Corrosion Resistance of GdTbDyHoSc and GdTbDyHoY High-Entropy Rare-Earth Alloys with Protective Coatings

— We have studied for the first time the feasibility of using Al 2 O 3 and Al : Zn (1 : 1) coatings produced by supersonic plasma spraying for protecting GdTbDyHoSc and GdTbDyHoY high-entropy rare-earth (RE) alloys from corrosion in a salt-fog chamber. The results demonstrate that, under salt fog conditions, Al 2 O 3 coatings break down through local surface activation, resulting in pitting corrosion, with a considerable fraction of the coating on the main material remaining intact. The alloys coated with Al : Zn (1 : 1) exhibit lower corrosion resistance under salt fog conditions as a consequence of electrochemical corrosion. Interaction of Al 2 O 3 with NaCl limits the suitability of such coatings for protecting high-entropy RE alloys under salt fog conditions. Limitations refer to the specimen test time and coating thickness.