Фазовая диаграмма системы Nd-Sc

К оглавлению: Другие диаграммы (Others phase diargams)

Nd-Sc (Neodymium-Scandium) K.A. Gschneidner, Jr. and F.W. Calderwood The assessed phase diagram for the Nd-Sc system is essentially the diagram presented by [65Bea]. The boundary for the transformation from the cph solid solution to the bcc form goes through a minimum at 22 at.% Sc and 800 C, as determined by differential thermal analysis data taken at 5 at.% intervals. Thermal analysis established the existence of the continuous series of bcc solid solutions. The shape of the immiscibility loop was established by metallographic examination of annealed alloys quenched from various temperatures. Anomalies were noted in the heating and cooling curves between 30 and 70 at.% Nd because of the large change in mutual solubility over a narrow temperature range. Thermal arrests were found to occur 20 to 40 C higher on heating than on cooling. To obtain consistent results, all of the thermal arrests were approached from a temperature above that of the arrest, because equilibrium conditions were easier to establish in the high- temperature single phase. There was no evidence of the Sm-type phase structures in the Nd-Sc alloys, even when annealed 2 weeks at 350 C or 1 month at 250 C. The absence of a two-phase region above 700 C in the Nd-Sc system, as determined by metallography, strongly indicates a continuous series of solid solutions between the dcph (ABAC) structure of Nd and the cph (ABAB) structure of Sc; this necessitates a continuous change in symmetry in passing from 0 to 100 at.% Sc. 65Bea: B.J. Beaudry, M. Michel, A.H. Daane, and F.H. Spedding, in Rare Earth Research III, L. Eyring, Ed., Gordon and Breach, New York, 247 (1965). Published in Bull. Alloy Phase Diagrams, 3(3), Dec 1982. Complete evaluation contains 1 figure and 3 references. 1