Preparation and oxidation behaviour of nanocrystalline Ni + CrAlYSiN composite coating with AlN diffusion barrier on Ni-based superalloy K417

A Ni + CrAlYSiN composite coating was prepared on a Ni-based superalloy K417 by vacuum arc evaporation, mainly consists of nanocrystalline γ-Ni, fcc-AlN and fcc-CrN. The oxidation behaviour of the specimens in air at 1000 °C for 100 h was studied. A double-layer oxide scale, inner Al2O3 layer and outer mixture layer mainly dominated by NiCr2O4, formed on the composite coating. Substantial interdiffusion between the composite coating and the substrate was observed. In contrast, a unique alumina scale formed on the composite coating with a nanocrystalline hcp-AlN barrier layer, and the interdiffusion between the composite coating and the substrate was undetectable.

► The composite Ni + CrAlYSiN coating comprises mainly nanocrystalline γ-Ni with dispersed fcc-AlN and fcc-CrN. ► The nitride addition does not damage the oxidation resistance of the coating. ► The AlN layer at the coating-substrate interface prevents interdiffusion.