Фазовая диаграмма системы Gd-Sm

К оглавлению: Другие диаграммы (Others phase diargams)

Gd-Sm (Gadolinium-Samarium) K.A. Gschneidner, Jr. and F.W. Calderwood The assessed phase diagram for the Gd-Sm system is based on the work of [67Lun] , with some modifications. [67Lun] investigated the liquidus-solidus and the bcc = cph transformation temperatures in the Gd-Sm system by thermal analysis of the two component metals and eleven alloys whose compositions varied by about 10 at.% across the range from Gd to Sm. Their data indicated a narrow gap between the liquidus and the solidus, as well as between the cph and the bcc fields. Furthermore, each of the lines involved is close to being a straight line. The phase diagram presented by [67Lun] covers only the high- temperature portion (above 850 C) of the system. The major difference between the two components in this system is the crystal structure. Both metals have cph structures, but differ in the stacking sequence from the nine-layered d phase structure (ABABCBCAC...) for bSm to normal two-layered cph (ABAB...) for aGd. Because Gd and Sm are trivalent, have similar atomic numbers, and have the same structures at high temperatures, the liquidus-solidus line and the bcc = cph transformation line in the assessed phase diagram are each drawn as a single straight line connecting the corresponding temperatures for the end members in accordance with [82Gsc]. The melting temperatures and transition temperatures have been adjusted slightly to bring these temperatures into agreement with the accepted values for the pure metals. The assessed phase diagram does not show the transformation of the d-phase structure to the cph structure. The d-phase solid solution area is bounded by a dashed line beginning at room temperature at the 60 at.% Sm composition and curving upward to join the 100 at.% Sm line at 734 C, the temperature for the a = b (rhomb = cph) transition in Sm. 67Lun: C.E. Lundin and A.S. Yamamoto, DRI-2437, final report, Denver Research Institute, University of Denver, Denver, CO (1967). 82Gsc: K.A. Gschneidner, Jr. and F.W. Calderwood, Bull. Alloy Phase Diagrams, 2(4), 444 (1982). Published in Bull. Alloy Phase Diagrams, 4(2), Sep 1983. Complete evaluation contains 1 table, 4 figures, and 3 references. 1