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.