POSSIBILITY OF FORMATION OF DEGENERATE POINT OF MINIMUM ON PHASE DIAGRAM OF SYSTEM Cd-Mg

Abstract

The purpose of the work was to clarify the physical and chemical nature of structural transformations near the alleged valley, and also defi nition of structure of this point. For the achievement of the goal it was necessary to solve the problem of the synthesis of a series of the diluted solid solutions Cd1-хMgхnear cadmium and to investigate their properties. For the research into the of a possibility of the formation of the valley on the phase diagram of the Cd–Mg system, the a concentration interval near clear cadmium was chosen (0÷5 mol. % Mg). Samples of the Cd–Mg system were prepared by direct alloying of components, which used Cd markings Kd0A and magnesium Mg98, additionally purifi ed from oxides by double sublimation in vacuum. For omogenization, the melt was isothermally aged for three hours, after which the samples were quenched in cold water to minimize the segregation processes. Measuring the concentration dependence of the parameters cadmium-magnesium system samples determined range of solid solutions with non-monotonic change in the physicochemical and electrical properties. The obtained experimental datas allows us to assume the existence on the phase diagram of the Cd–Mg near clear cadmium of the degenerate valley as it is shown in fi g. 4. The results given in the work allow us to assume that the tendency of solid solutions to structural streamlinings near clear components can be shown also in education on the phase diagram of the valley with invariant melting of a solid solution in this point. Final confi rmation of a possibility of formation of a degenerate point at least can be received carrying out a high-precision differential thermal analysis which will give the chance to estimate temperature raising of lines a liquidus and a solidus after structure 2.5 mol. Mg %.

Keywords

• solid solutions
• the minimum point
• degeneration.