Фазовая диаграмма системы Cd-Yb

К оглавлению: Другие диаграммы (Others phase diargams)


Cd-Yb (Cadmium-Ytterbium) K.A. Gschneidner, Jr. and F.W. Calderwood The Yb-Cd system is characterized by the existence of six compounds. The assessed phase diagram is based on the work of [71Pal]. The first intermetallic compound, YbCd, melts congruently at 796 C with no evidence of any solid solubility in this phase. A weak, reproducible thermal effect at 755 C indicated the possibility of a solid-state transformation, but this effect was not observed on the differential thermal analysis curves of samples that varied from the 50 at.% composition by с2.5% Cd; thus, its existence is doubtful. Efforts to quench the samples in a high-temperature YbCd form were not successful. YbCd2 melts congruently at 703 C and exists in two forms. The structure of the low-temperature form is hexagonal, of the C14, MgZn2 type. The high- temperature form is stable from 695 to 703 C, and in this study, the structure was not retained to room temperature by normal quenching methods. [71Pal] reported another compound at ~73 at.% Cd. This compound decomposed peritectically at 654 C and is isomorphous with Eu3Cd8 reported by [65Kos]. A compound that melted congruently at 655 C could not be identified directly. A single crystal of this compound was found to have hexagonal P6/m symmetry. [ 71Bai] reported this phase to be Yb14Cd51. [71Pal] also reported a compound with a congruent melting point of 636 C at ~85 at.% Cd with the approximate formula YbCd5.7. YbCd6 forms peritectically from the melt and YbCd5.7 at 614 C. A eutectoid-type lowering of the b = g transition in Yb occurs when small amounts of Cd are added. [71Pal] indicated that ~3.3 at.% Cd lowers this transformation temperature by a eutectoid reaction at 755 C. Alloys containing 98 to 100 at.% Cd showed no change in lattice spacings, indicating little solubility of Yb in (Cd). 65Kos: W. K”ster and J. Meixner, Z. Metallkd., 56, 695 (1965) in German. 71Bai: D.M. Bailey and G.R. Kline, Acta Crystallogr. B, 27, 650 (1971). 71Pal: A. Palenzona, J. Less-Common Met., 25, 367 (1971). Published in Bull. Alloy Phase Diagrams, 9(2), Apr 1988. Complete evaluation contains 1 table and 21 references. 1