Oxidation behaviour of the nickel-based superalloy DZ125 hot-dipped with Al coatings doped by Si

A pure Al coating and Al-Si coating were prepared on the surface of the DZ125 superalloy by hot-dipping. The Al-Si coating provides better thermal oxidation resistance than that of the pure Al coating due to the formation of a more compact Al2O3 layer. The microstructure of the Al-Si coating shows a silicon-aluminium-based layer with Ta5Si3 and AlHfSi phase forms after heat treatment in argon at 850 °C. This layer is a barrier to the diffusion of oxygen and other metal elements during cyclic oxidation, which has a significant effect on the formation of the compact Al2O3 layer.