Nanostructured amorphous Al2O3-ZrO2 (La2O3) ceramics with plastic deformation via interface inducing hierarchical shear bands

Ionic-bonded ceramics are featured by their thermal stability, corrosion resistance, hardness and strength, but their applications are limited by the inherent brittleness. Ceramics are composed of strong chemical bonding and intricate crystal structures, making plastic deformation by dislocation slip highly challenging. A nanostructured amorphous Al₂O₃-ZrO₂ ceramic comprising nanoscale amorphous particles and amorphous interfaces between particles was achieved in practice, where the amorphous interface is in scale of approximately 2.34 nm and amorphous particles is in width of approximately 6.75 nm. Based on nano-indentation tests, the shear transformation zone (STZ) volumes of nanostructured amorphous ceramics hot-pressed under various conditions are calculated, suggesting attenuation of free volume with the increase in pressure and temperature. The medium-temperature compression test of the samples exhibits a permanent plastic deformation of 14.6 %, with the presence of hierarchical shear bands in the deformed samples. The main shear bands (MSBs) in width of 0.84–9.15 μm are generated by the stress concentration in crystal-amorphous interface, and the small shear bands (SSBs) of 31–428 nm are related to abundant free volumes in the interface between amorphous particles.