Hierarchical {332}<113> twinning in a metastable β Ti-alloy showing tolerance to strain localization

Abstract

A hierarchical {332} twinning system is studied in a metastable beta Ti-12Mo-10Zr (wt%) alloy, which shows strong twinning-induced plasticity (TWIP) effect due to a three-level twinning mechanism. In-situ digital image correlation (DIC) indicates a good tolerance to strain localization until εmax = 0.4 thanks to TWIP hardening effect. The local shear misfit due to the intersection between the matrix slip bands and the primary twin boundaries is accommodated by the formation of secondary and tertiary sub-twinning structures. The strain accommodation postpones crack nucleation at the slip-twin intersections, contributing to the high tolerance of the strain localization.

Keywords

• beta twip ti-alloy
• hierarchical deformation twinning
• tensile ductility