2012•Procedia EngineeringOpen access
Isothermal oxidation behavior of Ni-Al-Co-Cr-Mo-Ti alloy at 850°C and 950°C
Xudong Lü, Junbao Yang, Ming Gao Yan, Cean Guo, Jie Wang, Shuwu Ma
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Abstract
The oxidation behavior of a superalloy with the chemical composition (wt.%) of Al 5.5-Ti 2.6-Co 4.8-Mo 3.9-W 5.0-Cr 11.0-Ni bal at 850°C and 950°C in air has been investigated. The kinetics curves of the oxidation were measured by thermal gravimtric analysis (TGA), and the microstructure and the elements distribution in the different regions of the specimens after oxidation were analysed by XRD and SEM/EDAX. The experimental results showed that the oxidation rate in the primary stage was high, then the mass gaining rate decreased gradually with the oxidation time, and the oxidation kinetics obeys parabolic law. A small amount of oxide scale spallation happened during the oxidation at 950°C. The analysis of the specimens after oxidized at 950°C revealed that three oxide layers formed, including the outer layer consisting of TiO2 and CrTiO3, the middle layer consisting of Cr2O3, Ni(Cr2O4) and TiO2 phases, and internal oxidizing layers identified as Al2O3 phase
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