Фазовая диаграмма системы Bi-Co

К оглавлению: Другие диаграммы (Others phase diargams)

Bi-Co (Bismuth-Cobalt) K. Ishida and T. Nishizawa The assessed phase diagram for the Bi-Co system is based on [08Lew] and on the data of [62Dam] and [65Wee] regarding the solubility of Co in the Bi-rich liquid phase. The diagram is characterized by an extended miscibility gap in the liquid phase, essential immiscibility in the solid solution, and the absence of intermediate phases. The equilibrium phases of the system are (1) the liquid, L, with a miscibility gap; (2) the fcc terminal solid solution, (aCo); (3) the cph solid solution, ( eCo); and (4) the rhombohedral solid solution, (Bi). The monotectic temperature of 1345 C was determined by [08Lew]. Although there are no experimental data on the liquid miscibility gap above the monotectic temperature, the existence of asymmetry is expected from the large positive value of the enthalpy of mixing. The solubility of Bi in (aCo) and (eCo) is negligibly small, and alloying with Bi does not influence the magnetic transformation [Hansen]. According to [65Wee], the solubility of Co at the monotectic temperature of 1345 C is estimated to be about 2.9 at.% Co. According to [62Dam], the eutectic point is at 0.04 at.% Co and 271.2 C; [65Wee] suggested that the eutectic contained 0.007 to 0.013 at.% Co at 271.5 C. Bi has no noticeable effect on the (aCo) = (eCo) martensitic transformation because the solubility of Bi in the (aCo) and (eCo) phases is negligible [ Hansen]. [66Mat] found the metastable superconducting compound BiCo, which has a critical temperature of 0.49 to 0.42 K, under pressure. 08Lew: A. Lewkonja, Z. Anorg. Allg. Chem., 59, 315-318 (1908) in German. 62Dam: R. Damm, E. Sheil, and E. Wachtel, Z. Metallkd., 53, 196-203 (1962). 65Wee: J.R. Weeks, Trans. ASM, 58, 302-322 (1965). 66Mat: B.T. Matthias, A. Jayaraman, T.H. Geballe, K. Andres, and E. Corenzwit, Phys. Rev. Lett., 17, 640-643 (1966). 83Nis: T. Nishizawa and K. Ishida, Bull. Alloy Phase Diagrams, 4(4), 387-390 ( 1983). Submitted to the APD Program. Complete evaluation contains 2 figures, 1 table, and 6 references. 1