Advanced Photon Source, Argonne National Laboratory, Argonne, IL, 60439, USA.
Center for Nanoscale Materials, Argonne National Laboratory, Argonne, IL, 60439, USA.
Nat Commun. 2018 Sep 17;9(1):3776. doi: 10.1038/s41467-018-06166-5.
The nucleation and propagation of dislocations is an ubiquitous process that accompanies the plastic deformation of materials. Consequently, following the first visualization of dislocations over 50 years ago with the advent of the first transmission electron microscopes, significant effort has been invested in tailoring material response through defect engineering and control. To accomplish this more effectively, the ability to identify and characterize defect structure and strain following external stimulus is vital. Here, using X-ray Bragg coherent diffraction imaging, we describe the first direct 3D X-ray imaging of the strain field surrounding a line defect within a grain of free-standing nanocrystalline material following tensile loading. By integrating the observed 3D structure into an atomistic model, we show that the measured strain field corresponds to a screw dislocation.
位错的成核和增殖是伴随材料塑性变形而普遍存在的过程。因此，自从 50 多年前第一台透射电子显微镜问世以来首次观察到位错以来，人们投入了大量精力通过缺陷工程和控制来调整材料的响应。为了更有效地实现这一目标，识别和描述缺陷结构以及在外部刺激下应变的能力至关重要。在这里，我们使用 X 射线布拉格相干衍射成象，描述了在拉伸载荷下，在独立纳米晶体材料晶粒内的线缺陷周围应变场的首次直接 3D X 射线成像。通过将观察到的 3D 结构集成到原子模型中，我们表明测量的应变场对应于螺位错。
