Фазовая диаграмма системы Ca-Na

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Ca-Na (Calcium-Sodium) A.D. Pelton The assessed Ca-Na phase diagram is based primarily on the work of [31Rin], with review of the work of [09Met], [29Lor1], and [29Lor2]. The smoothed liquidus and miscibility gap boundary were obtained from thermodynamic analysis. All phase boundaries indicated as dashed lines were also obtained from thermodynamic analysis and should be regarded as estimates. A monotectic occurs at 710 с 10 C, and the compositions of the two liquids in equilibrium are 22.1 с 10 and 95.9 с 10 at.% Na [31Rin]. The solid solubility of Na in (Ca) apparently has never been studied directly. However, from the limiting slope of the liquidus at the melting point of pure Ca, a solubility of several atomic percent is likely. The a = b phase transition of pure Ca occurs at 443 C. No data exist on the lowering of this temperature due to additions of Na. Assuming that Na is insoluble in (aCa) and that the solubility of Na in (bCa) calculated from the thermodynamic analysis is correct, a transformation point depression of 21 C can be computed from the enthalpy of transformation. However, by analogy with the Sr-Na system, in which Na has about the same solubility in (aSr) as in (bSr), it is more likely that Na is also quite soluble in (aCa). This would result in a much smaller transformation point depression, probably on the order of 1 to 5 C. 09Met: J. Metzger, Liebigs Ann., 355, 141 (1907) in German. 29Lor1: R. Lorenz and R. Winzer, Z. Anorg. Allg. Chem., 179, 281-286 (1929) in German. 29Lor2: R. Lorenz and R. Winzer, Z. Anorg. Allg. Chem., 181, 193-202 (1929) in German. 31Rin: E. Rinck, Compt Rend., 192, 1378-1381 (1931) in French. Published in Bull. Alloy Phase Diagrams, 6(1), Feb 1985. Complete evaluation contains 1 figure, 1 table, and 4 references. 1