Фазовая диаграмма системы Ir-Mn

К оглавлению: Другие диаграммы (Others phase diargams)

Ir-Mn (Iridium-Manganese) H. Okamoto The assessed Ir-Mn phase diagram is primarily based on the work of [55Rau]. The homogeneity range of aIrMn is based on lattice parameter data given by [ 65Bru]. The boundaries involving the liquid phase are speculated. The equilibrium phases of the Ir-Mn system are (1) the liquid, L; (2) the fcc Cu- type terminal solid solution, (Ir); (3) CsCl-type high-temperature bIrMn; (4) AuCu-type low-temperature aIrMn; (5) AuCu3-type IrMn3, which exists below 900 C; and (6) the (dMn), (gMn), (bMn), and (aMn) terminal solid solutions. Because (Ir) and (gMn) are the same fcc phase, the extensions of liquidus and solidus of (Ir) and (gMn) must be continuous. The continuity of (Ir) and (gMn) may or may not be interrupted by L and bIrMn. [55Rau] reported the solubility of Mn in (Ir) to be 48 and 44 at.% at 1350 and 650 C, respectively. Corresponding to the adjustment of the Mn-rich boundary of IrMn, the solubility limit of Mn in (Ir) is slightly shifted to the Ir-rich side in the assessed diagram. The existence of a high-temperature (above 940 C) modification of IrMn with CsCl-type structure was speculated by [55Rau]. bIrMn cannot be retained by quenching [55Rau]. In agreement, [65Bru] found aIrMn in specimens quenched from 950 C. According to [65Bru], the homogeneity range of IrMn is 45 to 60 at.% Mn at 950 C; these values are based on a large number of lattice parameter data and are accepted in the assessed diagram. Addition of Ir in Mn stabilizes (gMn) [55Rau]. The Mn-rich limit of (gMn) at room temperature is 91.5 at.% Mn [55Rau]. A 94 at.% Mn alloy quenched from 1200 to 900 C is single phase corresponding to (gMn) [55Rau]. Therefore, the temperature of the upper boundary of (gMn) probably increases with increasing Ir content. Magnetic susceptibility measurements showed that the N‚el temperatures of aIrMn are above 877 C [65Bru]. 55Rau: E. Raub and W. Mahler, Z. Metallkd., 46(4), 282-290 (1955) in German. 65Bru: K. Brun, A. Kjekshus, and W.B. Pearson, Acta Chem. Scand., 19(1), 107- 112 (1965). Submitted to the APD Program. Complete evaluation contains 1 figure, 2 tables, and 2 references. 1