Oxidation behavior of RE-modified nickel-based superalloy between 950 °C and 1150 °C in air
(State Key Laboratory of Materials Processing and Die and Mould Technology,
Huazhong University of Science and Technology, Wuhan 430074, China)
Huazhong University of Science and Technology, Wuhan 430074, China)
Abstract: A new Ni-based superalloy Ni48Cr28W5Co3Mn1Si1.6 was developed and the influence of a trace amount of rare earth (RE) metal addition on the oxidation resistance of this alloy was investigated. Isothermal oxidation behavior was investigated at 950-1150 °C in air, and then analyzed using scanning electronic microscopy and X-ray diffraction. The results showed that oxidation mass gain kinetics of the samples with and without RE elements follow the parabolic law. The effect of 0.20% RE on oxidation resistance is relatively small, and the oxidation rate constant of the alloy modified with 0.20% RE addition decreases by 5.9%-9.0%. Oxidation at 950-1150 °C for 100 h results in the formation of MnCr2O4, Cr2O3 and SiO2. A continuous and protective MnCr2O4 spinel layer forms as outer layer. The continuous middle oxide layer is confirmed to be Cr2O3, and the innermost layer consists of discontinuous SiO2.
Key words: Ni-based superalloy; rare earth element; high temperature oxidation; multi-layered oxides