Showing papers in "Journal of The Less Common Metals in 1979"

Concerning atomic sites and capacities for hydrogen absorption in the AB2 Friauf-Laves phases

Abstract: There is considerable confusion in the literature concerning the maximum number of hydrogen atoms per AB2 that can be absorbed by the C15 and C14 Friauf-Laves phases (variously reported as 5.125 and 7). If all the tetrahedral sites are independently available to hydrogen, the number could approach 17; since, in practice, it rarely exceeds five, we assume that one or more limiting principles operate. The one that we discuss here is assumed to be mainly electrostatic and to be due to electron transfer resulting from electronegativity differences between the hydrogen and metal atoms. Assuming the operation of an exclusion rule which states that two tetrahedra with a face in common may not both contain hydrogen atoms at their centers, after an exhaustive model study we find a maximum occupancy of six hydrogen atoms per AB2 in C15 and of 6 1 3 in C14. Two attractive models accommodating six hydrogen atoms (one for C15, the other for C14) are examined in some detail and the possible implications of these and related models with respect to the step-function absorption model of Jacob, Shaltiel and coworkers is discussed. The possible occupation of triangle sites is discussed briefly.

Hydrogen absorption in various zirconium- and hafnium-based intermetallic compounds

Abstract: The interaction with hydrogen gas of sixteen intermetallics containing zirconium or hafnium at a concentration of at least 50 at.% was studied. It was found that reversible hydrogen absorption involving the formation of a ternary hydride occurred for all the hafnium compounds and for the zirconium compounds of 50 at.% Zr composition. For all compounds of higher zirconium content hydrogen absorption was found to be irreversible because of the formation of the binary hydride ZrH2. Lattice parameters are given for the intermetallic compounds of hafnium before and after charging with hydrogen gas.

Phase diagrams of rare earth metals with gallium

Abstract: From the results obtained by differential thermal analysis and X-ray diffraction, the state diagrams of the binary systems R-Ga where R = Se, Y, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb and Lu are proposed. The liquidus line near Ga has been determined using the solubility data of R in liquid gallium. The previously unknown compounds Sc5Ga4, ScGa2, ScGa3, EuGa, DyGa3, Er2Ga3, Tm2Ga3, TmGa2, YbGa, Lu2Ga3 and LuGa2 are found. ScGa3 crystallizes in a cubic structure of the AuCu3 type. A short discussion of the change in the thermal stability of the intermediate phase and its dependence on the order number of the component R is given.

The effect of aluminum additions on the structural and hydrogen absorption properties of AB5 alloys with particular reference to the LaNi5−xAlx ternary alloy system

Abstract: The dissociation pressures of the hydrides LaNi46Al04H6, LaNi45Al05H6, CFMNi48Al02H6 (CFM = cerium-free mischmetal), CFMNi46Al04H6 and YNi4AlH4 were studied In all cases, the aluminum additions were found greatly to reduce the plateau pressure of the ANi5−x Alx hydride compared with that of the corresponding ANi5 hydride (A = La, CFM, Y) LaNi46Al04 and LaNi45Al05 were specially prepared homogeneous alloys whose enthalpies and entropies of transition were calculated as − 87 kcal (mol H2)−1, − 92 kcal (mol H2)−1 − 261 cal (mol H2)−1 deg−1 and 266 cal (mol H2)−1 deg−1, respectively A crystallographic model of LaNi4Al is shown and consideration of the nearest neighbor atom distribution leads to a rationalization of the observed linear relationship between the enthalpy change ΔH and the Al composition A recently proposed model of hydrogen interstitial site occupation is examined in the light of the present data Finally, correlations of hydride dissociation pressures with either alloy heats of formation or alloy cell volumes are discussed

Ternary rme2x2 alloys of the rare earths with the precious metals and silicon (or germanium)

Abstract: The structural characteristics of about 30 compounds with the composition RMe2X2 have been studied for R = rare earth (or uranium), Me = rhodium, palladium, silver, iridium, platinum or gold and X = silicon or germanium Their structures proved to be related to the Al4Ba (ThCu2Si2) types The average atomic volumes of these phases are compared with those of similar groups of alloys and are briefly discussed Special reference is made to the cerium and ytterbium compounds and the behaviour of these elements is compared with that shown in their binary alloys

Valence fluctuations of ytterbium in silicon-rich compounds

Abstract: The silicon-rich side of the YbSi system has been examined and a new phase Yb3Si5, not previously known, has been found. X-ray analysis, magnetic susceptibility measurements and linear expansion coefficients indicate that the two phases richest in silicon, YbSi1.8 (AlB2 type) and Yb3Si5 (Th3Pd5 type), correspond to two new temperature-induced valence fluctuation compounds.

