Фазовая диаграмма системы Au-Nd

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Au-Nd (Gold-Neodymium) K.A. Gschneidner, Jr., F.W. Calderwood, H. Okamoto, and T.B Massalski The calculated Nd-Au phase diagram is characterized by the existence of five compounds. The phase diagram has not been established experimentally, although it would be expected to resemble that of the light lanthanides with Au. [71Mcm] found that Nd2Au has the orthorhombic Co2Si-type structure, as do most of the other RE2Au compounds. NdAu was found to exist in three forms: the orthorhombic FeB-type structure at room temperature and up to 530 C on heating (below 420 C on cooling), another orthorhombic structure of the CrB type as the intermediate form, and the cubic CsCl-type structure above 1360 C. They also determined the melting point of NdAu to be 1450 с 10 C. [63Cha] found the cubic CsCl-type structure in NdAu on rapid quenching from the melt, an indication that this is a polymorphic form that is not stable at room temperature. [71Mcm] indexed an NdAu2 sample to a tetragonal structure designated as NdAu2 type. Some orthorhombic CeCu2-type reflections were observed in rapidly cooled NdAu2 samples, but the CeCu2 type was thought to be a mestastable form. The melting point of this phase has not been investigated. [69Don] investigated structures of "REAu3" compounds and reported a hexagonal structure. [71Mcm] also examined a Nd-Au compound in the same composition range and concluded that the single-phase structure existed at ~ 78.7 at.% Au. They also reported that Nd14Au51 crystallizes in the hexagonal Gd14Au51- type structure. No data were found relating to the melting temperature or the eutectic relationship with the neighboring compounds. The difference between the lattice parameters reported by [71Mcm] and those reported by [69Don] may indicate a range of solid solubility for the Nd14Au51 phase. [71Mcm] reported the existence of complex REAu6 phases that they could not successfully index. However, [71Mor] indexed REAu6 phases as being monoclinic. No data were found regarding the method of melting (congruent or incongruent) of this compound or the temperature involved. [65Rid] investigated the solid solubility of 13 rare earth metals including Nd in (Au), using the X-ray parametric method. A slight increase in the lattice parameter for the 5.2 at.% Nd specimen over the parameter for pure Au suggested a slight solubility of Nd in (Au). A quantitative estimate of solid solubility indicated a solubility limit of 0.2 to 0.3 at.% for Nd in (Au). The eutectic temperature for the light rare earths, including Nd, with Au remained fairly constant at 808 C. 63Cha: C.C. Chao, H.L. Luo, and P. Duwez, Jr., J. Appl. Phys., 34, 1971 (1963). 65Rid: P.E. Rider, K.A. Gschneidner, Jr., and O.D. McMasters, Trans. AIME, 1488, 436 (1965). 69Don: C. Donolato and S. Steeb, J. Less-Common Met., 18, 312 (1969). 71Mcm: O.D. McMasters, K.A. Gschneidner, Jr., G. Bruzzone, and A. Palenzona, J. Less-Common Met., 25, 135 (1971). 72Mor: J.M. Moreau and E. Parthe, Compt. Rend., 274B, 823 (1972). Published in Phase Diagrams of Binary Gold Alloys, 1987. Complete evaluation contains 2 figures, 2 tables,and 8 references. 1