Significantly enhanced tensile ductility and its origin of a 〈0001〉 micro-textured extrusion bar of a powder metallurgy near alpha titanium alloy

This study investigated the tensile properties and deformation mechanism of a hot-extruded powder metallurgy near α-Ti alloy characterized by a regular lamellar microstructure in which some colonies present a unique 〈0001〉 micro-texture, i.e. c-axes are parallel to the extrusion direction. Compared with the alloy's wrought ingot metallurgy counterpart, ultimate tensile strength (UTS) of the extruded bar was increased by approximately 300 MPa, with an equivalent elongation to fracture (EI) of 15.0%, due to the micro-texture being favorable for extensive 〈c + a〉 wavy slips and associated abnormal rise of work hardening rate. Moreover, annealing at 880 °C brought about a bi-lamellar microstructure with βt domains full of ultrafine acicular α-laths, whereas 〈0001〉 micro-texture was still retained. Heterogeneous deformation induced (HDI) effect at α/βt interfaces led to an extra strain hardening, which resulted in simultaneously enhanced EI up to 22.0% and UTS of 1070 MPa. [Display omitted]