Polyphase crystal plasticity for high strain rate: Application to twinning and retwinning in tantalum

Upon increasing strain rate a switch operates in tantalum response from a plasticity dominated regime to a twinning dominated regime. This transition is investigated by means of a polyphase crystal plasticity model which combines a Phase Field-Reaction Pathway formalism and a dislocation-based crystal plasticity model. The proposed formalism for twinning considers an unbounded number of variants which permits the observation of twinning, detwinning and retwinning phenomena. The crystal plasticity model takes into account slip systems interactions and includes two glide regimes to deal with high strain rates. A model for dislocation inheritance during twinning is proposed. Simulations highlight a dual role of plasticity: strain hardening inside the matrix may, under certain conditions, hinder the formation of twin variants whereas plasticity inside the variants further relaxes the residual stress due to twins interaction and contributes to shape the variant.

Automated summary

The transition of strain response from a plasticity dominated regime to a twinning dominated regime in tantalum with increasing strain rate is investigated. A polyphase crystal plasticity model, combining a Phase Field-Reaction Pathway formalism and a dislocation-based crystal plasticity model, is used. The simulations highlight the dual role of plasticity in the formation of twin variants.