Contribution of boundary non-stoichiometry to the lower-temperature plasticity in high-pressure sintered boron carbide

Abstract Non-oxide ceramics exhibit significant advantages in high-tech industry, but their applications have been limited by the brittle nature especially at low to moderate temperatures. It is a great challenge to improve the ceramic plasticity while maintaining the high-temperature strength through the classical strategy, which generally includes decreasing grain size to several nanometers or adding ductile binder phase. Herein, the plasticity of fully dense boron carbide (B 4 C) has been greatly enhanced due to the boundary non-stoichiometry induced by high-pressure sintering technology. The effect decreased the plastic deformation temperature of B 4 C by 200°C compared to that of conventionally-sintered specimens. Promoted grain boundary diffusion is found to enhance grain boundary sliding, which dominate the lower-temperature plasticity. In addition, the as-produced specimen maintained extraordinary strength before the occurrence of plasticity. The study provides a new and efficient strategy by boundary chemical change to facilitate the plasticity of ceramic materials.