High strength B4C–TiB2 composites fabricated by reaction hot-pressing

B4C based composites with 20 mol% TiB2 were fabricated by reaction hot-pressing of four different submicron size B4C powders with the addition of nanometer size TiO2 and C powders at 2000 °C, and their mechanical properties were examined. A B4C–TiB2 composite with both high strength of 866 MPa and modest fracture toughness of 3.2 MPa m1/2 could be obtained using B4C powder with a mean particle size of 0.50 μm and total metal impurity 0.3–0.5 wt.% (Al + Fe). It seems that this extremely high strength is attributed to the fine-grained B4C microstructure, uniform dispersion of TiB2 particles and improvement of fracture toughness.