Фазовая диаграмма системы Au-Li

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Au-Li (Gold-Lithium) A.D. Pelton The assessed phase diagram for the Au-Li system is taken from [61Kie], except for the melting points of the elements. Error limits of at least с10 C should be placed on all invariant temperatures, and limits of at least с20 C should be placed on the solidus and liquidus curves. Ranges of homogeneity of the solid phases were inferred from the thermal analysis results of [61Kie]. Evidence for the Au5Li4 compound is scanty. The invariant at 245 C was associated with the transformation of the d phase; however, another interpretation is quite possible. X-ray investigation of three alloys [33Zin] indicated extensive solubility of Li in (Au) and showed that the intermetallic phase at the equiatomic composition does not have a simple CsCl-type structure. [61Kie] proposed a solubility of Au in (Li) of 0.7 at.% at the eutectic. A eutectic liquid composition of 94.9 at.% Li was also suggested. Error limits of с5 to с10 C should be placed on the reported eutectic temperature of 155 C. The dashed lines separating the a, a1, and a2 regions are not to be taken as true phase boundaries, but only as indications of regions in which different structures were observed in X-ray studies. The existence of the a2 phase requires verification. The b phase, of nominal composition AuLi, was observed by [33Zin] at 50 and 52 at.% Li. The position of the Au-rich limit at about 47 at.% Li is inferred from only one thermal analysis point at 48.3 at.% Li at 636 C. If this point is actually a eutectic halt at 631 C, then the Au-rich homogeneity limit could easily be closer to 50 at.% Li, although the flatness of the liquidus also indicates a somewhat wider homogeneity range. The d phase is evidenced by a liquidus maximum near 511 C, with a homogeneity range from 62.5 to 65.5 at.% Li at 25 C. 33Zin: E. Zintl and G. Brauer, Z. Phys. Chem. (Leipzig), B20, 245-271 (1933) in German. 61Kie: G. Kienast and J. Verma, Z. Anorg. Allg. Chem., 310, 143-169 (1961) in German. Published in Phase Diagrams of Binary Gold Alloys, 1987, and Bull. Alloy Phase Diagrams, 7(3), Jun 1986. Complete evaluation contains 1 figure, 1 table, and 6 references. 1