Фазовая диаграмма системы Re-V

К оглавлению: Другие диаграммы (Others phase diargams)

Re-V (Rhenium-Vanadium) J.F. Smith The qualitative details of the Re-V diagram are well established [69Kuz, 78Gio, 83Ere1, 86Jor], but there is conflicting evidence concerning the quantitative specification of temperature and compositions defining the phase boundaries and invariant reactions. Of the four published phase diagrams [60Tyl1, 61Kom, 83Ere1, 86Jor], two [60Tyl1, 83Ere1] were generated with impure V whose melting point was measured as 50 C or more lower than that of high-purity metal [81Smi]. In a third diagram [61Kom], no great care was exercised in determining the phase boundaries because the study was part of a broad survey of binary V systems. Consequently, most of the detail in the assessed diagram is from [86Jor]. [83Ere1] and [86Jor] agreed as to the existence of two intermediate phases at elevated temperatures and concurred that one of these was a s phase and the other was a Cr3Si-type d phase. [86Jor] showed the s phase forming by a peritectic reaction at 2460 с 20 C. In contrast, [83Ere1] reported the s phase as melting congruently near 2630 C. This divergent result has not been accepted in the present assessment. [61Kom], [83Ere1], and [86Jor] agreed that the s phase has a narrow, but finite, range of homogeneity that includes the composition Re3V. [86Jor] reported the d phase to decompose eutectoidally near 1470 C. [83Ere1] and [86Jor] reported an azeotropic melting of the V-rich terminal solution, with the solidus dropping beyond the azeotropic composition to the solubility limit of 32 to 34 at.% V. This is the composition of the terminal solution participating in a eutectic reaction with the s phase to form liquid. There is lack of agreement as to the temperature and composition at the azeotropic maximum. Because of V purity, the 2400 C and 50 at.% V values of [ 86Jor] are preferred. There is general agreement [56Gre, 60Tyl1, 69Kuz, 83Ere1, 86Jor] that the solubility of Re in (V) is quite extensive. The solvus boundaries of [86Jor] appear to be best defined. In contrast, the solubility of V in (Re) is comparatively limited [60Tyl1, 83Ere1, 86Jor] and does not exceed ~12 at.% V, even at elevated temperatures. Superconductivity has been observed [86Jor] at most compositions across the system. In the Re-rich terminal solution, the superconducting transition temperature varies from 1.76 K for pure Re to 8.0 K at the maximum solubility limit. The s phase was found to transform at temperatures from 5.2 K on the Re- rich side to 4.5 K on the V-rich side. A width to the d phase field was confirmed by superconducting measurements with values of the transition temperature ranging from 9 K in the Re-rich phase to 6.5 K in the V-rich phase. In the V-rich terminal solution, the transition temperature of V was observed to drop with Re additions to below 1 K at 10 at.% Re, to reappear near 57 at.% Re (43 at.% V), and to reach 4.1 K near 62 at.% Re (38 at.% V). 56Gre: P. Greenfield and P.A. Beck, Trans. AIME, 206, 265-276 (1956). 60Tyl1: M.A. Tylkina, K.B. Povarova, and E.M. Savitskii, Zh. Neorg. Khim., 5(8) , 1907-1910 (1960); TR: Russ. J. Inorg. Chem., 5, 927-928 (1960). 60Tyl2: M.A. Tylkina, K.B. Povarova, and E.M. Savitskii, Dokl. Akad. Nauk SSSR, 131(2), 332-334 (1960); TR: Proc. Akad. Nauk SSSR Chem., 131, 247-249 (1960). 61Kom: S. Komjathy, J. Less-Common Met., 3, 468-488 (1961). 69Kuz: Yu.B. Kuz'ma, D.A. Kovalyk, and A. Sistema, Izv. Akad. Nauk SSSR, Neorg. Mater., 5(10), 1687-1960 (1969); TR: Inorg. Mater., 5, 1428-1430 (1969). 78Gio: A.L. Giorgi, B.T. Matthias, and G.R. Stewart, Solid State Commun., 27, 291-294 (1978). 81Smi: J.F. Smith, Bull. Alloy Phase Diagrams, 2(1), 40-41 and 2(2) 172 (1981). 83Ere1: V.N. Eremenko, A.M. Kharkova, and T.Ya. Velikanova Elikanova, Dop. Akad. Nauk Ukr. RSR. Ser. A; Fiz. Met.-Mat. Tekh. Nauk, (2), 72-76 (1983) in Ukrainian. 83Ere2: V.N. Eremenko, A.M. Kharkova, and T.Ya Velikanova, Dop. Akad. Nauk Ukr. RSR. Ser. A., Fiz. Met.-Mat. Tekh. Nauk, (1), 77-80 (1983) in Ukrainian. 86Jor: J.L. Jorda and J. Muller, J. Less-Common Met., 119, 337-345 (1986). Published in Phase Diagrams of Binary Vanadium Alloys, 1989. Complete evaluation contains 1 figure, 3 tables, and 11 references. Special Points of the Re-V System