Фазовая диаграмма системы Au-Pt

К оглавлению: Другие диаграммы (Others phase diargams)

Au-Pt (Gold-Platinum) H. Okamoto and T.B. Massalski The equilibrium phases of the Au-Pt system are (1) the liquid, L; and (2) the fcc continuous solid solution, (Au, Pt), encompassing a miscibility gap, (Au) + (Pt). The critical point of the miscibility gap is at about 61 at.% Pt and 1260 C. The Au-Pt phase diagram has been investigated extensively [07Doe, 30Joh, 51Gru, 52Dar], because of the experimental and theoretical interest in the miscibility gap occurring in the solid solution field, as well as the controversy regarding the form of the liquidus and solidus boundaries. The liquidus and solidus (0 to 80 at.% Pt) boundaries are based on the experimental data of [52Dar]. The remainder of the solidus, the miscibility gap, and the spinodal curve have been drawn according to a tentative thermodynamic model. The thermodynamic functions for the solid phase were determined from the trend of the miscibility gap. The liquid was assumed to be a subregular solution. The Au3Pt phase is considered metastable. X-ray patterns have revealed the existence of the Au3Pt superlattice in alloys up to 40 at.% Pt after severe cold working, followed by annealing at 900 C [51Gru]. X-ray diffraction studies of 10 and 25 at.% Pt alloys showed that the Au3Pt, AuPt, and AuPt3 phases materialize as metastable phases during heating of a two-phase mixture of (Au) and (Pt). It appears that the existence of these ordered structures is observed definitively only in transient states or in thin films. Formation of an amorphous phase has been achieved by implantation of Au+ ions into a Pt matrix [78Sin]. 07Doe: F. Doerinckel. Z. Anorg. Allg. Chem., 34, 333-366 (1907) in German. 30Joh: C.H. Johansson and J.O. Linde, Ann. Phys., 5(6), 762-792 (1930) in German. 51Gru: G. Grube, A. Schneider, and U. Esch, Festschrift aus Anlass des 100- Jahrigen Jubilaums der Firma, W.C. Heraeus G.m.b.H., 20-42 (1951). 52Dar: A.S. Darling, R.A. Mintern, and J.C. Chaston, J. Inst. Met., 81, 125- 132 (1952-1953). 78Sin: S.P. Singhal, H. Herman, and J.K. Hirvonen, Appl. Phys. Lett., 32(1), 25-26 (1978). Published in Phase Diagrams of Binary Gold Alloys, 1987, and Bull. Alloy Phase Diagrams, 6(1), Feb 1985. Complete evaluation contains 6 figures, 7 tables, and 59 references. 1