Kinetic nature of electrochemical plasticization

Abstract

The electrochemical plasticization (EP) of metallic materials has been known for decades, but the underlying mechanisms, especially the kinetic mechanisms, remain unclear. Herein, the kinetic nature of EP has been investigated by employing the electrochemical cold drawing of single-crystal copper (in a 0.35 mol L–1 dilute sulfuric acid aqueous electrolyte and with a current density of 0.67 × 10−2 A cm−2) through microstructural characterizations and reactive force field molecular dynamic simulations. The results intuitively reveal that the surface-loosened atoms, due to the selective corrosion dissolution, acts as the sources of dislocations to accelerate the formation of dislocations in a multi-slip manner, which then rapidly move toward the inside, and react with the internal early-formed dislocations to undergo abnormal slip of Lomer-Cottrell locks, cross-slip, and annihilation, leading the dislocation entanglements to reconfigure into the movable short-range wavy dislocations and their density to reduce, thus resulting in the softening and the weakening of work-hardening. These findings provide in-depth insights into the kinetic mechanism of EP, which will inevitably accelerate the development and engineering applications of new metal processing technologies based on EP as well as get a deeper understanding of stress corrosion cracking.