scholarly journals Comparison between a near-field and a far-field indexing approach for characterization of a polycrystalline sample volume containing more than 1500 grains

2014 ◽  
Vol 47 (4) ◽  
pp. 1402-1416 ◽  
Author(s):  
Laura Nervo ◽  
Andrew King ◽  
Jonathan P. Wright ◽  
Wolfgang Ludwig ◽  
Péter Reischig ◽  
...  
Keyword(s):  
Diffraction Data ◽  
Near Field ◽  
Three Dimensional ◽  
Pure Titanium ◽  
Polycrystalline Sample ◽  
Sample Volume ◽  
Polycrystalline Materials ◽  
Far Field ◽  
X Ray Diffraction ◽  
X Ray

A comparison of the performance of X-ray diffraction tomography, a near-field diffraction technique, and a far-field diffraction technique for indexing X-ray diffraction data of polycrystalline materials has been carried out by acquiring two sets of diffraction data from the same polycrystalline sample volume. Both approaches used in this study are variants of the three-dimensional X-ray diffraction (3DXRD) methodology, but they rely on different data-collection and analysis strategies. Previous attempts to assess the quality of 3DXRD indexing results from polycrystalline materials have been restricted to comparisons with two-dimensional electron backscatter diffraction cross sections containing a limited number of grains. In the current work, the relative performance of two frequently used polycrystalline-material indexing algorithms is assessed, comparing the indexing results obtained from a three-dimensional sample volume containing more than 1500 grains. The currently achievable accuracy of three-dimensional grain maps produced with these algorithms has been assessed using a statistical analysis of the measurement of the size, position and orientation of the grains in the sample. The material used for this comparison was a polycrystalline commercially pure titanium grade 2 sample, which has a hexagonal close-packed crystal structure. The comparison of the two techniques shows good agreement for the measurements of the grain position, size and orientation. Cross-validation between the indexing results shows that about 99% of the sample volume has been indexed correctly by either of these indexing approaches. The remaining discrepancies have been analysed and the strengths and limitations of both approaches are discussed.

Determining grain resolved stresses in polycrystalline materials using three-dimensional X-ray diffraction

2010 ◽  
Vol 43 (3) ◽  
pp. 539-549 ◽  
Author(s):  
Jette Oddershede ◽  
Søren Schmidt ◽  
Henning Friis Poulsen ◽  
Henning Osholm Sørensen ◽  
Jonathan Wright ◽  
...  
Keyword(s):  
Near Field ◽  
Three Dimensional ◽  
Polycrystalline Sample ◽  
Polycrystalline Materials ◽  
Interstitial Free ◽  
Outlier Rejection ◽  
X Ray Diffraction ◽  
Positional Accuracy ◽  
X Ray ◽  
Elastic Loading

An algorithm is presented for characterization of the grain resolved (type II) stress states in a polycrystalline sample based on monochromatic X-ray diffraction data. The algorithm is a robust 12-parameter-per-grain fit of the centre-of-mass grain positions, orientations and stress tensors including error estimation and outlier rejection. The algorithm is validated by simulations and by two experiments on interstitial free steel. In the first experiment, using only a far-field detector and a rotation range of 2 × 110°, 96 grains in one layer were monitored during elastic loading and unloading. Very consistent results were obtained, with mean resolutions for each grain of approximately 10 µm in position, 0.05° in orientation, and 8, 20 and 13 × 10−5in the axial, normal and shear components of the strain, respectively. The corresponding mean deviations in stress are 30, 50 and 15 MPa in the axial, normal and shear components, respectively, though some grains may have larger errors. In the second experiment, where a near-field detector was added, ∼2000 grains were characterized with a positional accuracy of 3 µm.

Structure Refinement of CePtSi and Hydrogenation Behavior of CePdGe, CePtSi and CePtGe

2007 ◽  
Vol 62 (4) ◽  
pp. 613-616 ◽  
Author(s):  
Wilfried Hermes ◽  
Ute Ch. Rodewald ◽  
Bernard Chevalier ◽  
Rainer Pötgena
Keyword(s):  
Single Crystal ◽  
Diffraction Data ◽  
Structure Refinement ◽  
Three Dimensional ◽  
Subsequent Annealing ◽  
X Ray Diffraction ◽  
X Ray ◽  
Hydride Formation ◽  
Arc Melting ◽  
Cerium Compounds

The intermetallic cerium compounds CePdGe, CePtSi, and CePtGe were synthesized from the elements by arc-melting and subsequent annealing. The structure of CePtSi was refined from single crystal X-ray diffraction data: LaPtSi-type (ordered α-ThSi2 version), 141md, a = 419.6(1) and c = 1450.0(5) pm, wR2 = 0.0490, 362 F2 values and 16 variables. The Pt-Si distances within the three-dimensional [PtSi] network are 242 pm, indicating strong Pt-Si interactions. Hydrogenation of the three compounds at 623 K and 4 MPa H2 gave no indication for hydride formation.

