INTERNAL OXIDATION OF Fe3Al DURING HIGH TEMPERATURE OXIDATION
(1.Department of Surface Science and Corrosion Engineering, University of Science and Technology Beijing, Beijing100083, P. R. China;
2.Department of Materials Science and Engineering, Northwestern Polytechnical University, Xi’an 710072, P. R. China)
2.Department of Materials Science and Engineering, Northwestern Polytechnical University, Xi’an 710072, P. R. China)
Abstract: The oxidation behavior of Fe3Al at 1 000℃in air was studied by thermobalance, scanning electron microscope (SEM) and X-ray diffraction (XRD). It was found that the oxidation kinetics approximately follows the parabolic law; the oxide scale consists of Al2O3 and a little amount of Fe2O3; and there occurs transgranular internal oxidation. Based on the analyses of the oxide scale and the matrix, an internal oxidation model was proposed, which considers the effect of the long-range ordered structure of Fe3Al on its hightemperature oxidation. The long-range ordered structure reduces the activity of Al in Fe3Al, thus reducing the diffusion coefficient of Al in the matrix. Consequently, in the oxidation process, the matrix surface will be seriously depleted in Al and then there occurs internal oxidation.
Key words: Fe3Al oxidation internal oxidation corrosion