Corrosion of an extruded magnesium alloy ZK60 component-The role of microstructural features

The microstructure and corrosion behavior of an extruded magnesium alloy ZK60 bumper were investigated using optical microscopy, SEM and EDS as well as potentiodynamic polarization technique. The results show that the microstructure of the component is characterized by two distinct layers: the skin with coarse grains and the interior with fine grains. Preferential attack on the interior is attributed to the macrogalvanic corrosion between the two layers with an initial potential difference. The size and distribution of the intermetallic compounds play a crucial role in pitting corrosion and intergranular corrosion. (c) 2011 Elsevier B.V. All rights reserved.