Study on Pre-oxidation Microstructure and High Temperature Oxidation Resistance of Fe-10Ni-10Cr-x Al-1Si Alloy

The oxidation behavior of Fe-10Ni-10Cr-x Al-1Si(x=0, 2, 4, 6wt%) alloy at 1000℃ and 10-20atm oxygen pressure was studied, and its high temperature oxidation resistance was tested by cyclic oxidation experiment. The results show that when Al is not added, a continuous Cr₂O₃ film form on the surface of the oxidized alloy, there are a small amount of FeCr₂O₄ spinel in the outermost layer and dendritic SiO₂ in the inner layer. When 2wt% Al is added, Al₂O₃ grows on the inner side of SiO₂ and SiO₂ content decreases. When 4wt% Al is added, the structure of the oxide film is similar to that when 2wt%Al is added, the oxidation degree is deepened, which is manifested in the increase of the thickness of the oxide film, and Al₂O₃ exists in dendritic form. When the amount of Al is 6wt%, a continuous and complete Al₂O₃ film form on the alloy surface. The samples without pre oxidation and after 5 h of pre oxidation are oxidized at 1000℃ for 300 h. The oxidation weight gain of the alloy without pre oxidation is more, and the oxidation weight gain of the alloy added with Al significantly reduce after pre oxidation treatment. The weight gain per unit area of the sample added with 6wt% Al is smallest and the high-temperature oxidation resistance is best. Among them, Al₂O₃ film plays a role in preventing the oxygen from entering into the alloy.