Showing papers on "Laves phase published in 1969"

Hyperfine interaction and susceptibility in some actinide metals and intermetallic compounds.

Abstract: Magnetic effects in a number of actinide metals and intermetallic compounds are being investigated utilizing the 59.6 keV Mossbauer resonance of 237Np in conjunction with bulk susceptibility measurements. The cubic Laves phase compound NpAl2 is found to be ferromagnetic. The paramagnetic moment is 2.30 μB, somewhat lower than in other cubic Np magnetic materials. The saturation magnetic hyperfine field is found to be (3155±50) kOe. Taking H(T)/H(0) = D[1−T/Tc]β, we find D = 1.48±0.10, Tc = 55.8±0.1°K and β = 0.355±0.017 for 0.994>T/Tc>0.83. At lower temperatures, departure from molecular field behavior is seen. In cubic actinide magnetic materials, an electric‐quadrupole hyperfine interaction will be observed due to alignment of the unquenched orbital momentum. In NpAl2 we find e2qQ = − (27±1) MHz. For NpC, which has the NaCl structure, we obtain the hyperfine parameters Hi = (4789±50) kOe and e2qQ = (577±58) MHz at 4.2°K. Metallic neptunium (orthorhombic) and americium (hexagonal) show no magnetic hyperf...

Pressure Dependence of the Curie Temperature of Ferromagnetic Laves Phase Alloys

Abstract: The pseudobinary system (Zr1−xNbx)Fe2, with the cubic Laves structure, shows ferromagnetism for samples with x≤0.45. The lattice parameter decreases with increasing Nb content, but the major part of the change in TC is not due to this, as was seen in the case of (Zr1−xTix)Fe2. Zr(Fe1−xCox)2 behaves similarly. We have studied the effect of high pressure on the Curie temperatures of some of these alloys, using the method of McWhan. All of these samples show a linear decrease of TC with pressure. In the (Zr, Nb)Fe2 series, dTC/dP=−3.3°K/kbar for x=0.3 and −3.5°K/kbar for x=0.35. The permeability decreases with pressure, and the permeability‐temperature curves behave as if the compounds become paramagnetic when the Curie temperature falls below 230°K. This is the Curie temperature (at 1 atm) of (Zr0.6Nb0.4)Fe2, which is the limiting composition of the ferromagnetic region. Zr(Fe1−xCox)2 behaves similarly, with dTC/dP=−4.7°K/kbar for x=0.35 and −6.6°K/kbar for x=0.4.

Structure Changes in Fe-23 at.% Be Alloy

Abstract: Structure changes in Fe-23 at.% Be alloy aged at temperatures between 300° and 800°C were studied by transmission electron microscopy. The structural changes with aging were classified depending on aging temperatures as follows: 1) 300° to 400°C; ordered structure, modulated structure, continuous precipitation of 1st metastable phase and discontinuous precipitation of 2nd metastable phase without grain boundary migration. 2) 500° to 800°C; continuous precipitation of 1st metastable phase in matrix, formation of discontinuously precipitated regions along boundaries, and continuous precipitation of stable phase in matrix. 3) Above 800°C; formation of dislocation networks, stable phase precipitation on them, and further formation of finer dislocation networks and precipitates. The structure of 1st metastable phase was f.c.c. and expected to be Laves phase of MgCu2 type. Variously shaped stable phase precipitates were Laves phase of MgZn2 type.

The lattice parameters of various series of pseudo-binary rare-earth-transition metal laves phase compounds

Abstract: Measurements have been made of the lattice parameters in several series of substituted rare-earth-transition metal Laves phase compounds. It has been found that a general curve may be used to represent the variation of the lattice spacing in those compounds which contain iron. Most of the specimens examined show a positive deviation from Vegard's Law for the cubic C15 structure. In addition however, the hexagonal C36 phase has been found to coexist in some compounds and the atomic volume of this phase shows a negative deviation from a linear interpolation between the terminal phases.

Alloys and Metal Articles Coated therewith.

Abstract: 1,150,286. Coating with metals. E.I. DU PONT DE NEMOURS & CO. May 3, 1966, No. 19550/66. Headings C7A and C7F. A protective metal coating (e. g. applied to a Fe, Ni or Co base alloy article) comprises an alloy containing at least two heavy transition elements (i.e. selected from Fe, Co, Ni, Ru, Rh, Re, Os, Ir, Pt, Pd, Mn, Cr, Mo, W, U, V, Nb, Ta, Ti, Zr, Hf, Th, Sc, Y, La and Ce) forming at least 60 atomic per cent of the alloy, the ratio of the largest to the smallest atomic radii thereof being in the range 1A05-1A5 and from 30-85% by volume of the alloy being present as Laves phase the remainder being the matrix which is softer than the Laves phase. Exemplary alloy, for the coatings include:- W 51, Ni 40 Si 9, Ta 52, Co 38, Si 10, Mo 52 Fe 30 Si 18, Mo 36 Fe 46 Ge 18 and Mo 36 Ni 10 Fe 36 Si 18. The coatings may be applied by forming the appropriate alloy (as by ore melting in an inert atmosphere, powdering it, heating the substrate with a layer of the powder thereon (e.g. applied by metal spraying or by brushing, dipping or spraying with a slurry of the metal in a temporary binder) in a non-oxidizing atmosphere to the incipient melting point of the alloy and cooling it at such a rate as to give a matrix in the coating alloy which is softer than the matrix phase therein. The coating may also be applied to bodies of Ti, Zr, Nb, Ta, Mo, W, Cr, Cu and U and may be applied by roll cladding hot dipping or resin bonding of a sheet thereof to the base.