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 {1 0 −1 0} and {1 1 −2 0} oriented prism planes is more electrochemically stable and corrosion resistant than the surface with a high concentration of {0 0 0 2}, {1 0 −1 0} and {1 1 −2 0} 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.