Effect of sintering temperature on the structure and properties of in situ synthesized B₄C- TiB₂ composites

Boron carbide ( B_4C ) ceramics, owing to their ultra-high hardness, low density and excellent neutron absorption capability, have significant potential in applications such as armour, nuclear industry and cutting tools. However, their inherently low fracture toughness at ambient temperature and difficulty in achieving full densification during sintering limit broader utilisation. In this study, TiB2 reinforcement phases were fabricated in situ within B_4C via high-temperature and high-pressure sintering. The influence of sintering temperature on the phase composition, microstructure and mechanical properties of the B_4C - TiB_2 composites was systematically investigated to optimise the sintering process and performance. The results indicate that, with increasing sintering temperature, Ti progressively reacts with B_4C to form TiB_2 , achieving complete Ti consumption at 1300°C. At 1500°C, the composites exhibited optimal performance: relative density of 99.6%TD, Vickers hardness of 35.2GPa, flexural strength of 694.6MPa, and fracture toughness of 8.2MPa•m1/2. Further temperature increase to 1600°C led to abnormal grain coarsening and consequent properties degradation. High-temperature and high-pressure sintering combined with in situ reaction enables the fabrication of highly dense, high-performance B_4C - TiB_2 composites, with temperature of 1500°C identified as the optimal sintering temperature. This work provides not only a viable pathway for manufacturing, but also a theoretical basis for designing high-performance B4C composites.