Фазовая диаграмма системы Ag-Mg

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Ag-Mg (Silver-Magnesium) A.A. Nayeb-Hashemi and J.B. Clark The assessed Ag-Mg phase diagram consists of (1) the liquid; (2) the cph solid solution, (Mg) (or d), with a maximum solid solubility of 3.83 at.% Ag (96.17 at.% Mg) at the eutectic temperature of 472 C; (3) the fcc solid solution, ( Ag) (or a), with a maximum solid solubility of 29.3 at.% Mg at the eutectic temperature of 759.3 C; (4) the intermediate phase Ag3Mg (or a›), a AuCu3 cP4- type structure, ordered with one-dimensional anti-phase domain; (5) the congruently melting Ag-Mg compound (or b›), a CsCl cP2-type structure, with a wide range of homogeneity that narrows at lower temperatures (this intermediate phase is in ordered condition up to the melting point); and (6) the intermediate phase AgMg3 (or e), with a complex structure that forms by a peritectic reaction at 492 C. The present diagram is based primarily on the results of [06Zem], [37Hum], [37Pay], [43And], and [68Gan]. Although the solubility of monovalent Ag in divalent Mg is very limited, the solubility of divalent Mg in Ag is quite extensive. The atomic diameter of Ag is within the favorable size factor with respect to Mg, but the relative valency factor restricts the solubility of monovalent Ag in divalent Mg. Martensitic structures have been reported in splat-cooled alloys in the composition range of the AgMg phase. X-ray analysis of Mg-12.6 at.% Ag alloys ( 87.4 at.% Mg) aged at room temperature showed the presence of two kinds of G.P. zones. Editor's note: An X-ray diffraction study by [85Pro] established that "AgMg3" in conventional diagrams consists of a high-temperature, bct e› phase and a low-temperature, fcc e phase. [88Kol] (the same authors as [85Pro]) clarified the phase relationship between e› and e. The assessed phase diagram has been modified accordingly. [88Kol] found hexagonal AgMg4, which was probably identified as hexagonal "AgMg3" in conventional phase diagrams. The structure formula of e› is Ag17Mg54 [88Kol].- H.O. 06Zem: S.F. Zemczuznyj, Z. Anorg. Chem., 49, 400-414 (1906) in German. 37Hum: W. Hume-Rothery and E. Butchers, J. Inst. Met., 60, 345-350 (1937). 37Pay: R.J.M. Payne and J.L. Haughton, J. Inst. Met., 60, 351-363 (1937). 43And: K.W. Andrews and W. Hume-Rothery, J. Inst. Met., 69, 485-493 (1943). 68Gan: A. Gangulee and M.B. Bever, Trans. AIME, 242, 278-283 (1968). 85Pro: M.V. Prokof'ev, V.E. Kolesnichenko, and V.V. Karonik, Izv. Akad. Nauk, SSSR, Neorg. Mater., 21(8), 1332-1334 (1985) in Russian; TR: Inorg. Mater., 21( 8), 1168-1170 (1985). 88Kol: V.E. Kolesnichenko, V.V. Karonik, S.N. Tsyganova, T.A. Kupriyanova, and L.N. Sysoeva, Izv. Akad. Nauk, SSSR, Met., (5), 186-191 (1988) in Russian; TR: Russ. Metall., (5), 188-192 (1988). This supersedes the evaluation published in Phase Diagrams of Binary Magnesium Alloys, 1988, and Bull. Alloy Phase Diagrams, 5(4), Aug 1984. Complete evaluation contains 3 figures, 20 tables, and 58 references. Special Points of the Ag-Mg System