Фазовая диаграмма системы Hf-Ta

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Hf-Ta (Hafnium-Tantalum) R. Krishnan, S.P. Garg, and N. Krishnamurthy The assessed Hf-Ta phase diagram is based on [64Ode], [64Sve], [69Rud], [71Car] , and [75Kru] and on earlier reviews by [Hultgren,B] and [Tantalum]. The system is characterized by complete miscibility in the liquid state and a miscibility gap with a monotectoid reaction in the solid state. The melting points of pure Hf and Ta, 2231 and 3020 C, respectively, are from [Melt]. The solidus data are in good agreement. However, only approximate liquidus temperatures can be determined by the specimen collapse method used by [64Ode] and [69Rud]. Therefore, the liquidus data given in the assessed diagram are uncertain. Both [64Ode] and [69Rud] found a minimum in the solidus/ liquidus curves at 2130 C and ~20 at.% Ta. The monotectoid isotherm at 1083 C was determined by [75Kru]. The observation of a thermal arrest at 1083 C from 15 to 65 at.% Ta is convincing evidence for the existence of the isotherm in the Hf-Ta system. [75Kru] confirmed that the isotherm results from the monotectoid reaction (bHf,Ta) = (aHf) + (Ta). The solubility limit of Ta in (aHf) is 6.7 at.%. 64Ode: L.L. Oden, D.K. Deardorf, M.I. Copeland, and H. Kato, U.S. Bureau of Mines Rep. Invest. No. 6521 (1964); Chem. Abstr., 61, 14287C (1964). 64Sve: V.N. Svechnikov, A.K. Shurin, and G.P. Dmitrieva, Sb. Nauchn. Tr. Inst. Metallofiz., Akad, Nauk, Ukr. SSR, 19, 206 (1964); Chem Abstr. 62, 15847C ( 1965). 69Rud: E. Rudy, Rep. No. AFML-Tr-65-2, Part V, Air Force Materials Laboratory, Wright-Patterson Air Force Base, OH (1969). 71 Car: R.W. Carpenter, C.T. Liu, and P.G. Mardon, Metall. Trans., 2, 125-131 ( 1971). 75Kru: M.P. Krug, L.L. Oden, and P.A. Romans, Metall. Trans. A, 6A, 997-1002 ( 1975). Published in J. Alloy Phase Diagrams, 5(2), 1989. Special Points of the Hf-Ta System