Abstract
Electroplasticity is defined as the reduction in flow stress of a material undergoing deformation on passing an electrical pulse through it. The lowering of flow stress during electrical pulsing has been attributed to a combination of three mechanisms: softening due to Joule-heating of the material, de-pinning of dislocations from paramagnetic obstacles, and the electron-wind force acting on dislocations. However, there is no consensus in literature regarding the relative magnitudes of the reductions in flow stress resulting from each of these mechanisms. In this paper, we extend a dislocation density based crystal plasticity model to incorporate the mechanisms of electroplasticity and perform simulations where a single electrical pulse is applied during compressive deformation of a polycrystalline FCC material with random texture. We analyze the reductions in flow stress to understand the relative importance of the different mechanisms of electroplasticity and delineate their dependencies on the various parameters related to electrical pulsing and dislocation motion. Our study establishes that the reductions in flow stress are largely due to the mechanisms of de-pinning of dislocations from paramagnetic obstacles and Joule-heating, with their relative dominance determined by the specific choice of crystal plasticity parameters corresponding to the particular material of interest.
Highlights
Electroplasticity is the phenomenon where a material undergoing deformation displays a drop in flow stress whenever subjected to an electrical pulse
The discovery of this phenomenon can be credited to Troitskii and Likhtman [1] who first observed the reductions in flow stress while passing current pulses through Zn single crystals
Conrad and co-workers [5, 9], present the first among the athermal theories, which is based on the transfer of momentum from the flowing electrons to the dislocations. It is known as the “electron-wind force” theory and was conjectured to be the principal contributor to EP till Molotskii et al, [13] presented an analysis which demonstrated its effect to be small compared to the reductions in flow stress observed during experiments
Summary
Electroplasticity ( called as “EP”) is the phenomenon where a material undergoing deformation displays a drop in flow stress whenever subjected to an electrical pulse. Conrad and co-workers [5, 9], present the first among the athermal theories, which is based on the transfer of momentum from the flowing electrons to the dislocations It is known as the “electron-wind force” theory and was conjectured to be the principal contributor to EP till Molotskii et al, [13] presented an analysis which demonstrated its effect to be small compared to the reductions in flow stress observed during experiments. Molotskii and co-workers [13, 14] present a different explanation for the reductions in flow stress They claim that the induced magnetic field due to the applied current alter the electronic states of the bonds between the obstacles and the dislocation cores which promote de-pinning of dislocations from such obstacles. Molotskii et al, [13, 14] present an analysis of the reductions in flow stress due to such an effect and find the softening to be quite substantial compared to the two earlier mechanisms
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