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Scanning-3DXRD Reconstructions - A Novel Reconstruction Method for Intragranular Orientation and Strain Fields In Crystalline Materials.

Henningsson, Axel LU (2019) In ISRN LUTFD2/TFHF-19/5232-SE(1-68) FHLM01 20191
Solid Mechanics
Abstract
Far-field three dimensional x-ray diffraction (3DXRD) data acquired by repetitive acquisitions with a beam much smaller than the sample width is sometimes referred to as scanning-3DXRD. We here analyse the scanning 3DXRD approach and present a novel reconstruction technique capable of reconstructing intra-crystal variations in crystal structure from a set of recorded 2D diffraction patterns. The method solves the inverse reconstruction problem simultaneously for each grain in a tomogram, aiming for an intragranular resolution of strain and orientation. This stands in contrast to current methods, which rely on solving a set of independent sub problems, one for each point in the grain. The new reconstruction technique relies on a forward... (More)
Far-field three dimensional x-ray diffraction (3DXRD) data acquired by repetitive acquisitions with a beam much smaller than the sample width is sometimes referred to as scanning-3DXRD. We here analyse the scanning 3DXRD approach and present a novel reconstruction technique capable of reconstructing intra-crystal variations in crystal structure from a set of recorded 2D diffraction patterns. The method solves the inverse reconstruction problem simultaneously for each grain in a tomogram, aiming for an intragranular resolution of strain and orientation. This stands in contrast to current methods, which rely on solving a set of independent sub problems, one for each point in the grain. The new reconstruction technique relies on a forward model of diffraction, in which the diffraction of x-rays by the crystals is simulated to originate from discrete elements, each carrying an independent crystal state. The contribution from several illuminated elements are evaluated jointly to find an approximate diffraction pattern for a given crystal geometry and strain-orientation state. A numerical gradient based solver is then adapted to find the crystal state that minimises error between recorded and simulated diffraction patterns. It is found that the novel method provides better accuracy both in the reconstruction of strain and orientation as well as a better scope for future extensions than the currently existing method. (Less)
Popular Abstract
Many solid materials found in nature are called crystals. They are characterised by a remarkable symmetry. When illuminated with light, or so called x-rays, the electrons of the crystal start to radiate. Due to the periodic arrangement of atoms within the crystal, distinct light patterns can be recorded as a result of illumination. Combining the recorded patterns with governing equations and clever mathematics it is possible to deduce the arrangement of the atoms within the crystals.
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author
Henningsson, Axel LU
supervisor
organization
course
FHLM01 20191
year
type
H3 - Professional qualifications (4 Years - )
subject
publication/series
ISRN LUTFD2/TFHF-19/5232-SE(1-68)
report number
TFHF-5232
language
English
id
8972668
date added to LUP
2019-03-18 13:43:08
date last changed
2019-03-18 13:43:08
@misc{8972668,
  abstract     = {Far-field three dimensional x-ray diffraction (3DXRD) data acquired by repetitive acquisitions with a beam much smaller than the sample width is sometimes referred to as scanning-3DXRD. We here analyse the scanning 3DXRD approach and present a novel reconstruction technique capable of reconstructing intra-crystal variations in crystal structure from a set of recorded 2D diffraction patterns. The method solves the inverse reconstruction problem simultaneously for each grain in a tomogram, aiming for an intragranular resolution of strain and orientation. This stands in contrast to current methods, which rely on solving a set of independent sub problems, one for each point in the grain. The new reconstruction technique relies on a forward model of diffraction, in which the diffraction of x-rays by the crystals is simulated to originate from discrete elements, each carrying an independent crystal state. The contribution from several illuminated elements are evaluated jointly to find an approximate diffraction pattern for a given crystal geometry and strain-orientation state. A numerical gradient based solver is then adapted to find the crystal state that minimises error between recorded and simulated diffraction patterns. It is found that the novel method provides better accuracy both in the reconstruction of strain and orientation as well as a better scope for future extensions than the currently existing method.},
  author       = {Henningsson, Axel},
  language     = {eng},
  note         = {Student Paper},
  series       = {ISRN LUTFD2/TFHF-19/5232-SE(1-68)},
  title        = {Scanning-3DXRD Reconstructions - A Novel Reconstruction Method for Intragranular Orientation and Strain Fields In Crystalline Materials.},
  year         = {2019},
}