β-transformed domains enhanced tensile properties and the related deformation behavior of a near alpha titanium alloy

Abstract

Abstract The dependence of tensile properties and deformation behavior on microstructures of a near alpha titanium alloy Ti–3Al–2Zr–2Mo (wt.%) were investigated systematically. The positive roles of ultrafine α aciculae strengthened β-transformed (βt) domains on simultaneous enhancement of tensile strength and ductility of equiaxed and in particular bi-lamellar microstructures were explained. Compared with regular lamellar α/β microstructure, bi-lamellar microstructure consisting α/βt structures brought about a remarkable heterogeneous deformation introduced (HDI) strengthening and a much higher work hardening rate, which lead to enhanced strength and ductility. Only slip systems were found to operate in the equiaxed and fully lamellar microstructures, while multiple systems including and slips were activated in bi-lamellar microstructure. Besides, the fracture modes of tensile samples with different microstructures were discussed in detail. It is suggested that introducing βt domains is feasible to simultaneously enhance tensile strength and ductility of near α titanium alloys.