The crystal structure of gersdorffite (III), a distorted and disordered pyrite structure

1968 ◽  
Vol 36 (283) ◽  
pp. 940-947 ◽  
Author(s):  
P. Bayliss ◽  
N. C. Stephenson
Keyword(s):  
Crystal Structure ◽  
Metal Atom ◽  
Diffraction Data ◽  
Three Dimensional ◽  
Unit Cell ◽  
X Ray Diffraction ◽  
Space Group ◽  
X Ray ◽  
Partially Ordered ◽  
The Ideal

SummaryThe crystal structure of gersdorffite (III) has been examined with three-dimensional Weissenberg X-ray diffraction data. The unit cell is isometric with a 5·6849 ± 0·0003 Å, space group PI, and four formula units per cell. This structure has the sulphur and arsenic atoms equally distributed over the non-metal atom sites of pyrite. All atoms show significant random displacements from the ideal pyrite positions to produce triclinic symmetry, which serves to distinguish this mineral from a disordered cubic gersdorffite (II) and a partially ordered cubic gersdorffite (I). Factors responsible for the atomic distortions are discussed.

A REFINEMENT OF THE CRYSTAL STRUCTURES OF (NH4)2TeBr6 AND Cs2TeBr6

1966 ◽  
Vol 44 (8) ◽  
pp. 939-943 ◽  
Author(s):  
A. K. Das ◽  
I. D. Brown
Keyword(s):  
Least Squares ◽  
Crystal Structures ◽  
Diffraction Data ◽  
Bromine Atom ◽  
Three Dimensional ◽  
X Ray Diffraction ◽  
Full Matrix ◽  
X Ray ◽  
Anisotropic Temperature ◽  
Temperature Factors

(NH4)2TeBr6 and Cs2TeBr6 crystals have the cubic K2PtCl6 structure with space group: [Formula: see text] with a0 = 10.728 ± 0.003 Å and 10.918 ± 0.002 Å respectively. The positional coordinate of the bromine atom, and the anisotropic temperature factors of all atoms in the unit cell, have been refined for both crystals by a full matrix least-squares analysis of the three dimensional X-ray diffraction data (R = 0.08). The Te—Br distance, corrected for probable thermal motions of atoms forming the bond, is 2.70 ± 0.01 Å in both crystals.

High Resolution Synchrotron X-Ray Diffraction Tomography Of Large-Grained Samples

1996 ◽  
Vol 437 ◽  
Author(s):  
D.P. Piotrowski ◽  
S.R. Stock ◽  
A. Guvenilir ◽  
J.D. Haase ◽  
Z.U. Rek
Keyword(s):  
Spatial Distribution ◽  
High Resolution ◽  
Three Dimensional ◽  
Polycrystalline Materials ◽  
Diffraction Tomography ◽  
Two Dimensional ◽  
X Ray Diffraction ◽  
Image Storage ◽  
X Ray ◽  
Dimensional Distribution

AbstractIn order to understand the macroscopic response of polycrystalline structural materials to loading, it is frequently essential to know the spatial distribution of strain as well as the variation of micro-texture on the scale of 100 μm. The methods must be nondestructive, however, if the three-dimensional evolution of strain is to be studied. This paper describes an approach to high resolution synchrotron x-ray diffraction tomography of polycrystalline materials. Results from model samples of randomly-packed, millimeter-sized pieces of Si wafers and of similarly sized single-crystal Al blocks have been obtained which indicate that polychromatic beams collimated to 30 μm diameter can be used to determine the depth of diffracting volume elements within ± 70 μm. The variation in the two-dimensional distribution of diffracted intensity with changing sample to detector separation is recorded on image storage plates and used to infer the depth of diffracting volume elements.

scholarly journals Maximum a posteriori estimation of crystallographic phases in X-ray diffraction tomography

2015 ◽  
Vol 373 (2043) ◽  
pp. 20140392 ◽  
Author(s):  
Doĝa Gürsoy ◽  
Tekin Biçer ◽  
Jonathan D. Almer ◽  
Raj Kettimuthu ◽  
Stuart R. Stock ◽  
...  
Keyword(s):  
National Laboratory ◽  
Spinous Process ◽  
Argonne National Laboratory ◽  
Three Dimensional ◽  
Polycrystalline Materials ◽  
Reconstruction Method ◽  
Diffraction Tomography ◽  
A Posteriori ◽  
X Ray Diffraction ◽  
X Ray

