Effect of substrate orientations on the electrochemical and localized corrosion behavior of a quad-layer Al alloy composite

Electrochemical and localized corrosion behavior of a 4045/7072/3003 M/4045 Al alloy composite in 3.5 wt.% NaCl solution was investigated from cross-sectional and plane directions by electrochemical impedance spectroscopy, polarization curves, and high-resolution microscopic examination. Plane directions showed higher corrosion resistance than the cross-sectional surface, with almost all localized corrosion initiated from Si-containing inclusions. The cross-section showed a complex galvanic effect among the four layers, the galvanic coupling between 4045/7072 accelerated the dissolution of 7072 because 7072 served as the anode, however, the galvanic coupling between 3003 M/4045 protected 4045 from corrosion, indicating that 3003 M served as the anode.(c) 2023 Published by Elsevier Ltd on behalf of The editorial office of Journal of Materials Science & Technology.