Overcoming the intrinsic brittleness of high-strength Al2O3–GdAlO3 ceramics through refined eutectic microstructure

High-strength ceramic materials are known for their exceptional mechanical properties; however, they are often plagued by brittleness, limiting their applications. Because of the inherent difficulty of dislocation glide and multiplication in ceramics, efforts to overcome the brittleness of ceramics by activating plastic deformation have faced challenges. This work demonstrates that Al₂O₃-GdAlO₃ (Gadolinium Aluminum Perovskite: GAP) eutectic micropillars with submicron-scale fibrous microstructures exhibit remarkable plastic deformability. They displayed engineering plastic strains of up to 5% even at 25 °C, while the micropillars of Al₂O₃ or GAP single crystals exhibited brittle fracture similar to conventional high-strength ceramics. The plasticity in Al₂O₃-GAP eutectic was attributed to the activation of primary prismatic slip and secondary basal slip in the Al₂O₃ phase, which is typically considered inactive at room temperature. These findings suggest that plastic deformability can be achieved in high-strength ceramic materials by fabricating refined eutectic microstructures.