Effects of the extrusion temperature on the microstructure and mechanical properties of TiBw/Ti6Al4V composites fabricated by pre-sintering and canned extrusion

TiBw/Ti6Al4V composite bars with in situ synthesized TiBw were successfully fabricated by the pre-sintering and subsequently canned hot extrusion from the original powder particles. In order to investigate the effects of the extrusion temperature systematically, 950 °C (dual α+β region), 1050 °C (near the β transus) and 1150 °C (single β phase region) were selected as extrusion temperatures. After the hot extrusion, the length direction of the TiBw almost all turned to the extrusion direction. With the increasing extrusion temperature, the Ti6Al4V matrix exhibited the elongated α phase + transformed β phase (950 °C), Widmanstätten structure (1050 °C) and bi-modal structure (1150 °C), respectively. The 〈101¯0〉 deformation texture of primary α phase was weakened, and the 〈0001〉 and 〈101¯1〉 texture of α phase precipitated from primary β phase was strenghthened as the extrusion temperature increased. The strength and hardness of Widmanstätten structure (1050 °C) were highest, but its plasticity was lowest, while the other two microstructures exhibited favorable plasticity. What's more, the bi-modal structure had the best performance, achieving a satisfactory mechanical property, with an ultimate tensile strength of 1156 MPa, a fracture elongation of 7.8% and a Vickers hardness of 392 HV.