Improvements in mechanical properties of TiB2 ceramics tool materials by the dispersion of Al2O3 particles

TiB2–Al2O3 composites with Ni–Mo as sintering aid have been fabricated by a hot-press technique at a lower temperature of 1530 °C for 1 h, and the mechanical properties and microstructure were investigated. The microstructure consists of dispersed Al2O3 particles in a fine-grained TiB2 matrix. The addition of Al2O3 increases the fracture toughness up to 6.02 MPa m1/2 at an amount of 40 vol.% Al2O3 and the flexural strength up to 913.86 MPa at an amount of 10 vol.% Al2O3. The improved flexural strength of the composites is a result of higher density than that of monolithic TiB2. The increase of fracture toughness is a result of crack bridging by the metal grains on the boundaries, and crack deflection by weak grain boundaries due to the bad wetting characters between Ni–Mo and Al2O3.