Фазовая диаграмма системы Ag-Na

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Ag-Na (Silver-Sodium) A.D. Pelton In the assessed phase diagram of the Ag-Na system, the melting points of the pure elements are taken from [Melt], and the liquidus has been obtained from thermodynamic modeling. The present diagram is based on review of the work of [10Que], [11Mat], [68Lam], and [69Wee]. Good agreement exists between the calculated diagram and experimental data, which exhibit appreciable scatter. Error limits of с 15 degrees should be applied to the liquidus. The solubility of Na in solid (Ag) is probably significantly less that 1 at.%. The existence of an intermediate Laves phase, Ag2Na, has been reported in one study [61Kie]. However, other investigators failed to detect this phase. An arrest observed during thermal analysis at 322 C [61Kie] may be the peritectic associated with this phase. The measured solubility of Ag in liquid Na at the melting point of Na is 0.03 at.%. If it is assumed that the solubility of Ag in solid (Na) is negligibly small, a freezing point depression at the eutectic of 0.13 C may be calculated from the enthalpy of fusion of Na [83Cha]. This is in agreement with the work of [1889Tam], who observed a lowering of the melting point of Na by 0.09 C upon addition of Ag. The extremely flat shape of the liquidus indicates a strong tendency to immiscibility in the liquid phase. Thermodynamic analysis places the consolute point of the immiscibility gap within 10 C of the liquidus. The existence of a liquid immiscibility gap, extending roughly over the range 30 to 60 at.% Ag at a monotectic temperature of approximately 744 C with a consolute point about 10 to 20 C higher, is quite possible. 1889Tam: G. Tammann, Z. Phys. Chem., 3, 447 (1889) in German. 10Que: E. Quercigh, Z. Anorg. Chem., 68, 301-306 (1910) in German. 11Mat: C.H. Mathewson, Int. Z. Metall., 1, 51-63 (1911). 61Kie: G. Kienast and J. Verna, Z. Anorg. Chem., 310, 143-169 (1961) in German. 68Lam: G.J. Lamprecht and P. Crowther, Trans. AIME, 242, 2169-2171 (1968). 69Wee: J.R. Weeks, Trans. ASM, 62, 304 (1969). 83Cha: M.W. Chase, Bull. Alloy Phase Diagrams, 4, 124 (1983). Published in Bull. Alloy Phase Diagrams, 7(2), April 1986. Complete evaluation contains 1 figure, 1 table, and 15 references. 1