Effect of the crystallographic orientation and twinning on the corrosion resistance of an as-extruded Mg-3Al-1Zn (wt.%) bar

By investigating the corrosion behavior of two oriented surfaces for an as-extruded Mg-3% Al-1% Zn alloy bar, we demonstrate that the surface with a high concentration of {10-10} and {11-20} oriented prism planes is more electrochemically stable and corrosion resistant than the surface with a high concentration of {0002}, {10-10} and {11-20} oriented planes. Further analysis confirms that the corrosion performance is mainly determined by the galvanic corrosion between grains and between twinned and untwinned areas due to their different crystallographic orientations. (C) 2014 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.