Effect of Sn content on the mechanical properties and corrosion behavior of Mg-3Al-xSn alloys

Abstract

Abstract The effect of Sn content on the mechanical properties and corrosion behavior of Mg-3Al-xSn alloys was investigated by SEM-EDXS, XRD, electrochemical measurements, and scanning Kelvin probe force microscopy (SKPFM). The results showed that when the Sn content was 1.4 wt%, Sn dissolved in the α -Mg matrix and then precipitated as an intermetallic compound (Mg 2 Sn). The combined results of mass loss, hydrogen evolution, and electrochemical measurements indicated that Mg-3Al-1Sn had a low corrosion rate. The SKPFM results showed that the Volta potential of Mg 2 Sn particles, Al-Mn, and β -Mg 17 Al 12 phases were 100, 80, and 50 mV higher than the matrix, respectively. Therefore, the Mg 2 Sn phase that formed in Mg-3Al-xSn served as a local cathode due to its high potential, which accelerated microgalvanic corrosion along with the secondary local cathode (Al-Mn). The Sn solution strengthening and secondary phase strengthening (fine Mg 2 Sn particles) improved the mechanical properties of the Mg-3Al-xSn alloys.