Abstract:B-Ti-C composites toughened by TiB₂ particles were produced by reaction sintering of B₄C, TiC and TiB₂ powders. Microstructure and mechanical properties of the composites were studied. A notable improvement on flexure strength and fracture toughness were achieved in B₄C composites containing 10%TiB₂ and 20%-30%TiC(volume fraction). The highest flexure strength and fracture toughness, 425MPa and 8.2MPa·m^1/2, respectively, resulted for B₄C-10%TiB₂-30%TiC composite, are much higher than those for monolithic B₄C. The main toughening mechanism is microcrack toughening and crack deflection toughening. 

Key words:  B-Ti-C composites; microstructure; mechanical properties; toughening mechanism