Mechanisms of electrically assisted deformation of an Al–Mg alloy (AA5083-H111): Portevin–Le Chatelier phenotype transformation, suppression, and prolonged necking

Abstract

Aluminum-magnesium wrought alloys are well known for their advantageous properties and their application in various industries. However, the occurrence of the Portevin–Le Chatelier (PLC) effect leads to the formation of bands on the surface, thereby restricting the application of parts from Al–Mg alloys, primarily due to aesthetic concerns. Applying electrical pulses during deformation may not only improve the mechanical properties, moreover, it also affects the PLC effect. In this work, the properties of AA5083-H111 were investigated using standardized and electrically assisted tensile tests. Tensile behavior was assessed at room temperature, 250 °C, cryogenic conditions, and at two distinct electrically assisted conditions. We found that electrically assisted tensile testing leads to increased fracture strain compared to standard room temperature and cryogenic conditions. Furthermore, there was a transformation in PLC phenotypes, which included a partial suppression of the PLC effect. A spatio-temporal analysis of strain rate and strain highlights considerable differences in the occurrence of PLC bands and prolonged necking compared to standard room temperature testing. Furthermore, a modified dislocation pattern was observed using transmission electron microscopy.