Фазовая диаграмма системы Be-Ga

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Be-Ga (Beryllium-Gallium) H. Okamoto and L.E. Tanner The assessed Be-Ga phase diagram was obtained by thermodynamic modeling and closely reproduces the solubility of Be in liquid Ga measured by [52Ell]. The monotectic temperature and composition are slightly different from the values estimated by [52Ell], due to the difference in the assumed values of the melting point and the enthalpy of transformation of Be. The calculated critical point of the liquid miscibility gap is expected to be at 31.2 at.% and 1842 C. The phase boundary at high temperatures must be considered a rough estimate because of the excessive extrapolation from the low-temperature data. The melting point of bBe and the bBe = aBe allotropic transformation temperature are 1289 с 5 and 1270 с 6 C, respectively. Ga is not soluble in ( Be), according to [52Ell]. The solubility of Be in liquid Ga was measured by [ 52Ell] as 11.7 at.% at 1200 C, 4.5 at.% at 1000 C, 1.3 at.% at 800 C, 0.19 at.% at 580 C, and 0.03 at.% at 540 C. The triple point of Ga is 29.7741 C [ Melt]. The monotectic temperature was estimated as 1251 C (relative to a Be melting point of 1280 C) from thermal arrest data obtained from a 1.4 at.% Ga alloy [ 52Ell]. Because the assessed melting point of Be is 9 C higher than the value used by [52Ell], the monotectic temperature is placed at 1260 C (9 C higher than in [52Ell]) in the assessed diagram. The monotectic composition was calculated to be about 1.4 at.% Ga by [52Ell] using Raoult's law. [73Ale] considered that superconducting transitions found in BexGa alloys (x = 2 to 22) at ~6 K are due to the presence of Be3Ga, which is distributed only on grain boundaries. 52Ell: R.O. Elliott and E.M. Cramer, U.S. Atomic Energy Comm. AECU-3022, 10 p ( 1952). 73Ale: N.E. Alekseevskii and V.M. Zakosarenko, Dokl. Akad. Nauk SSSR, 208(2), 303-306 (1973) in Russian; TR: Sov. Phys. Dokl., 18(1), 45-47 (1973). Published in Phase Diagrams of Binary Beryllium Alloys, 1987. Complete evaluation contains 1 figure, 3 tables, and 5 references. 1