scholarly journals A flexible and standalone forward simulation model for laboratory X-ray diffraction contrast tomography

2020 ◽  
Vol 76 (6) ◽  
pp. 652-663 ◽  
Author(s):  
H. Fang ◽  
D. Juul Jensen ◽  
Y. Zhang
Keyword(s):  
Crystal Structure ◽  
Simulation Model ◽  
Forward Simulation ◽  
X Ray Diffraction ◽  
Bulk Materials ◽  
X Ray ◽  
Diffraction Contrast ◽  
Input Structure ◽  
Grain Orientations ◽  
Non Destructive

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.

scholarly journals Improved grain mapping by laboratory X-ray diffraction contrast tomography

IUCrJ ◽  
2021 ◽  
Vol 8 (4) ◽  
Author(s):  
H. Fang ◽  
D. Juul Jensen ◽  
Y. Zhang
Keyword(s):  
Spatial Resolution ◽  
Ground Truth ◽  
Shape Reconstruction ◽  
Grain Structure ◽  
Forward Simulation ◽  
X Ray Diffraction ◽  
X Ray ◽  
Diffraction Contrast ◽  
Iron Sample ◽  
Non Destructive

Laboratory diffraction contrast tomography (LabDCT) is a novel technique for non-destructive imaging of the grain structure within polycrystalline samples. To further broaden the use of this technique to a wider range of materials, both the spatial resolution and detection limit achieved in the commonly used Laue focusing geometry have to be improved. In this work, the possibility of improving both grain indexing and shape reconstruction was investigated by increasing the sample-to-detector distance to facilitate geometrical magnification of diffraction spots in the LabDCT projections. LabDCT grain reconstructions of a fully recrystallized iron sample, obtained in the conventional Laue focusing geometry and in a magnified geometry, are compared to one characterized by synchrotron X-ray diffraction contrast tomography, with the latter serving as the ground truth. It is shown that grain indexing can be significantly improved in the magnified geometry. It is also found that the magnified geometry improves the spatial resolution and the accuracy of the reconstructed grain shapes. The improvement is shown to be more evident for grains smaller than 40 µm than for larger grains. The underlying reasons are clarified by comparing spot features for different LabDCT datasets using a forward simulation tool.

scholarly journals Quantitative non-destructive 3D Crystallographic Imaging of Microstructures using Laboratory X-ray Diffraction Contrast Tomography

2018 ◽  
Vol 24 (S2) ◽  
pp. 554-555
Author(s):  
Hrishikesh Bale ◽  
Ron Kienan ◽  
Stephen T Kelly ◽  
Nicolas Gueninchault ◽  
Erik Lauridsen ◽  
...  
Keyword(s):  
X Ray Diffraction ◽  
X Ray ◽  
Diffraction Contrast ◽  
Non Destructive

X-ray diffraction contrast tomography: a novel technique for three-dimensional grain mapping of polycrystals. I. Direct beam case

2008 ◽  
Vol 41 (2) ◽  
pp. 302-309 ◽  
Author(s):  
Wolfgang Ludwig ◽  
Søeren Schmidt ◽  
Erik Mejdal Lauridsen ◽  
Henning Friis Poulsen
Keyword(s):  
Three Dimensional ◽  
Reconstruction Technique ◽  
X Ray Diffraction ◽  
X Ray ◽  
Direct Beam ◽  
Novel Technique ◽  
Diffraction Contrast ◽  
Orientation Space ◽  
Grain Orientations ◽  
Projection Images

The principles of a novel technique for nondestructive and simultaneous mapping of the three-dimensional grain and the absorption microstructure of a material are explained. The technique is termed X-ray diffraction contrast tomography, underlining its similarity to conventional X-ray absorption contrast tomography with which it shares a common experimental setup. The grains are imaged using the occasionally occurring diffraction contribution to the X-ray attenuation coefficient each time a grain fulfils the diffraction condition. The three-dimensional grain shapes are reconstructed from a limited number of projections using an algebraic reconstruction technique. An algorithm based on scanning orientation space and aiming at determining the corresponding crystallographic grain orientations is proposed. The potential and limitations of a first approach, based on the acquisition of the direct beam projection images only, are discussed in this first part of the paper. An extension is presented in the second part of the paper [Johnson, King, Honnicke, Marrow & Ludwig (2008).J. Appl. Cryst.41, 310–318], addressing the case of combined direct and diffracted beam acquisition.

