Influence of boron contents on oxidation behavior and the diffusion mechanism of Fe–B based alloys at 1073 K in air

Highlights: • The oxidation mechanism of Fe–B based alloys are discussed. • The oxidation resistance is enhanced with the increase of boron concentration. • The pyrolysis rate of Fe2B boride at high temperature is estimated. - Abstract: The microstructure and oxidation behavior of Fe–B alloys have been investigated. Oxide scale cross-sectional microstructures oxidized at 1073 K for 100 h have been studied. EPMA investigations show that B₂O₃–SiO₂ oxides accumulates in the inner oxide layer which improves the oxidation behavior and oxide layer adhesion considerably. Cyclic oxidation kinetics data indicates that Fe–B 3.08 wt.% alloy presents the best oxidation resistance. The formation of diffusion zone in the Fe–B alloys indicate that the oxidation of the Fe₂B boride is controlled by boron diffusion. The diffusion zone increases with time and reaches a maximum width of 60–65 μm.