Фазовая диаграмма системы Al-Be

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Al-Be (Aluminum-Beryllium) J.L. Murray and D.J. Kahan The equilibrium solid phases of the Al-Be system are (1) the fcc (Al) solid solution containing up to 0.3 с 0.1 at.% Be [81Cer]; (2) the low-temperature cph (aBe) solid solution, stable up to approximately 1270 C and containing less than ~0.007 at.% Al; and (3) the high-temperature bcc (bBe) solid solution, stable between 1270 C and its melting point. Because of the exceedingly low solubility of Al in (aBe) up to 800 C, the effect of Al on the (aBe) = (bBe) transformation can be assumed to be negligible. The assessed phase diagram does not differ greatly from previous evaluations [ Hansen, 76Mon, 80Ell]. The detailed shape of the liquidus has been improved by incorporating thermodynamic data. The Al-rich liquidus is taken from a thermodynamic calculation and is consistent with the thermal analysis and microscopic work of [28Arc]. For the purpose of thermodynamic calculations, it is assumed that the mutual solubilities of Al and Be in the solid phases are zero. The assessed Be-rich liquidus is the result of thermodynamic optimizations using data of [16Oes], [ 40Los], [66Nis], and [67Pot]. Al-rich alloys are age-hardening. The decomposition of supersaturated (Al) solid solutions involves the formation of Guinier-Preston zones, or solute clustering, as shown by a resistometric study of quenching and isochronal and isothermal aging of a 0.03 at.% Be alloy. Vapor-deposited Al-Be alloy films with Be content greater than 3 at.% were found to be amorphous. The structure of vapor-deposited Be-rich alloys is controversial, because of disagreement concerning the structure of vapor- deposited pure Be. Several noncrystalline low-temperature phases in Be have been reported, but when the purity of Be is carefully maintained, cph crystals are observed. Ultra-rapid liquid quenching was carried out on alloys containing 2.9, 13.6, and 92.3 at.% Be. After rapid quenching, no new phases were found; only Al was detected in the first two samples, and only Be and Al in the third. 16Oes: G. Oesterheld, Z. Anorg. Chem., 97, 9-14 (1916) in German. 23Arc: R.S. Archer and W.L. Fink, Trans. AIME, 78, 616-643 (1928). 40Los: L. Losana, Aluminio, 9, 8-13 (1940) in Italian. 66Nis: S. Nishi, Light Met. Jpn., 16, 5-8 (1966) in Japanese. 67Pot: C. Potard, G. Bienvenu, and B. Schaub, Thermodynamics of Nuclear Materials, Proc. IAEA Conf., Vienna, 809-825 (1967) in French. 76Mon: L.F. Mondolfo, Aluminum Alloys: Structure and Properties, Butterworths, London, Boston, MA (1976). 80Ell: R.P. Elliott and F.A. Shunk, Bull. Alloy Phase Diagrams, 1(1), 49-50 ( 1980). 81Cer: S. Ceresara, Philos. Mag., 43A, 1093-1101 (1981). Published in Phase Diagrams of Binary Beryllium Alloys, 1988, and Bull. Alloy Phase Diagrams, 4(1), Jun 1983. Complete evaluation contains 2 figures, 8 tables, and 30 references. Special Points of the Al-Be System