PHASE-EQUILIBRIA IN THE PRASEODYMIUM-INDIUM SYSTEM

The Pr-In system has been studied in the composition range 30-100 at.% In by differential thermal analysis, metallography and X-ray examination. The Pr-rich alloys have been reinvestigated and confirmed. The following intermediate phases were observed: Pr3In (decomposes at 930 ± 10 °C), Pr2In (decomposes at 1020 ± 10 °C), Pr1+xIn (m.p. 1170 ± 15 °C), ≈Pr3In5 (m.p. 1190 ± 15 °C) and PrIn3 (m.p. 1210 ± 15 °C). As well as the Pr-rich eutectic, three other eutectics occur: Pr1+x-In≈Pr3In5 (1110 + 10 °C, 54.0 ± 0.5 at.% In), ≈Pr3In5-PrIn3 (1130 ± 10 °C, 65.0 ± 0.5 at.% In) and PrIn3-In (155 °C, ≥99.5 at.% In). The crystal structures of Pr3In (ordered-disordered cP4, AuCu3 type), Pr2In (hP6, Ni2In type) and PrIn3 (cP4, AuCu3 type) have been confirmed. An oC32, Pu3Pd5-type structure has been proposed for the approximate Pr3In5 phase. The characteristics of the phase diagram are compared with those of the La-In and Nd-Tl systems. The molar volumes of the Pr-In alloys are discussed and compared with those of a number of binary rare earth alloys. © 1979.