Фазовая диаграмма системы Au-Ga

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Au-Ga (Gold-Gallium) T.B. Massalski and H. Okamoto The equilibrium phases of the Au-Ga system are (1) the liquid, L; (2) the fcc terminal solid solution, (Au), having about 12.4 at.% solid solubility of Ga in (Au); (3) the orthorhombic terminal solid solution, (Ga), having no reported solid solubility; (4) the a› phase with cph symmetry, stable between 348 and 415.4 C; (5) the hexagonal b phase extending from about 20.4 to 22.1 at.% Ga between 282 and 409.8 C; (6) the b› phase with an orthorhombic distortion of the b phase unit cell, forming peritectically at 375.0 C and having a homogeneity range of about 2 at.%; (7) the orthorhombic g phase, forming congruently at 348.9 C and 30.5 at.% Ga and extending from about 29.8 to 31 at.% Ga; (8) the g› phase, forming by an order-disorder transformation from the g phase at temperatures ranging between 274 and 286 C; (9) the MnP- type orthorhombic intermetallic compound AuGa, forming congruently at 461.3 C; and (10) the CaF2-type cubic AuGa2, forming congruently at 491.3 C. An unknown type, three peritectic, three eutectic, and two eutectoid reactions occur in this system [66Coo]. The reaction involving the liquid, L, and the solid phases, AuGa2 and (Ga), has not been determined. The assessed Au-Ga phase diagram is based mainly on the work of [66Coo], who updated the diagram of [39Wei]. It is supplemented partly by thermodynamic calculations. The electrical resistivity measurements of [59Mul] showed that the maximum solubility of Ga in (Au) is greater than 10 at.%. The assessed liquidus, based on the work of [66Coo], differs substantially from the calculated contour, which is in rather good agreement with the liquidus of [39Wei]. The model used in the thermodynamic calculation is based on the work of [71Ber]. A series of amorphous alloys were observed in vapor deposited films with compositions ranging from 30 to 80 at.% Ga [74Kor]. 39Wei: F. Weibke and E. Hesse, Z. Anorg. Allg. Chem., 240(4), 289-299 (1939) in German. 59Mul: K. Muller and W. Merl, Elektrotech. Z., 80, 515-518 (1959) in German. 66Coo: C.J. Cooke and W. Hume-Rothery, J. Less-Common Met., 10, 42-51 (1966). 71Ber: C. Bergman, J.P. Bros, M. Carbonel, M. Gambino, and M. Lafitte, Rev. Int. Hautes Temp. Refract., 8(3-4), 205-210 (1971) in French. 74Kor: D. Korn, H. Pfeifle, and G. Zibold, Z. Phys., 270, 195-202 (1974). Published in Phase Diagrams of Binary Gold Alloys, 1987, and Bull. Alloy Phase Diagrams, 2(3), Dec 1981. Complete evaluation contains 5 figures, 7 tables, and 38 references. Special Points of the Au-Ga System