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

•Cu-containing phases exhibit much higher volta potential than Mg17Al12 and α-Mg.•The volume fraction of Cu-containing phase determines the corrosion rate of alloys.•Al content and annealing adjust the corrosion performances of Mg-Cu-Al alloys.•The alloy is feasible for making fracturing tools.