Фазовая диаграмма системы Pm-V

К оглавлению: Другие диаграммы (Others phase diargams)


Pm-V (Promethium-Vanadium) J.F. Smith and K.J. Lee Pm is not a naturally occurring element, but enough of it has been formed in nuclear reactors to determine some of its properties and characteristics. The reactivity of Pm is much like the reactivities of other light, trivalent rare earths, with behavior tending to be intermediate between Nd and Sm. In view of the limited availability of Pm, it is not surprising that no experimental information has been found concerning the phase relationships in the Pm-V system. However, because Pm tends to behave as a typical light rare earth, the Pm-V phase diagram was calculated. To obtain Gibbs energies, temperatures for fusion and for the allotropic transformation in Pm were taken from [Gschneidner] and were combined with heats of transformation from [83Cha] to develop expressions for the fusion of the two allotropic forms of Pm. Data for the fusion of bcc V were taken from [ 81Smi]; data for the fusion of dcph V were obtained by prorating the dcph structure as 50% fcc stacking and 50% cph stacking and using data from [70Kau]. An initial evaluation of the interaction parameters for all trivalent RE-V binary systems was made with the best available experimental data. These parameters were then plotted against the rare earth atomic number, and smooth curves were drawn through the plots to develop refined parameters. 70Kau: L. Kaufmann and H. Bernstein, Computer Calculation of Phase Diagrams, Academic Press, New York, 184 (1970). 81Smi: J.F. Smith, Bull. Alloy Phase Diagrams, 2(1), 40-41, 172 (1981). 83Cha: M.W. Chase, Bull. Alloy Phase Diagrams, 4(1), 124 (1983). Published in Phase Diagrams of Binary Vanadium Alloys, 1989. Complete evaluation contains 1 figure, 2 tables, and 4 references. Special Points of the Pm-V System