Фазовая диаграмма системы Ca-Pb

К оглавлению: Другие диаграммы (Others phase diargams)

Ca-Pb (Calcium-Lead) V.P. Itkin and C.B. Alcock The assessed phase diagram for the Ca-Pb system is based primarily on [76Bru], with review of the data of [08Don], [11Baa], [21Cow], [30Sch], [59Vig], [62Fed] , and [63Lan]. The equilibrium phases are (1) the liquid, L; (2) the fcc solid solution, (Pb), with solid solubility of about 0.35 at.% Ca at the eutectic temperature; (3) the solid solutions, (aCa) and (bCa), with negligibly small solubility of Pb; (4) two intermediate compounds, Ca2Pb and CaPb3, which melt congruently; and (5) two compounds, CaPb and Ca5Pb3, which are formed by peritectic reactions. For L = (Pb) + CaPb3, the nature of the reaction (eutectic), its temperature (326.2 C), and the maximum solubility of Ca in (Pb) were accepted from [ 59Vig]. However, the composition of the eutectic point, suggested in [ 59Vig], is probably not accurate. This composition was estimated by the present authors as 0.55 at.% Ca, assuming ideal dilute solutions of Ca in (Pb) and using 4800 J/mol for the enthalpy of fusion of Pb [83Cha]. This value is higher than that given in [59Vig] and [30Sch]. [63Lan] suggested this point at 0.77 at.% Ca. Therefore, the eutectic reaction needs further investigation. To achieve equilibrium composition, the Ca-rich alloys need a prolonged annealing at high temperatures. If this condition is not satisfied, a thermal arrest near 670 C is observed on the cooling curves. This corresponds to the melting point of the CaPb3 phase. [73Dam] measured the critical temperature of superconductivity in CaPb3, which was about 0.8 K. [84Bou] discovered an unknown compound that had not been reported previously, " phase I," with a tetragonal structure in samples containing from 50 to 75 at.% Pb. This information, as well as the arrest temperatures found in [84Bou], requires independent confirmation. 08Don: L. Donski, Z. Anorg. Allg. Chem., 57, 208-211 (1908) in German. 11Baa: N. Baar, Z. Anorg. Allg. Chem., 70, 372-377 (1911) in German. 21Cow: W.A. Cowan, L.D. Simpkins, and G.O. Hiers, Chem. Met. Eng., 25, 1182- 1185 (1921). 30Sch: E.E. Schumacher and G.M. Bouton, Met. Alloys, 1, 405-409 (1930). 33Zin: E. Zintl and S. Neumayr, Z. Elektrochem., 39, 86-97 (1933) in German. 59Vig: V.N. Vigdorovich and A.Ya. Nashel›skii, Russ. J. Inorg. Chem., 4, 922- 925 (1959). 61Eck: P. Eckerlin, E. Leicht, and E. Wolfel, Z. Anorg. Allg. Chem., 307, 145- 157 (1961) in German. 62Fed: P.I. Fedorov and V.I. Shachnev, Russ. J. Inorg. Chem., 7, 758-759 (1962) . 63Hel: O. Helleis, H. Kandler, E. Leicht, W. Quiring, and E. Woelfel, Z. Anorg. Allg. Chem., 320, 86-100 (1963) in German. 63Lan: A. Lange and B. Beyer, Neue Huette, 8, 585-593 (1963) in German. 73Dam: H. Damsa and E.E. Havinga, J. Phys. Chem. Solids, 34, 813-816 (1973). 76Bru: G. Bruzzone and F. Merlo, J. Less-Common Met., 48, 103-109 (1976). 83Cha: M.W. Chase, Bull. Alloy Phase Diagrams, 4(4), 124 (1983). 84Bou: L. Bouirden, M. Notin, and J. Hetrz, Calorim. Anal. Therm., 15, 309-320 (1984) in French. Submitted to the APD Program. Complete evaluation contains 3 figures, 4 tables, and 27 references. Special Points of the Ca-Pb System