Фазовая диаграмма системы Nd-Si

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Nd-Si (Neodymium-Silicon) A.B. Gokhale, A. Munitz, and G.J. Abbaschian The assessed phase diagram for the Nd-Si system is based primarily on [84Ere], with modifications incorporated on the basis of other studies on the synthesis and physical properties of various intermediate phases in the system. The tetragonal intermediate phase Nd5Si3 is the richest in Nd in the system, and decomposes peritectically at 1447 C. [84Ere] indicated the phase to be nearly stoichiometric. However, based on the data of [68Ram], a homogeneity range of 1 at.% Si has been tentatively indicated. The nearly stoichiometric intermediate phase Nd3Si4 decomposes peritectoidally at 1397 C. Its structure has not been determined. [84Ere] indicated a homogeneity range of 64 to 65 at.% Si for NdSix. However, based on the data of [65Dvo1], [65Dvo2], [65Sam], and [66Dvo], the range has been extended to 66.79 at.% Si in this evaluation. [84Ere] indicated a polymorphic transformation for the phase at 147 C on the Si-deficient side ( 64 at.% Si), and at 97 C on the Si-rich side (65 at.% Si), with an orthorhombic (aGdSi2-type), low-temperature modification; they did not specify the high-temperature form. In this evaluation, the transformation temperature at the Si-rich limit (66.79 at.% Si) has been calculated to be 7.5 C, using a linear extrapolation of the polymorphic transformation data of [84Ere], and the high-temperature modification is indicated to be tetragonal (ThSi2 type) [ 68Ram]. [60Bin] noted that the melting temperature of "NdSi2" was 1525 C. In the present evaluation, the phase field of NdSix has been drawn to take this into account. The liquidus in the system has been determined reliably by [84Ere]. Because no thermodynamic data on the properties of the liquid solution were available in the literature, they were assessed in this evaluation by using the experimental solubility data of [84Ere]; the mixing process was found to be slightly endothermic. The mutual solid solubility limits of Si and Nd have not been reported. Based on the interaction of Si with other rare earths, the solubility is probably negligible. 60Bin: I. Binder, J. Am. Ceram. Soc., 43(6), 287-292 (1960). 65Dvo1: L.A. Dvorina and T.S. Verkhoglyadova, Izv. Akad. Nauk SSSR, Met., (6), 62-68 (1965) in Russian; TR: Russ. Metall., (6), 38-44 (1965). 65Dvo2: L.A. Dvorina, Izv. Akad. Nauk SSSR, Neorg. Mater., 1(10), 1772-1777 ( 1965) in Russian; TR: Inorg. Mater., 1, 1604-1608 (1965). 65Sam: G.V. Samsonov, T.S. Verkhogluadov, and L.A. Dvorina, Fiz. Met. Metalloved., 19, 939-941 (1965) in Russian; TR: Phys. Met. Metallogr., 19(6), 129-131 (1965). 66Dvo: L.A. Dvorina, Poroshk. Met., (6), 92-94 (1966) in Russian; TR: Sov. Powder Metall. Met. Ceram., 507-509 (1966). 66Hoh: D. Hohnke and E. Parthe, Acta Crystallogr., (20), 572-582 (1966). 67Ram: A. Raman and H. Steinfink, Inorg. Chem., 6(10), 1789-1791 (1961). 68Ram: A. Raman, Trans. Indian Inst. Met., 5-8 (Dec 1968). 72May: I. Mayer and I. Felner, J. Less-Common Met., 29, 25-31 (1972). 84Ere: V.N. Eremenko, K.A. Meleshevich, Yu.I. Buyanova, and I.M. Obushenko, Dop. Akad. Nauk Ukr. RSR A, 11, 77-82 (1984) in Ukrainian. Published in Bull. Alloy Phase Diagrams, 10(3), Jun 1989. Complete evaluation contains 3 figures, 3 tables, and 24 references. Special Points of the Nd-Si System