Three-dimensional plastic response in polycrystalline coppervianear-field high-energy X-ray diffraction microscopy

Abstract

The evolution of the crystallographic orientation field in a polycrystalline sample of copper is mapped in three dimensions as tensile strain is applied. Using forward‐modeling analysis of high‐energy X‐ray diffraction microscopy data collected at the Advanced Photon Source, the ability to track intragranular orientation variations is demonstrated on an ∼2 µm length scale with ∼0.1° orientation precision. Lattice rotations within grains are tracked between states with ∼1° precision. Detailed analysis is presented for a sample cross section before and after ∼6% strain. The voxel‐based (0.625 µm triangular mesh) reconstructed structure is used to calculate kernel‐averaged misorientation maps, which exhibit complex patterns. Simulated scattering from the reconstructed orientation field is shown to reproduce complex scattering patterns generated by the defected microstructure. Spatial variation of a goodness‐of‐fit or confidence metric associated with the optimized orientation field indicates regions of relatively high or low orientational disorder. An alignment procedure is used to match sample cross sections in the different strain states. The data and analysis methods point toward the ability to perform detailed comparisons between polycrystal plasticity computational model predictions and experimental observations of macroscopic volumes of material.

Shock induced damage in copper: A before and after, three-dimensional study

“…The optimal registration was obtained by minimizing integrated misorientation angle 6,39 under rigid body rotations and translations. Higher order corrections to this registration could be computed on a grain-by-grain basis by allowing optimization within the full affine space.…”

Deformation-induced orientation spread in individual bulk grains of an interstitial-free steel

“…Reconstruction from near-field data only has resulted in detailed space-filling grain maps, including spatial information about the orientation spread within individual grains [11,40]. The method is especially well-suited for direct comparison with finite-element-based crystal plasticity simulations, focusing on the local effects of grain interaction, e.g.…”

“…Small distances (near-field detectors) have the advantage of good spatial resolution, whereas large distances (far-field detectors) provide good orientation resolution. Set-ups with only one detector, either near-field [11] or far-field [39], have been employed, whereas the present study employs both.…”

“…As the technique is nondestructive it enables studies of the same set of bulk grains before and after some external stimuli, e.g. elastic [5][6][7] and plastic deformation [8][9][10][11] or thermal annealing [12][13][14]. Several experimental set-ups are possible, each with specific advantages, e.g.…”

“…Several experimental set-ups are possible, each with specific advantages, e.g. high temporal resolution [12,15], high spatial resolution of grain maps [11,16] or high resolution of crystallographic orientations [17,18].…”