Role of Sn in corrosion and passive behavior of extruded Mg-5 wt%Sn alloy

Corrosion behavior of extruded Mg and Mg5Sn (in wt%) alloy was investigated, and a passivated surface of the Mg5Sn was examined. Immersion test in a 0.6 M NaCl solution revealed that corrosion of the Mg was significantly faster than the Mg5Sn alloy, and vigorous H-2 evolution was accompanied with the severe corrosion of Mg. Polarization tests confirmed that cathodic reaction was inhibited in the Mg5Sn alloy. It was considered that the decreased H-2 evolution of the Mg5Sn alloy was attributed to the formation of Sn-accumulated layer between the passive film and matrix, which was examined by an XPS analysis. (C) 2015 Elsevier Ltd. All rights reserved.