Thermodynamic evaluation and optimization of the K2O-Al2O3-SiO2 system

The K2O-Al2O3-SiO2 system is an important component of microcrystalline glass. The K2O-Al2O3 and K2O-SiO2 binary systems and the K2O-Al2O3-SiO2 ternary system were thermodynamically evaluated and optimized using the CALculation of PHAse Diagram (CALPHAD) method. The liquid phase is described by using the ionic two-sublattice model, and the solid solutions involved in the ternary system are all described using the compound energy formalism (CEF) model. The new parameters obtained from the optimization are capable of describing the equilibrium phase relations of the ternary system and its subsystems, and the calculated thermodynamic properties of the ternary compounds are in good agreement with the experimental data.