Abstract
The objective of this work was to determine the corrosion susceptibility of extruded Mg Alloy ZAEM 1100 in NaCl (aq). Cross sectional examination of the ZAEM 1100 microstructure using microscopy techniques revealed three distinct metallurgical zones: (i) a very thin altered surface layer that arises from die friction during extrusion, (ii) a recrystallized coarse-grained skin layer and (iii) a fibrous fine-grained core. The relative corrosion susceptibility of each zone as a starting surface was investigated using potentiodynamic polarization, scanning vibrating probe and volumetric hydrogen evolution measurements as a function of immersion time in 0.1 M NaCl (aq). Post-exposure examination of corroded surfaces was conducted in cross-section using focused ion beam milling coupled with electron microscopy techniques to identify the microstructure features that control corrosion. The implications of the results for structure automotive application will be discussed.