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Showing papers on "Laves phase published in 1975"


Journal ArticleDOI
TL;DR: Magnetostriction measurements have been carried out in the cubic Laves phase compounds DyCo2, HoCo2 and ErCo2 from 10K to well above their respective Neel temperatures.
Abstract: Magnetostriction measurements have been carried out in the cubic Laves phase compounds DyCo2, HoCo2 and ErCo2 from 10K to well above their respective Neel temperatures TN. The observed magnetostrictions are very large ( approximately 10-3). The measurements confirm the extremely high anisotropy of these materials. The expected values of the saturation magnetostriction at 0K are similar in sign and magnitude to those found in the corresponding rare earth metals. This fact and the scaling of magnetostriction with rare earth sublattice magnetization indicates that the rare earth ion is the main source of the magnetostriction. The metamagnetic transition above TN has been studied, the relation between critical field and temperature being nonlinear for HoCo2 and ErCo2. The compounds are highly anisotropic above TN and all the features indicate that the field-induced phases are likely to be ferrimagnetic.

27 citations


Journal ArticleDOI
TL;DR: The crystal structure of the intermediate phase known as BaAl2 has been determined and its composition established; this corresponds to Ba7Al13 and the phase crystallizes in the trigonal space group P 3 m1 with the lattice constants.
Abstract: The crystal structure of the intermediate phase known as BaAl2 has been determined and its composition established; this corresponds to Ba7Al13 and the phase crystallizes in the trigonal space group P 3 m1 with the lattice constants: a = 6099 ± 0002, c = 17269 ± 0006 A The atomic arrangement appears to be closely related to that of the Laves phase polytype, MgNi2 The influence of the electron concentration on the stability of the Ba7Al13 phase has been examined by partial or total substitution of Al atoms, but evidence of the AlB2-type of structure was found in every case (BaAl15-Si05, a = 437, c = 514 A ; BaZnSi, α = 4388, c = 4841 A )

22 citations


Journal ArticleDOI
TL;DR: In this article, the electrical resistivity of a series of Fe 2 A Laves phase compounds was measured in order to investigate its mutual correlation with their magnetic properties, and a linear relation between the magnetic resistivity at temperatures above the Curie or Neel point and the localized magnetic moment was found.
Abstract: The electrical resistivity of a series of Fe 2 A Laves phase compounds was measured in order to investigate its mutual correlation with their magnetic properties. In the ferromagnetic or antiferromagnetic Fe 2 A compounds (A=Sc, Y, Ti, Zr, Hf, and U), a linear relation between the magnetic resistivity at temperatures above the Curie or Neel point and the localized magnetic moment was found, which means that the magnetic resistivity of these compounds is governed by the magnitude of magnetic moments. The electrical resistivity in the Pauli-paramagnetic Fe 2+ x Nb 1- x and Fe 2+ x Ta 1- x compounds with x ≈0 shows a fairly large temperature variation, which seems to be due to the paramagnon scattering, whereas ρ- T curves in the iron-rich compounds suggest that the appearance of ferromagnetism is caused by the existence of the excess iron atoms occupying the wrong atomic sites.

21 citations


Journal ArticleDOI
TL;DR: In this article, the orientation relationship between ferrite and precipitate particles of the hexagonal Laves phase, Fe2Nb, has been determined using electron diffraction techniques, and a model of the interface between the two phases is developed on the basis of this orientation relationship.
Abstract: The orientation relationship between ferrite and precipitate particles of the hexagonal Laves phase, Fe2Nb, has been determined using electron diffraction techniques. There exists a single orientation relationship, which may be stated as:A model of the interface between the two phases is developed on the basis of this orientation relationship and the observed morphology and habit of the precipitate particles are discussed in terms of this model.

14 citations


Journal ArticleDOI
M. Shiga1
TL;DR: A thermal expansion anomaly similar to that of the invar alloy was observed in a Laves phase intermetallic compound, Zr0.7Nb0.3Fe2 as discussed by the authors.

