High temperature oxidation behavior of laser clad NiCrAlY layer

The oxidation behavior of laser clad NiCrAlY layers with different aluminum content and the influence of heat treatment were investigated. The oxidation behavior was found to obey the parabolic rate law. The parabolic rate constant of the clad layer with low aluminum content was approximately the same order with that of the bulk material. The oxides formed on the clad layers was mainly α-Al2O3, regardless of the aluminum content. However, θ-Al2O3 was also formed on the clad layer with high aluminum content and this increased the growth rate of the oxide. The heat treatment made the distribution of aluminum in the clad layer more homogeneous and enhanced the nucleation of Al2O3 denser at the initial stage of the oxidation, resulting in the lower growth rate.