Interdiffusion behavior and lifetime prediction of Co-Al coating on Ni-based superalloy

Abstract The Co-Al coating was deposited on Ni-based superalloy DZ125 by pack cementation. The lifetime and interdiffusion behavior of the Co-Al coating on the Ni-based superalloy at 1050 °C, 1075 °C and 1100 °C were investigated. Surface oxidation and interdiffusion between the coating and the substrate led to depletion of Al in the coating, and β-Ni(Co)Al was gradually degraded into γ and γ' phases. Oxidation activation energy of the coating was calculated through oxidation weight gain curves of different temperatures. The formula of the coating lifetime related to the coating thickness and the temperature was established by calculating intermediate parameters. The lifetime determined by the formula and experiment showed good agreement.