Electrochemical investigation of the influence of laser surface melting on the microstructure and corrosion behaviour of ZE41 magnesium alloy – An EIS based study

Surface melting of a magnesium alloy, ZE41 (4%-Zn, 1%-RE) was performed to achieve electrochemical homogeneity at the surface by microstructure refinement. Large secondary precipitates are particularly known to cause severe pitting in magnesium alloys. The corrosion resistance of the laser treated and untreated alloy was investigated by potentiodynamic polarisation and electrochemical impedance spectroscopy. Contrary to the reported behaviour of other magnesium alloys (such as AZ series alloys), laser surface melting did not significantly improve the corrosion resistance of ZE41. This observation is attributed to the absence of beneficial alloying elements such as Al in ZE41 alloy.

Research highlights
► Laser surface melting of ZE41 produced a refined and homogeneous microstructure.
► Superior corrosion resistance was achieved for two specimens at 1 h of immersion.
► No significant improvement in corrosion resistance was observed after 3 h.
► Absence of beneficial alloying elements in ZE41 might have led to this outcome.