Фазовая диаграмма системы Au-Mg

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Au-Mg (Gold-Magnesium) A.A. Nayeb-Hashemi and J.B. Clark The Mg-Au phase diagram consists of (1) the liquid, L; (2) the cph terminal solid solution, (Mg), with negligible solid solubility of Au; (3) the stoichiometric Mg3Au compound, which melts congruently at 818 C; (4) the stoichiometric Mg5Au compound, which is stable between 721 and 796 C (the stoichiometric Mg5Au compound forms by a peritectic reaction at 796 C and decomposes by a eutectoid reaction at 721 C); (5) the stoichiometric Mg2Au compound, which melts congruently at 788 C; (6) the nonstoichiometric (MgAu) ordered intermediate phase, which at 50 at.% Au melts congruently at 1150 C; and (7) the terminal solid solution, (Au). The assessed phase diagram is based primarily on the work of [09Ura], with review of the work of [09Vog], [10Ura], [65Bur], and [66Sch]. It is essentially the same as the diagram of [Hansen]. The maximum solid solubility is ~0.1 at.% Au in (Mg). The solid solubility limits of Mg in (Au) have not been determined. However, thermal analyses of [ 09Ura] and [09Vog] showed a wide range of solid solubility of Mg in (Au). They also showed the ordered intermediate MgAu phase to have a wide homogeneity range. [65Bur] reported several new phases in the Mg-Au system in the composition range of 70 to 80 at.% Au around the MgAu3 composition. The alloys were annealed for long periods of time at different temperatures, followed by quenching. [65Bur] observed evidence for six structures. However, only the structure of Mg22Au78 (Al3Zr-type) and the substructures of Mg24Au76 and Mg26Au74 were identified. 09Ura: G.G. Urasow, Z. Anorg. Allg. Chem., 63, 169-183 (1909) in German. 09Vog: R. Vogel, Z. Anorg. Allg. Chem., 64, 375-396 (1909) in German. 10Ura: G.G. Urasow and R. Vogel, Z. Anorg. Allg. Chem., 67, 442-447 (1910) in German. 65Bur: K. Burkhardt and K. Schubert, Z. Metallkd., 56, 864-870 (1965) in German. 66Sch: K. Schubert, Metall, 20(5), 424-430 (1966) in German. Published in Phase Diagrams of Binary Magnesium Alloys, 1988, and Phase Diagrams of Binary Gold Alloys, 1987. Complete evaluation contains 2 figures, 3 tables, and 27 references. Special Points of the Mg-Au System