Some aspects of elemental behaviour in HVOF MCrAlY coatings in high-temperature oxidation

MCrAlY coatings are widely used to protect superalloys against oxidation and corrosion at high temperature in gas turbine engines. To design a durable MCrAlY coating, the behaviour of alloying elements in coating-superalloy system needs to be better understood. After oxidation tests in temperature range between 900 °C and 1100 °C, the development of the microstructures in the samples was analysed at the coating surface or in areas near the coating-superalloy interface. Some interdiffusion simulations were also done to model the diffusion behaviour of alloying elements in different coating-superalloy couples. The results show that both oxidation at the coatings' surface and the elements' diffusion inside of the materials were temperature- and chemical-composition dependent. The behaviour of some minor elements like Y, Hf, Ru and Ir in the oxidation processes was particularly studied by tracking their position and composition in the materials.