Oxidation behavior of the Fe-36Al-0.09C-0.09B-0.04Zr alloy at 1250°C

To explore and study the Fe-Al system alloy presenting exceptional oxidation resistance at high temperature, the Fe-36Al-0.09C-0.09B-0.04Zr alloy was designed and developed. The microstructure and hardness of the backing at 1250°C were analyzed and measured. Thermodynamics and kinetics of the oxidation behavior were also analyzed by X-ray diffraction, scanning electron microscopy, and energy-dispersive X-ray spectroscopy techniques. The results show that the microstructure of the Fe-36Al-0.09C-0.09B-0.04Zr alloy is FeAl phase at ambient temperature and is stable at 1250°C. It displays the excellent property of oxidation resistance because the oxide film has only the Al₂O₃ layer, and its oxidation kinetics curve obeys the parabolic law at 1250°C. The oxidation mechanism at 1250°C is presumed that in the early oxidation period, the alloy oxidizes to form a large number of Al₂O₃ and a little Fe₂O₃, then, the enrichment of Al caused by Fe oxidization combines with O to form Al₂O₃.