Three-dimensional full-field X-ray orientation microscopy

Nicola Viganò (1, 2, 3) , Alexandre Tanguy (4) , Simon Hallais (5) , Alexandre Dimanov (5) , Michel Bornert (6) , Kees Joost Batenburg (3, 7) , Wolfgang Ludwig (1, 2)

1 MATEIS - Matériaux, ingénierie et science [Villeurbanne]
2 ESRF - European Synchrotron Radiation Facility [Grenoble]
3 UA - University of Antwerp
4 LaMCoS - Laboratoire de Mécanique des Contacts et des Structures [Villeurbanne]
5 LMS - Laboratoire de mécanique des solides
6 navier umr 8205 - Laboratoire Navier
7 CWI - Centrum Wiskunde & Informatica

A previously introduced mathematical framework for full-field X-ray orientation microscopy is for the first time applied to experimental near-field diffraction data acquired from a polycrystalline sample. Grain by grain tomographic reconstructions using convex optimization and prior knowledge are carried out in a six-dimensional representation of position-orientation space, used for modelling the inverse problem of X-ray orientation imaging. From the 6D reconstruction output we derive 3D orientation maps, which are then assembled into a common sample volume. The obtained 3D orientation map is compared to an EBSD surface map and local misorientations, as well as remaining discrepancies in grain boundary positions are quantified. The new approach replaces the single orientation reconstruction scheme behind X-ray diffraction contrast tomography and extends the applicability of this diffraction imaging technique to material micro-structures exhibiting sub-grains and/or intra-granular orientation spreads of up to a few degrees. As demonstrated on textured sub-regions of the sample, the new framework can be extended to operate on experimental raw data, thereby bypassing the concept of orientation indexation based on diffraction spot peak positions. This new method enables fast, three-dimensional characterization with isotropic spatial resolution, suitable for time-lapse observations of grain microstructures evolving as a function of applied strain or temperature.

Domaines: Sciences de l'ingénieur [physics]

Nicola Viganò, Alexandre Tanguy, Simon Hallais, Alexandre Dimanov, Michel Bornert, et al.. Three-dimensional full-field X-ray orientation microscopy. Scientific Reports, 2016, 6, ⟨10.1038/srep20618⟩. ⟨hal-01310912⟩