Фазовая диаграмма системы Cu-Gd

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Cu-Gd (Copper-Gadolinium) P.R. Subramanian and D.E. Laughlin The equilibrium phases of the Cu-Gd system are (1) the liquid, L, with no miscibility gaps; (2) the fcc terminal solid solution, (Cu), with negligible solid solubility of Gd in (Cu); (3) the Gd-rich bcc terminal solid solution, ( bGd), based on the high-temperature phase of pure Gd; (4) the Gd-rich cph terminal solid solution, (aGd), stable below 1235 C; (5) the hexagonal intermediate phase, Cu7Gd, stable only at elevated temperatures; (6) the orthorhombic intermediate phase, Cu6Gd, stable up to the peritectic melting temperature of 865 C; (7) the phase Cu5Gd, present in two allotropic modifications, of which the low-temperature cubic form is stable up to 660 C and the high-temperature hexagonal form is stable between 660 C and the peritectic melting temperature of 925 C; (8) the phase Cu9Gd2, with an unknown crystal structure and stable up to the congruent melting temperature of 930 C; (9) the orthorhombic phase Cu2Gd, stable up to the congruent melting temperature of 860 C; and (10) the most Gd-rich intermediate phase, CuGd, with a cubic structure and stable up to the congruent melting temperature of 830 C. The assessed phase diagram is based on the work of [83Car], with adjustments to the elemental melting points to bring them in accord with the accepted values [Melt]. The bGd = aGd transformation temperature has been changed from 1265 to 1235 C. Minor changes also have been made in the liquidus in the vicinity of the congruent point at 830 C to conform to thermodynamic rules for construction of congruent inflection points and, accordingly, the eutectic composition at 770 C has been shifted slightly toward higher Gd content. [72Ray] obtained metastable solid solutions of Cu in Gd with up to 10 to 12.5 at.% Cu under conditions of splat cooling. M”ssbauer studies of the quenched samples indicated the complete absence of equilibrium intermediate phases in the resultant solid solutions. [74Dom] prepared thin-film samples of Cu2Gd by thermal evaporation followed by condensation under vacuum onto glass substrates preheated to 200 C. The resultant thin-film specimens could be indexed by X-ray diffraction on the basis of the MgCu2 (Laves phase) type unit cell with a = 0.750 nm. [79Mcg] obtained amorphous films with the stoichiometry Cu0.58Gd0.42 by sputtering from arc-melted specimens and by thermal evaporation followed by deposition on liquid nitrogen-cooled sapphire substrates. 72Ray: R.Ray, M. Segnini, and B.C. Giessen, Solid State Commun., 10, 163-167 ( 1972). 74Dom: V.A. Domyshev, V.A. Yegorov, V.A. Buravikhin, L.M. Sidorenko, and N.I. Luzgin, Fiz. Met. Metalloved., 38(1), 102-109 (1974) in Russian; TR: Phys. Met. Metall., 38(1), 89-95, (1974). 79Mcg: T.R. McGuire and R.J. Gambino, J. Appl. Phys., 50(11), 7653-7655 (1979). 83Car: M.M. Carnasciali, S. Cirafici, and E. Franceschi, J. Less-Common Met., 92, 143-147 (1983). Published in Bull. Alloy Phase Diagrams, 9(3a), Aug 1988. Complete evaluation contains 3 figures, 5 tables, and 27 references. Special Points of the Cu-Gd System