How Al and Ta Diffusion Responses the Oxidation of NiCoCrAlYTa Coatings – Experiments

This study investigates how Al and Ta diffusion affects the growth of surface oxides in NiCoCrAlYTa coatings and the interdiffusion that occurs between coatings and single-crystal substrates in high-temperature oxidation processes. HVOF-sprayed layers were tested at temperatures between 900 °C and 1100 °C and the corresponding oxidation behavior of Al and Ta was assessed. It was found that higher amounts of Al in MCrAlY coatings promote the selective oxidation of Al₂O₃ and that the addition of Ta increases the stability of the γ’-Ni₃(Al,Ta) phase.