Reactions of uranium and the platinide elements. III. The uranium-iridium system

Abstract

The phase diagram of the uranium-iridium system was constructed from data obtained by thermal analysis, metallographic examination, and x-ray diffraction. The system is characterized by five intermetallic compounds: U3Ir, formed peritectically near 945 °C and decomposing eutectoidally near 758 °C; U3Ir2, formed peritectically near 1121 °C; UIr, melting congruently at about 1470 °C; UIr2, formed peritectically above 1850 °C; and UIr3, having a congruent melting point above 1950 °C. U3Ir2 has a solid state transition near 898 °C. One eutectic occurs at 914 °C at about 15 atom percent (a/o) iridium between uranium and U3Ir; a second occurs between UIr and UIr2 near 1450 °C; and a third occurs between UIr3 and iridium at about 1950 °C The solid solubility of iridium in gamma-uranium is about 5.5 a/o and of uranium in iridium is under 3 a/o. Iridium lowers the gamma-beta uranium transformation to about 681 °C and the beta-alpha transformation to about 565 °C.