Фазовая диаграмма системы Ru-V

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Ru-V (Ruthenium-Vanadium) J.F. Smith The assessed Ru-V phase diagram is primarily based on [76Wat]. However, a number of uncertainties exist. Specifically, there are significant disparities in the reports of the compositions associated with the (Ru) solvus and the (V) solvus; there is uncertainty as to the phase relationship between the CsCl structure and the bcc (V) terminal solution; and it is questionable whether or not a tetragonal phase that has been observed at lower temperatures in the central portion of the system is an equilibrium feature of the system. There is definitive evidence for the existence of a two-phase region between the cubic and tetragonal phases [71Chu, 71Mar]. It was reported that the unit cell volumes were respectively 1.4% and 1.5% larger for the tetragonal as compared to the cubic structure for the 50 and 51 at.% V alloys. However, for the 50 at.% alloy the volume difference decreased with increasing temperature and was tending toward zero at the onset of the transition. No such behavior was noted in the 51 at.% V alloy. No phase boundary separating the A2 and B2 structures is shown in the assessed diagram, although a dashed line is shown near 75 at.% V to indicate that this represents a demarcation between observable diffraction patterns. [71Mar] found an unannealed alloy of 55 at.% V to be no more than 36% ordered, while annealed alloys of 50 and 51 at.% V were essentially 100% ordered. This certainly suggests that a study of the degree of order as a function of composition and temperature might be enlightening. [76Wat] have pointed out that this type of CsCl-bcc relationship is also observed in the Ru-Nb [64Hur] and Ru-Ta [Elliott] systems, and that diffusion couples showed no evidence of a two-phase region between A2 and B2 structures in the Ru-Nb system. 64Hur: G.F. Hurley and J.H. Brophy, J. Less-Common Met., 7, 267-277 (1964). 71Chu: C.W. Chu, E. Bucher, A.S. Cooper, and J.P. Maita, Phys. Rev. B, 4, 320- 325 (1971). 71Mar: M. Marezio, P.D. Dernier, and C.W. Chu, Phys. Rev. B, 4, 2825-2826 ( 1971). 76Wat: R.M. Waterstrat and R.C. Manuszewski, J. Less-Common Met., 48, 151-158 ( 1976). Published in Phase Diagrams of Binary Vanadium Alloys, 1989, and J. Alloy Phase Diagrams, 3(3), Sep 1987. Complete evaluation contains 4 figures, 4 tables, and 14 references. Special Points of the Ru-V System