The localized corrosion behavior of a Cu-free 6111-like alloy was studied in solutions with different chloride concentrations. It was found that the alloy was susceptible to pitting and intergranular corrosion (IGC). The IGC attack on the alloy was less conspicuous unless the pits were cross sectioned. The pitting attack propagates via crystallographic tunneling regardless of the applied potential or heat treatment conditions. Scanning transmission electron microscopy (STEM)/ x-ray microanalysis detected preferential segregation of Mg and Si at some high-angle grain boundaries (GB) and approximately 30-nm-wide Mg- and Si-depleted regions across GB of the alloy. Such findings have experimentally confirmed the assumptions made by others regarding the IGC susceptibility of 6XXX Al alloys, which was based on the noble GB precipitates and/or the preferential segregation of noble elements and adjacent solute-depleted regions. As a result, a link between the GB elemental profiles and the alloy's IGC susceptibility has been established on a Cu-free 6XXX Al alloy.
All Science Journal Classification (ASJC) codes
- Chemical Engineering(all)
- Materials Science(all)