Strain hardening mechanism induced by basal/pyramidal dislocation reactions in a 3D-printed high-strength titanium alloy

Abstract

The high yield ratio and low strain hardening ability of titanium alloys significantly limit their engineering applications. In this work, a Ti65Zr30Cu5 (at.%) alloy with nanoscale α laths was additively manufactured and achieved a high yield strength of 1274 MPa and a high strain hardening rate up to 40% of the shear modulus. Results show that universal basal/pyramidal dislocation reactions occur during the tensile deformation process. This triggers high-density sessile 〈c 〉 dislocation junctions, which accumulate and pin other mobile dislocations. Consequently, abundant dislocation walls are induced, leading to a strong hetero-deformation-induced strain hardening effect.

Keywords

• Laser direct energy deposition
• titanium alloys
• basal-pyramidal dislocation reactions
• hetero-deformation-induced strain hardening
• nanostructure