Formation of eutectic microstructure in Al2O3-GdAlO3-ZrO2 ceramics by flash sintering

The flash-sintering behavior of Al2O3-GdAlO3-ZrO2 powders with a eutectic composition was investigated. The flash-sintered bulks contained two distinct regions: a normally sintered region and a channel region. The Al2O3-GdAlO3-ZrO2 eutectic microstructure observed in the channel region was caused by current localization. We suggest that the eutectic temperature is reached locally in some regions during flash sintering, thus leading to the formation of a eutectic microstructure. The produced eutectic microstructure exhibited high hardness (17.7 GPa) and relatively high fracture toughness (4.3 MPa m(1/2)). The results suggest that the current localization that occurs in flash sintering can be used to prepare eutectic ceramics.