Фазовая диаграмма системы Ir-Mg

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Ir-Mg (Iridium-Magnesium) A.A. Nayeb-Hashemi and J.B. Clark The proposed Mg-rich equilibrium phase diagram (0 to 25 at.% Ir) is based on the results of [62Fer], [72Wes], and interpolation from the homologous Mg-Pd phase diagram [85Nay]. Except for the Mg-rich eutectic reaction, the reactions for the formation of the intermediate phases shown in the assessed diagram need to be confirmed. The equilibrium in the Mg-rich region was established as eutectic, with the eutectic point "most probably" at 3.2 at.% Ir and 615 C [62Fer]. [Shunk] noted that the solid solubility of Ir in (Mg) is less than 0.18 at.% Ir. However, incorporating the data of [50Bus], it appears that the solid solubility of Ir in Mg is less than 0.13 at.% Ir. The solid solubility of Mg in (Ir) remains to be determined. [62Fer] showed the existence of three intermediate phases, which were designated z (with an average composition of Mg44Ir7), Mg4Ir, and Mg3Ir. However, [62Fer] could obtain structural data for only z and Mg3Ir. For alloys between z and Mg3Ir, [62Fer] noted that equilibrium was not obtained. In spite of very slow cooling and long thermal treatment, the alloys showed three phases. According to [62Fer], the X-ray patterns of the third phase could not be obtained because of the domination of the patterns of the other phases. [62Fer] reported the composition of z saturated with Mg and Ir, respectively, as 11.22 and 12.05 at.% Ir. The homogeneity range was reported to be greater at higher temperatures than at lower temperatures [62Fer]. [72Wes] determined the structure of the intermetallic compound in equilibrium with (Mg) and showed that this compound is isomorphous with Mg44Rh7, and thus has the formula of Mg44Ir7. [72Wes] suggested a narrow homogeneity range for Mg44Ir7. 50Bus: R.S. Busk, Trans. AIME, 188, 1460-1464 (1950). 62Fer: R. Ferro, G. Rombaldi, and R. Capelli, J. Less-Common Met., 4, 16-23 ( 1962). 72Wes: L. Westin and L.E. Edshammer, Acta Chem. Scand., 26(9), 3619-3626 (1972) . 85Nay: A.A. Nayeb-Hashemi and J.B. Clark, Bull. Alloy Phase Diagrams, 6(2), 164-167 (1985). Published in Phase Diagrams of Binary Magnesium Alloys, 1987. Complete evaluation contains 1 figure, 3 tables, and 4 references. 1