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 degrees C and 1100 degrees 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. (C) 2014 Elsevier B.V. All rights reserved.