Understanding the mechanisms of intergranular corrosion in 2024 Al alloy at the polycrystal scale

Abstract

This paper provides a new insight into the understanding of the susceptibility to intergranular corrosion (IGC) of 2024 Al alloy. Whatever the exposure conditions, coincidence site lattice high-angle grain boundaries (CSL HAGBs) slightly contributed to IGC damage because of their low contribution to the cumulative length of GBs. Low-angle grain boundaries (LAGBs) showed intrinsic susceptibility to corrosion initiation almost similar to random HAGBs and lower susceptibility to IGC propagation. However, cyclic corrosion tests promoted both corrosion initiation and propagation at LAGBs. This was mostly due to the trapping of corrosion-induced hydrogen in the core of the dislocations defining the LAGBs.