Electroplasticity mechanism study based on dislocation behavior of Al6061 in tensile process

The thermal and athermal influence of electric current on dislocation motion is the fundamental mechanism for the electroplastic effect in different metals. Due to the significant scale difference between dislocation evolution and macroscopic deformation, it is difficult to figure out how the electric current affects the dislocation motion and further leads to the macroscopic electroplastic behavior since several interweaving mobile and immobile dislocations are involved. As a macroscopic manifestation of the interaction between dislocations and interstitial atoms, the Portevin-Le Chatelier (PLC) effect provides a satisfying entry point for solving the above problems by connecting the microscopic dislocation mechanism to the macro-scale electroplastic effect in a straightforward manner. Experiments of Al6061 in the tensile process show that the introduction of current causes two opposite effects, i.e., an increase of the pinning strength and a reduction of the time for dislocations to escape from pinning. Further microscopic characterization reveals that the reasons for the above phenomena include two aspects: (1) Promotion of the dissolution of the precipitated phase and increases in the concentration of interstitial atoms in the system. (2) Promotion of the motion of dislocations and the activation of additional slip systems. Those changes are closely related to the thermal and athermal effects of the current. Based on the observation results in this paper, the contradictions in the existing literature can be well explained.(c) 2022 Elsevier B.V. All rights reserved.