Фазовая диаграмма системы V-W

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V-W (Vanadium-Tungsten) S.V. Nagender Naidu, A.M. Sriramamurthy, M. Vijayakumar, and P. Rama Rao The V-W system belongs to the binary isomorphous category. A continuous series of solid solutions with a bcc structure occurs between V and W at all temperatures. The assessed diagram is based primarily on the experimental data of [69Rud] and [75Kol] and has been obtained by thermodynamic modeling. Earlier studies reported a minimum in the liquidus at 6.5 at.% W and 1630 C [ 59Kie]. [60Bar] placed the minimum in the liquidus and solidus at 4.5 at.% W and 1635 C. However, [69Rud] indicated that the melting points of V-W alloys increase monotonically with increasing W content, without any minimum, although experimental details are not available. [75Kol] established that there is no minimum in the liquidus and solidus curves up to 12 at.% W. The minimum found by the earlier investigators must be associated with impurities. In the phase diagram, no minimum in the liquidus/solidus is shown. [69Rud] also established the existence of a continuous series of solid solutions. [61Kom] reported formation of severe coring in these alloys that could not be eliminated by annealing. The data of [60Bar] are the only experimental data available on the liquidus, and the experimental values utilized in the determination of interaction parameters pertain to compositions will beyond the reported minimum. The solidus of the assessed diagram passes through most of the data points of [ 69Rud], whereas the liquidus fits well with [60Bar] in the composition region beyond 30 at.% W. 59Kie: R. Kieffer, K. Sedlatschek, and H. Braun, Z. Metallkd., 50, 18-24 (1959) in German. 60Bar: V.V. Baron, Yu. V. Efimov, and E.M. Savitskii, Russ. Met. Fuels, (1), 45-49 (1960). 61Kom: S. Komjathy, J. Less-Common Met., 3, 468-488 (1961). 61Sem: M. Semchyshen and R.Q. Barr, Climax Molybdenum Co., Final Report, 1-133 (1961). 62Rud: E. Rudy, F. Benesovsky, and E. Rudy, Monatsh. Chem., 93, 693-707 (1962). 69Rud: E. Rudy, Wright-Patterson Air Force Base, Rep. No. AFML-TR-65-2, Part V, 121-123, May (1969). 75Kol: V.M. Koltygin, M.V. Pikunov, and A.S. Petukhova, Izv. V.U.Z. Tsvetn. Metall., (6), 126-129 (1975) in Russian. Published in Phase Diagrams of Binary Vanadium Alloys, 1989. Complete evaluation contains 4 figures, 3 tables, and 21 references. 1