Phase relations in the ZrO₂-Sm₂O₃-Y₂O₃-Al₂O₃ system: experimental investigation and thermodynamic modelling

Abstract

Abstract Sub-solidus phase relations in the ZrO 2 -Sm 2 O 3 -Y 2 O 3 and Sm 2 O 3 -Al 2 O 3 -Y 2 O 3 systems were experimentally studied at 1523-1873 K and thermodynamic databases for these systems were developed. Analysis of phase equilibria in the Sm 2 O 3 -Y 2 O 3 -Al 2 O 3 system indicated that REAM phase (Sm,Y) 4 Al 2 O 9 is not stable in the Sm 2 O 3 rich-composition. Therefore, the stability limit of the Sm 4 Al 2 O 9 phase was established experimentally and thermodynamic parameters of the Sm 2 O 3 -Al 2 O 3 system were re-optimised. The eutectic melting in the Sm 2 O 3 -Y 2 O 3 -Al 2 O 3 system was investigated using differential thermal analysis and scanning electron microscopy. The results obtained were used to assess the mixing parameter of the liquid phase. A new description of binary system was introduced into the database of the ZrO 2 -Sm 2 O 3 -Al 2 O 3 system and phase diagrams were re-calculated. The obtained thermodynamic databases were combined with literature data for the ZrO 2 -Y 2 O 3 -Al 2 O 3 system and a thermodynamic database for the ZrO 2 -Sm 2 O 3 -Y 2 O 3 -Al 2 O 3 system was developed.