▣ 세미나 안내 ▣

■ 제목 : Ultrastrong Metals with High Reliability  

■ 연사 : Prof. Hyokyung Sung (Kookmin Univ.)

■ 일시 : 2025년 2월 18일 (화) 오후 3시

■ 장소 : W1-1 2427호

■ Abstract : Achieving high strength and reliability in metallic materials is critical for applications in aerospace, energy, and infrastructure. However, the long-standing strength-ductility trade-off and susceptibility to environmental degradation present major challenges. This presentation discusses advanced strategies for developing ultrastrong metals that maintain mechanical integrity under extreme conditions.First, we introduce the design and processing of martensitic steels with superior resistance to stress corrosion cracking (SCC). Through optimized alloy compositions, heat treatment processes, and microstructural refinement, these steels achieve ultra-high strength (>2.0 GPa) while reducing embrittlement. We analyze the hierarchical microstructure, including prior austenite grain boundaries, lath structures, and carbide precipitation, which collectively enhance both mechanical performance and corrosion resistance. Furthermore, we evaluate the influence of hydrogen on fracture behavior and discuss strategies to suppress environmentally assisted cracking. Next, we explore the development of high-strength Ni-based superalloys for applications at elevated temperatures (650°C). The integration of laser powder bed fusion (LPBF) enables precise microstructural control, promoting the formation of stable γ′/γ′′ strengthening phases while suppressing detrimental δ-phase embrittlement. A combination of advanced characterization techniques, including transmission electron microscopy (TEM) and atom probe tomography (APT), provides insights into phase evolution, dislocation interactions, and creep resistance. The results highlight the critical role of nano-scale precipitate engineering in maintaining high-temperature mechanical properties. These advancements enable the development of next-generation structural materials with enhanced durability and performance in extreme environments.