Hydrogen sorption properties of some ab2 laves phase compounds

Abstract: The hydrogen sorption properties of the hydrides of the Laves phase compounds GdB2 (B=Mn, Fe, Co, Ni, Rh, Ru) and LaRh2 have been studied at various temperatures in the pressure range up to 20 atm. Hydrogen absorption in LaB2 (B=Ru, Pt, Ir, Al) and GdB2 (B=Ir, Al) was measured in the pressure range up to 70 atm. A model that calculates the prefered interstitial sites occupied by the hydrogen is presented for the AB2 compounds. A gradual decrease of the hydrogen absorption capacity is observed for the GdNi2 and GdCo2 compounds after several absorption-desorption cycles. The hydrogen-cycled GdRh2 exhibited a change in its thermodynamic properties.

A search for superconductivity below 1 k in transition metal borides

Abstract: We examined some AlB2-type (C32 structure) boron compounds for superconductivity down to 0.42 K; the compounds have the formula MeB2(MeTi,Zr,Hf,V,Nb,Ta,Cr,Mo) (the atomic ratio of metal to boron was 0.5). Only NbB2 was found to be superconducting with Tc = 0.62 K and a surprisingly high value of Hc(0), about 1600 Oe. Other transition metal as well as non-transition metal boron phases were also tested for superconductivity down to 0.42 K; these compounds were MeB6 (MeCa,Sr,Ba), W2B5, CrB, Cr5B3, UB2, UB4 and UB12. None of these compounds proved to be superconducting above 0.42 K; nor was any trace of superconductivity down to 0.42 K observed in MoB and NbB.

Solid solubility and residual resistivity of scandium in aluminum

Abstract: The solid solubility and the residual resistivity of Sc in Al were determined by means of the measurement of the electrical resistivity at 77 K of AlSc alloys air cooled after annealing at various temperatures for a time sufficient to complete the precipitation of the equilibrium phase (ScAl3). Moreover, the solidus line of the Al-rich alloys was determined by thermal analysis. The solid solubilities of Sc in Al were found to vary from 0.186 at.% at 913 K to 0.033 at.% at 743 K. From the temperature dependence of the solid solubility the excess entropy of mixing Δs and the heat of mixing Δh associated with the solid solution of Sc in Al were calculated to be 6.0 R and 59 kJ mol−1, respectively. The compound ScAl3 reacts eutectically with Al to form an Al-rich solid solution. The eutectic temperature is 823 ± 1 K. Using the values of Δs and Δh, the maximum solid solubility of Sc in Al was estimated as 0.21 at.% at the eutectic temperature. The resistivity increment caused by Sc atoms in solution is linearly proportional to the concentration of Sc. The residual resistivity for Sc in Al is (3.4 ±0.1) × 10 −8 Ω m ( at.% ) −1 .

Les systemes binaires cobalt-gallium et nickel-gallium-étude comparée

Abstract: Resume Les systemes binaires CoGa et NiGa ont ete repris par ATD, diffraction des rayons X, micrographie et microsonde electronique. Malgre la parente des metaux Co et Ni, les deux diagrammes de phase obtenus avec Ga sont assez differents. CoGa donne deux phases intermediaires seulement, CoGa tres large (25 – 64,5 at.% Ga) et CoGa 3 etroite, alors qu'on trouve pour NiGa six phases intermetalliques a fusion non congruente: NiGa 3 , Ni 5 Ga 3 , Ni 3 Ga 2 , Ni 3 Ga 4 , Ni 2 Ga 3 et NiGa 4 ,ainsi que la phase NiGa a fusion congruente, la seule qui soit analogue a CoGa par sa structure (CsCl) et son point de fusion (1215°C). Les raisons possibles de cette dissemblance des deux systemes ont ete etudiees.

