Abstract
In this study, the partial pressure values of magnesium over Mg–Ag system alloys were determined by the boiling point method and are presented as a temperature–concentration dependence. A similar dependence for the partial vapor pressure of silver was obtained with the numerical integration of the Gibbs–Duhem equation. The boundaries of the vapor–liquid equilibrium fields were calculated at atmospheric pressure (101.3 kPa) and under vacuum (1.33 kPa). A complete phase diagram was constructed, including the boundaries of the liquid–vapor phase transition at the specified pressures. It was shown that the composition of the equilibrium vapor phase is represented almost entirely by magnesium over nearly the entire range of component concentrations. Thus, when the melt contains 1 wt. % in the melt and exhibits a boiling temperature of 1187 °C (1460 K), the vapor phase contains 94.67 wt. % magnesium, with silver accounting for the remainder. Therefore, the separation of liquid magnesium–silver alloys presents no significant technological difficulties. Based on the thermodynamic activities of the components, the partial and integral mixing functions, namely, entropy and enthalpy, were determined. The thermodynamic functions of formation and evaporation of Mg–Ag system alloys may be used for energy calculations of distillation processes and will supplement the physicochemical database.