the yield strength enhancement of discontinuously reinforced Al alloy matrix MMCs, for the case of low temperature yield behavior where deformation occurs by dislocation slide.
Abstract: Possible explanations are investigated for the yield strength enhancement of discontinuously reinforced Al alloy matrix MMCs, for the case of low temperature yield behavior where deformation occurs by dislocation slide. The Al alloys contain 0.1-10 micron diameter equiaxed particle discontinuous reinforcements of TiB2, Al2O3, and TiC. Attention is given to a single dislocation-particle interaction model, and both dislocation pile-up and forest-hardening multiple-dislocation particle interaction models.
TL;DR: In this article, C addition (2 wt%) to MoSi2 acted as deoxidant, removing the otherwise ubiquitous siliceous grain boundary phase in hot-pressed samples, and causing formation of SiC and Mo5Si3C1 (a variable-composition Nowotny phase).
Abstract: C addition (2 wt%) to MoSi2 acted as a deoxidant, removing the otherwise ubiquitous siliceous grain boundary phase in hot-pressed samples, and causing formation of SiC and Mo5Si3C1 (a variable-composition Nowotny phase). Both hardness and fracture toughness of the C-containing alloy were higher than those of the C-free (and oxygen-rich) material; more significantly, the fracture toughness of the MoSi2+ 2% C alloy increased from 5.5 MPa·m1/2 at 800°C to ∼11.5 MPa·m1/2 at 1400°C.
TL;DR: In this paper, a multilayer composite of chromium, gold, and tin and gold is used to form a die-to-die die composite, where the die and the substrate are brought into contact and heated to 310-320 degrees C. This technology eliminates the requirement of preforms, prevents tin oxidation, and provides precise control of the bonding thickness.
Abstract: A bonding technology which utilizes chromium, gold, and tin and gold deposited directly on the backside of a device die to form a multilayer composite is reported. The substrate accepting the die is coated with chromium and gold layers. The die and the substrate are brought into contact and heated to 310-320 degrees C. Due to the unique feature of the gold-tin alloy system, the tin layer melts first and dissolves the gold layers of the composite to produce a solution mixed with solid, which in turn would dissolve a portion of the gold layer on the substrate to develop a near eutectic bonding. In the composite, since the tin layer is protected by an outer gold layer in the same vacuum cycle, tin oxidation, which is a major cause of difficulty in achieving quality bondings, is reduced. This technology thus eliminates the requirement of preforms, prevents tin oxidation, and provides precise control of the bonding thickness. Results of bonding 4-mm by 4-mm GaAs dice on alumina substrates show that high-quality bondings are obtained as determined by a scanning acoustic microscope (SAM). >
TL;DR: In this article, the role of alloy microstructure and Si content on oxidation properties was investigated at 900°C in pure O2 and was found to be detrimental to oxide scale adherence when the silica layer was continuous.
Abstract: Austenitic Fe-18Cr-20Ni-1.5Mn alloys containing 0, 0.6, and 1.5 wt.% Si were produced both by conventional and rapid solidification processing. The isothermal and cyclic oxidation resistance of the alloys were studied at 900°C in pure O2 to elucidate the role of alloy microstructure and Si content on oxidation properties. The conventionally-processed, large-grained alloy that contained no silicon formed Fe-rich nodules during oxidation. The nodule formation was effectively eliminated by either reducing the alloy grain size by rapid solidification or by adding Si to the alloy. The lowest weight gains were achieved when a continuous silica layer formed between the alloy and the external chromia scale. The formation of the continuous silica layer required a ombination of fine alloy grain size and high Si content. The presence of S in the alloy was found to be detrimental to oxide scale adherence when the silica layer was continuous.
TL;DR: In this paper, the mechanism of formation of the oxide films on titanium-based alloys is radically different from that on Ni-Al and Ti-Si alloys, and thermodynamic factors appear to dominate the alloy compositions needed to form a continuous film of alumina and silica.
Abstract: Thermodynamic calculations are performed to estimate isothermal sections of Ti-Al-O, Ti-Si-O, and Ni-Al-O phase diagrams. Very small aluminum levels (<10−10 at. %) are needed to stabilize alumina on Ni-Al alloys. However, much higher aluminum (≳50%) and silicon (≳40%) levels are needed to stabilize alumina and silica on Ti-Al and Ti-Si alloys, respectively. These calculations suggest that the mechanism of formation of the protective oxide films on titanium-based alloys is radically different from that on nickel-based alloys. The aluminum levels needed to form a continuous film of alumina on nickel-based alloys are dominated by kinetic factors. On the other hand, thermodynamic factors appear to dominate the alloy compositions needed to form protective films of alumina and silica on titanium-based alloys. Further work is needed to evaluate any possible role of kinetic factors.