The interaction of transition and rare earth metals with boron

Abstract: From our measurements on the R-M-B systems 47 phase equilibria diagrams were constructed and 142 new ternary borides were found. An analysis of the data we obtained showed that the number of ternary compounds in the R-M-B systems increases as the difference between the electronegativities of the transition and rare earth metals increases. The ternary borides of the R-M-B systems are characterized by the formation of new types of structure and by the formation of two homologous series, one based on the CaCu 5 -type and the CeCo 3 B 2 -type structures and the other on the MgZn 2 -type and the CeCo 3 B 2 -type structures.

The HfNi and ZrNi systems in the region 65 – 80 at.% Ni

Abstract: The HfNi and ZrNi systems have been examined in the region 65 – 80 at.% Ni by microscope and X-ray analyses. In the HfNi system the following intermediate phases were observed: Hf 3 Ni 7 , Hf 8 Ni 21 , HfNi 3 (h. t.), HfNi 3 (l. t.) and Hf 2 Ni 7 . Hf 3 Ni 7 , which is formed peritectically at 1250 ± 20 ° C , decomposes eutectoidally at 1016 ± 3 ° C into Hf 7 Ni 10 and HfNi 3 (l. t.). Hf 8 Ni 21 is stable from 1300 ± 20 ° C , where it forms peritectically, to 1175 ± 10 ° C where it decomposes eutectoidally into Hf 3 Ni 7 and HfNi 3 (l. t.). HfNi 3 (h. t.) is a high temperature phase, forming peritectically at 1350 ± 20 ° C and transforming into HfNi 3 (l. t.) below 1200 ± 10 ° C . Hf 2 Ni 7 melts congruently. A eutectic between Hf 7 Ni 10 and Hf 3 Ni 7 occurs at 1190 ± 10 ° C . In the ZrNi system only one phase forming peritectically exists; this is Zr 8 Ni 21 , which is stable at least down to 800 °C. ZrNi 3 is formed in a reaction between Zr 8 Ni 21 and Zr 2 Ni 7 at 920 ± 10 ° C . Crystallographic data for the intermediate phases in the HfNi and ZrNi systems in the region 65–75 at.% Ni are presented.

Hydrogen absorption-desorption characteristics of mischmetal-nickel-aluminum alloys

Abstract: The hydrogen absorption and desorption characteristics of mischmetal (Mm)-nickel-aluminum alloys were investigated. MmNi5−xAlx (x = 0.25 −0.5) have been found to have the same hexagonal structure as LaNi5 and MmNi5, and they reacted readily with hydrogen to form the hydrides MmNi4.75 Al0.25H5.4, MmNi4.65Al0.35H 5.3H5.3 and MmNi4.5Al0.5H4.9 (hydrogen content: 1.3,1.2 and 1.2 wt.%, respectively) under 60 atm hydrogen pressure at room temperature. The dissociation pressures of these hydrides were dependent on the aluminum content (aluminum partially substitutes for nickel) and the value of log Pbecame lower than the value for MmNi5 hydride as x increased. The enthalpy change on hydride formation as determined from the dissociation isotherms for the MmNi4.5Al0.5-H system was − 5.5 kcal (mol H2)−1; this value was smaller than those for LaNi5 and MmNi5. The dissociation pressure at 30 °C was 3 atm and was nearly the same as that of LaNi5. The desorption rate of hydrogen for MmNi4.5Al0.5 was larger than those for LaNi5 and MmNi5) and a value of 2.1 – 4.3 kcal mol−1 was obtained for the apparent activation energy of hydrogen desorption. For MmNi4.5Al0.5 the hydrogen absorption-desorption cycle was repeated 30 times, but no variation in the hydrogen absorption-desorption capacity was observed. The hydride of MmNi4.5A10.5 proved to be suitable for use as a stationary hydrogen storage material.

Terminal solubility of hydrogen in NbTa alloys and characterization of the solid solutions

Abstract: Solvus temperatures for 2, 5 and 12 at.% H were determined resistometrically in tantalum, niobium and nine NbTa alloys. The terminal solubility of hydrogen in the alloys reached a maximum for Nb 0.3 Ta 0.7 . For example, at 250 K the solvus for this pseudobinary metal-metal hydride system lies at 12 at.% H compared with 1.5 for Nb and 6 for Ta. Pressure-composition-temperature measurements were made on the Nb 0.3 Ta 0.7 -H solid solutions, but the resulting thermodynamic data exhibited no anomalous behavior. The effects of hydrogen on lattice parameters and resistivities were also determined for these systems. The apparent terminal solubilities are discussed in terms of these observations and in terms of metal atom size effects, electronic structure and the properties of the hydride phase.

