In situ synthesis and sintering of B4C/ZrB2 composites from B4C and ZrH2 mixtures by spark plasma sintering

B4C/ZrB2 composites were fabricated from raw mixtures of B4C and ZrH2 by spark plasma sintering at 1700 °C in vacuum by applying 32 MPa pressure and held at 1700 °C for 10 min. X-ray diffraction analysis illustrated that a chemical reaction took place between B4C and ZrH2 which resulted in B4C/ZrB2 composites. The in situ reaction between B4C and ZrH2 produced elemental carbon and ZrB2, both of them aided the sintering process. The effect of ZrH2 addition on the microstructure and mechanical properties of B4C matrix was studied. Microstructrual coarsening was restrained by the incorporation of ZrB2 particles and its mechanical properties were consequently enhanced. The specimen with 8 wt% of ZrH2 as a sintering aid was found to have 98.73% relative density, 31.28 GPa hardness, 511 MPa flexural strength, and 4.2 MPa m1/2 fracture toughness.