Achieving high-performance PM TC4 alloy manufacturing through β extrusion combined with unique oxygen scavenger

• The scavenging of O by CaC 2 addition improves the tensile ductility. • The as-extruded TC4-0.2CaC 2 alloy possesses fine equiaxed grains. • The as-extruded TC4-0.2CaC 2 alloy displays extraordinary tensile properties. The inherent defects of powder metallurgy (PM), including residual porosity, coarse microstructure and interstitial oxygen (O) contamination, remain to be critical issues for manufacturing high-performance titanium (Ti) alloys. Herein, this work designs a feasible route to overcome the dilemma by β extrusion with unique CaC 2 oxygen-scavenger. The microstructure, texture orientation, and strengthening mechanisms were systematically investigated. Results show that the CaC 2 addition can relieve the oxygen-embrittling effect, the tensile elongation (EL) of as-sintered TC4 alloy is increased from the 6.5 ± 1.2% to the 14.6 ± 1.2% by the incorporation of 0.2 wt% CaC 2 . After hot extrusion, the micro-pores are completely eliminated, and the alloy displays fine equiaxed grains with embedded lamellar structure consisting of α and β phases. Furthermore, the addition of CaC 2 promotes the in-situ formation of second-phase particles and activates dynamic recrystallization (DRX), refining the average grain size of α-Ti from 51.36 μm of as-sintered TC4 to the 1.71 μm of as-extruded TC4-0.2CaC 2 . The as-extruded TC4-0.2CaC 2 possesses an exceptional strength-ductility synergy, with the ultimate tensile strength (UTS) of 1159 ± 24 MPa, yield strength (YS) of 1129 ± 18 MPa and EL of 17.3 ± 1.5%. The findings offer a pathway to design the high-performance Ti alloys