3D grain mapping by laboratory X-ray diffraction contrast tomography implemented on a conventional tomography setup

Abstract

Non-destructive 3D characterization of grain orientations, shapes and sizes, i.e. grain mapping, offers immense opportunities for studying microstructural evolution in polycrystalline materials. In addition to a number of well-established grain mapping techniques available at synchrotron facilities, a polychromatic variant - laboratory diffraction contrast tomography (LabDCT) - using lab-based x-rays, has been developed and commercialized. Yet, the product is bounded to a specific instrument and requires a commercial license, which limits the use on widely available laboratory instruments. To promote the availability of LabDCT, we have developed a grain reconstruction method and implemented it on a conventional X-ray tomography setup at the SIMaP laboratory for LabDCT grain mapping. First, we tested the grain reconstruction algorithm by comparing an input virtual grain structure and a reconstructed volume using the forward simulated diffraction projections from the input structure. Then, we experimentally characterized an AlCu alloy sample using LabDCT and validated the grain mapping result by a grain reconstruction from synchrotron DCT measurement. Last, perspectives on further development of generalizing LabDCT technique on conventional tomography setups are discussed.