Microdiffraction Experiments and Modeling for Analyzing Multiscale Dislocation Ensembles in Materials

摘要

The intensity distribution of Laue diffraction is analyzed as a function of local misorientation. We show how unpaired dislocations alter the white beam Laue patterns for isolated dislocations, for dislocation walls, and for a combination of both. We consider the effect of different statistically and geometrically necessary dislocation densities on the intensity distribution along and perpendicular to the Laue streak. A 3D x-ray crystal microscope is used to analyze the complicated plastic-elastic field in a grain of a Ni polycrystalline sample during in-situ uniaxial pulling. A change of dislocation activity with depth is demonstrated. The dislocation slip systems and their densities are determined at various depths. The model parameters are used to simulate the whole Laue pattern including details about the contours for specific Laue spots; good agreement is found between simulated and experimental contours.