Фазовая диаграмма системы Ca-Li

К оглавлению: Другие диаграммы (Others phase diargams)

Ca-Li (Calcium-Lithium) C.W. Bale and A.D. Pelton The Ca-Li system contains one stoichiometric intermetallic compound, CaLi2, whose crystal structure is well established. Other intermetallic phases have been reported, but have not been confirmed. The system is virtually ideal in the liquid phase. There is limited solid solubility on the Li-rich side. On the Ca-rich side, solid solubility seems to be fairly extensive, but this is not well established, particularly at the higher temperatures. The assessed phase diagram is based primarily on the work of [60Kan], [62Kan], [64Kan], and [66Car]. All phase boundaries were calculated from thermodynamic optimization of experimental data. The dashed lines indicate major modifications to the diagram of [66Car]. The differences be- tween the assessed diagram and the reported diagram of [66Car] are primarily due to a third allotrope of Ca that was believed to exist at the time of the experiments. The spurious appearance of this allotrope was most likely due to hydrogen impurity and the undesirable formation of calcium hydride, but this is not fully resolved. Also, the incongruently melting compound and the peritectic reaction reported by [66Car] have been replaced by a congruently melting compound and a eutectic reaction. Thermal analysis indicated a solid solubility on the Li side of less than 0.4 at.% Ca, based on the appearance of the eutectic arrest at 0.4 at.% Ca. Because solid diffusion at these temperatures is so slow that nonequilibrium segregation is unavoidable, this indication is uncertain. 60Kan: F.A. Kanda and A.J. King, U.S. Dept. of Energy, TID-5691 (1960). 62Kan: F.A. Kanda and A.J. King, U.S. Dept. of Energy, TID-15150 (1962). 64Kan: F.A. Kanda and D.V. Keller, U.S. Dept. of Energy, TID-20849 (1964). 66Car: D.G. Carfagno, Ph.D. thesis, Syracuse Univ., Syracuse, NY (1966). Published in Bull. Alloy Phase Diagrams, 8(2), Apr 1987. Complete evaluation contains 1 figure, 4 tables, and 12 references. 1