High-temperature oxidation and hot-corrosion behaviour of EB-PVD β-NiAlDy coatings

Cr/Dy doped β-NiAl coatings were produced by electron beam physical vapour deposition (EB-PVD). Cyclic oxidation and hot-corrosion behaviour of the coatings was investigated. The addition of 0.1 at.% Dy to the β-NiAl coating significantly improved the cyclic oxidation resistance, while the addition of 1.3 at.% Cr to the NiAlDy accelerated the scale spallation. Spinels containing Mg, Na and Ca and pitting resulting from spallation of the spinels were observed on the NiAlDy coating after 200 h hot-corrosion at 950 °C. The NiAlDyCr coating effectively suppressed the formation of pitting and spinels.

Research highlights
► Cr/Dy doped β-NiAl coatings were produced by electron beam physical vapor deposition.
► The microstructures of the Cr/Dy doped β-NiAl coatings were characterized.
► The effect mechanisms of Dy and Cr on the cyclic oxidation of the NiAl coatings were investigated.
► Hot-corrosion behavior and associated failure mechanism of the NiAl coatings were investigated.