12 citations


Journal ArticleDOI
TL;DR: In this paper, a Laves phase, Fe2Ta, was utilized to obtain good elevated temperature properties in a carbon-free iron alloy containing 1 at.pct Ta and 7 at. pct Cr. This was accomplished by thermally cycling the alloys through the alpha to gamma transformation.
Abstract: A Laves phase, Fe2Ta, was utilized to obtain good elevated temperature properties in a carbon-free iron alloy containing 1 at. pct Ta and 7 at. pct Cr. Room temperature embrittlement resulting from the precipitation of the Laves phase at grain boundaries was overcome by spheroidizing the precipitate. This was accomplished by thermally cycling the alloys through the alpha to gamma transformation. The short-time yield strength of the alloys decreased very slowly with increase in test temperature up to 600 C, but above this temperature, the strength decreased rapidly. Results of constant load creep and stress rupture tests conducted at several temperatures and stresses indicated that the rupture and creep strengths of spheroidized 1 Ta-7 Cr alloy were higher than those of several commercial steels containing chromium and/or molybdenum carbides but lower than those of steels containing substantial amounts of tungsten and vanadium. When molybdenum was added to the base Fe-Ta-Cr alloy, the rupture and creep strengths were considerably increased.

12 citations


Journal ArticleDOI
TL;DR: The Jaccarino-Walker model of moment collapse was applied to explain the composition dependence of the Co moment in this system and the absence of a Ni moment in the isomorphic ferromagnet, GdNi 2.

11 citations




Journal ArticleDOI
TL;DR: The hyperfine interaction of holmium in the ferrimagnetic alloy system Ho0.03GdxY0.97-xCo2 has been studied by NMR at liquid helium temperatures as discussed by the authors.
Abstract: The hyperfine interaction of holmium in the ferrimagnetic alloy system Ho0.03GdxY0.97-xCo2 has been studied by NMR at liquid helium temperatures. Well-resolved satellite spectra show that each gadolinium ion in a nearest-neighbour site contributes about 3T to the field at the holmium nucleus.

10 citations


Journal ArticleDOI
TL;DR: In this article, a tentative explanation of the role of conduction electrons in creating the crystal field in Laves phase di-aluminide compounds is given, and q shift and linewidth measurements are sufficient to enable absolute deduction of the exchange parameters.
Abstract: The results are reported of paramagnetic resonance measurements on Er and Dy in ScAl2, the ground states are in both cases Gamma 7 doublets. The temperature dependence of the linewidth shows that the exchange parameters are equal within experimental error. The authors show that in general q shift and linewidth measurements are sufficient to enable absolute deduction of the exchange parameters. A tentative explanation of the role of conduction electrons in creating the crystal field in Laves phase di-aluminide compounds is given.

Patent
15 May 1975
TL;DR: Nickel base alloy contg. molybdenum plus addns. as mentioned in this paper is composed of the elements Co, Cr, Al, Si and B in a concn. such that by directional solidification in a temp. gradient, a two- or multi-phase composite material is formed in which a single component phase is embedded parallel to the direction of solidification.
Abstract: Nickel base alloy contg. molybdenum plus addns. 1 of the elements Co, Cr, Al, Si and B, in a concn. such that by directional solidification in a temp. gradient, a two- or multi-phase composite material is formed in which a single- or multi-component phase is embedded parallel to the direction of solidification in a matrix of nickel mixed crystals. The intermetallic phase is pref. (a) the sigma phase (Ni-Cr-Mo) or the rho phase (Ni-Cr-Mo); (b) the Laves phase Mo (Ni1-xSix)2; (c) Mo2NiB2; and the alloy may contain Mo fibres. The alloy may also contain the following maxima in atom % 10% Ti, 0.5% Zr, 0.05% Fe, 10% W, 4% Ta, 2% Hf, 0.03% Y, to increase strength and corrosion resistance, plus 2% max. Si or B in excess of that in cpds. (b) or (c). The heat resisting alloys obtd. are used e.g. for gas turbine applications. They have increased strength and corrosion resistance, e.g. when Si is added it is present in the reinforcing lamellae so the ductility of the matrix is not impaired.