Patent•
21 May 1991TL;DR: In this article, an aluminum paste flux is applied to the titanium oxide coated surface of a nickel-titanium alloy member and heating the flux to its activation temperature to remove and suspend titanium oxide therein along with leaching titanium from the base alloy member surface.
Abstract: A joint and a laminate including a nickel-titanium alloy such as nitinol and a method for preparing the surface of a nickel-titanium alloy member for bonding solder material and, electively, another similar or dissimilar member thereto. The method includes applying an aluminum paste flux to the titanium oxide coated surface of a nickel-titanium alloy member and heating the flux to its activation temperature. The flux removes and suspends the titanium oxide therein along with leaching titanium from the base alloy member surface to form a nickel-rich interface surface. The activated flux also coats the nickel-rich interface layer for protection from further oxidation. A bonding material such as a tin-silver solder is flowed onto the nickel-rich interface surface to displace the activated flux. Electively, another member is applied to the molten solder to form a joint between the two members. The residual flux is cleaned from the joint to prevent further deterioration of the base metal. The solder joint includes the base nickel-titanium alloy metal, the nickel-rich interface surface, and the solder material. Electively, any other member may be applied to this joint in the molten state to form a metallic bond therebetween.
TL;DR: The role of surface diffusion in alloy corrosion processes is explored within the framework of the kink-ledge-terrace model of a crystal surface and a recent model of alloy corrosion based on a variant of percolation theory.
Abstract: An in situ scanning tunneling microscope (STM) was used to observe the morphological changes accompanying the selective dissolution of Ag from low-Ag content Ag-Au alloys in dilute perchloric acid. This study was undertaken to explore the role of surface diffusion in alloy corrosion processes. These results are interpreted within the framework of the kink-ledge-terrace model of a crystal surface and a recent model of alloy corrosion based on a variant of percolation theory. The corrosion process leads to roughening of the surface by dissolution of Ag atoms from terrace sites. Annealing or smoothening of the surface occurs by vacancy migration through clusters and the subsequent annihilation of clusters at terrace ledges.
TL;DR: In this article, a ternary iron-chromium-manganese alloys were studied at 900°C in an oxygen partial pressure of 26.7 kPa.
Abstract: The oxidation of nine ternary iron-chromium-manganese alloys was studied at 900°C in an oxygen partial pressure of 26.7 kPa. The manganese concentration was set at 2, 6, and 10 wt. %, and chromium at 5, 12, and 20 wt. %. The scales formed on the low-chromium alloys consisted of (Mn,Fe)2O3, α-Fe2O3, and Fe3O4. These alloys all exhibited internal oxidation and scale detachment upon cooling. The scales formed on the higher-chromium alloys were complicated by nodule formation. Initially, these scales had an outer layer of MnCr2O4 with Cr2O3 underneath, adjacent to the alloy. With the passage of time, however, nodules formed, and the overall reaction rate increased. This tendency was more marked at higher manganese contents. Although these alloys contained a high chromium content, the product chromia scale usually contained manganese. It was concluded that the presence of manganese in iron-chromium alloys had an adverse effect on the oxidation resistance over a wide range of chromium levels.
TL;DR: In this article, a low-cost negative battery electrode for MmNi-5-based alloys (Mm, mischmetal) was proposed and induction-melting tests showed that the surface region with a columnar structure had a longer cycle lifetime than the inner region with an equiaxed structure.
Abstract: Extensive work has been carried out on utilizing MmNi 5 -based alloys (Mm, mischmetal) as a low cost negative battery electrode. The replacement of nickel by cobalt was effective in improving cycle lifetime but caused a decrease in capacity and high rate capability. The replacement of lanthanum by large amounts of cerium of neodymium gave the alloy a satisfactory cycle lifetime with small amounts of cobalt present and without impairing the high rate capability. The alloy MmNi 3.5 Co 0.7 Al 0.8 was selected consistent with the above requirements. Induction-melting tests showed that the surface region with a columnar structure had a longer cycle lifetime than the inner region with an equiaxed structure. Annealing treatment also caused a decrese in the cycle lifetime. It was considered that alloys with smaller crystal grains had a longer cycle lifetime because the protective surface layer on the grain would remain effective after pulverization. The deviation from stoichiometric composition to the nickel-rich side or the Mm-rich side also caused a decrease in cycle lifetime, accompanied by the precipitation of nickel or Mm on the grain boundaries. It was concluded that the surface layer of the crystal grain played a very important role in preventing capacity decay.
