LAUSR

Abstract Isothermal oxidation behavior of Al/Y co-modified sputtering nanocrystalline coatings with various Al content on the Rene N5 single-crystal superalloy is investigated. Results indicate that precipitation and redissolution of the Y-containing σ-phase during oxidation are strongly dependent on the original Al content, which leads to different segregation behavior of Y-enriched oxides in alumina scales and oxidation kinetics. Higher Al content inhibits the intensive oxidation of Y, but causes elements interdiffusion with the alloy substrate. The nanocrystalline coating with moderate content of Al and equilibrium single γ′ phase, possesses the best comprehensive properties, i.e. low oxidation rate, meanwhile little elements interdiffusion.