Comparing intergranular corrosion in Al‐Mg‐Si‐Cu alloys with and without α‐Al(Fe,Mn,Cu)Si particles

Abstract

In this study, a model alloy without Fe and Mn additions, is compared with a commercial AA6005 alloy to further understand how the α‐Al(Fe,Mn,Cu)Si particles affect intergranular corrosion (IGC) behaviour. Both alloys were subjected to an accelerated IGC test for durations ranging from 1 to 120 h. Microstructures were studied using scanning and transmission electron microscopy, and electron backscatter diffraction. The presence of α‐Al(Fe,Mn,Cu)Si particles yields significantly more uniform IGC attacks and higher corrosion rates. However, the maximum depth of IGC attacks reaches similar values after ~24 h of exposure. This is attributed to the formation of Cu‐rich particles along the grain boundaries during the corrosion process, which further catalyses the cathodic reactions.