Effect of Al addition and heat treatment on the microstructures and corrosion resistance of Mg-Cu alloys

Abstract The effects of Al content and annealing condition on the microstructures and corrosion performances of Mg-3 wt.%Cu-xAl (x = 0, 4 wt.%, 8 wt.%) alloys were investigated. The Mg-3 wt.%Cu alloy contains Mg2Cu phase, but Al-bearing alloys contain MgAlCu and Mg17Al12 phases. The Mg2Cu and MgAlCu phases exhibit much higher Volta potential compared to Mg17Al12 and α-Mg, and their volume fractions are related to Al content of alloys and annealing condition. The weight loss measurement and electrochemical tests are conducted to explore the corrosion performances of alloys. The close relationship between weight loss rate of alloys and volume fraction of Cu-bearing phases indicates that the corrosion performances of alloys can be controlled by adjusting Al content of alloys and annealing conditions.