Microstructure and oxidation behavior of a Ni+CrAlYSiHfN/AlN multilayer coating fabricated by reactive magnetron sputtering

A multilayer coating, about 40 μm thick, was prepared on superalloy René N5 by reactive sputtering from a NiCrAlYHfSi target and an Al target. The as-deposited coating comprised alternating γ-Ni+CrN+hcp-AlN layers, about 300 nm thick, and hcp-AlN + Al layers, about 400 nm thick. XRD analysis showed that CrN and Al disappeared and β-NiAl was formed in the coating after annealing at 1000 °C. The multilayer coating exhibited good oxidation resistance by forming thin and adherent alumina scales at 1050 °C and 1100 °C, and better spallation resistance of oxide scale than sputtered NiCrAlYHfSi coating.