Synthesis mechanism and mechanical properties of TiB2-SiC composites fabricated with the B4C-TiC-Si system by reactive hot pressing

High-performance TiB2-SiC composites were fabricated with a new reaction system of B4C-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 TiB2 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 TiB2-SiC composites respectively reached 28.6 ± 0.6 GPa, 654 ± 49 MPa, and 6.8 ± 0.5 MPa m1/2. Both the intergranular fracture resulting from mismatch in thermal expansion coefficient between TiB2 and SiC and the transgranular fracture resulting from the network structure of TiB2 can enhance the fracture toughness of the TiB2-SiC composite.