Exceptional high-temperature oxidation resistance and mechanisms of a novel chemically complex intermetallic alloy

A novel chemically complex intermetallic alloy (CCIMA) dominated with an ordered L12 structure was designed based on the multicomponent Ni-Co-Cr-Al-Mo-Ti-Ta-Nb-B system. Its oxidation behaviors and underlying mechanisms were systematically investigated. Oxidation at 900 ℃ and 1000 ℃ results in the formation of main multicomponent spinel oxides in the outmost layer, spinel oxides containing rutile-type oxides and boron oxides in the intermediate layer, and continuous Al2O3 in the inner layer. Furthermore, oxidation leads to phase transformation from L12 to D024 at the matrix/oxide layer interface due to Al-depletion. The continuously formed inner Al2O3 oxides have well protected the alloy from oxidizing.