The structure and properties of sintered boron carbide

Abstract: An analysis of the crystallochemical structure of boron carbide has shown that, despite strong covalent atomic bonds, directional mass transfer in boron carbide can occur during activated sintering of disperse powders. Dilatometry and electrical conductivity methods were used to investigate the kinetics of densification for boron carbide specimens obtained by pressing powders with particle sizes smaller than 1 μm. The processes that occurred on heating the samples were studied and the mechanisms of mass transfer at various temperatures were identified. The kinetics of recrystallization in sintered and hot-pressed boron carbide were investigated. The process of recrystallization was found to start at temperatures above 1800 °C; at temperatures above 2200 °C grains grew rapidly. Deformation by twinning is characteristic of boron carbide. These twins can be removed very slowly by high temperature annealing.

Slip systems and plastic deformation of silicon carbide single crystals at high temperatures

Abstract: Knoop hardness measurements have been made on the (0001), {1010} and {1120} planes of 6H-SiC single crystals in the temperature range from room temperature to 1600 °C. The hardness varies with the orientation of the long axis of the indenter on each plane. For all planes the hardness anisotropy is dependent on the temperature and the converse anisotropy was observed at temperatures below and above about 300–400 °C. It is concluded from the hardness anisotropy that the active slip system of 6H-SiC is {1010}〈1120〉 near room temperature and (0001)〈1120〉 at high temperatures. At about 300–400 °C both the basal and prismatic slip systems are operative. The 〈1120〉 slip lines are observed around Knoop and Vickers indentations only on the prismatic planes at approximately 800 °C, above which they become pronounced with increasing temperature. This suggests that the plasticity of 6H-SiC will increase substantially above 800 °C.

The chemical vapor deposition of TiB2 on graphite

Abstract: In this paper we describe an experimental investigation of the coating of graphite with TiB 2 by chemical vapor deposition using the H 2 reduction of BCl 3 and TiCl 4 at 925 °C and 1 atm. Reasonable matching of the thermal expansion of TiB 2 and graphite was necessary to eliminate cracking. A suitable graphite was POCO DFP-1. Adhesion was improved by using a slightly rough graphite surface. Heat treatment at 2000 °C and above resulted in a certain degree of diffusion. No melting or solid phases other than TiB 2 and graphite were detected up to 2400 °C. The coatings showed no failure when repeatedly submitted to an electron beam pulse of 2 kW cm −2 for 0.8 s.

Formation of fine silicon carbide powders by a vapor phase method

Abstract: The formation of silicon carbide powders by the vapor phase reaction of SiCl4 + CH4 (1400–1500°C), CH3SiCl3 (800–1400°C) and (CH3)4Si (800–1400°C) was studied. The effectiveness of the silicon sources was in the sequence (CH3)4Si > CH3SiCl3 > SiCl4, in accordance with the thermodynamic parameters. Fine β-SiC powders were produced by the pyrolysis of (CH3)4Si in hydrogen above 900°C. The crystallinity of the products increased with increasing reaction temperature. The particles were spherical and had average sizes of 0.02–0.12μm which decreased with increasing reaction temperature and with decreasing (CH3)4Si concentration. A reaction process consisting of the formation of particles of organosilicon polymers and their subsequent decomposition was proposed for the formation of SiC particles by the pyrolysis of (CH3)4Si.

The free energy of formation of GeO2(hex) by e.m.f. measurements

Abstract: The values of the standard free energy of formation ΔfG0m of the stable tetragonal form of GeO2 as well as of the metastable hexagonal modification were obtained from e.m.f. measurements on the following types of cells ∗ . Pt, C, Ge, GeO2(tet)/15 wt.% Y2O3ZrO2/inert gas (Po2≈ 10−4atm), Pt and Pt, C, Ge, GeO2(hex)/15 wt.% Y2O3ZrO2/inert gas (Po2 ≈ 10−4atm), Pt The e.m.f. data yielded the following least-squares expressions. ΔF0m (GeO2, hex) ± 1.2 kJ−1 = −549.86 + 0.16837 T (810−1180K) Δ0m (GeO2, tet) ± 1.15 kJ−1 = − 571.39 + 0.18657 T (800 −1150 K) Combining the data for GeO2(hex) with calorimetric data, a value of − 559.7 ± 0.9 kJ was obtained for ΔfH0m(GeO2, hex, 298 K) from a third law plot. The transformation from GeO2(tet) to GeO2(hex) had an enthalpy value of − 21.5 kJ at 1176 K.

