Influence essential of current on electrochemical plasticization of single-crystal copper

Despite the long-standing identification of electrochemical plasticization (EP) in the metal surface layer, the mechanisms governing the impact of electric current density on EP remain incompletely understood. This study investigates the effect of current density (ranging from 0 mA cm-2 to 10.0 mA cm-2) on EP during electrochemical cold drawing of single-crystal copper in a 0.35 mol L-1 dilute H2SO4 electrolyte through microstructural characterizations and reactive force field molecular dynamic simulations. The results indicate that with increasing density, more atoms in the high-energy {110} and {001} planes in the copper surface are selectively dissolved, causing the atoms in the low-energy uncorroded {111} planes to become more loosened. This activates more abundant dislocations in a multi-slip way, thereby facilitating dislocation entanglements to reconfigure into movable short-range wavy dislocations and decreasing dislocation density through reactions, ultimately resulting in improved EP. However, when the density exceeds 6.7 mA cm-2, an opposite effect is observed due to the dissolution of fewer atoms resulting from enhanced local passivation.