Effects of the extrusion temperature on the microstructure and mechanical properties of TiBw/Ti6A14V composites fabricated by pre-sintering and canned extrusion

TiBw/Ti6AI4V 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 degrees C (dual alpha + beta region), 1050 degrees C (near the beta transus) and 1150 degrees C (single beta 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 Ti6A14V matrix exhibited the elongated a phase + transformed beta phase (950 degrees C), Widmanstatten structure (1050 degrees C) and bi-modal structure (1150 degrees C), respectively. The (1010) deformation texture of primary a phase was weakened, and the (0001) and (1011) texture of a phase precipitated from primary (3 phase was strenghthened as the extrusion temperature increased. The strength and hardness of Widmanstatten structure (1050 degrees 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. (C) 2017 Elsevier B.V. All rights reserved.