Texture Evolution and Dynamic Recrystallization Behavior of Hybrid-Reinforced Titanium Matrix Composites: Enhanced Strength and Ductility

TiB, TiC and La2O3 hybrid-reinforced Ti-6Al-4V matrix composites were fabricated by common casting and processed by the following forging and isothermal extrusion. The texture evolution, dynamic recrystallization (DRX) behavior and mechanical properties of the as-extruded composites were investigated. The results show that DRXed regions and deformed regions formed during extrusion, strong < 0001 & rang;(alpha), 101 over bar 0 alpha fiber textures parallel to extrusion direction were formed due to the selection of slip system in alpha phase and inheritance from phase transformation according to Burgers orientation relationship. Additionally, the orientation of alpha grain in DRXed regions became randomized in comparison with the deformed regions. Micro-sized TiB short fibers not only acted as source to generated dislocations, but hindered dislocation slip to cause pile-ups around TiB, which is beneficial to stimulate dynamic recrystallization. Submicro-sized La2O3 particles distributed at the triple junction of grain boundaries could pin grain boundaries and hinder grain growth. Tensile test results show that the ultimate tensile strength got a 9.8 pct enhancement, from 834.3 +/- 10 to 916.0 +/- 10.6 MPa, accompanied by simultaneous improvement of elongation from 5.4 +/- 0.6 to 12.2 +/- 0.7 pct at room temperature. The simultaneous increase of strength and ductility was principally attributed to TiB fracture modes and grain refinement after extrusion.