Mechanical properties of Al₂O₃-LaPO₄ composites with eutectic microstructure produced by flash sintering

The mechanical properties of Al2O3-LaPO4 composites with varying microstructures produced by flash sintering and conventional sintering are evaluated. Specifically, Vickers and Knoop hardness values were measured and calculated for different resultant microstructures, including eutectic microstructures with varying layer thickness, polycrystalline (noneutectic) microstructures, and single-phase samples of Al2O3, LaPO4, and 8YSZ. The findings indicate that eutectic microstructures exhibited higher hardness values than polycrystalline counterparts on the flash-sintered sample. However, the hardness values of eutectic microstructures with varying layer thicknesses show no significant or systematic variation. The grain size, indentation size, eutectic colony size, indentation shape (elastic recovery in Knoop indentations), and crack propagation pathways in the indented samples are also discussed. Overall, the results suggest that Al2O3-LaPO4 eutectic composites have higher hardness than their polycrystalline counterparts and have great potential as abradable coatings with high machinability and durability.