2024-10-08 カリフォルニア大学校アーバイン校(UCI)
＜関連情報＞
- https://news.uci.edu/2024/10/08/uc-irvine-researchers-discover-atomic-level-mechanism-in-polycrystalline-materials/
- https://www.science.org/doi/10.1126/science.adk6384
ナノ結晶材料における結晶粒回転メカニズム 白金薄膜におけるマルチスケール観察 Grain rotation mechanisms in nanocrystalline materials: Multiscale observations in Pt thin films
Yuan Tian, Xiaoguo Gong, Mingjie Xu, Caihao Qiu, […], and Xiaoqing Pan
Science Published:3 Oct 2024
DOI:https://doi.org/10.1126/science.adk6384
Editor’s summary
Determining exactly how materials deform is key to better engineering and design, but certain processes, such as the mechanism behind rigid body rotation of grains, have been challenging to isolate. Tian et al. used four-dimensional transmission electron microscopy to study the mechanism behind nanograin rotation in a platinum thin film. The authors identified a primary mechanism for rotation, along with a correlation between rotation and grain growth or shrinkage. These observations should help us better understand the mechanical properties of a wide range of materials. —Brent Grocholski
Abstract
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.
