Enhanced corrosion resistance of Mg–Sn–Zn–Al alloy by Y microalloying

A significant enhancement in corrosion resistance by Y microalloying was achieved for the Mg–8Sn–1Zn–1Al (wt%) alloy in the extruded condition. Average corrosion rates obtained by immersion tests in 0.6 M NaCl solution at 25 °C were 4.2 and 12.7 mm y−1 for the alloys with and without microalloying with 0.04 wt% Y, respectively. Microstructural investigations indicated that the enhanced corrosion resistance is a result of a transition in a type of second-phase particles toward lowering the difference in electrochemical nobility between the α-Mg and these particles, thereby reducing the susceptibility of the alloy to microgalvanic corrosion.