Influence alloying elements of Al and Y in Mg Li alloy on the corrosion behavior and wear resistance of microarc oxidation coatings

Abstract

Microarc oxidation (MAO) coatings were performed on different Mg Li alloys (Mg 14Li, Mg-14Li-3Al, Mg-14Li-3Al-1Y) in silicate electrolyte. The morphology, thickness, corrosion behavior and wear resistance of the coatings were characterized and analyzed. Results indicate that, compared to Mg 14Li alloy, adding Al and Y in the substrate refines the grains and forms the AlLi and Al 2 Y phases, contributing to the differences in corrosion behaviors of the Mg Li alloys. The alloying elements and uniformly fine microstructure modify the MAO growth process and promote the formation of thick coatings with fewer defects. The MAO coating on the Mg-14Li-3Al-1Y alloy possesses the best corrosion resistance with the i corr of 7.485 × 10 −6 A/cm 2 , due to the densest coating and the thickest inner layer. The reduced porosity and smoother surface enhance the hardness and wear resistance of the MAO coatings on the Mg-14Li-3Al and Mg-14Li-3Al-1Y alloys. It is worth considering the refinement of microstructure and incorporation of passive elements for preparing compact MAO coatings with excellent performances on Mg Li alloys. • The formation mechanism of MAO coatings was influenced by Al and Y in Mg 14Li alloy. • A compact and thick MAO coating was formed on Mg-14Li-3Al-1Y alloy. • High corrosion and wear resistant MAO coating can be obtained on Mg-14Li-3Al-1Y.