The work builds on earlier development of Ni- and Fe-based heat-resistant materials such as Nimonic, Inconel, Ni-Cr-Al alloys, and austenitic and alumina-forming steels, which form chromia or alumina scales but face limits under extreme operating conditions.
The research team is led by Associate Professor Jae-Gil Jung of the Division of Advanced Materials Engineering at Jeonbuk National University and Principal Researcher Ka Ram Lim of the Extreme Materials Research Institute at the Korea Institute of Materials Science, with postdoctoral researchers Dr. Sang-Hwa Lee and Dr. Sang Hun Shim participating from each institute. They developed alumina-forming ferritic alloys using a high-entropy alloy concept, aiming for alpha-alumina scale formation at high temperatures, precipitation-hardened strength, and favorable specific strength through low-density alloying elements.
The study examines the steam oxidation behavior of a previously reported alumina-forming ferritic alloy with composition Al16Cr13.3Fe55.5Ni11.2Ti4 (atomic percent) and a variant containing an additional 2 atomic percent molybdenum. The results were released online on October 12, 2025 and published in Volume 258 of Corrosion Science dated January 1, 2026.
"Our research presents a novel alloying strategy that simultaneously improves heat resistance and oxidation/corrosion resistance while maintaining economic feasibility. This dual improvement is important because it enables materials to stay stronger and more durable in extreme high-temperature environments," remarks Prof. Jung.
To evaluate oxidation resistance, the team exposed the alloys to a steam-containing atmosphere at 700 degrees Celsius for 500 hours. Under these conditions, an austenitic stainless steel reference alloy undergoes rapid oxidation because its chromia scale volatilizes in steam, accelerating degradation. In contrast, the alumina-forming ferritic alloys developed a dense alpha-alumina layer about 100 nanometers thick during prolonged exposure, which restricted oxygen diffusion and stabilized the surface over the test period.
"The body-centered cubic-based AFF alloys can accommodate much higher amounts of Al than face-centered cubic-based AFA alloys, making them more favorable for the formation of a uniform and dense protective scale," explains Dr. Lim. The study reports that these alloys achieve high specific yield strength at elevated temperatures comparable to Ni-based superalloys, and that molybdenum addition increases mechanical strength without reducing oxidation resistance under steam.
According to the authors, the combination of high-temperature strength, oxidation resistance, and controlled alloying cost positions these materials for use in systems that must tolerate both extreme heat and chemically aggressive environments.
Potential applications include reusable space launch vehicles, advanced armor materials, molten salt reactors, thermal energy storage systems, high-temperature steam electrolysis units, ammonia-cracking reactors, and lithium-ion battery recycling processes, all of which require materials that stay strong and resist chemical attack at high temperatures. The researchers also highlight the importance of low-cost alloy systems for real-world deployment and suggest that these alloys could enter large-scale practical use within the next five to ten years as reliability and economic criteria are met.
Research Report: High-temperature oxidation resistance of alumina-forming ferritic alloys in a steam-containing atmosphere
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