A Statistical Model for Localized Corrosion in 7xxx Aluminum Alloys

A statistical model was developed to rationalize the effect of grain structure on the localized corrosion kinetics in 7xxx aluminum alloys. The model utilized a two-dimensional brick-wall description of the grain structure. Differences in localized corrosion kinetics in different orientations were attributed to differences in path lengths calculated by assigning probabilities of continued growth at various grain intersections in the microstructure. The goal was to use the statistical method and simulations to describe the localized corrosion growth in 7xxx aluminum alloys and to understand the mechanism of corrosion, which was observed to be selective grain attack. Scenarios for the mechanism of selective grain attack are discussed in light of the results from the modeling and simulations.