Abstract
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.
Highlights
The nucleation and propagation of dislocations is an ubiquitous process that accompanies the plastic deformation of materials
Bragg coherent diffraction imaging (CDI) (BCDI) is a technique where 3D electron density and strains fields in a sample are obtained from scattered coherent X-rays in the far-field around a coherently scattered Bragg peak[19]
Discussion we explore the energetics of the imaged dislocation structure
Summary
The nucleation and propagation of dislocations is an ubiquitous process that accompanies the plastic deformation of materials. 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. With two exceptions[23,24], BCDI has been restricted to isolated nanoparticles (~0.5 μm in size) or extended single crystals through ptychography[25,26] Both of the previous BCDI studies on polycrystalline samples were performed on substrate supported thin films, which are not amenable to in situ characterization under mechanical loading. To better understand the complex amplitude and strain variation in the crystal that was observed, we imported the reconstructed 3D electron density of the grain into an atomistic model
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