Фазовая диаграмма системы Ti-V

К оглавлению: Другие диаграммы (Others phase diargams)

Ti-V (Titanium-Vanadium) J.L. Murray A miscibility gap in the (bTi,V) phase (designated b) gives rise to a monotectoid reaction, (bTi) = (aTi) + (V), based on the recent work of [80Nak]. This contradicts previous assessments [Hansen, Elliott, Shunk, 81Mur], in which the b miscibility gap was shown as entirely metastable, and the (bTi,V)/( bTi,V) + (aTi) boundary was shown as a single curve. The miscibility gap data of [80Nak] was used in calculating the assessed diagram. The liquidus has not been determined experimentally. [52Ade] and [69Rud] determined the solidus by incipient melting techniques. The results of [69Rud] are preferred, because pure alloys were used. The liquidus and solidus have a congruent minimum at approximately 32 at.% V and 1605 с 5 C. The (bTi,V) miscibility gap and (bTi,V)/(aTi) + (bTi,V) boundary are based on [ 61Erm] and [80Nak] for Ti-rich alloys and on [80Nak] for alloys containing more than 20 at.% V. The evidence for the monotectoid reaction comes from resistivity measurements on heating and cooling, supported by X-ray diffraction of both quenched and annealed specimens [80Nak]. Depending on the V content, a cph (a›) or an orthorhombic (a›) structure forms martensitically during quenching from the b phase. The a› martensite forms in the Ti-rich alloys. The martensite becomes distorted to the a› structure at 9 at.% V according to [58Bag] and [63Bor], but at 5 at.% V according to [75Age], [78Gus], and [82Gus]. For compositions greater than about 10 at.% V, b or (b + w) begins to be retained following the quench [58Bag]. Above 14 to 15 at.% V, the martensitic a› and a› phases disappear [58Bag, 78Gus]. The w phase forms in the metastably retained b phase either during quenching or after aging at temperatures up to about 500 C [55Bro]. As-quenched w is found coexisting with b in alloys containing more than about 11 to 14 at.% V [ 68Hic]. With increasing V content, the w diffraction lines broaden and disappear; the transition from small w particles to short-range order is not a clear one. During low-temperature aging, the composition of w changes until it reaches a metastable equilibrium value. This composition is 13.5 to 15 at.% [ 68Hic] and is independent of aging temperature. 52Ade: H.K. Adenstedt, J.R. Pequignot, and J.M. Raymer, Trans. AIME, 44, 990- 1003 (1952). 55Bro: F.R. Brotzen, E.L. Harmon, and A.R. Troiano, Trans. AIME, 203, 413-419 ( 1955). 58Bag: Yu.A. Bagariatskii, G.I. Nosova, and T.V. Tagunova, Dokl. Akad. Nauk SSSR, 122, 593-596 (1958) in Russian; TR: Sov. Phys. Dokl., 3, 1014-1018 (1958) . 61Erm: F. Ermanis, P.A. Farrar, and H. Margolin, Trans. AIME, 221, 904-908 ( 1961). 63Bor: B.A. Borok, E.K. Novikova, L.S. Golubeva, R. Shchegoleva, and N.A. Ruch'eva, Metalloved. Term. Obrab. Met., (2), 32-36 (1963) in Russian; TR: Met. Sci. Heat Treat., (2), 94 (1963). 68Hic: B.S. Hickman, J. Inst. Met., 96, 330-337 (1968). 69Rud: E. Rudy, USAF Tech. Rep. AFML-TR-65-2, Part V (1969). 75Age: N.V. Ageyev, L.N. Guseva, and L.K. Dolinskaya, Izv. Akad. Nauk SSSR, Met., (4), 151 (1975) in Russian; TR: Russ. Metall., (4), 113-115 (1975). 78Gus: L.N. Guseva and L.K. Dolinskaya, Krist. Strukt. Svoistva Met. Splavov, 59-63 (1978) in Russian. 80Nak: O. Nakano, H. Sasano, T. Suzuki, and H. Kimura, Titanium '80, Proc. 4th Int. Conf. on Titanium, Kyoto, Japan, H. Kimura and O. Izumi, Ed., Vol. 2, 2889-2895 (1980). 81Mur: J.L. Murray, Bull. Alloy Phase Diagrams, 2(1), 49-55 (1981). 82Gus: L.N. Guseva and L.K. Dolinskaya, Titanium and Titanium Alloys, J.C. Williams and A.F. Delov, Ed., Scientific and Technological Aspects, No. 2, 1559-1565 (1982). Published in Phase Diagrams of Binary Vanadium Alloys, 1989, and Phase Diagrams of Binary Titanium Alloys, 1987. Complete evaluation contains 6 figures, 7 tables, and 75 references. Special Points of the Ti-V System