Thermodynamic reassessment of the Y 2O3-Al2O3-SiO2 system and its subsystems

Phase equilibria and thermodynamic properties at 1 bar in the Y 2O3-Al2O3-SiO2 ternary system and its constituent binaries Y 2O3-Al2O3 and Y 2O3-SiO2 have been reevaluated using the CALPHAD approach. The liquid phase is described by the ionic two-sublattice model with the formula (Al+3,Y +3)P(AlO2−1,O−2,SiO4−4,SiO20)Q. The SiO2 solubility in the YAM phase was described using a compound energy model. Two datasets of self-consistent model parameters are presented. However, the rather meagre and scattered experimental data imply that the present assessments should be regarded as provisional. Some critical experiments are suggested for this system.