Microstructures and mechanical properties of the in situ TiB–Ti metal–matrix composites synthesized by spark plasma sintering process

In situ synthesized TiB reinforced titanium matrix composites have been synthesized by spark plasma sintering (SPS) process at 950–1250 °C, using mixtures of 15 wt% TiB2 and 85 wt% Ti powders. The effects of the sintering temperature on densification behavior and mechanical properties of the TiB–Ti composites were investigated. The results indicated that with rising sintering temperatures, relative densities of the composites increase obviously, while the in situ TiB whiskers grow rapidly. As a result, bending strength of the TiB–Ti composites increases slowly at the combined actions of the factors referred above. Fracture toughness of the composites is improved remarkably due to the large volume fraction of Ti matrix, the crack deflection, pull-out and the micro-fracture of the needle-shaped TiB grains. The results also suggested that TiB–Ti composite sintered at 1250 °C by SPS process exhibits the highest relative density of 99.6% along with bending strength of 1161 MPa and fracture toughness of 13.5 MPa m1/2.

► The TiB–Ti composites were synthesized by SPS process at 950–1250 °C.
► The in situ synthesized TiB whiskers grow rapidly with rising sintering temperatures.
► The composite sintered at 1250 °C exhibits dense microstructures and good properties.
► Bending strength of the composite sintered at 1250 °C is 1161 MPa.
► Fracture toughness of the composite sintered at 1250 °C is 13.5 MPa m1/2.