Effect of Ni content on microstructures and mechanical properties of hot-pressed TiC–TiB2–Ni composite

Abstract A TiC–TiB 2 –Ni composite with different Ni contents was synthesized using a hot pressing method. XRD analyses showed that the TiC–TiB 2 –Ni composite mainly consisted of TiC and TiB 2 phases, and a small amount of metal Ni was also detected except the uncertain peaks. SEM observations showed that TiB 2 phases were homogeneously distributed on the TiC matrix and the Ni enriched area in white contrast uniformly distributed on the phase interface, grain boundaries between the TiB 2 and TiC grains or the triple junctions among the grains. The Ni enriched area contained metal Ni and NiTi 2 compound according to TEM analyses. The experimental results showed that with increasing the Ni content, the volume density of the TiC–TiB 2 –Ni composite increased, and the hardness, flexural strength and fracture toughness all first increased and then decreased. When the Ni content was 8%, the optimum hardness, flexural strength and fracture toughness of the TiC–TiB 2 –Ni composite was 18.8 GPa, 604 MPa and 8.9 MPa·m 1/2 , respectively.