Liquidus projections and isothermal sections of Mg-Al-Ca system using different geometrical models

Thermodynamic properties of ternary phase diagram were predicated based on thermodynamic properties of optimized binary sub-systems. In this work, liquidus projection and isothermal sections of Mg-Al-Ca ternary system were calculated using Kohler and Muggianu (symmetric model) and Toop where Ca, and Mg were singled out (asymmetric model). The choice of ternary geometric model plays an important role in predicting the thermodynamic property of the ternary system and the misjudging of the asymmetric component results in error of predicting these properties. It was found that different extrapolations model predicted different liquidus projection as well as isothermal sections, although the same binary parameters were used. Comparing with the phase transformation temperature, Kohler and Toop (Mg is singled out) models were found to be the best models for the predicting phase transformation temperature of Mg-Al-Ca ternary system.