Фазовая диаграмма системы Al-Sr

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Al-Sr (Aluminum-Strontium) C.B. Alcock and V.P. Itkin The assessed phase diagram for the Al-Sr system is based on the experimental data of [75Bru], with review of the work of [74Vak] and [79Vak]. The temperature of the eutectic reaction on the Al side, 654 C, was taken from [ 86Clo]. The composition of the eutectic point was estimated on the basis of thermodynamic properties. The temperatures of the peritectic reactions of formation of Al2Sr and Al7Sr8 and the temperature of the congruent melting of Al4Sr were taken from [75Bru]. The compound Al7Sr8 is shown in the assessed diagram instead of the previously reported Al2Sr3 or AlSr compounds. It should be noted that no other investigators mentioned the allotropic transformation in Sr at 547 C [85Cha], which should influence the shape of the phase diagram. This transformation is shown by a dashed line in the assessed diagram. The equilibrium phases of the Al-Sr system are (1) the liquid, L; (2) the terminal fcc solid solution, (Al), with small solubility in Sr; (3) the terminal bcc solid solution, (bSr), with small solubility in Al; (4) the terminal fcc solid solution, (aSr), with small solubility in Al; and (5) three intermetallic phases-Al4Sr, Al2Sr, and Al7Sr8. [39Now] did not observe any solubility of Sr in Al. They concluded that Al4Sr possesses a homogeneity range from about 15 to 25.7 at.% Sr at 700 C, and that "AlSr" dissolves some Sr. The solubility in the intermetallic phases was not confirmed in subsequent publications. [75Bru] did not mention any mutual solubility of the compounds or homogeneity ranges in the intermetallics. In the Al-Ca system, the most reliable information shows very small solubility of Ca in (Al) (< 0.05 at.%). It would seem doubtful that the larger Sr atoms have a higher solubility in (Al). Therefore, it is assumed that the mutual solubility of components in the Al-Sr system is very small. 39Now: H. Nowotny and H. Wesenberg, Z. Metallkd., 31, 363-364 (1939) in German. 74Vak: A.V. Vakhobov, T.T. Dzhuraev, and B.N. Vigdorovich, Russ. J. Phys. Chem. , 48, 1306-1308 (1974). 75Bru: G. Bruzzone and F. Merlo, J. Less-Common Met., 39, 1-6 (1975). 79Vak: A.V. Vakhobov, K.K. Eshonov, and T.D. Dzhurayev, Russ. Metall., (4), 167-172 (1979). 83For: M.L. Fornasini, Acta Crystallogr. C, 39, 943-946 (1983). 85Cha: M.W. Chase, Jr., C.A. Davies, J.R. Downey, Jr., D.J. Frurip, R.A. McDonald, and A.N. Syverud, JANAF Thermochemical Tables, 3rd ed., J. Phys. Chem. Ref. Data, 14(1) (1985). 86Clo: B. Closset, H. Dugas, M. Pekguleryuz, and J.E. Gruzleski, Metall. Trans. , A, 1250-1253 (1986). Published in Bull. Alloy Phase Diagrams, 10(6), Dec 1989. Complete evaluation contains 3 figures, 4 tables, and 17 references. Special Points of the Al-Sr System