Improvement of Corrosion Resistance of Mg-3Sn-2Al-1Zn Alloy by Heat Treatment and Y/Nd Addition

The electrochemical corrosion behavior of Mg-3Sn-2Al-1Zn-(0.6Nd/0.6Y) alloy in 3.5 wt.% NaCl solution under different heat treatment processes was investigated via electrochemical test, immersion weight loss test, and microstructure observation. The results show that the corrosion mechanism of Mg-3Sn-2Al-1Zn-(0.6Nd/0.6Y) alloy is similar to that of pure magnesium, which is the process of electrochemical reaction between magnesium and water to generate magnesium hydroxide and hydrogen gas. The solid solution treatment by holding at 400 °C for 24 h significantly improved the corrosion resistance of Mg-3Sn-2Al-1Zn-(0.6Nd/0.6Y) alloys. Nd/Y is formed intermetallic compounds with Mg and Al to increase the corrosion resistance of Mg-3Sn-2Al-1Zn alloy. However, the effect of adding Nd was not as excellent as that of Y, and the solid solution Mg-3Sn-2Al-1Zn-0.6Y alloy exhibited the best corrosion resistance. Graphical Abstract