TL;DR: In this paper, the geometric and electronic effect of tin atoms in different chemical states on/in the platinum surface was studied by using single-crystal faces of the ordered alloy Pt{sub 3}Sn and pure Pt modified by electrodeposited/adsorbed tin, i.e., the so-called adatom state.
Abstract: To understand the role of tin as a promoter in the electrochemical oxidation of methanol, the authors have studied the geometric and electronic effect of tin atoms in different chemical states on/in the platinum surface by using single-crystal faces of the ordered alloy Pt{sub 3}Sn and single-crystal faces of pure Pt modified by electrodeposited/adsorbed tin, i.e., the so-called adatom state. They found that none of the alloy surfaces were more effective catalysts than any of the pure platinum surfaces under the conditions of measurement employed here and that alloying platinum with tin to any extent significantly reduced the activity. As reported previously by others, they observed tin to spontaneously adsorb on platinum surfaces from dilute sulfuric acid supporting electrolyte containing Sn(II) in concentrations above ca. 5 {mu}M. At a given concentration, the coverage by tin decreased as the atomic density of the platinum surface increased. However, they did not observe any enhancement of methanol oxidation on any platinum modified by this irreversibly adsorbed tin. They did observe a diffusion-limited enhancement on Pt(111) and on Pt(100) due to Sn(II) in the electrolyte at 1 {mu}M concentration. At this concentration, tin did not appear to be adsorbed to any observable extent, andmore » the catalysis appeared to occur via the direct interaction of a dissolved tin species with the surface. They propose a mechanism of catalysis that is a hybrid homogeneous-heterogeneous sequence based on known homogeneous Pt-Sn catalysts.« less
TL;DR: In this article, the epitaxial properties of the CoSi2 films are attributed to the role played by Ti in removing the native oxide layer on the Si wafer surfaces, which causes the nucleation of CoSi 2 grains with random orientations.
Abstract: Using coevaporated Ti‐Co alloy and sequentially evaporated Ti‐Co bimetallic layer source materials, CoSi2 films have been grown on (001) Si. The film resistivity and resistance thermal stability are excellent. The CoSi2 are epitaxial single‐crystal films containing antiphase domains in the Ti‐Co bimetallic layer cases and are polycrystalline films containing a substantial portion of epitaxial grains in the Ti‐Co alloy cases. The epitaxial or substantially epitaxial nature of these CoSi2 films is the reason for the excellence in the film resistivity and resistance thermal stability. We believe that the epitaxial nature of the CoSi2 films results from two roles played by Ti. In the first, Ti served as a getterer for removing the native oxide layer on the Si wafer surfaces, which causes the nucleation of CoSi2 grains with random orientations. In the second, Ti silicides formed in the early stage of the annealing process served as Co diffusion barriers preventing Co2Si and CoSi formation, which would also lea...
TL;DR: In this article, the evolution of the structural and magnetic properties have been studied as a function of annealing conditions, and are compared to those previously observed with Fe-based materials.
Abstract: Ultrafine face‐centered‐cubic Co particles in a conducting Cu matrix have been produced by annealing of sputtered metastable CoxCu1−x alloy films (0.10≤x≤0.80). The average size of the particles, and therefore the magnetic properties of these materials, can be easily controlled by the processing parameters. Single‐domain behavior results in coercivities in excess of 600 Oe, while the magnetization is determined by the choice of alloy composition. The evolution of the structural and magnetic properties have been studied as a function of annealing conditions, and are compared to those previously observed with Fe‐based materials.
01 Dec 1991-Metallurgical and Materials Transactions B-process Metallurgy and Materials Processing Science
TL;DR: In this article, the energy equation for solidifying dendritic alloys that includes the effects of heat of mixing in both the dendrite solid and the interdendritic liquid is derived.
Abstract: The energy equation for solidifying dendritic alloys that includes the effects of heat of mixing in both the dendritic solid and the interdendritic liquid is derived. Calculations for Pb-Sn alloys show that this form of the energy equation should be used when the solidification rate is relatively high and/or the thermal gradients in the solidifying alloy are relatively low. Accurate predictions of transport phenomena in solidifying dendritic alloys also depend on the form of the solute conservation equation. Therefore, this conservation equation is derived with particular consideration to an accounting of the diffusion of solute in the dendritic solid. Calculations for Pb-Sn alloy show that the distribution of the volume fraction of interdendritic liquid (gL) in the mushy zone is sensitive to the extent of the diffusion in the solid. Good predictions ofgL are necessary, especially when convection in the mushy zone is calculated.