Oxidation Behavior of the Nickel-Based Superalloy DZ125 at 980 °C

The isothermal oxidation behavior of the nickel-based superalloy DZ125 was investigated at 980 degrees C through SEM/EDX and XRD. The weight loss process exhibited three periods-initial, transient and steady stages, which correspond to the formation of three layers on the surface. The outer layer was composed of NiO, whereas the intermediate layer mainly consisted of spinels and was accompanied with Ta-rich oxide. Alumina was evident as the inner continuous layer close to the substrate. The first formation of alumina was responsible for the initial stage of weight loss, and the formation of NiO and intermediate layer may dramatically affect on the transient and steady stage, respectively. The oxide scales effect on growth mechanism was discussed.