Фазовая диаграмма системы Al-Li

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Al-Li (Aluminum-Lithium) A.J. McAlister The equilibrium phases of the Al-Li system are (1) the liquid, L; (2) fcc (Al), with a maximum solubility of Li of approximately 14 at.% at the 600 с 5 C eutectic; (3) the bcc (bLi) solid solution above -193 C, for which the maximum solubility of Al has not been determined; (4) the cph (aLi) phase below -193 C (only pure Li has been investigated in this temperature range); ( 5) the broad intermediate b phase, of NaTl-type structure, which melts congruently at 700 с 15 C and has a maximum solubility range of about 45 to 55 at.% Li; (6) the narrow phase Al2Li3, stable up to 520 C, of rhombohedral structure, and reported by [79Wen] to have a solubility range of 1.4 at.% Li at 423 C; and (7) the line compound Al4Li9, stable up to 335 C, of monoclinic structure and reported by [76Myl] to transform to a different, as yet unclassified, structure at 275 C. Only a few features of the Al-Li diagram are well established: the L = (Al) + b eutectic temperature, 600 с 5 C; the b + L = Al2Li3 peritectic temperature, 520 с 5 C; the L = Al4Li9 + (bLi) eutectic temperature, 175 с 5 C; the (Al) solvus between 400 and 600 C; and the (Al) + b/b boundary from 400 to 500 C. Other features of the diagram are probably qualitatively correct, but particularly in regard to the liquidus and (Al)/(Al) + L boundary, quantitatively unreliable. The occurrence of the metastable Al3Li phase in the equilibrium (Al) + b field is of considerable significance to the determination of the equilibrium (Al) solvus. The assessed phase diagram is based on review of the literature [35Gru, 37Sha, 62Cos, 63Lev, 68Han, 73Teb, 76Myl, 79Wen, 80Wen] and on thermodynamic modeling. No attempts to determine the solubility of Al in bcc (bLi) have been reported. The present thermodynamic calculations suggest negligible solubility. Occurrence of an ordered AuCu3-type (L12 superlattice crystal) coherent precipitate in the (Al) + b field has been reported [59Sil]. The observed coherent (Al) + Al3Li metastable field, determined by kinetic competition between metastable Al3Li and equilibrium b formation in supersaturated (Al) alloys, has also been studied. Editor's note: Recently, [89Che] examined the solid + liquid phase equilibria between (Al) and b, using differential thermal analysis (DTA), metallography, and thermal analysis. The (Al)-b eutectic temperature and composition were determined to be 600 с 1 C and 25.8 с 0.5 at.% Li, respectively, in good agreement with the assessed values. The calculated diagram of [89Che] also is in essential agreement with experimental data. 35Gru: G. Grube, L. Mohr, and W. Breuning, Z. Electrochem., 41, 880-882 (1935) in German. 37Sha: F.I. Shamray and P.Ya. Saldau, Izv. Akad. Nauk SSSR, Otd. Khim., 631- 640 (1937) in Russian. 59Sil: J.M. Silcock, J. Inst. Met., 88, 357-364 (1959). 62Cos: L.P. Costa and R.P. Marshall, Trans. Metall. Soc. AIME, 224, 970-974 ( 1962). 63Lev: E.D. Levine and E.J. Rapperport, Trans. Metall. Soc. AIME, 227, 1204- 1208 (1963). 68Han: D.A. Hansen and J.F. Smith, Acta Crystallogr. B, 24, 913-918 (1968). 73Teb: K.-F. Tebbe, H.G. von Schnering, B. Ruter, and G. Rabanek, Z. Naturforsch. B, 28, 600-605 (1973). 76Myl: K.M. Myles, F.C. Mrazek, J.A. Smaga, and J.L. Settle, Proc. Symp. and Workshop on Adv. Battery Res. and Design: U.S. ERDA Report ANL-76-8, B50-B73, Mar (1976). 79Wen: C.J. Wen, B.A. Boukamp, R.A. Huggins, and W. Weppner, J. Electrochem. Soc., 126, 2258-2266 (1979). 80Wen: C.J. Wen, W. Weppner, B.A. Boukamp, and R.A. Huggins, Metall. Trans. B, 11, 131-137 (1980). 89Che: S.-W. Chen, C.-H. Jen, J.-C. Lin, and Y.A. Chang, unpublished manuscript (1990). Published in Bull. Alloy Phase Diagrams, 3(2), Sep 1982. Complete evaluation contains 3 figures, 12 tables, and 31 references. Special Points of the Al-Li System