Effects of magnesium addition to the CuSn matrix in the composite-processed Nb3Sn superconductor

Abstract: The effects of the addition of a small amount of magnesium to the CuSn matrix in the composite-processed (bronze-processed) Nb 3 Sn super-conductor were investigated. It was found that the magnesium addition significantly suppresses the Nb 3 Sn grain coarsening. The fine Nb 3 Sn grain structure produced in the Nb/CuSnMg composite enhances the grain boundary diffusion of tin and consequently makes the Nb 3 Sn growth rate nearly twice as much as that of the Nb/CuSn composite. The significant increase in superconducting critical current attained in the Nb/CuSnMg composite shows that the magnesium addition is promising for the improvement of the current-carrying capacities of multifilamentary Nb 3 Sn superconductors.

Sputtering deposition, XPS and X-ray diffraction characterization of oxygen-platinum compounds

Abstract: Thin films of oxygen-platinum compounds have been prepared by reactive sputtering and investigated mainly by X-ray diffraction and photoelectron spectroscopy. As a result of this study, platinum oxide films such as PtO and PtO 2 were obtained by adjustment of the deposition rate and the chemical composition of the gaseous phase. In addition, a new phase with an intermediate oxidation state between PtO and PtO 2 was observed. Binding energies and intensities of platinum core lines and valence bands as well as oxygen 1s lines are discussed in connection with stoichiometry and chemical bonding in these compounds.

The magnetic and electrical properties of some rare earth tetraborides

Abstract: A study of the magnetic and electrical properties of some rare earth tetraborides (PrB 4 , SmB 4 , GdB 4 , TbB 4 , DyB 4 , HoB 4 , ErB 4 and YbB 4 ) was carried out on powders and single crystals prepared by the flux method. The tetraborides were found to be metallic. The only exceptions are PrB 4 which is ferromagnetic and YbB 4 where no magnetic ordering was found down to 0.34 K; they are antiferromagnetic at low temperatures. PrB 4 and ErB 4 have a strong anisotropy along the c axis from the susceptibility and magnetization measurements. ErB 4 is of special interest because at low temperature it is antiferromagnetic in a weak magnetic field but shows two successive magnetic transitions with increasing field, leading finally to a purely ferromagnetic structure.

The melting of boron carbide and the homogeneity range of the boron carbide phase

Abstract: Various mixtures of boron and carbon were electron beam melted. The samples were characterized by electron microprobe analysis, metallographic techniques, X-ray diffraction and Knoop microhardness measurements. The metallographic investigations, together with the electron microprobe phase analysis, showed that the boron carbide phase exists in the homogeneity range 9 – 20 at.% C (with a relative accuracy of 3 – 5%). Boron carbide melts congruently and forms a eutectic between carbon-rich compounds and graphite. For the boron-rich compounds we assumed the existence of a peritectic transformation with a solid solution of carbon in the β rhombohedral boron structure. We studied the crystal lattice dimensions and the microhardness of boron carbide in the above homogeneity range. As the carbon content increased, the crystal lattice dimensions decreased and the microhardness increased regularly with an extreme value of HK200g = 2840 +- 60 kg mm−2 for 20 at.% C (B4C) (after electrolytic etching).

On the valence state of Yb and Ce in transition metal intermetallic compounds

Abstract: In the pure state Yb is a divalent metal, similar to Ca; in alloys it can become trivalent like the majority of the rare earth metals Using a value of 38 kJ (mol Yb)−1 for the energy difference between divalent and trivalent Yb metal and using model calculations for the heat of formation of intermetallic compounds, we are able to account for the existing information on the valence state of Yb in transition metal compounds A similar analysis of compounds of Ce with transition metals shows that a model in which the 4f electron is treated as a core electron, ie being absent in the tetravalent modification of Ce and present as a fully localized electron in trivalent Ce, does not apply

Effect of oxygen sorption layers on the kinetics of hydrogen absorption by tantalum at 77– 700 K

Abstract: Hydrogen absorption from the gas phase by tantalum is strongly impeded by oxygen sorption layers at temperatures below 700 K. The removal of these layers increases the absorption rate by several orders of magnitude. Experiments performed between 77 and 700 K using.specimens with and without such oxygen surface layers enabled us to identify the processes which determine the rate of hydrogen absorption at low temperature.

