Cyclic oxidation and interdiffusion behavior of a NiAlDy/RuNiAl coating on a Ni-based single crystal superalloy

A novel NiAlDy/RuNiAl coating was deposited onto a Ni-based single crystal superalloy DD3. The cyclic oxidation and interdiffusion of the NiAlDy/RuNiAl coating and a NiAlDy coating at 1100 °C were investigated. For the NiAlDy coating, secondary reaction zone (SRZ) consisting of γ′, γ and σ-topologically-closed-packed phase (σ-TCP) needles was formed in the superalloy after 100 h annealing. The NiAlDy/RuNiAl coating effectively suppressed the formation of SRZ as the RuNiAl layer worked as a buffer layer. Premature scale spallation was observed on the NiAlDy coating after about 80 h cyclic oxidation, whereas the NiAlDy/RuNiAl coating exhibited improved oxidation-resistance property.

► A novel NiAlDy/RuNiAl coating has been deposited onto a single crystal superalloy.
► The coating exhibits a better oxidation-resistance than the NiAlDy coating.
► The coating effectively suppresses secondary reaction zone in the superalloy.