The role of trace Sc and Y in the corrosion resistance of cold drawn Al-0.2Ce based alloys with high electrical conductivity

The effects of trace Sc and Y on the corrosion behaviors of cold-drawn Al-0.2Ce alloys were revealed by scanning Kelvin probe force microscopy (SKPFM), transmission electron microscopy (TEM), scanning electron microscopy (SEM), Electron Probe Micro-analyzer (EPMA), and electrochemical measurements. The results showed that the Al3Sc particles not only enable the increase of subgrain boundaries in the modified alloy after cold drawing but also improve the morphology and size of the Al13Fe3Ce phase. SKPFM analysis showed that the enrichment of Y around the Al13Fe3Ce phase in the modified alloy can decrease its electrochemical inertness and thus reduce the micro-galvanic corrosion susceptibility of the alloy. The results of the electrochemical analysis showed that the individual and composite addition of Sc and Y can improve the corrosion resistance of the cold-drawn Al-0.2Ce alloy. The corrosion potential and current of Al-0.2Ce-0.2Sc alloy are −0.892 V and 0.91 μA·cm−2, while the corrosion potential and current of Al-0.2Ce-0.1Y alloy are −0.918 V and 1.08 μA·cm−2, respectively. It is obvious that Sc element improves the corrosion resistance of Al-0.2Ce alloy more effectively than Y element. The corrosion depth of Al-0.2Ce-0.2Sc-0.1Y alloy was the smallest tested by immersion under the same conditions, and its corrosion potential and corrosion current were −0.842 V and 0.79 μA·cm−2, respectively, corresponding to the best corrosion resistance. The formal mechanism of pitting corrosion in the alloys is also discussed.