Abstract
The low work hardening is a prominent deficiency for high-strength titanium(Ti)alloys.The gradient de-sign of oxygen content was adopted to realize the coupling deformation of {332}<113>twinning and dis-location slip in the Ti-15Mo alloy.This oxygen gradient alloy exhibited an optimal balance of yield/tensile strength(700 and 848 MPa)and elongation(25％),with remarkable work hardening behavior.The dom-inated dislocation slip deformation and the solution strengthening of oxygen atoms in the oxygen-rich region resulted in a remarkable increase in yield strength.The successive formation of {332)<113>twins and piled-up geometrically necessary dislocations around the twin boundaries in the oxygen-free region induced remarkable back stress strengthening,maintaining the high work hardening rate,which resulted in a stable increase in strength.The twins and dislocations formed at the crack tips effectively hindered the cracking behavior,avoiding premature necking.The present study provides a novel idea for designing oxygen layer-distributed Ti alloys,which further improves the strength-ductility tradeoff.
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