Improvement of Al coating adhesive strength on the AZ91D magnesium alloy electrodeposited from ionic liquid

► A dense Zn undercoat was deposited on both the α- and β-phase surfaces of AZ91D. ► Al coatings upon AZ91D were achieved by electrodeposition employing ionic liquid. ► The morphology of the Al deposits was controlled by the polarization conditions. ► Adhesion of Al coatings electrodeposited on AZ91D was improved by the dense Zn undercoat.