The effect of vacuum hot-press sintering temperature on the microstructure and properties of TiB_w/TC4 composites

Titanium matrix composites (TMCs) exhibit promising application prospects in aerospace and other fields, yet the synergistic optimization of their strength and ductility remains a challenge. In this paper, bimodal heterogeneous TiB whisker-reinforced TC4 (TiB_w/TC4) composites were fabricated using fine-grained TC4 as the matrix and coarse-grained TC4 as the soft region via a two-step low-energy ball milling combined with vacuum hot pressing sintering (HPS) process. The effects of four hot pressing sintering temperatures (1100℃, 1150℃, 1200℃ and 1250℃) on the densification, microstructure, phase composition, mechanical properties and fracture behavior of the materials were systematically investigated. The results show that as the hot-press sintering temperature increases from 1100℃ to 1250℃, the density of the composite first rises and then levels off, TiB_w becomes more evenly distributed, α grain size slightly grows, and the β phase content increases. However, too low a temperature (1100℃) leads to insufficient density, and TiB_w tends to cluster along the original powder boundaries. When the temperature rises, atomic diffusion is sufficient, and the amount of agglomeration drops significantly. On the other hand, Excessively high temperatures (1250℃) cause grain coarsening, interface weakening, and TiB_w growth and coarsening. In comparison, hot-press sintering at 1200℃ can maintain good interface bonding and moderate grain size on a high-density basis, which helps form heterogeneous interfaces and back-stress strengthening effects. Therefore, composites prepared at this temperature achieve both improved strength and ductility, with the best overall mechanical performance: average tensile strength of 1129.5±8.23 MPa, elongation of 4.3±0.3%, and apparent fracture toughness of 37.9±1.7 MPa·√m.