Thermodynamic Reassessment of the Al 2 O 3 –MgO and Al 2 O 3 –CaO–MgO Systems

ABSTRACT Due to a few issues in previous assessments, a comprehensive thermodynamic reassessment of the Al 2 O 3 –MgO and Al 2 O 3 –CaO–MgO systems was performed using the CALPHAD method. In the present work, the modeling of the Al 2 O 3 –MgO system focused on refining the parameters of the MgAl 2 O 4 spinel phase to better match the degree of inversion data and enhance the reliability of the parameters at different temperature ranges. By integrating reliable phase equilibria and thermodynamic properties data for optimization, a consistent thermodynamic description of the Al 2 O 3 –MgO system was obtained. Subsequently, the Al 2 O 3 –CaO–MgO ternary system was reassessed by combining the thermodynamic descriptions of the CaO–MgO and Al 2 O 3 –CaO systems from the literature. The thermodynamic parameters for the liquid phase and the ternary compounds (3CaO·MgO·2Al 2 O 3 , CaO·∙2MgO·8Al 2 O 3 , and 2CaO·2MgO·14Al 2 O 3 ) were optimized to reproduce the phase diagrams, including various vertical sections and the liquidus projection. The present thermodynamic modeling has solved the discrepancies between previous thermodynamic assessments and subsequent experimental data regarding solid‐phase equilibria, thereby improving consistency with the experimental results.