Microstructure and Strength of Ni-TiB<sub>2</sub> Composites Containing TiB<sub>2</sub> Different Powder Sizes

TiB2 is challenging to sinter to high density due to its low self-diffusion coefficient and high melting point. Typically, metals are used as a binder phase to lower the sintering temperature. In previous research, metal-TiB2 composites were prepared using the SPS sintering method at temperatures exceeding 1500°C. In this study, TiB2 powders of 3μm (denoted as S-TiB2) and 63μm (denoted as L-TiB2) were utilized. The powders were mixed in proportions where L-TiB2 constituted 0%, 25%, 50%, 75%, and 100% of the total TiB2 mass. TiB2-10Ni composites were then prepared by the SPS sintering method at 1100°C under a pressure of 50 MPa. At this temperature, TiB2 grains did not grow, and the composites contained only TiB2 and Ni phases. where the hardness of the composites with 25% of L-TiB2 can reach 2122 HV, while the relative density of the composites with 50% of L-TiB2 exhibited a hardness of 1904 HV, while the composite with 50% L-TiB2 achieved a relative density of 99.6%. Observations indicated that the composites with 25% and 50% L-TiB2 had smaller Ni-rich areas. The L-TiB2 particles adsorbed a portion of the Ni, inhibiting its aggregation, which in turn improved the density and hardness of the composites.