Фазовая диаграмма системы Ho-Y

К оглавлению: Другие диаграммы (Others phase diargams)

Ho-Y (Holmium-Yttrium) K.A. Gschneidner, Jr. and F.W. Calderwood The assessed Ho-Y phase diagram is based on the work of [67Mar], with modifications to bring it into agreement with the work of [73Spe], who investigated five other heavy lanthanide systems, including one with yttrium, and found that no measurable gap between the liquidus and the solidus exists when high-purity metals are used. The shape of the solidus-liquidus can be determined only by using sensitive experimental techniques and high-purity metals; that is, it may be curved with a minimum (as in the Er-Y system), or it may be linear (as in the Dy-Ho system). The solidus and solvus merge, indicating a peritectic reaction. Because Ho does not have the high-temperature bcc form as does Y, the cph solid solutions in the Ho-rich composition range melt without undergoing a solid-state transformation, whereas alloys in the Y-rich composition range transform to the bcc structure before melting. A boundary of this bcc = cph transformation was estimated from the behavior of the bcc structure in the five systems cited above. The estimated range of existence for the bcc phase in this system is from 8.5 to 100 at.% Y. The estimate of the termination of the bcc phase at 8.5 at.% Y is subject to rather wide error (i.e., the termination point could lie between 1 and 30 at.% Y) and should be determined experimentally. 67Mar: I.A. Markova, V.F. Terekhova, and E.M. Savitskii, Izv. Akad. Nauk SSSR, Neorg. Mater., 3, 392 (1967); TR: Inorg. Mater., 3, 343 (1967). 73Spe: F.H. Spedding, B. Sandeen, and B.J. Beaudry, J. Less-Common Met., 31, 1 (1973). Published in Bull. Alloy Phase Diagrams, 4(1), Jun 1983. Complete evaluation contains 2 figures, 1 table, and 5 references. 1