Oxide-Scale Evolution on a New Ni–Fe-Based Superalloy at High Temperature

Abstract

The isothermal oxidation behavior and oxide-scale evolution on a newly developed Ni–Fe-based superalloy were investigated. Three oxidation stages were generally observed, an initial stage of rapid mass gain, then a second stage of parabolic kinetics, followed by an equilibrium period after about 50, 75, and 100 h at 1000, 1100, and 1200 °C, respectively. Cr2O3 and NiAl2O4 play an important role in protecting the matrix from oxidation at 1000 °C. The chromium supply becomes insufficient to support the continuously growing chromia scale with the increased oxidation temperature. Ultimately, the high-temperature oxidation resistance mainly depends on the formation of the inner continuous α-Al2O3 oxide layer. The quick formation of continuous α-Al2O3 oxide layer at 1200 °C compared to that at 1100 °C leads to a significantly reduced parabolic rate constant, which indicates that the new Ni–Fe-based superalloy has excellent oxidation resistance properties at higher temperatures.