Kink bands-mediated ultrahigh plasticity and sustained work hardening in a metastable β titanium alloy

Abstract

This study systematically investigated the role of kink bands (KBs) in achieving an exceptional strength-plasticity synergy in β-solutionized TB18 titanium alloy, where the tensile strength ranges from 769 to 790 MPa and elongation from 30 % to 42 %. The results show that the prolonged work hardening platform with the work hardening rate (WHR) of 590 MPa maintained over a significant strain range of 0.05–0.17, originating from the coordinated activation of {112}<111>_β slip system and KBs. The KBs nucleate at intersections of ω-depleted dislocation channels, effectively relaxing stress concentration via lattice rotation. As the strain increased, the {112}<111>_β slip system is continuously activated, promoting the generation of dislocation channels. Stress concentrations occur at the intersection of dislocation channels due to the high density of {112}<111>_β dislocations, and KBs when β-matrix by reorienting to facilitate coordinated deformation. The V segregation at β/ω interfaces stabilizes dislocation channels promoting KBs proliferation is also discussed. This work provides a novel pathway for designing metastable β-Ti alloys through KBs engineering, surpassing the conventional trade-off between TWIP/TRIP-induced plasticity and low yield strength.