Фазовая диаграмма системы Li-Mg

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Li-Mg (Lithium-Magnesium) A.A. Nayeb-Hashemi, A.D. Pelton, and J.B. Clark The Mg-Li phase diagram is based primarily on [Hansen], with a review of the work of [34Gru], [45Hum], [53Fre], [59Ray], 77Sab], and [78Fei]. The solubility of Li in (Mg) was found to diminish slightly above 500 C [ 45Hum]. This drop in solubility at high temperatures is not great and was determined to be on the order of 0.4 to 0.5 at.% Li over the temperature range of 200 to 588 C [45Hum]. [59Ray] suggested that the drop in solubility for Li in (Mg) at higher temperatures is similar to the drop in solubility for many alloys of Cu and Ag. [59Fre] showed that the (Li)/[(Mg) + (Li)] boundary, although almost vertical up to 500 C (at 30 at.% Li), curves toward higher Mg content at higher temperatures. Pure bcc Li undergoes a spontaneous martensitic transformation to the cph structure at very low temperatures. It was noted that the bcc <259> cph transformation of Li is not complete, and the cph structure is significantly faulted. On cooling to 78 K, the bcc Li alloys of compositions between 83.6 and 100 at.% Li spontaneously underwent a martensitic transformation to the cph structure. Cold working of Li alloys with compositions as low as 75.8 at.% Li at 78 K induces a transformation to the fcc structure. The Ms temperature for the bcc <259> cph transformation increases with Mg content. The maximum Ms temperature was found to be 130 с 10 K at 88 at.% Li. For alloys of less than 74 at.% Li, bcc (Li) is stable at 37 or 78 K, even after cold working. Good agreement between the calculated and experimental diagram is evidenced, except for the [(Mg) + (Li)] region. The calculated solidus lies somewhat above the reported solidus, indicating that the reported solidus may be too low, by up to 5 C. It was not possible with simple functions for the thermodynamic properties to reproduce the sharp curvature of the (Li)/[(Mg) + ( Li)] boundary toward higher Mg content above 500 C. 34Gru: G. Grube, H.V. Zeppelin, and H. Bumm, Z. Elecktrochem., 40(3), 160-164 ( 1934) in German. 45Hum: W. Hume-Rothery, G.V. Raynor, and E. Butcher, J. Inst. Met., 71, 589- 601 (1945); see also J. Inst. Met., 72, 538-542 (1946). 53Fre: W.E. Freeth and G.V. Raynor, J. Inst. Met., 82, 575-580 (1953-1954). 59Ray: G.V. Raynor, The Physical Metallurgy of Magnesium and Its Alloys, Pergamon Press, New York, 118-120 and 254-263 (1959). 77Sab: M.L. Saboungi and C.C. Hsu, Calphad, 1(3), 237-251 (1977). 78Fei: P.D. Feitsma, T. Lee, and W. Van Der Lugt, Physica, B + C, 93(1), 52-58 (1978). Published in Phase Diagrams of Binary Magnesium Alloys, 1988 and Bull. Alloy Phase Diagrams, 5(4), Aug 1984. Complete evaluation contains 4 figures, 9 tables, and 37 references. Special Points of the Mg-Li System