Characterization and Oxidation Behavior of a Sputtered Nanocomposite Ni+CrAlYSiHfN Coating

Abstract

A dense nanocomposite coating of Ni+CrAlYSiHfN was prepared on superalloy K417G by reactive magnetron sputtering. The coating was mainly composed of nanocrystalline γ-Ni, hcp-AlN, Cr2N, and CrN. Isothermal oxidations were performed at 900°C and 1,000°C in static air for 200 h. The nanocomposite coating exhibited good oxidation resistance in both temperatures in contrast to the substrate. Decomposition of Cr2N and CrN in the coating, formation of (Ti,V)N in the substrate, and uphill diffusion of Al from the substrate to the coating were observed. The thermally grown oxide (TGO) formation mechanism and the microstructure evolution of the coating are discussed.