Abstract:
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.