Effects of RE Micro-Alloying Additions on the Corrosion Behavior of an Al-Mg-Si Alloy

AlMg5Si1-xRE (x=0%, 0.9%) alloys were prepared by resistance melting method, and the phases of alloy were analyzed by X-ray diffraction (XRD) and scanning electron microscope (SEM). The effects of RE (rare earth) on the corrosion resistance of AlMg5Si1 alloy immersed in seawater in different time were investigated by potential measurements and electrochemical impedance spectroscopy. The results showed that the strengthening phase β (Mg2Si) was short rod like and dispersing distributed in α (Al) in the AlMg5Si1 alloy after adding 0.9% RE. Under the conditions of seawater immersion, the corrosion rate of the AlMg5Si1RE0.9 alloy was less than that of AlMg5Si1 alloy, and the corrosion rate of AlMg5Si1RE0.9 immersed 12h in seawater was the slowest, 5.7 uA·cm-2. The improved corrosion resistance is due to the changes in microstructure and corrosion products.