Phase relations in the ZrO2–La2O3–Y2O3–Al2O3 system: Experimental studies and phase modelling

Thermodynamic parameters of the La2O3–Y2O3 and La2O3–Al2O3 binary systems were re-assessed based on new experimental information. Phase relations in the La2O3–Y2O3–Al2O3 system were investigated at temperatures 1523, 1673 and 1873 K by phase equilibration followed by phase identification by X-ray diffraction and microstructure investigation by scanning electron microscopy. Melting relations in the system were studied by differential thermal analysis. Temperature and liquid composition for two invariant reactions were determined. The obtained results were used to developed thermodynamic database for the La2O3–Y2O3–Al2O3 system. Mutual solubility of La and Y in aluminates was taken into account. The obtained thermodynamic description was combined with already available databases of ternary systems and thermodynamic database of the ZrO2–La2O3–Y2O3–Al2O3 was derived.