Фазовая диаграмма системы Cu-Th

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Cu-Th (Copper-Thorium) D.J. Chakrabarti, D.E. Laughlin, and D.E. Peterson The Cu-Th system is characterized by the occurrence of four congruently melting intermediate phases that are essentially line compounds; two terminal solid solution phases, (Cu) and (Th), with negligible homogeneity ranges; and five eutectic transformations. The equilibrium phases in the Cu-Th system are (1) the fcc terminal solid solution, (Cu), which is stable below 1084.87 C; (2) the fcc terminal solid solution, (aTh), which is stable below about 1363 C; (3) the bcc terminal solid solution, (bTh), which is stable between 1755 C and ~1363 C; (4) the orthorhombic Cu6Th phase, stable below 1055 C; (5) the hexagonal Cu3.6Th phase, stable below 1052 C; (6) the hexagonal Cu2Th phase, stable below 1015 C; and (7) the tetragonal CuTh2 phase, stable below 1007 C. The assessed Cu-Th phase diagram is based primarily on the work of [71Sch] for the compound phases and the associated liquidus boundaries, and also on [43Rau] . The (Th) liquidus as well as the predicted eutectoid decomposition of Cu6Th are derived from thermodynamic modeling. No data pertaining to the solubility of Cu in (Th) are available, but the solubility is expected to be very restricted. There is negligible solubility of Th in (Cu), amounting to less than 0.01 at.% at 900 C. All intermediate phases appear to have negligible solubility ranges that resemble line compounds. A metatectic, or alternatively, a peritectic transformation occurs in the solidus, depending on whether the (bTh) = (aTh) transformation temperature is lowered or raised, respectively, relative to that of pure Th at 1360 C. [ 74Gie] observed the formation of the metastable compound CuTh, having the CrB-type structure. 43Rau: E. Raub and M. Engel, Z. Elektrochem., 49, 487-493 (1943) in German. 71Sch: R.J. Schiltz, E.R. Stevens, and O.N. Carlson, J. Less-Common Met., 25, 175-185 (1971). 74Gie: B.C. Giessen, AEC Rep. COO-3395-11 (1974). Published in Bull. Alloy Phase Diagrams, 7(1), Feb 1986. Complete evaluation contains 2 figures, 8 tables, and 34 references. Special Points of the Cu-Th System