Фазовая диаграмма системы Bi-V

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Bi-V (Bismuth-Vanadium) J.F. Smith Data concerning the phase equilibria in the Bi-V system are limited. Consequently, the assessed diagram has been calculated after review of the experimental data. The data of [65Wee] were taken into account to the extent that the interaction parameter for the calculation was adjusted to produce reasonable accord between the experimental results and the calculated liquidus. The assessed diagram is for pressures sufficiently high to retain all phases in condensed form. For purposes of calculating the assessed diagram, pure liquid elements were used as the reference states for both Bi and V. Regular solution approximations were made for the liquid and bcc phases, and an ideal gas approximation was made for the gas phase. [65Wee] determined the composition of the Bi-rich liquidus at 350 to 825 C as log Cv (at.%) = 1.15 - 2520/T, where Cv is the V content of the saturated liquid Bi and T is in K. This relationship indicates that the V solubility decreases through the range of measurement from a mole fraction near Xv = 7 x 10-4 at the upper limit of measurement, falling to about Xv = 10-5 at the lower limit of measurement. The solid in equilibrium with the saturated Bi was indicated in this solubility study to be V. [66Sav] indicated the existence of an intermediate phase BiV3 with the A15, Cr3Si structure, but this report is viewed skeptically. Two speculative diagrams have been proposed. These diagrams are quite different from one another, in that one is theoretically based [80Deb] and proposes the likelihood of extensive to complete immiscibility both between liquid Bi and solid V and between solid Bi and solid V. The other proposed diagram [69Sav] was completely empirical and anticipated that the system should contain a series of intermediate phases that, in progressing from V to Bi, melted at successively lower temperatures in a series of peritectic reactions. No weight has been given to the diagram of [69Sav] in this evaluation. 65Wee: J.R. Weeks, Trans. ASM, 58, 302-322 (1965). 66Sav: E.M. Savitskii, V.V. Baron, and Yu.V. Efimov, Sov. Phys. Dokl., 11, 988- 989 (1967); Dokl. Akad. Nauk SSSR, 171, 331-332 (1966). 69Sav: E.M. Savitskii and Yu.V. Efimov, Plans. Pulvermetal., 17, 103-110 (1969) in German. 80Deb: F.R. de Boer, R. Boom, and A.R. Miedema, Physica, 101B, 294-319 (1980). Published in Phase Diagrams of Binary Vanadium Alloys, 1989. Complete evaluation contains 2 figures, 2 tables, and 6 references. Special Points of the Bi-V System