Microstructural evolution of the NiCrAlY/CrON duplex coating system and its influence on mechanical properties

The microstructural evolution of the NiCrAlY/CrON system during vacuum heat treatment and thermal exposure was investigated by scanning electron microscopy (SEM), X-ray diffraction (XRD) and transmission electron microscopy (TEM). The elastic modulus and residual stress of the coating system were measured by nanoindentation and photo-stimulated luminescence spectrum (PSLS) methods, respectively. It was shown that the series reaction of β → γ′ → γ took place in the NiCrAlY coating, which contributed to a decrease in the Young’s modulus. The replacement of Cr2O3 by Al2O3 during thermal exposure resulted in an increase of the Young’s modulus of the barrier layer. A change in the residual stress in the barrier layer was due to a combination of thermal and growth stresses.