Фазовая диаграмма системы As-Mg

К оглавлению: Другие диаграммы (Others phase diargams)

As-Mg (Arsenic-Magnesium) A.A. Nayeb-Hashemi and J.B. Clark The complete Mg-As phase diagram has not been determined experimentally. However, it may be expected to be similar, on the Mg-rich side, to the Mg-Bi and Mg-Sb systems. The assessed phase diagram illustrates the most probable phase relationships under 4 MPa pressure, based on the behavior exhibited by these systems. Binary As-rich alloys should be prepared under a back vapor pressure of As because, at atmospheric pressure, As sublimes at 614 C. The solid solubility of As in (Mg) is very limited. The nonmetallic compound Mg3As2 undergoes an allotropic transformation at 1000 to 1100C [64Juz]. The melting point of Mg3As2 was reported to be above 1200 C. MgAs4 decomposes on heating to Mg3As2 (solid) and As4 (gas), but under 500 kPa (~5 atm) of As vapor pressure, MgAs4 melts at 792 с 5 C [61Pig]. [64Bre] reported that metastable Mg3As is formed when Mg is added to As- treated a brasses. They noted that the compound decomposes instantaneously in contact with water and forms AsH3 (gas). 61Pig: K. Pigon, Helv. Chim. Acta, 44, 30-34 (1961) in German. 64Bre: C. Breckon and P.T. Gilbert, Chem. Ind., 35-36 (1964). 64Juz: R. Juza and R. Kroebel, Z. Anorg. Allg. Chem., 331, 187-199 (1964) in German. Published in Phase Diagrams of Binary Magnesium Alloys, 1988, and Bull. Alloy Phase Diagrams, 6(5), Oct 1985. Complete evaluation contains 1 figure, 1 table, and 21 references. 1