Фазовая диаграмма системы Ba-Mg

К оглавлению: Другие диаграммы (Others phase diargams)


Ba-Mg (Barium-Magnesium) A.A. Nayeb-Hashemi and J.B. Clark The equilibrium phases of the Mg-Ba system at atmospheric pressure are (1) the liquid; (2) the (Mg) phase with negligible solid solubility of Ba; (3) the stoichiometric compound Mg9Ba (more accurately, Mg17Ba2) with a congruent melting point of 707 C; (4) the stoichiometric compound Mg4Ba (more accurately, Mg23Ba6) formed by a peritectic reaction at 598 C; (5) the stoichiometric compound Mg2Ba with a congruent melting point of 607 C; and (6) the (Ba) phase with limited solid solubility of Mg. In the assessed diagram, the (Mg) liquidus curve is taken from [56Zee], with the Mg-rich eutectic point of [47Kle]. The Mg17Ba2, Mg23Ba6, and Mg2Ba liquidus curves are taken from [47Kle], [56Zee], and [57And]. The thermodynamic modeling was done by coupled optimization of thermodynamic and phase diagram data. Except for the (Ba) liquidus, there is good agreement between the calculated and the assessed diagram; all the specific points of the assessed diagram have been closely reproduced. It appears that the Mg-rich and Ba-rich eutectic horizontals extend to almost pure Mg and pure Ba, respectively [38Gru]. The solid solubility of Ba in (Mg) is negligible (~0.002 at.% Ba). Thermal analysis of [47Kle] and [56Zee] showed negligible solid solubility of Mg in (Ba). 38Gru: G. Grube and A. Dietrich, Z. Electrochem., 44, 755-767 (1938) in German. 47Kle: W. Klemm and F. Dinkelocker, Z. Anorg. Chem., 255, 2-12 (1947) in German. 56Zee: W.C. Zeek, Ph.D. thesis, Syracuse Univ., Syracuse, NY (1956). 57And: K.P. Anderko, Trans. AIME, 209, 612 (1957). 83Cha: M.W. Chase, Bull. Alloy Phase Diagrams, 4(1), 123-124 (1983). Published in Phase Diagrams of Binary Magnesium Alloys, 1988, and Bull. Alloy Phase Diagrams, 7(2), Apr 1986. Complete evaluation contains 1 figure, 7 tables, and 33 references. Special Points of the Mg-Ba System