Фазовая диаграмма системы Cd-La

К оглавлению: Другие диаграммы (Others phase diargams)


Cd-La (Cadmium-Lanthanum) K.A. Gschneidner, Jr. and F.W. Calderwood The assessed phase diagram for the La-Cd system is based primarily on the work of [66Joh] and [73Bru]. [66Joh] determined the low-temperature portions of the liquidus by measuring the solubility of La in liquid Cd. Thermal analysis was used to obtain the peritectic decomposition temperature of LaCd11. Because of a strong tendency to supercool, only heating curve data were used in determining the peritectic decomposition temperature. Liquidus compositions in the temperature range above the highest solubility temperature (580 C) and the peritectic decomposition temperature (625 C) were estimed by extrapolation of the solubility data. A eutectic occurs between (gLa) and LaCd at 642 C and 23 at.% Cd. [66Joh] and [73Bru] estimated the solid solubility of Cd in (gLa) at the eutectic temperature to be 21 at.% Cd. According to these investigators, the addition of Cd to La raises the a = b transition temperature of La from 310 to 451 C and, by a eutectoid reaction, lowers the g = b transition temperature from 865 to 451 C. The composition of this eutectoid and the limit of solubility of Cd in (bLa) were estimated at 13.5 at.% Cd and 2.5 at.% Cd, respectively. The solubility of La becomes negligible below the a = b transformation temperature. However, their phase diagram failed to show an area where (aLa) and (bLa) coexist. The assessed diagram represents schematically the probable phase relationships in the La-rich portion of this system. LaCd melts congruently at 946 C and forms a eutectic with LaCd2 at 58 at.% Cd and 891 C. LaCd2 also melts congruently (953 C) and forms a eutectic with La13Cd58 at 826 C and 75.8 at.% Cd. La13Cd58 melts congruently at 874 C and ~81.7 at.% Cd. The two Cd-rich compounds decompose peritectically, La2Cd17 at 688 C and LaCd11 at 625 C. La is the only lanthanide metal to form a RE2Cd17 compound. 66Joh: I. Johnson, K.E. Anderson, and R.A. Blomquist, ASM Trans. Q., 59, 352 ( 1966). 73Bru: G. Bruzzone and F. Merlo, J. Less- Common Met., 30, 303 (1973). Published in Bull. Alloy Phase Diagrams, 9(1), Feb 1988. Complete evaluation contains 1 figure, 1 table, and 10 references. 1