X-ray diffraction contrast of the dislocation image in the bragg case

1980 ◽  
Vol 57 (1) ◽  
pp. 105-112 ◽  
Author(s):  
J. Gronkowski
2016 ◽  
Vol 105 ◽  
pp. 417-428 ◽  
Author(s):  
Laura Nervo ◽  
Andrew King ◽  
Arnas Fitzner ◽  
Wolfgang Ludwig ◽  
Michael Preuss

2008 ◽  
Vol 41 (2) ◽  
pp. 310-318 ◽  
Author(s):  
Greg Johnson ◽  
Andrew King ◽  
Marcelo Goncalves Honnicke ◽  
J. Marrow ◽  
Wolfgang Ludwig

By simultaneous acquisition of the transmitted and the diffracted beams, the applicability of the previously introduced diffraction contrast tomography technique [Ludwig, Schmidt, Lauridsen & Poulsen (2008).J. Appl. Cryst.41, 302–309] can be extended to the case of undeformed polycrystalline samples containing more than 100 grains per cross section. The grains are still imaged using the occasionally occurring diffraction contribution to the X-ray attenuation coefficient, which can be observed as a reduction in the intensity of the transmitted beam when a grain fulfils the diffraction condition. Automating the segmentation of the extinction spot images is possible with the additional diffracted beam information, even in the presence of significant spot overlap. By pairing the corresponding direct (`extinction') and diffracted beam spots a robust sorting and indexing approach has been implemented. The analysis procedure is illustrated on a real data set and the result is validated by comparison with a two-dimensional grain map obtained by electron backscatter diffraction.


2012 ◽  
Vol 1421 ◽  
Author(s):  
Melanie Syha ◽  
Wolfgang Rheinheimer ◽  
Michael Bäurer ◽  
Erik M. Lauridsen ◽  
Wolfgang Ludwig ◽  
...  

ABSTRACT3D x-ray diffraction contrast tomography (DCT) is a non-destructive technique for the determination of grain shape and crystallography in polycrystalline bulk materials. Using this technique, a strontium titanate specimen was repeatedly measured between annealing steps.. A systematic analysis of the growth history of selected grains before and after the ex-situ annealing step allows to extract the topological and morphological changes during grain growth. Furthermore, misorientation as well as interface orientation information of the microstructure reconstructions have been determined. The interface normal distribution clearly shows a preference for (100) oriented interfaces in the selected grains when annealed at 1600°C. This observation can be connected to existent interfacial energy estimations resulting from capillarity vector reconstructions.


2020 ◽  
Vol 76 (6) ◽  
pp. 652-663 ◽  
Author(s):  
H. Fang ◽  
D. Juul Jensen ◽  
Y. Zhang

Laboratory X-ray diffraction contrast tomography (LabDCT) has recently been developed as a powerful technique for non-destructive mapping of grain microstructures in bulk materials. As the grain reconstruction relies on segmentation of diffraction spots, it is essential to understand the physics of the diffraction process and resolve all the spot features in detail. To this aim, a flexible and standalone forward simulation model has been developed to compute the diffraction projections from polycrystalline samples with any crystal structure. The accuracy of the forward simulation model is demonstrated by good agreements in grain orientations, boundary positions and shapes between a virtual input structure and that reconstructed based on the forward simulated diffraction projections of the input structure. Further experimental verification is made by comparisons of diffraction spots between simulations and experiments for a partially recrystallized Al sample, where a satisfactory agreement is found for the spot positions, sizes and intensities. Finally, applications of this model to analyze specific spot features are presented.


2010 ◽  
Vol 66 (a1) ◽  
pp. s100-s100
Author(s):  
Wolfgang Ludwig ◽  
Andrew King ◽  
Peter Reischig ◽  
Michael Herbig ◽  
E. M. Lauridsen

2022 ◽  
Vol 55 (1) ◽  
Author(s):  
Adam Lindkvist ◽  
Yubin Zhang

Laboratory diffraction contrast tomography (LabDCT) is a recently developed technique to map crystallographic orientations of polycrystalline samples in three dimensions non-destructively using a laboratory X-ray source. In this work, a new theoretical procedure, named LabXRS, expanding LabDCT to include mapping of the deviatoric strain tensors on the grain scale, is proposed and validated using simulated data. For the validation, the geometries investigated include a typical near-field LabDCT setup utilizing Laue focusing with equal source-to-sample and sample-to-detector distances of 14 mm, a magnified setup where the sample-to-detector distance is increased to 200 mm, a far-field Laue focusing setup where the source-to-sample distance is also increased to 200 mm, and a near-field setup with a source-to-sample distance of 200 mm. The strain resolution is found to be in the range of 1–5 × 10−4, depending on the geometry of the experiment. The effects of other experimental parameters, including pixel binning, number of projections and imaging noise, as well as microstructural parameters, including grain position, grain size and grain orientation, on the strain resolution are examined. The dependencies of these parameters, as well as the implications for practical experiments, are discussed.


2018 ◽  
Vol 24 (S2) ◽  
pp. 554-555
Author(s):  
Hrishikesh Bale ◽  
Ron Kienan ◽  
Stephen T Kelly ◽  
Nicolas Gueninchault ◽  
Erik Lauridsen ◽  
...  

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