Фазовая диаграмма системы Ce-Y

К оглавлению: Другие диаграммы (Others phase diargams)


Ce-Y (Cerium-Yttrium) K.A. Gschneidner, Jr. and F.W. Calderwood The assessed phase diagram for the Ce-Y system does not show a peritectoid reaction to form the Sm-type phase, as did the earlier work of [58Lun], but rather a first-order transformation, based on study of the nature of the formation of the d phase. The melting points and transformation temperatures of the pure metals have been adjusted to conform with the accepted values of [ Gschneidner]. In a study of the effects of high pressure and temperature on binary Ce rare- earth alloys, [66Jay] tested three Ce-Y alloys that had the cph, Sm-type, and dcph structures under normal conditions. Pressure-induced phase transformations in the sequence cph <259> Sm-type <259> dcph <259> fcc were observed in several other intra-rare-earth alloys systems tested, but in the Ce-Y system, one composition (Ce-75 at.% Y) retained the cph structure at all pressures, and the other two compositions (Ce-50 at.% Y and Ce-25 at.% Y) decomposed into two phases, (gCe) and (aY). The decompositions were attributed to a change under temperature and pressure of normally trivalent Ce to tetravalent Ce with a subsequent reduction in metallic radius. [76Wan] splat cooled five intra-rare-earth alloy systems, including Ce-Y. He found that by splat cooling, the cph phase was extended into the composition range that under equilibrium conditions should have the Sm-type structure. The Sm-type structure was not suppressed by the cph phase, but was pushed toward higher concentrations of Ce. 58Lun: C.E. Lundin and D.T. Klodt, APEX Report 424 (Aug 1958); XDC Report 59-8- 187 (Nov 1958), XDC Report 59-8-188 (Feb 1959), Denver Res. Inst., Univ. of Denver, CO (1958). 66Jay: A. Jayaraman, R.C. Sherwood, H.J. Williams, and E. Corenzwit, Phys. Rev. , 148, 502 (1966). 76Wan: R. Wang, Mater. Sci. Eng., 23, 135 (1976). Published in Bull. Alloy Phase Diagrams, 3(2), Sep 1982. Complete evaluation contains 3 figures and 13 references. 1