Intermitted 3D Diffraction Tomography Combined with In situ Laue Diffraction to Characterize Dislocation Structures and Stress Fields in Microbending Cantilevers

Abstract

The mechanisms of plastic deformation are investigated using different characterization tools as scanning electron microscopy (SEM), transmission electron microscopy, or synchrotron‐based X‐ray techniques like Laue microdiffraction (μLaue). However, structural information can be limited to the specimen surface (SEM), to extremely thin samples (TEM), or depth averaging (μLaue). Until today, a nondestructive in situ investigation of a dislocation population, and de facto, the determination of the local stress tensor in bulk samples, remain challenging. To decompose the depth‐integrated μLaue signals, the so‐called “differential aperture X‐ray microscopy” (DAXM), allowing the 3D determination of the local structural crystal properties, is used. Using this approach, the local crystallographic phase, orientation, and the elastic strain tensor are obtained with 1 μm3 voxel size. In order to accomplish the experiment, a protocol and a new combined in situ mechanical testing rig with a DAXM microscope is created. The experiment is conducted on a severely bent focused ion beam copper single‐crystal microcantilever (10 × 10 × 25 μm3). The local deviatoric strain tensor and the local lattice curvature in the deformed sample are analyzed in 3D. The advantages and resolution limits of the technique are discussed in detail.