Coexistence of multi-deformation modes in beta Ti alloys with improved yielding strength and ductility

Abstract

By suppressing SIM (stress induced martensitic) phase transformations, a strong and ductile beta TWIP (twinning induced plasticity) Ti-Mo based alloy was achieved, thanking to the coexistence of mechanical twinning ({112}<111> mode and {332} <113> mode) and dislocation glide. The alloy displayed extra high yielding stress, stable strain-hardening rate and adequate ductility. In-situ traction/EBSD technique and TEM characterizations were employed to investigate the plastic deformation mechanism. The dislocation slipping was mediated by bimodal twinning mechanism, composed by high density nano-scale {112} twinning in micro {332} twinning grid. The study aims to exploit novel design strategy for strengthening ductile TWIP Ti alloys, attributed to multimodal twinning effects.