In situ formation of micro arc oxidation ceramic coating on refractory high entropy alloy

Micro arc oxidation (MAO) coatings were in situ prefabricated on refractory high entropy alloys (RHEAs). We systematically studied the evolution of the surface and cross-sectional morphologies and composition of the MAO ceramic coatings on AlTiCrVZr substrate with oxidation time. It was found that the surface elements in AlTiCrVZr exhibit competitive oxidation behavior during the MAO process. The inner layer of the MAO ceramic coating was mainly composed of ceramic oxides of the substrate elements, and the outer layer primarily consisted of ceramic oxides formed by the solute ions. Finally, we propose a growth model of the ceramic oxide coatings based on the formation mechanism of the MAO ceramic coating and the physical and chemical properties of the ceramic oxides formed by the principal elements in the RHEAs.