High-Hardness High-Fracture-Toughness B4C-TiB2 Composite Produced by Reactive Hot Pressing

B4C-TiB2 composite was synthesized by in situ reaction of TiO2 , C, and B4C during vacuum hot pressing. The composition of the composite was varied from 0 to 20 vol.% TiB2. The reaction step was controlled to produce homogenous distribution of TiB2 in B4C matrix with - 100% density. The hardness, bending strength, and fracture toughness of B4C monolith and B4C-TiB2 composite were evaluated. B4C-TiB2 composite with 20 vol.% TiB2 content showed 39.4 GPa hardness, 800 MPa bending strength, and 9.8 MPa.m(1/2) fracture toughness. The increase in hardness, bending strength, and fracture toughness in B4C-TiB2 composite sample was 29, 56, and 292%, respectively, as compared to B4C monolith. Improvement in hardness and bending strength is attributed to the smaller grain size, i.e., 1.3 mu m. The increase in fracture toughness is due to the presence of free carbon at the B4C-TiB2 interface, which creates microcracks at the interfacial boundary.