Topological grain boundary segregation transitions

• 成果类型: Article
• 署名作者: Devulapalli, Vivek; Chen, Enze; Brink, Tobias; Frolov, Timofey; Liebscher, Christian H.
• 署名单位: Max Planck Society; Stanford University; United States Department of Energy (DOE); Lawrence Livermore National Laboratory; Ruhr University Bochum; Ruhr University Bochum
• 刊物名称: SCIENCE
• ISSN/ISSBN: 0036-8321
• DOI: 10.1126/science.adq4147
• 发表日期: 2024-10-25
• 页码: 420-424
• 关键词: alloys; ti; transformations; superstructures; complexion; DESIGN; phase

摘要

Engineering the structure of grain boundaries (GBs) by solute segregation is a promising strategy to tailor the properties of polycrystalline materials. Solute segregation triggering phase transitions at GBs has been suggested theoretically to offer different pathways to design interfaces, but an understanding of their intrinsic atomistic nature is missing. We combined atomic resolution electron microscopy and atomistic simulations to discover that iron segregation to GBs in titanium stabilizes icosahedral units (cages) that form robust building blocks of distinct GB phases. Owing to their five-fold symmetry, the iron cages cluster and assemble into hierarchical GB phases characterized by a different number and arrangement of the constituent icosahedral units. Our advanced GB structure prediction algorithms and atomistic simulations validate the stability of these observed phases and the high excess of iron at the GB that is accommodated by the phase transitions.