Towards a multiscale model of aluminum corrosion: Assessing the strength of protective oxide films*

Aluminum metal reacts readily with the environment and forms a nanometer-scale protective oxide/hydroxide film at the surface. Once formed, these films greatly reduce further corrosion by shielding the bare metal underneath. Fracturing of the protective film can expose the metal, accelerating corrosion chemistry. Information about the strength properties of these materials can be leveraged by component-scale predictive lifetime models to make more refined predictions about net reaction kinetics. In this work, we use molecular dynamics with a reactive force field to calculate the stress response of bulk aluminum oxide and hydroxide under uniaxial deformation for various boundary conditions and strain rates. The inclusion of crystal defects such as grain boundaries and porosity and their effects on material response to deformation are also considered.