Фазовая диаграмма системы Ca-Zn

К оглавлению: Другие диаграммы (Others phase diargams)

Ca-Zn (Calcium-Zinc) V.P. Itkin and C.B. Alcock The assessed Ca-Zn phase diagram is based mainly on the work of [63Mes] and was obtained by thermodynamic modeling of the available experimental data. The Gibbs energies of formation of [67Chi] were used by the present authors for the calculation of the phase diagram, which was very different from that of [ 63Mes]. Therefore, an attempt was made to improve the thermodynamic description of the system. [63Mes] described eight compounds in the Ca-Zn system: CaZn2, CaZn5, and CaZn11 melt congruently at 704, 695, and 724 C, respectively; Ca3Zn, Ca7Zn4, CaZn, Ca7Zn20, and CaZn13 undergo peritectic decomposition at 394, 414, 439, 642, and 669 C, respectively. The formulas of Ca7Zn4 and Ca7Zn20 have been changed to Ca5Zn3 and CaZn3, respectively, in the assessed diagram in agreement with recent crystal structure measurements. The assessed phase diagram includes most of the features of the diagram of [63Mes]. An additional dashed horizontal line corresponding to the a = b transformation in Ca at 443 C appears in the assessed diagram based on the work of [85Cha]. The boundaries of the homogeneous phases CaZn3 and CaZn5 are also shown by dashed lines, because their positions have not been studied. Solubility data for Ca in Zn from 650 to 725 C were reported by [65Joh] as log XCa = -7395/T + 6.326 (quoted from [67Chi]), where XCa is a mole fraction of Ca and T is temperature in K. 61Sch: G.E.R. Schulze and J. Wieting, Z. Metallkd., 52, 743-746 (1961) in German. 63Mes: A.F. Messing, M.D. Adams, and R.K. Steunenberg, Trans. ASM, 56, 345-350 (1963). 65Jon: I. Johnson and I.G. Dillon, USAEC Report ANL-7083, NBS, U.S. Dept. of Commerce, Springfield, VA (1965). 67Chi: P. Chiotti and R.J. Hecht, Trans. Metall. Soc. AIME, 239, 536-542 (1967) . 67Ian: A. Iandelli and A. Palenzona, J. Less-Common Met., 12, 333-343 (1967). 78Bru: G. Bruzzone, E. Franceschi, and F. Merlo, J. Less-Common Met., 60, 59- 63 (1978). 80For: M.L. Fornasini and F. Merlo, Acta Crystallogr. B, 36, 1739-1744 (1980). 81For: M.L. Fornasini, F. Merlo, and K. Schubert, J. Less-Common Met., 79, 111- 119 (1981). 85Cha: M.W. Chase, Jr., C.A. Davies, J.R. Downey, Jr., D.J. Frurip, R.A. McDonald, and A.N. Syverud, JANAF Thermochemical Tables, 3d ed., J. Phys. Chem. Ref. Data, 14(1), 685-688, 1842-1845 (1985). Published in Bull. Alloy Phase Diagrams, 11(4), Aug 1990. Complete evaluation contains 2 figures, 5 tables, and 18 references. Special Points of the Ca-Zn System