Voxel-based strain tensors from near-field High Energy Diffraction Microscopy

High energy X-ray diffraction microscopy is one of several techniques that use spatially resolved diffraction to nondestructively map crystal unit cell orientations in three dimensions inside bulk polycrystalline samples. The near-field variant of the technique (nf-HEDM) yields grain shapes, grain boundary character information, and intra-granular orientation variations. Here, we demonstrate, through analysis of simulated and physical data sets, the extension nf-HEDM to include mapping of heterogeneous intra-granular strain states with spatial resolution on the micron scale. Sensitivity to all strain tensor components is <5×10-4. The GPU assisted implementation of an optimization algorithm is described.