Фазовая диаграмма системы Cr-Sn

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Cr-Sn (Chromium-Tin) M. Venkatraman and J.P. Neumann The assessed Cr-Sn phase diagram is a composite of the studies of [61Ste], [ 69Dar], and [69Pre]. It is characterized by partial immiscibility in the liquid state and extensive immiscibility of Cr and Sn in the solid state. [ 69Pre] established the boundaries of the liquid miscibility gap by differential thermal analysis of alloys in the composition range 20 to 90 at.% Sn. The alloys were prepared by melting high-purity Cr and Sn in alumina crucibles in an argon atmosphere. The liquid miscibility gap extends at the monotectic temperature of 1374 C from 22.8 to 55.5 at.% Sn [69Pre]; the critical point of the liquid miscibility gap occurs at 1485 C and 39.5 at.% Sn [69Pre]. The solubility of solid Cr in liquid Sn was measured by [61Ste], [69Dar], and [ 69Pre] in the temperature range 600 to 1300 C. A regression analysis of the experimental data yields a value of 3 x 10-4 at.% for the solubility of Cr in liquid Sn at the melting point of pure Sn. No stable intermediate phases exist in the Cr-Sn system, and the mutual solubilities of Cr and Sn are small [47Nia]. The solubility of Sn in solid (Cr) at the monotectic temperature is approximately 2 at.% [08Hin], in accord with a solubility of approximately 1.4 at.% Sn at room temperature, according to measurements of the N‚el temperature of Cr-Sn alloys by [72Fuk]. The influence of Cr on the (aSn) = (bSn) transformation is not known. The existence of an intermediate phase (Cr2Sn3) was reported by [64Hol], who prepared it by amalgamation of Cr and Sn. Its structure was established clearly by [66Hol], but its thermodynamic stability is questionable, because on heating it decomposes irreversibly at 438 C [64Hol]. The irreversible decomposition might explain why other investigators did not observe the phase in alloys cooled from higher temperatures. Because the Cr2Sn3 phase is probably metastable, it is not shown in the assessed diagram. [72Fuk] determined the influence of Sn on the N‚el temperature of Cr from measurements of the electrical resistivity and the thermal expansion. The N‚el temperature increases linearly with increasing Sn concentrations from 311.5 K for pure Cr to ~394 K at ~1.4 at.% Sn. Presumably, this composition corresponds to the solubility limit of the (Cr) solid solution. The metastable phase Cr2Sn3 is paramagnetic [66Hol]. 08Hin: G. Hindrichs, Z. Anorg. Allg. Chem., 59, 414-449 (1908) in German. 47Nia: O. Nial, Sven. Kem. Tidskr., 59, 165-183 (1947). 61Ste: D.A. Stevenson and J. Wulff, Trans. AIME, 221, 271-275 (1961). 64Hol: L. Hollan, P. Lecocq, and A. Michel, Compt. Rend., Ser. C, 258, 3309- 3310 (1964) in French. 66Hol: L. Hollan and P. Lecocq, Compt. Rend., Ser. C, 262, 1577-1578 (1966) in French. 69Dar: J.B. Darby, Jr. and D.B. Jugle, Trans. Metall. Soc. AIME, 245, 2515- 2518 (1969). 69Pre: B. Predel and H. Sandig, Z. Metallkd., 60, 208-214 (1969) in German. 72Fuk: K. Fukamichi and H. Saito, J. Phys. Soc. Jpn., 33, 1485 (1972). Published in Bull. Alloy Phase Diagrams, 9(2), Apr 1988. Complete evaluation contains 2 figures, 2 tables, and 12 references. Special Points of the Cr-Sn System