A novel rapid route for in situ synthesizing TiB-TiB2 composites

The in situ synthesized TiB-TiB2 ceramic-matrix composite is prepared by spark plasma sintering using Ti and TiB2 powders. The microstructures, mechanical properties and the sintering mechanism of the composites are investigated. The composite sintered at 1700 °C has a relative density of 99.4%, average Vickers hardness of 26.5 GPa, flexural strength of 661 MPa and fracture toughness of 6.95 MPa m1/2. According to the microstructure evolution of the composites, the description of the sintering process can be divided into four stages: activation and melt of the metal powder, reaction of Ti with TiB2, coarsening of TiB, and rapid densification. Only if the above mentioned sintering stages proceed in turn and are all fully completed, the high quality composite can be obtained.