Phase relations in the HfO2-Y 2O3-Al2O3 system

The thermodynamic parameters are assessed for the HfO2-Y 2O3 system based on phase equilibrium data, calorimetric and vapour pressure data. The thermodynamic description for the HfO2-Al2O3 system is derived from phase equilibrium data. The obtained thermodynamic descriptions of binary systems are combined with literature data for the Y 2O3-Al2O3 system and the thermodynamic database for the HfO2-Y 2O3-Al2O3 system is derived assuming that ternary interaction parameters in all phases are equal to zero. The isothermal sections are calculated in the temperature range 1373-2073 K. The calculated liquidus surface for the HfO2-Y 2O3-Al2O3 system is similar to the one for the ZrO2-Y 2O3-Al2O3 system.