Synthesis, microstructure, and mechanical properties of Al ₃BC₃

In situ synthesis of bulk Al₃BC₃ was achieved via a reactive hotpressing method using Al, B₄C, and graphite powders at 1800°C for 2 h. The reaction path for synthesizing Al₃BC ₃ was investigated. It was found that Al₃BC₃ formed via the reaction of C, B₄C, and Al₄C₃ above 1180°C. Dense Al₃BC₃ was prepared with a little B₄C and graphite remained. Microstructure observations revealed the plate-like morphology of Al₃BC₃ grains. Moreover, the mechanical properties of Al₃BC₃ were characterized (Vickers hardness of 11.1 GPa, bending strength of 185 MPa, fracture toughness of 2.3 MPa .m^1/2, and Young's modulus of 163 GPa). Young's modulus decreased slowly with increasing temperature, and at 1600°C remained 79% of that at ambient temperature. These results show that Al₃BC ₃ is a promising lightweight high temperature structural material.