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 (B4C) has been greatly enhanced due to the boundary non-stoichiometry induced by high-pressure sintering technology. The effect decreased the plastic deformation temperature of B4C 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.