Effect of permanganate ions on corrosion inhibition of Mg-Al-Mn alloys containing different amounts of Li

Lithium-containing magnesium alloys are promising materials for high-demanding industrial applications. In the present contribution, three different AZ31 magnesium alloys AZ31-xLi (x = 4, 8, and 12 wt.%) were cast and their corrosion processes were examined in 0.05 M NaCl solution utilizing potassium permanganate as a potential corrosion inhibitor. The microstructure of the alloys was analyzed by scanning electron microscopy. Scanning Kelvin probe force microscopy demonstrated high susceptibility of the alloys to localized corrosion attack. Electrochemical techniques showed high effectiveness of the permanganate inhibitor (up to 97 %) at concentrations starting from 10 to 50 mM. Post-corrosion surface analyses allowed establishment of the corrosion inhibition mechanism based on the reduction of permanganate ions on the surface of AZ31-xLi alloys to form an insoluble protective layer of Mn(IV) oxide.