Dynamic strain aging: A coupled dislocation-solute dynamic model

A model for dynamic strain aging is proposed. It is written as a local constitutive formulation but can easily be extended to account for spatial interactions. The model is obtained by embedding accepted 'slow' time scale formulations for dislocation dynamics and aging kinetics in a multiple time scales dynamic system. Dislocation and solute dynamics are coupled at the 'fast' time scale pertaining to dynamic aging. Features of jerky flow described by standard models such as the negative strain rate sensitivity of the flow stress and critical strains for the occurrence of the Portevin-Le Chatelier effect are retrieved. In addition, negative strain rate sensitivity of the threshold stress for instability is predicted. (c) 2005 Published by Elsevier B.V.