Role of microalloyed Sm in enhancing the corrosion resistance of hot-rolled Mg–8Sn–1Al–1Zn alloy

Abstract We report that the corrosion resistance of hot-rolled Mg–8Sn–1Al–1Zn alloy was significantly enhanced by Sm microalloying. Corrosion rates, measured after immersion for 72 h in 0.6 M NaCl solution, were found to be 2.7 and 19 mm y−1 for the alloys with and without an addition of 0.02 wt% Sm, respectively. Electrochemical and microstructural analyses revealed that the enhanced corrosion resistance achieved by Sm microalloying is mainly a result of a reduced H2 evolution rate owing to the presence of Al8Fe4Sm particles instead of nobler Al5Fe2 particles, which highly accelerate microgalvanic corrosion in the alloy without Sm microalloying.