Фазовая диаграмма системы Cd-Mg

К оглавлению: Другие диаграммы (Others phase diargams)


Cd-Mg (Cadmium-Magnesium) Z. Moser, W. Gasior, J. Wypartowicz, and L. Zabdyr The assessed phase diagram for the Cd-Mg system is essentially the same as that reported by [Hansen], with some modifications based on the work of [80Cas] and [71Fra]. The positions of the liquidus and solidus curves have been made consistent with available thermodynamic data, and minor corrections have been made in the phase boundaries of the intermediate ordered phases. Continuous mutual solubility exists in the liquid phase and in the cph solid solution, (Cd,Mg), at elevated temperatures. Below 526 K (253 C), an ordered phase of equiatomic stoichiometry, a› (or CdMg), forms by a congruent reaction. At temperatures below 200 C, additional ordered phases, a› (or Cd3Mg) and a››› (or CdMg3), form on both sides of the a› phase by peritectoidal reactions between a and a››, as shown in the assessed diagram. All three ordered phases have appreciable homogeneity ranges. In the Cd-rich region, the cph disordered a phase exists in equilibrium with the ordered a› phase at room temperature. In the region of the ordered a› phase, no disordered phases were obtained on quenching, even to temperatures as low as -70 C. In a››› (or CdMg3) alloys, the orthorhombic B19 superlattice was observed in very thin foil areas and was assumed to be a metastable phase. The occurrence of hysteresis on heating and cooling involving the two-phase region in an 80 at.% Mg alloy has been reported and is believed to be associated with the retained disordered cph phase below its equilibrium range. In other Mg-rich alloys, the high-temperature a phase has also been observed after quenching, but with altered lattice parameters. 71Fra: C. Frantz and M. Gantois, J. Appl. Crystallogr., 4, 387-395 (1971) in French. 80Cas: R. Castanet, Z. Moser, and W. Gasior, Calphad, 4, 231-239 (1980). Published in Bull. Alloy Phase Diagrams, 5(1), Feb 1984. Complete evaluation contains 6 figures, 7 tables, and 42 references. 1