Abstract:Fe-Al-Cr alloy has good resistance to high temperature oxidation and has wide application prospects, but it is usually faced with the problem of coarse grains. By adding austenitizing elements such as nickel, carbon and copper to the Fe-Al-Cr alloy, the FeCr phase is formed during the cooling process, which hinders grain growth and the grain size can be controlled within 100 μm. The formation mechanism of oxide film and the effect of grain control on the high temperature oxidation resistance of Fe Al Cr alloy were discussed. The Fe-Al-Cr alloy oxidized at different oxidation times at high temperature was observed by metallography. It was found that the alumina film was preferentially formed at the grain boundary, and the number of grain boundaries was more favorable for the formation and growth of Al2O3. Scanning electron microscopy and energy spectrum analysis revealed that (Al0.9Cr0.1)2O3 and Al2O3 formed a multilayer oxide. Combined with the first principle calculation, it is concluded that the multilayer oxide is formed on the surface of the alloy due to the diffusion of Cr, which is beneficial to improve the high temperature oxidation resistance of the Fe-Al-Cr alloy. Finally, it was confirmed that the Fe-Al-Cr alloy having a smaller grain size has better resistance to high temperature oxidation.