Фазовая диаграмма системы Ho-V

К оглавлению: Другие диаграммы (Others phase diargams)


Ho-V (Holmium-Vanadium) J.F. Smith and K.J. Lee Relatively little information is available concerning phase relationships in the Ho-V system. The phase diagram for the Ho-V system was calculated using the diagram of [73Sav] as input information and with some knowledge of the V-Y and Er-V systems. Data for the melting of bcc V were taken from [81Smi], for cph V from [70Kau], and for cph Ho from [Gschneidner]; data for the melting of bcc Ho were generated from [75Gsc] for the entropy of melting in combination with an estimated melting point from an extrapolation of the melting points of the trivalent bcc rare earth elements. An initial set of interaction parameters for the Gibbs energies of formation of the competing phases in the system were estimated within the constraints of the uncertainties of the monotectic and eutectic temperatures and the limited terminal solubilities. These initial interaction parameters, together with similarly derived interaction parameters for the other trivalent lanthanon-vanadium binary systems, were then plotted against atomic number, and smooth curves were drawn through the trends. Refined parameters were read from these smooth curves. The solid solubility of Ho in (V) was indicated by [73Sav] to be ~0.1 at.% or less at all temperatures below the melting point of V, and the maximum solubility of V in Ho at the eutectic temperature was shown to be <0.5 at.%. 70Kau: L. Kaufman and H. Bernstein, Computer Calculation of Phase Diagrams, Academic Press, New York, 184 (1970). 73Sav: E.M. Savitskii, in Redkozemel 'nye Metally, Splavy I Soedineniya, Izdatel 'stvo Nauka, Moscow, 310-316 (1973). 75Gsc: K.A. Gschneidner, Jr., J. Less-Common Met., 43, 179-189 (1975). 81Smi: J.F. Smith, Bull. Alloy Phase Diagrams, 2(1), 40-41, 172 (1981). Published in Phase Diagrams of Binary Vanadium Alloys, 1989. Complete evaluation contains 1 figure, 2 tables, and 6 references. Special Points of the Ho-V System