Effects of TiC particle size on microstructures and mechanical properties of B4C-TiB2 composites prepared by reactive hot-press sintering of TiC-B mixtures

Effects of the starting TiC particle size on the phase compositions, microstructures and mechanical properties of B4C-TiB2 composites prepared by reactive hot-press sintering of TiC-B mixtures were investigated. B4C-TiB2 composites were prepared from a single grade amorphous B powder (0.9 pm) and three different TiC powders (50 nm, 0.8 mu m and 3.0 mu m), respectively. The composites prepared from 50 nm and 3.0 pm TiC powders exhibited finer microstructures and higher hardness (29-30 GPa). The composite prepared from 0.8 mu m TiC powder showed the coarsest microstructure but possessed the highest strength of 659 MPa due to its homogenous phase distribution without C impurity and abnormal grain growth that presented in the other two composites. The results indicated that the mechanical properties of B4C-TiB2 composite could be controlled by the particle size matching between TiC and B powders.