Achieving highly variable mechanical behaviors in TiBw/TA15(Si) composite by microstructure manipulation

Discontinuously reinforced titanium matrix composites (DRTMCs) are competitive candidates for aero-space applications. However, the high processing temperature of DRTMCs often yields fully lamellar microstructures, making their properties hard to be tailored by heat treatment. In our previous work, a TiBw/TA15(Si) composite with fine microstructure was fabricated, showing a good potential for microstructure and mechanical properties manipulation. In the present work, heat treatments of different conditions were conducted to this TiBw/TA15(Si) composite. Controllable microstructures from bimodal to fully laminated, and varied mechanical properties, with the ultimate strength ranging from 1136 MPa to 1347 MPa and the elongation ranging from 6.7% to 12.9%, were obtained. The softening induced by microstructure coarsening was balanced by the strengthening of the lath microstructure, and the deformation behaviors of heat-treated composites were determined to be influenced by the strain softening and the constraint of Burgers orientation relationship in the lath microstructure. The present work provided an insight into the deformation and strengthening mechanism of TiBw/TA15(Si) composite, and revealed the possibility of DRTMCs to fulfill the requirements from different service conditions without changing the chemical composition and fabrication procedures.