Фазовая диаграмма системы Ir-U

К оглавлению: Другие диаграммы (Others phase diargams)

Ir-U (Iridium-Uranium) H. Okamoto The assessed Ir-U phase diagram was constructed primarily from thermal, metallographic, and X-ray diffraction data obtained by [68Par]. According to the work of [74Sch], a single-phase reaction for the coupled reduction of (Ir) containing up to 2 at.% U with U was observed at 800 C. The L = (Ir) + Ir3U eutectic temperature is 1950 C [68Par]. The relationship between the initial slopes of the (Ir) liquidus and solidus is consistent with the van't Hoff equation, but the maximum solubility of U at this temperature is speculative. AuCu3-type Ir3U was observed by [59Dwi] and [61Dwi]. A difference in the room- temperature lattice parameter is indicative of a temperature-dependent homogeneity range [67Kri]. The melting point of Ir3U is above 2000 C [68Par]. Cu2Mg-type Ir2U was observed by [55Hea]. The congruent melting point of IrU is 1470 с 20 C [68Par]. The bIr2U3 = aIr2U3 transformation temperature is 898 C [68Par]. The crystal structures and the type of transformation between the polymorphs are unknown. [68Par] found high-temperature IrU3 in 75.3 at.% U alloys by metallographic examination. [65Ber] found monoclinic "IrU2," whose peritectoid formation temperature of 775 с 5 C was determined by heating a homogeneous specimen to successively higher temperatures until the reaction was observed. However, [68Par] failed to find IrU2. More conclusive work is needed, because the data of [65Ber] and [ 68Par] involve some uncertainty. The homogeneity ranges of the (U) terminal phases shown in [68Par] are expanded slightly (maximum ~1 at.%) in the assessed diagram, in consideration of the van't Hoff relationship. (bU) may be retained by quenching when the Ir content is 2 at.% [65Sey]. 55Hea: T.J. Heal and G.I. Williams, Acta Crystallogr., 8, 494-498 (1955). 59Dwi: A.E. Dwight and M.V. Nevitt, USAEC, ANL-6099, 76-92 (1959); quoted in [ Elliott]. 61Dwi: A.E. Dwight, J.W. Downey, and R.A. Conner, Jr., Acta Crystallogr., 14, 75-76 (1961). 64Sho: C.B. Shoemaker and D.P. Shoemaker, Trans. AIME, 230(4), 486-490 (1964). 65Ber: A.F. Berndt and A.E. Dwight, Trans. AIME, 233(12), 2075-2078 (1965). 65Sey: A.U. Seybolt, H.A. Saller, and F.A. Rough, USAEC, Pub. BMI-1000 (1965). 67Kri: N.H. Krikorian, T.C. Wallace, M.C. Krupka, and C.L. Radosevich, J. Nucl. Mater., 21(2), 236-238 (1967). 68Par: J.J. Park and L.R. Mullen, J. Res. Nat. Bur. Stand. A, 72(1), 19-25 ( 1968). 74Sch: N. Schmidt, Rep. KfK-1987, Kernforschungszentrum, Karlsruhe (1974). Submitted to the APD Program. Complete evaluation contains 1 figure, 3 tables, and 14 references. Special Points of the Ir-U System