Preparation and hot corrosion properties of the AlCrFeCoNi0.5Si high-entropy alloy coating deposited by the air plasma spraying

Normal AlCrFeCoNi and Si-modified AlCrFeCoNi0.5Si high-entropy alloy (HEA) coatings were deposited on a Ni-based superalloy by air plasma spraying technique. Hot corrosion properties of the normal and Si-modified AlCrFeCoNi0.5Si HEA-coated samples were evaluated at 900 °C under the corrosive salt environment containing 45% Na₂SO₄ and 55% V₂O₅. The hot corrosion kinetics of both normal and Si-modified coatings were accordingly investigated using mass gain measurements. X-ray diffraction, field emission scanning electron microscopy, and energy dispersive x-ray analysis were used for the microstructural characterizations. The results indicated that the Si-modified AlCrFeCoNi0.5Si HEA coating has a greater resistance to hot corrosion compared with the normal AlCrFeCoNi HEA coating. The results obtained are primarily related to the formation of Si-rich precipitates, which inhibit the outward diffusion and, therefore, reduce the formation of the corrosion products on the AlCrFeCoNi0.5Si HEA coating surface.