Фазовая диаграмма системы Fe-V

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Fe-V (Iron-Vanadium) J.F. Smith The Fe-V system is characterized by an azeotropic minimum in its melting behavior, continuous solid solution at elevated temperatures, a closed g loop on the Fe-rich side, and an intermediate phase that forms congruently from the high-temperature solid solution near equiatomic stoichiometry. The assessed phase diagram is based on review of the work of [30Wev] and [Kubaschewski], with modifications based on the results of [83And] and [83But]. The solidus and liquidus are a combination of the calculated results of [79Hac] and [83And]. The boundaries associated with the g loop are based primarily on the experimental work of [70Fis] and have been corroborated by the calculations of [83And]. Both [83And] and [79Hac] used the enthalpy data of [ 73Spe] and the Gibbs energy data of [77Kub] as the basis for the development of self-consistent sets of thermodynamic functions for calculating the phase equilibria. The boundaries associated with the s phase are taken from [83But]. A complete range of solid solubility in the (aFe,V) or a phase at elevated temperatures has been verified by X-ray diffraction. Even at compositions where the s phase tends to form, the a phase may be retained readily by quenching. There is general agreement that V additions to Fe cause the Curie temperature of the (aFe,V) phase to pass through a maximum above 800 C and below 20 at.% V. The maximum in the assessed diagram between 13 and 14 at.% V near 840 C is a compromise among the composite data. Metastable alloys of the s phase with V content below 53 to 54 at.% also exhibit ferromagnetism at temperatures significantly below room temperature. This compositional limit for magnetic order was established by extrapolating spontaneous magnetization data to find the composition where the spontaneous moment vanished. A metastable a› phase with the CsCl structure has been observed at compositions in the central portion of the Fe-V system. At room temperature, the kinetics of (aFe,V) <259> a› and of (aFe,V) <259> s transformations are so slow that (aFe,V) itself can be retained by quenching from temperatures above the stability limit of the s phase. A number of investigations, however, showed that initial quenching from above 1200 C to retain the (aFe,V) phase, followed by annealing for a few hours at 600 to 625 C, caused the appearance of the a› phase. 30Wev: F. Wever and W. Jellinghaus, Mitt. Kaiser-Wilhelm Inst. Eisenforsch. Dusseldorf, 12, 317-322 (1930). 65Han: R.E. Hannemann, R.E. Ogilvie, and H.C. Gatos, Trans. Metall. Soc. AIME, 233, 685-691, 691-698 (1965). 70Fis: W.A. Fischer, K. Lorenz, H. Fabritius, and D. Schlegel, Arch. EisenhЃttnwes., 41, 489-498 (1970). 73Spe: P.J. Spencer and F.H. Putland, J. Iron Steel Inst., 211, 293-297 (1973) . 77Kub: O. Kubaschewski, H. Probst, and K. H. Geiger, Z. Phys. Chem. (Neue Folge), 104, 23-30 (1977). 79Hac: K. Hack, H.D. Nussler, P.J. Spencer, and G. Inden, Calphad VIII, 244- 265 (1979). 83And: J.O. Anderson, Calphad, 7, 295-305 (1983). 83But: J. Buth, Ph.D. thesis, Max Planck Inst. fЃr Eisenforsch., Dusseldorf: G. Inden, thesis research advisor (1983). Published in Phase Diagrams of Binary Vanadium Alloys, 1989, and Bull. Alloy Phase Diagrams, 5(2), Feb 1984. Complete evaluation contains 5 figures, 7 tables, and 99 references. 1