Modeling electrochemical and metal-phase processes during alkaline aluminum corrosion

Abstract

In stress corrosion cracking, the chemical pathways are not yet well-understood by which corrosion produces metal-phase defects responsible for degradation. Open-circuit dissolution of aluminum in alkaline solutions was investigated using a modeling approach, focusing on both electrochemical reactions and metal-phase processes. Pathways were identified leading to corrosion-induced tensile stress and formation of hydride, both of which can influence metal degradation processes. The model was based on the formation of vacancy–hydrogen defects during metal dissolution, and their subsequent aggregation in the metal to form hydride. Calculations successfully explained several transient measurements reported during dissolution, namely formation of subsurface voids and hydride, as well as open-circuit potential and stress.