Synthesis mechanism and mechanical properties of TiB sub(2)-SiC composites fabricated with the B sub(4)C-TiC-Si system by reactive hot pressing

High-performance TiB sub(2)-SiC composites were fabricated with a new reaction system of B sub(4)C-TiC-Si by reactive hot pressing. The reaction process was controlled by the diffusion of boron atoms and hindered by the accumulated product layer of TiB sub(2) and C. The melting Si can offer another diffusion path for boron atoms, thereby promoting the reaction process. The Vickers hardness, flexural strength, and fracture toughness of the fabricated TiB sub(2)-SiC composites respectively reached 28.6 + or - 0.6 GPa, 654 + or - 49 MPa, and 6.8 + or - 0.5 MPa m super(1/2). Both the intergranular fracture resulting from mismatch in thermal expansion coefficient between TiB sub(2) and SiC and the transgranular fracture resulting from the network structure of TiB sub(2) can enhance the the fracture toughness of the TiB sub(2)-Sic composite.