Towards high strengthening efficiency by in-situ planting nano-TiB networks into titanium matrix composites

The coarsening of the matrix microstructure and hybrid reinforcements caused by the excessive-high sintering temperature has been a widespread problem for powder metallurgical titanium matrix composites (TMCs). In this study, inspired by the unique eutectic precipitation path in Ti–B system, we innovatively proposed a new strategy to optimize the microstructure by in-situ planting nano-TiB networks into the composite powder. During the hot-pressing process, the pre-planted networks significantly refined the matrix grain and assembled the special interfacial/intragranular structure, containing interfacial submicron-TiB and intragranular nano-TiB. The well-designed TiB/IMI834 composites exhibited a great improvement in mechanical properties, the compressive yield strength was improved to 1438 MPa with an increase of 24.5%, and the tensile strength at 600 °C was increased to 825 MPa, superior to many thermo-mechanically processed TMCs. The grain refinement and the interfacial/intragranular nano-TiB both contributed to the high strengthening efficiency. This new strategy provided a controllable and facile way to refine the microstructure and achieve high strengthening efficiency in TMCs.