Crystallographic orientation-dependent corrosion behavior of aluminum under residual stress

Abstract

The role of residual stress in the crystallographic orientation-dependent corrosion behavior of Al at the pit initiation and propagation stages was investigated. A clear correlation between step dissolution of Al, the crystallographic orientation of Al, and residual stress was experimentally and theoretically demonstrated. Al atoms exhibit sequential dissolution behaviors, resulting in step configuration of the surface. Residual stress can slightly restrain or promote pit nucleation at the pit initiation stage, depending on its sign. However, on the step surface, residual stress is a primary factor that can decrease and increase the dissolution rates of atoms up to 10% during the pit propagation stage, regardless of the crystallographic orientation. Neighboring coordination numbers and distance between atoms were measured to elucidate the effects of crystallographic orientation and residual stress on the corrosion behavior of Al. Results of the work function and density of states calculations were adequately consistent with each other and supported the experimentally determined pit density and depth behaviors.