Grain rotation mechanisms in nanocrystalline materials: Multiscale observations in Pt thin films

• 成果类型: Article
• 署名作者: Tian, Yuan; Gong, Xiaoguo; Xu, Mingjie; Qiu, Caihao; Han, Ying; Bi, Yutong; Estrada, Leonardo Velasco; Boltynjuk, Evgeniy; Hahn, Horst; Han, Jian; Srolovitz, David J.; Pan, Xiaoqing
• 署名单位: University of California System; University of California Irvine; University of Hong Kong; University of California System; University of California Irvine; City University of Hong Kong; Helmholtz Association; Karlsruhe Institute of Technology; University of Oklahoma System; University of Oklahoma - Norman; University of Hong Kong; University of California System; University of California Irvine
• 刊物名称: SCIENCE
• ISSN/ISSBN: 0036-10559
• DOI: 10.1126/science.adk6384
• 发表日期: 2024-10-04
• 页码: 49-54
• 关键词: boundary migration; motion; GROWTH; dislocations; deformation; kinetics

摘要

Near-rigid-body grain rotation is commonly observed during grain growth, recrystallization, and plastic deformation in nanocrystalline materials. Despite decades of research, the dominant mechanisms underlying grain rotation remain enigmatic. We present direct evidence that grain rotation occurs through the motion of disconnections (line defects with step and dislocation character) along grain boundaries in platinum thin films. State-of-the-art in situ four-dimensional scanning transmission electron microscopy (4D-STEM) observations reveal the statistical correlation between grain rotation and grain growth or shrinkage. This correlation arises from shear-coupled grain boundary migration, which occurs through the motion of disconnections, as demonstrated by in situ high-angle annular dark-field STEM observations and the atomistic simulation-aided analysis. These findings provide quantitative insights into the structural dynamics of nanocrystalline materials.