Ex situ TEM observation of localized attack on AA 6061

Ex situ transmission electron microscopy (TEM) was used in conjunction with energy dispersed spectrometry (EDS) to monitor evolution near the pre‐selected inclusions during initial stages of localized dissolution on the aluminum alloy (AA) 6061 immersed in 0.1 M NaCl solution. On the alloy TEM foil, Mg₂Si phase particles were observed to preferentially dissolve after 3 min immersion. Nevertheless, different dissolution behaviors were observed to form in the vicinities of the different structure Fe‐rich precipitates; the trenches were observed near the anorthic phase particle, but no obvious priority dissolution was detected in the vicinity of hexagonal phase particles. The preferential sites of alloy dissolution were found to depend on both the component and the structure of the intermetallics. The shift of electrochemical potential was found to relate the dissolution of the heterogeneous phases.