The intrinsic mechanism of stress corrosion in single-crystal copper: Perspectives from crystal orientation and dislocation

In this work, we employed single-crystal copper as a model material and combined experimental and computational methods to investigate the electrochemical effects induced by variations in atomic spacing and dislocation emergence. The results demonstrate that the electrochemical reaction activity of different crystal planes is correlated with their crystal plane indices. Electrochemical reaction activity follows the order: (001) > (101) ≈ polycrystalline > (111), with the (111) plane showing the lowest activity. The local corrosion initiation induced by dislocation emergence and variations in interplanar spacing across different crystal planes is identified as the microscale mechanism responsible for the observed differences in such macroscale electrochemical behavior. The presence of dislocations leads to a reduction in the work function and charge density in the lattice distortion regions, rendering the dislocation emergence sites active locations for cathodic reactions and triggering pitting corrosion initiation in the surrounding matrix. This result was also verified during the stress electrochemical process, where dislocation emergence was found to promote the electrochemical cathodic reaction.