Corrosion behaviour of extruded AM30 magnesium alloy under salt-spray and immersion environments

The mechanisms associated with general, pitting, and filiform corrosion were quantified at various intervals for extruded AM30 magnesium alloy exposed to a cyclical salt spray and immersion environment. The three mechanisms were quantified using optical microscopy, laser profilometry, and SEM coupled with EDX for over 60 h of testing. General corrosion and pitting corrosion were more severe in the immersion environment, and filiform corrosion was more severe in the salt-spray environment. The presence of a sodium ion (Na+) diffusion region around the edge of the corrosion pits functioned as cathodic sites, accelerating the localised pitting corrosion rates in immersion environment. (C) 2013 Elsevier Ltd. All rights reserved.