A critical review on the Portevin-Le Chatelier effect in aluminum alloys

The plastic deformation showing instability has been a subject receiving considerable attention for centuries due to its importance in many industrial processes. For Al alloys, the major instability is the Portevin-Le Chatelier (PLC) effect that appears within a certain region of strain, strain rate and temperature. It manifests itself on the stress — strain curve as serrations associating with the rapid accumulation of plastic deformation within inclined slip bands. The PLC effect has severe practical consequences, which damages the surface quality after the sheet metal forming process and threatens the tensile ductility. Therefore, it is crucial to investigate the fundamental mechanisms underlying the PLC effect and in particular to investigate how it can be tempered by tailoring the material microstructure. In this paper, we review the common interpretations of the PLC effect and summarize the experimental results of the effects of the precipitation and the grain refinement, two conventional strengthening methodologies in Al alloys, on the serrated plastic flow. The effectiveness of solute atom clusters in suppressing the PLC effect is emphasized.