Фазовая диаграмма системы Si-Ti

К оглавлению: Другие диаграммы (Others phase diargams)


Si-Ti (Silicon-Titanium) J.L. Murray Comprehensive studies of the Ti-Si phase diagram were made by [52Han] and [ 70Sve]. Both used thermal analysis, metallography, and X-ray diffraction. In addition, [52Han] performed incipient melting studies. Additional work limited to Ti-rich alloys was done by [54Sut1], [54Sut2], [62Pyl], [63Luz], and [78Pli] . [53Gla] measured the melting point of TiSi2. There is good general agreement among all studies (с15 C) on the positions of the eutectic reactions, the congruent melting points, and the (aTi)/(bTi) boundaries. The existence of a thermal effect in TiSi2 at about 1200 C suggests the possibility of an allotropic transformation in TiSi2. Concerning phase equilibria involving Ti3Si and Ti5Si4 [70Sve], there are marked disagreements. [52Han] did not show either of these compounds. The two diagrams [52Han, 70Sve] predict different phases appearing in as-cast and heat treated alloys over a wide temperature and composition range. The assessed diagram is based on [70Sve]. This judgment is based on (1) the probable purity of the alloys, (2) the fact that the phases of composition 25 and 45 at.% Si were also observed by [65Ros] and [62Sch], respectively, and (3) the present thermodynamic analysis of the system. A (bTi) = (aTi) massive transformation was shown to exist for alloys containing up to 1.1 at.% Si [78Pli]. From continuous cooling experiments, the start temperature for the martensitic transformation was also found to be 808 and 814 C for 0.68 and 1.1 at.% Si alloys, respectively. [78Pol] prepared an amorphous 20 at.% Si alloy by rapid solidification. The crystallization temperature was reported as 594 C. Rapidly solidified alloys containing 15 and 20 at.% Si were crystalline. The phase diagram was calculated by [79Kau]. 52Han: M. Hansen, H.D. Kessler, and D.J. McPherson, Trans. ASM, 44, 518-538 ( 1952). 53Gla: F.W. Glaser and D. Moskowitz, Powder Met. Bull., 6(6), 178-185 (1953). 54Sut1: D.A. Sutcliffe, Met. Treat., 21, 191-197 (1954). 54Sut2: D.A. Sutcliffe, Rev. Met., 51, 524-536 (1954) in German. 62Pyl: E.N. Pylaeva and M.A. Volkova, Titan y Ego Splavy, Akad. Nauk SSSR, Inst. Met., 7, 74-77 (1962) in Russian. 62Sch: O. Schob, H. Nowotny, and F. Benesovsky, Planseeber. Pulvermet., 10, 65- 71 (1962) in German. 63Luz: L.P. Luzhnikov, V.M. Novikova, and A.P. Mareev, Metalloved. Term. Obrab. Met., (2), 13-16 (1963) in Russian: TR: Met. Sci. Heat Treat., (2), 78-81 ( 1963). 65Ros: W. Rossteutscher and K. Schubert, Z. Metallkd., 56(11), 813-822 (1965) in German. 70Sve: V.N. Svechnikov, Yu.A. Kocherzhisky, L.M. Yupko, O.G. Kulik, and E.A. Shishkin, Dokl. Akad. Nauk SSSR, 193(2), 393-396 (1970) in Russian. 78Pli: M.R. Plichta, H.I. Aaronson, and J.H. Perepezko, Acta Metall., 26, 1293- 1305 (1978). 78Pol: D.E. Polk, A. Calka, and B.C. Giessen, Acta Metall., 26, 1097-1103 ( 1978). 79Kau: L. Kaufman, Calphad, 3(1), 45-76 (1979). Published in Phase Diagrams of Binary Titanium Alloys, 1987. Complete evaluation contains 3 figures, 5 tables, and 29 references.