Cyclic oxidation behavior of Cr-/Si-modified NiAlHf coatings on single-crystal superalloy produced by EB-PVD

Abstract

The Cr-/Si-modified NiAlHf coatings were produced on single-crystal (SC) superalloy N5 by electron beam physical vapor deposition (EB-PVD). The cyclic oxidation behavior of the coatings at 1100°C was investigated. The microstructures of the oxide scales grown on the coatings were characterized by scanning electron microscope (SEM) with energy-dispersive X-ray spectrum (EDX), electron probe micro-analyzer (EPMA) and X-ray diffraction (XRD). The effects of Cr and Si on the cyclic oxidation behavior of the NiAlHf coatings were discussed. The addition of Si to the NiAlHfCr coating not only reduces the oxidation rate but also enhances the oxide scale adherence.Owing to the addition of Si in the coating, the segregation of Cr and Mo beneath the oxide scale is effectively avoided, which contributes to enhancing oxide scale adherence.