Improving the Mechanical Properties and Intergranular Corrosion Resistance of Al-9.2Mg-0.8Mn-0.2Zr Alloy by Sn Addition

Microalloying is believed to improve the performance of Al-Mg alloys, and the effect of Sn addition (0-1.2 wt.%) on the microstructure, mechanical properties and intergranular corrosion behavior of Al-9.2Mg-0.8Mn-0.2Zr alloys has been investigated to extend the application of Al-Mg alloys. The Sn addition forms the Mg₂Sn phase, which refines the grain size and improves the strength, where the yield strength of the alloy improves by 27 MPa with the addition of 0.6 wt.% Sn. Moreover, the addition of Sn improves the intergranular corrosion resistance of the alloys, where the intergranular corrosion mass loss of as-sensitized alloy with the addition of 0.3 wt.% Sn decreases by 35.2% compared to the Sn-free alloy. This is attributed to the formation of the Mg₂Sn phase which reduces the driving force for the precipitation of the β-Al₃Mg₂ phase.