Diffraction Contrast Tomography - A Synchrotron Radiation Technique for Mapping Polycrystalline Microstructures in 3D

2008 ◽  
Vol 571-572 ◽  
pp. 207-212 ◽  
Author(s):  
Andrew King ◽  
Greg Johnson ◽  
Wolfgang Ludwig
Keyword(s):  
X Ray Diffraction ◽  
Transmitted Beam ◽  
X Ray ◽  
Diffraction Contrast ◽  
Diffraction Geometry ◽  
Radiation Technique ◽  
Non Destructive ◽  
Diffraction Microscopy

In this paper the authors describe a technique based on synchrotron x-ray diffraction which has been used to produce full 3D grain maps (both grain shapes and orientations) in annealed aluminium alloy and stainless steel samples containing around 500 grains. The procedure is termed diffraction contrast tomography (DCT), reflecting its similarities with conventional absorption contrast tomography. It is an extension of the 3D X-ray diffraction microscopy (3DXRD) concept, and has been developed in collaboration with its inventors. The specimen is illuminated using a monochromatic synchrotron x-ray beam, and grains imaged using the extinction contrast that appears in the transmitted beam when grains are aligned in the diffraction condition during rotation of the sample. The beams of radiation diffracted by the grains are captured simultaneously on the same detector as the direct beam image. The combination of diffraction and extinction information aids the grain indexing operation, in which pairs of diffraction and extinction images are assigned to grain sets. 3D grain shapes are determined by algebraic reconstruction from the limited number of extinction projections, while crystallographic orientation is found from the diffraction geometry. The non-destructive nature of the technique allows for in-situ studies of mapped samples. Research is in progress to extend the technique to allow the determination of the elastic strain and stress tensors on a grain-by-grain basis.

Highlights in the history of X-ray topography1

1995 ◽  
Vol 210 (6) ◽  
Author(s):  
A. R. Lang
Keyword(s):  
Magnetic Domain ◽  
Diffraction Theory ◽  
Dislocation Loops ◽  
X Ray Diffraction ◽  
X Ray ◽  
Domain Structures ◽  
Structure Factors ◽  
History Of ◽  
Dislocation Sources ◽  
Non Destructive

AbstractX-ray topography provides a non-destructive method of mapping point-by-point variations in orientation and reflecting power within crystals. The discovery, made by several workers independently, that in nearly perfect crystals it was possible to detect individual dislocations by X-ray diffraction contrast started an epoch of rapid exploitation of X-ray topography as a new, general method for assessing crystal perfection. Another discovery, that of X-ray Pendellösung, led to important theoretical developments in X-ray diffraction theory and to a new and precise method for measuring structure factors on an absolute scale. Other highlights picked out for mention are studies of Frank-Read dislocation sources, the discovery of long dislocation helices and lines of coaxial dislocation loops in aluminium, of internal magnetic domain structures in Fe-3 wt.% Si, and of stacking faults in silicon and natural diamonds.

Crystal structure of an inclusion complex between chiral monoaza-15-crown-5 and S(–)-1-phenyl-ethyl ammonium percholorate

2003 ◽  
Vol 218 (5) ◽  
Author(s):  
Süheyla Özbey ◽  
F. B. Kaynak ◽  
M. Toğrul ◽  
N. Demirel ◽  
H. Hoşgören
Keyword(s):  
Crystal Structure ◽  
Inclusion Complex ◽  
Single Crystal ◽  
X Ray Diffraction ◽  
Space Group ◽  
X Ray ◽  
New Type

AbstractA new type of inclusion complex, S(–)-1 phenyl ethyl ammonium percholorate complex of R-(–)-2-ethyl - N - benzyl - 4, 7, 10, 13 - tetraoxa -1- azacyclopentadecane, has been prepared and studied by NMR, IR and single crystal X-ray diffraction techniques. The compound crystallizes in space group

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