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Present study investigates the effect of microstructure on electrochemical response of commercially pure aluminium. Electrochemical testing included OCP measurements and potentiodynamic polarization. Results reveal insignificant differences for samples with different grain size, shape and fraction of HAGBs. These parameters are assumed as only slightly affecting electrochemical response. Fe-containing intermetallics have the highest impact, as pits nucleate in their vicinity. In examined materials intermetallic particles retained a consistent size and distribution for all samples. Therefore, no difference in electrochemical parameters or number of pits is observed. The only difference is in the shape of the pits, because dissolution occurred along HAGBs.

The corrosion mechanisms of Al Cr Fe and Al Cu Fe Cr complex metallic alloys have been investigated by potentiodynamic and potentiostatic polarization. Very good passivation of the Al Cr Fe surface is exhibited from 1 M H2SO4 to 1 M NaOH solutions which was confirmed by ICP OES analysis over a period of 273 days. Potentiostatically formed passive films analysed by XPS revealed chromium enrichment in the outermost layer of the aluminium oxy hydroxide film. Although Al Cu Fe Cr showed passivation during potentiodynamic polarization heavy active corrosion at OCP was revealed by ICP OES. For the Al Cu Fe Cr alloy the 10 content of Cr is insufficient to maintain a protective "chemically stable" Cr oxide/hydroxide. (c) 2011 Elsevier Ltd. All rights reserved.