Thermal cyclic oxidation and interdiffusion of NiCoCrAlYHf coating on a Ni-based single crystal superalloy

A NiCoCrAlYHf coating was deposited onto a third generation single crystal superalloy DD10 by arc ion plating (AIP). In the present study, thermal cyclic oxidation and interdiffusion of NiCoCrAlYHf coating at 1100 degrees C were investigated to 1000 h. The coating surface, interface morphology and phase structure of the organization were characterized by scanning electron microscopy (SEM), energy dispersion X ray spectroscopy (EDS) and X ray diffraction (XRD). An interdiffusion zone (IDZ) and a secondary reaction zone (SRZ) were formed after 300 h. Severe inward diffusion of Al, Co and Cr from NiCoCrAlYHf coating and outward diffusion of Ni and refractory elements such as Re and W from the superalloy occur at 1100 degrees C in air. The SRZ consisting of gamma, gamma ' and topologically closed-packed phase (TCP) was formed 60 mu m distance from the surface of coating in the superalloy after 300 h oxidation. Additionally, the development of IDZ and growth of the SRZ was also observed during thermal cyclic oxidation. Subsequently, interdiffusion coefficients of Al were presented by using a modified form of the Boltzmann-Matano analysis. (C) 2015 Elsevier B.V. All rights reserved.