Age hardening of AgPdCu dental alloy

Abstract: The age-hardening characteristics of Au-containing AgPdCu dental alloys were investigated. The composition ranges of the three commercial alloys tested were: Ag 49.3–52.5 at.%, Pd 24.5–29.3 at.%, Cu 15.3–21.0 at.% and Au 2.6–6.5 at.%. From the electron microscope study it is concluded that the cause of hardening in this alloy is the precipitation of a CuPd ordered phase, which has the AuCuI type face-centred tetragonal structure.

Etude de la diffusion de l'oxygene dans le titane α oxyde entre 700 °c et 950 °c

Abstract: Resume La diffusion de l'oxygene dans le titane α de structure hexagonale compacte a ete etudiee directement par microanalyse nucleaire, au moyen d'echantillons polycristallins oxydes dans l'oxygene pur sous pression atmospherique, a des temperatures comprises entre 700 et 950 °C. Les profils de diffusion ont ete determines point par point, ce qui a permis le calcul des valeurs du coefficient de diffusion, avec une energie d'activation de 48 kcal mol−1. La concentration en oxygene a l'interface metal-oxyde est toujours inferieure a 34 at.%, qui est la valeur a saturation resultant du diagramme d'equilibre titane-oxygene. La masse totale d'oxygene ayant diffuse dans le metal, calculee par integration des profils de concentration, suit une loi parabolique en fonction du temps. Toutefois, l'assimilation des profils a des fonctions erreur complementaires n'est pas parfait, ce qui pourrait indiquer des anomalies du processus de diffusion, en relation avec la structure feuilletee de l'oxyde. Cette etude a ete completee par la mesure des parametres a et c de la maille du titane, et par celle de la microdurete, en fonction de la concentration en oxygene de la solution solide, ainsi que par un examen metallographique.

Phase diagrams of the CaF2-(Y,Ln) F3 systems II. A discussion

Abstract: Earlier and new results of a study of CaF2-(Y,Ln)F3 systems are discussed. It is shown that the series of CaF2-LnF3 systems provides an interesting example of gradual change in phase diagrams upon successive replacement of one of the components by an analogous component from the periodic system. The variation of the limiting solubilities and the temperature stability of phases in the CaF2-LnF3 systems is also discussed. It has been shown that the main phases in the temperature range investigated are non-stoichiometric phases with statistical distributions of various valency cations on the positions of the fluorite and LaF3 structural types (the α-UO3-type solid solution is stable only at high temperatures). The nonstoichiometric Ca1−xLnxF2+x and Ln1−yCayF3−y phases are characterized by disordering of the anion sublattice. Such phases may be considered as solid solutions with a variable number of anions in the unit cell when the cation sublattices are fully occupied.

Studies of the (Sc, Zr, Hf)-(Rh, Ir)-b systems☆

Abstract: The (Zr, Hf)-(Rh, Ir)-B systems were investigated by X-ray analysis and phase equilibria were established at 1100 °C within the region below 40 at.% IVa metal. Three ternary compounds were found within the Zr-Ir-B system: ZrIr 3 B 4 , ZrIr ≈3 B ≈4 and ZrIr ≈3 B ≈2 . The corresponding hafnium compounds are isotypic. Hf 3 Ir 5 B 2 is isostructural with Ti 3 Co 5 B 3 . ScIr 3 B 4 was found to crystallize with a ZrIr 3 B 4 -type structure. At 1100 °C rhodium does not form ternary borides with zirconium or hafnium. A remarkably high solubility of boron was found for the (Zr, Hf)(Rh, Ir) 3 compounds (perovskite borides). Because of the high stability of the perovskite borides, ZrB 2 and HfB 2 cannot coexist in thermodynamic equilibrium with rhodium or iridium metal respectively.

The intermetallic compound Ni3Zr

Abstract: The intermetallic compound Ni3Zr has been isolated; it is stable at room temperature but decays by a peritectoid reaction at 940 °C according to: 4Ni3Zr → Ni7Zr2 + Ni5Zr2. Ni3Zr is a hexagonal close-packed compound of the Ni3Sn type (D019), space group P6 3 mmc . The lattice parameters are a = 5.309 A and c = 4.303 A .