The ability to measure 3D orientation fields and to determine grain boundary character plays a key role in understanding many material science processes, including: crack formation and propagation, grain coarsening, and corrosion processes. X-ray diffraction imaging techniques offer the ability to retrieve such information in a non-destructive manner. Among them, Diffraction Contrast Tomography (DCT) is a monochromatic beam, near-field technique, that uses an extended beam and offers fast mapping of 3D sample volumes. It was previously shown that the six-dimensional extension of DCT can be applied to moderately deformed samples (≤ 5% total strain), made from materials that exhibit low levels of elastic deformation of the unit cell (≤ 1%). In this article, we improved over the previously proposed 6D-DCT reconstruction method, through the introduction of both a more advanced forward model and reconstruction algorithm. The results obtained with the proposed improvements are compared against the reconstructions previously published in [1], using Electron Backscatter Diffraction (EBSD) measurements as a reference. The result was a noticeably higher quality reconstruction of the grain boundary positions and local orientation fields. The achieved reconstruction quality, together with the low acquisition times, render DCT a valuable tool for the stop-motion study of polycrystalline microstructures, evolving as a function of applied strain or thermal annealing treatments, for selected materials.

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Journal of Instrumentation
International Congress on X-ray Optics and Microanalysis
Centrum Wiskunde & Informatica, Amsterdam (CWI), The Netherlands

Viganò, N.R, & Ludwig, W. (2018). Advances in 6d diffraction contrast tomography. 24th International congress on x-ray optics and microanalysis (ICXOM24), 13(4). doi:10.1088/1748-0221/13/04/C04017