Microstructure and mechanical properties of B4C-TiB2-SiC-BN composites fabricated by in-situ reaction spark plasma sintering

B4C-TiB2-SiC-BN composites are fabricated by employing B4C, Si3N4, and TiC as raw powders via in-situ reaction spark plasma sintering. The densification behavior, microstructure, and mechanical properties of composites with different additive amounts of (Si3N4+TiC) are investigated. It is confirmed that the in-situ reaction during the sintering procedure of the composites effectively promotes the densification process. Toughening mechanisms including crack deflection, crack branching, crack bridging coupled with BN pull-out lead to the improvement of flexural strength and fracture toughness. As a result, the composites exhibit optimal performance when 15 wt% (Si3N4+TiC) are added, with the bulk density, flexural strength, fracture toughness and Vickers hardness of 2.59 g/cm(3), 705 MPa, 4.4 MPa m(1/2), and 27.8 GPa, respectively. This provides a novel route to preserve the lightweight characteristics and simultaneously enhance the mechanical performance of B4C-based composites.