Фазовая диаграмма системы Au-Se

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Au-Se (Gold Selenium) H. Okamoto and T.B. Massalski The equilibrium phases of the Au-Se system are (1) the liquid, L, with two miscibility gaps, L1 + L2 and L2 + L3; (2) the fcc terminal solid solution, ( Au), with no reported solid solubility of Se in (Au); (3) the hexagonal solid solution, (Se), with no reported solid solubility of Au in (Se); and (4) the monoclinic intermetallic compound aAuSe, with no reported solubility range. aAuSe is stable below 425 C. Monoclinic bAuSe is metastable below 376 C. The assessed Au-Se phase diagram is based primarily on the work of [68Cra] and [71Rab]. Because the specimens used to derive the assessed diagram were prepared in sealed ampoules, the diagram may not correspond to the usual 1 atm pressure condition. The extents of the miscibility gaps are defined by the L1 = L2 + (Au) and L2 = L3 + (Au) monotectic reactions. The shape of the L1 + L2 miscibility gap has not been investigated. The L2 + L3 miscibility gap was tentatively reported with a maximum temperature of 800 C by [68Cra]. The metastable bAuSe structure decomposes at 376 C on heating [71Rab]. A hexagonal modification of AuSe formed in an AuSe thin-film couple when pulse annealed with an electron beam. Au2Se has been prepared by the action of hydrogen selenide on a potassium aurate (L) solution in the absence of air. Au2Se3 forms when hydrogen selenide is introduced into an Au+3 salt solution in the dark. Either of these selenides may not be true chemical compounds, but only an intimate mixture of Au and Se. 68Cra: G.E. Cranton and R.D. Heyding, Can. J. Chem., 46(16), 2637-2640 (1968). 71Rab: A. Rabenau, J. Less-Common Met., 24(3), 291-299 (1971). Published in Phase Diagrams of Binary Gold Alloys, 1987. Complete evaluation contains 4 figures, 1 table, and 14 references. 1