On the mechanisms of nucleation and subsequent development of the PLC bands in an AlMg alloy

The nucleation and subsequent development of the Portevin-Le Chatelier bands during tensile deformation in a binary AlMg alloy was investigated by the digital image correlation technique. The following states of the material were employed for the current investigation: coarse-grained (CG), fine-grained (FG) after equal channel angular pressing (ECAP), severely strained (SS) after ECAP followed by cold rolling. Special attention was paid to the nucleation of an embryo band by maximizing the contrast of the deformation images. Particular spatiotemporal patterns of the alloy in three different conditions, testifying to the initiation of an embryo band having a wedge shape on the lateral surface of the specimen, were obtained at high and intermediate strain rates. The evaluation of the serration amplitude and the band velocity showed that the dependence of these values on strain consists of two stages (the linear growth-up/drop stage and the steady-state stage) for CG materials and only one stage (the linear growth-up/drop stage) for FG materials. The nucleation of deformation bands always occurs according to a mixed mechanism, in which the thick-ening of the embryo slows down with a decrease in the strain rate. (C) 2021 Elsevier B.V. All rights reserved.

Automated summary

The nucleation and subsequent development of Portevin-Le Chatelier bands during tensile deformation in a binary AlMg alloy were investigated using digital image correlation techniques. Different material states were analyzed to reveal specific spatiotemporal patterns of the alloy, indicating that the nucleation of deformation bands follows a mixed mechanism.