Фазовая диаграмма системы Ga-Ti

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Ga-Ti (Gallium-Titanium) J.L. Murray The equilibrium phases of the Ti-Ga system include (1) the cph (aTi), bcc (bTi) , and complex cubic (Ga) solution phases; (2) the ordered hexagonal phases Ti3Ga and Ti2Ga with the D019 and Ni2In structures, respectively, which are well established as equilibrium phases, and (3) the Ga-rich ordered fcc phase TiGa3, and TiGa2 with a related structure. [Shunk] constructed a phase diagram for the Ti-Ga system based on thermal analysis, X-ray diffraction, and examination of cast alloys by [62Pot]. This is the only complete Ti-Ga phase diagram in the literature. The present evaluation must nevertheless reject it as a representation of binary equilibrium basically because the pub- lished microstructures are inconsistent with the phase diagram as drawn. It is not possible to reconstruct a better diagram based on the available information. The present assessment is therefore limited to the Ti-rich portion of the diagram, which has been more reliably established. The assessed diagram is constructed from the thermodynamic calculation by [73Kau], except for the homogeneity range of Ti2Ga, which is drawn. The composition range 0 to 35 at.% Ga was examined by [57And] and [58And] up to 1100 C and in the as-cast condition. Equilibria were examined among (aTi), (bTi), Ti3Ga, and Ti2Ga. Alloys in composition increments of 2.5 at.% were equilibrated at temperatures in 50 C increments and in 20 C increments for the (aTi)/(bTi) boundaries. 57And: K. Anderko and U. Zwicker, Naturwissenschaften, 44, 510 (1957) in German. 58And: K. Anderko, Z. Metallkd., 49, 165-172 (1958) in German. 62Pot: M. Potzschke and K. Schubert, Z. Metallkd., 53, 474-488 (1962) in German. 73Kau: L. Kaufman and H. Nesor, Titanium Science and Technology, Vol. 2, R.I. Jaffee and H.M. Burte, Ed., Plenum Press, New York, 773-789 (1973). Published in Phase Diagrams of Binary Titanium Alloys, 1987, and Bull. Alloy Phase Diagrams, 6(4), Aug 1985. Complete evaluation contains 1 figure, 5 tables, and 17 references. Special Points of the Ti-Ga System