Synergistic enhancement of plasticity and corrosion resistance in laser additively manufactured Ti-10Mo-6Al-1.5Zr alloy via electropulsing treatment

Additively manufactured metastable β titanium alloys suffer from an inherent severe strength-ductility trade-off and inadequate corrosion resistance, originating from ultrafast solidification-induced nonequilibrium microstructures and high-density crystallographic defects. Conventional thermal post-treatments, relying on thermally activated atomic diffusion, lack the spatiotemporal precision to tailor defect architectures and inevitably cause grain coarsening, precluding synergistic optimization of mechanical and electrochemical properties. Herein, a single-step electropulsing treatment (EPT) strategy is proposed for laser additively manufactured Ti-10Mo-6Al-1.5Zr alloy, enabling concurrent modulation of α′ martensite crystallographic alignment and topological reconstruction of dislocation/stacking fault (SF) networks. After treatment at 150 A for 10 min, the alloy achieves 9.5% tensile elongation (2.5-fold increase over the as-deposited state) while retaining 1446 MPa ultrahigh ultimate tensile strength, with a 93% reduction in corrosion current density. HRTEM observations reveal that α′/β interface dislocation pileups induce intense local stress concentrations, triggering SF/deformation twin nucleation and sustained twinning-induced plasticity (TWIP) effect. Electrochemical measurements demonstrate that moderately regulated dislocations and SF crystallographic defects provide fast ion diffusion pathways in TiO₂ passive films, accelerating their self-healing and inhibiting Cl⁻ penetration. This work overcomes fundamental limitations of conventional thermal processing, opening a promising paradigm for integrated multi-property optimization in additively manufactured alloys.