Фазовая диаграмма системы Au-Bi

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Au-Bi (Gold-Bismuth) Editor The equilibrium phases of the Au-Bi system, which is essentially a simple eutectic, are (1) the liquid, L; (2) the fcc terminal solid solution, (Au), having less than 0.06 at.% solid solubility of Bi in (Au); (3) the rhombohedral terminal solid solution, (Bi), with no reported solubility of Au in (Bi); and (4) the Cu2Mg-type intermetallic compound, Au2Bi, stable between ~116 and 371 C. The liquidus curves in the assessed phase diagram were determined by [62Nat]. [ 06Vog] determined the general form of the liquidus, except for the portion between the peritectic and eutectic temperatures. Because [06Vog] failed to observe the presence of the Au2Bi intermediate phase, the liquidus in this temperature range most likely corresponds to the metastable L/[L + (Au) ] phase boundary. The phase diagram calculated on the basis of thermodynamic experimental data obtained at 700 and 1100 C agrees very well with the experimentally determined liquidus boundaries. If the thermodynamic properties of the Au2Bi phase are estimated from the equilibrium relationships at the peritectic and eutectic temperatures, the phase diagram calculation predicts a eutectoidal decomposition, Au2Bi = (Au) + (Bi), at 116 C on cooling. This decomposition was predicted earlier from the superconducting behavior of Au2Bi. Two thermodynamic models proposed by [88Che] agree well with the experimental phase diagram. The eutectoid decomposition temperature of Au2Bi was calculated to be about 77 or 110 C. 06Vog: R. Vogel, Z. Anorg. Chem., 50, 145-157 (1906) in German. 62Nat: M.W. Nathans and M. Leider, J. Phys. Chem., 66(10) 2012-2015 (1962). 68Gie: B.C. Giessen, U. Wolff, and N.J. Grant, Trans, AIME, 242(4), 597-602 ( 1968). 88Che: P.Y. Chevalier, Thermochim. Acta, 130, 15-24 (1988). This supersedes the evaluation published in Phase Diagrams of Binary Gold Alloys, 1987, and Bull. Alloy Phase Diagrams, 4(4), Dec 1983. Complete evaluation contains 5 figures, 9 tables, and 29 references. 1