High-temperature oxidation behavior of a 9Cr oxide dispersion strengthened alloy under limited oxygen condition

Hot compression bonding is a promising process to fabricate large-scale oxide dispersion strengthened alloys. Inevitable interface oxidation could affect the effectiveness of the joint. The high-temperature oxidation behavior of a 9Cr ODS alloy under limited oxygen condition was investigated. The oxidized surface consisted of inner Fe2O3 scale and outer Cr2O3 particles at 800 degrees C. Reoxidation at 1000 degrees C, Cr2O3 particles were decomposed and converted into Cr(Ti)O-2. With increasing oxidation time, Fe2O3 and Cr(Ti)O-2 were decomposed and Y2O3 pegs formed. Furthermore, TiO2, Y2O3 and Y-Ti-O nanoparticles formed along grain boundaries. In conclusion, the oxide evolution could be summarized as Fe2O3 -> Cr2O3 -> Cr(Ti)O-2 -> TiO2 -> Y2O3 -> Y-Ti-O nanoparticles. The evolution from initial coarse Cr-rich and Fe-rich oxides to fine Y-Ti-O nanoparticles is expected to be critical for hot compression bonding processes.