Synergy of Nanocrystallinity, Temperature, and “the Third Element Effect” for Uncommon Oxidation Resistance of Fe‐Cr‐Al Alloys

Nanocrystalline structure, oxidation temperature, and "The Third Element Effect" are among the factors that can profoundly govern the characteristics of the oxide scales that develop on oxidation-resistant alloys, thereby, their synergistic effect can considerably influence alloys' oxidation kinetics. As a result of the synergy, certain iron-chromium-aluminium (Fe-Cr-Al) alloy showed superior oxidation resistance at 800 °C than at 700 °C (whereas oxidation resistance commonly decreases with the increase in temperature). The superior resistance at higher temperatures is considerably enhanced when the structure of the alloy is nanocrystalline vis-à-vis the common microcrystalline structure. Nanocrystalline alloy oxidizes at a negligible rate (c.f., its microcrystalline counterpart). The characterization of the oxide scale demonstrates that the oxidation temperature governs the formation of the protective oxide scale with/without the assistance of the "Third element Effect". The findings may potentially have considerable commercial implications.