Фазовая диаграмма системы Al-Sn

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Al-Sn (Aluminum-Tin) A.J. McAlister and D.J. Kahan Al-Sn is a simple eutectic system with limited solid solubilities in the two terminal solid solutions, fcc (Al) and tetragonal (bSn). Pure Sn transforms from bct bSn to a diamond cubic structure aSn at low temperature. The assessed phase diagram was obtained by nonlinear least-squares optimization of parameterized free energy functions using select experimental phase boundary data [06Gwy, 49Sul, 55Sam, 64Bon, 76Dor]. The solubility of Sn in (Al) is retro-grade, with a maximum of approximately 0. 026 at.% Sn dissolving at 625 с 20 C. There are no reports of determination of the solubility of Al in (bSn), but the occurrence of the eutectic at 3.3 с 0.5 C below the melting point of Sn suggests that some solubility exists. In the modeling carried out in the present evaluation, it was necessary to introduce some solubility of Al in (bSn) to reproduce the experimentally observed eutectic temperature. In X-ray diffraction studies of 0.05 wt.% Sn alloys solutionized at 530 C, quenched, and aged at 130, 190, 220, 300, and 400 C, only equilibrium Sn precipitates were observed at 300 C and above. At lower aging temperatures, a precipitate that could be indexed as Sn with a slightly expanded lattice was detected. [70Kir1] and [70Kir2] reported X-ray diffraction studies of splat-quenched samples containing 0.06, 0.12, 0.17, 0.23, and 0.26 at.% Sn. Lattice parameters of the (Al) phase fall on a straight line, indicating metastable solubility to at least 0.26 at.% Al. [70Kun] condensed evaporated alloys of 0. 72, 1.44, and 5.1 at.% Sn on SiO substrates at -190 C, and on the basis of electron-probe analysis, concluded that single-phase (Al) films were obtained. [66Kan] splat quenched samples containing 15 and 50 at.% Al at -190 C. X-ray diffraction studies were carried out at -190 C, and continuously with temperature up to 20 C. At -190 C, the 15 at.% Al alloy was reported to contain (bSn) with as much as 2.0 at.% Al, the 50 at.% solution to contain (Al) , and a metastable hexagonal G-phase containing <50 at.% Al that completely decomposed upon heating to -100 C. It is interesting to note that the extended (Al) solubility occurs near the intersection of the metastable Sn-rich liquidus with the (Al)-L T0 curve of the present fitted diagram. 06Gwy: A.C.G. Gwyer, Z. Anorg. Allg. Chem., 49, 311-316 (1906) in German. 49Sul: A.H. Sully, H.K. Hardy, and T.J. Heal, J. Inst. Met., 76, 269-294 (1949) . 55Sam: L.E. Samuels, J. Inst. Met., 84, 333-336 (1955). 64Bon: E. Bonnier, F. Durand, and G. Massart, C.R. Acad. Sci. Paris, 259, 380- 383 (1964). 66Kan: R.H. Kane, B.C. Giessen, and N.J. Grant, Acta Metall., 14, 605-609 ( 1966). 70Kir1: A. Kirin and A. Bonefacic, Scr. Metall., 4, 525-528 (1970). 70Kir2: A. Kirin and A. Bonefacic, Fizika, 2, Suppl. (2), 14.1-14.4 (1970) in Russian. 70Kun: D. Kunstelj and A. Bonefacic, Fizika, 2, Suppl. (2), 15.1-15.5 (1970) in Russian. 76Dor: R.C. Dorward, Metall. Trans. A, 7, 308-310 (1976). Published in Bull. Alloy Phase Diagrams, 4(4), Dec 1983. Complete evaluation contains 2 figures, 8 tables, and 28 references. Special Points of the Al-Sn System