Stronger and more durable steels for extreme conditions
Dr. Hyung-Jun Cho wins Humboldt Research Fellowship
How can we design steels that are strong, cost-effective, and capable of withstanding extreme environments, without relying on expensive elements like nickel or cobalt? Dr. Hyung-Jun Cho, postdoctoral researcher at the Max Planck Institute for Sustainable Materials (MPI-SusMat), is tackling exactly this challenge. For his research, he has now been awarded a Humboldt Research Fellowship.
Cho’s project focuses on designing next-generation steel alloys that remain durable under demanding conditions, such as cryogenic temperatures or hydrogen exposure - two key factors in technologies for renewable energy. “Transporting liquefied hydrogen, for instance, requires steels that can endure very low temperatures without becoming brittle,” explains Cho. Traditionally, these steels contain large amounts of nickel and chromium, which are costly and require special heat treatments.
Instead, Cho’s approach centres on controlling the steels’ microstructure through tailored heat and thermomechanical treatments, while avoiding critical alloying elements. He explores how smaller interstitial atoms like boron, carbon, or nitrogen can enhance strength and durability, enabling a lightweight design through reducing material usage overall.
His work also has the potential to replace nickel-based superalloys in applications such as turbines. The challenge lies in fine-tuning heat-treatment processes to fit new alloy compositions. To understand how processing impacts microstructure and properties, Cho uses a range of advanced microscopy techniques, including scanning and transmission electron microscopy.
Hyung-Jun Cho completed his PhD at the Pohang University of Science and Technology in South Korea, where he studied the role of copper and nickel in austenitic stainless steels. He joined MPI-SusMat in September 2024 and was awarded the Humboldt Fellowship in 2025 to continue his research.