A maximum a posteriori approach is proposed for X-ray diffraction tomography for reconstructing three-dimensional spatial distribution of crystallographic phases and orientations of polycrystalline materials. The approach maximizes the a posteriori density which includes a Poisson log-likelihood and an a priori term that reinforces expected solution properties such as smoothness or local continuity. The reconstruction method is validated with experimental data acquired from a section of the spinous process of a porcine vertebra collected at the 1-ID-C beamline of the Advanced Photon Source, at Argonne National Laboratory. The reconstruction results show significant improvement in the reduction of aliasing and streaking artefacts, and improved robustness to noise and undersampling compared to conventional analytical inversion approaches. The approach has the potential to reduce data acquisition times, and significantly improve beamtime efficiency.

High Resolution Synchrotron X-Ray Diffraction Tomography of Polycrystalline Samples

1994 ◽  
Vol 375 ◽  
Author(s):  
S. R. Stock ◽  
A. Guvenilir ◽  
D. P. Piotrowski ◽  
Z. U. Rek
Keyword(s):  
Spatial Distribution ◽  
High Resolution ◽  
Three Dimensional ◽  
Compact Tension ◽  
Polycrystalline Materials ◽  
Diffraction Tomography ◽  
X Ray Diffraction ◽  
Image Storage ◽  
X Ray ◽  
Nondestructive Measurements

AbstractThe macroscopic response of polycrystalline materials to loading depends on both the spatial distribution of strain and the variation of microtexture on the scale of 100 μm. Nondestructive measurements are needed if the three-dimensional evolution of strain is to be studied. This paper describes approaches for high resolution synchrotron polychromatic x-ray diffraction tomography of polycrystalline materials. Preliminary experiments are reported on partially cracked compact tension samples of Al-Li 2090 and on model samples of randomly-packed, millimeter-sized pieces of Si wafers. Polychromatic beams collimated to 100 μm diameter have been used, and the distribution of diffracted intensity has been collected on high resolution x-ray film as well as on image storage plates. The depths of diffracting volume elements are determined from the changes in the spatial distribution of diffracted intensity with varying sample to detector separation.

The crystal structure of, and the bismuth-copper distribution in synthetic cuprobisrauthite

1975 ◽  
Vol 142 (3-4) ◽  
Author(s):  
T. Ozawa ◽  
W. Nowacki
Keyword(s):  
Crystal Structure ◽  
Diffraction Data ◽  
Three Dimensional ◽  
X Ray Diffraction ◽  
Space Group ◽  
X Ray ◽  
Copper Distribution

AbstractThe crystal structure of synthetic cuprobismuthite has been determined using three-dimensional x-ray diffraction data. The space group isAll atoms he on mirror planes of the space group at

The crystal and molecular structure of ovalene: some three-dimensional refinements

1973 ◽  
Vol 137 (2-3) ◽  
Author(s):  
R. G. Hazell ◽  
G. S. Pawley
Keyword(s):  
Molecular Structure ◽  
Diffraction Data ◽  
Crystal And Molecular Structure ◽  
Three Dimensional ◽  
X Ray Diffraction ◽  
X Ray

AbstractThree-dimensional x-ray diffraction data have been taken from ovalene, C

scholarly journals Three-dimensional α colony characterization and prior-β grain reconstruction of a lamellar Ti–6Al–4V specimen using near-field high-energy X-ray diffraction microscopy

2015 ◽  
Vol 48 (4) ◽  
pp. 1165-1171 ◽  
Author(s):  
E. Wielewski ◽  
D. B. Menasche ◽  
P. G. Callahan ◽  
R. M. Suter
Keyword(s):  
Near Field ◽  
Three Dimensional ◽  
High Energy ◽  
Grain Structure ◽  
X Ray Diffraction ◽  
Orientation Field ◽  
X Ray ◽  
Hexagonal Close Packed ◽  
Flood Fill ◽  
Diffraction Microscopy

Near-field high-energy X-ray diffraction microscopy has been used to characterize the three-dimensional (3-D) crystallographic orientation field of the hexagonal close-packed α phase in a bulk Ti–6Al–4V specimen with a lamellar (β-annealed) microstructure. These data have been segmented using a 3-D misorientation-based grain finding algorithm, providing unprecedented information about the complex 3-D morphologies and spatial misorientation distributions of the transformed α lamella colonies. A 3-D Burgers orientation relationship-based flood-fill algorithm has been implemented to reconstruct the morphologies and crystallographic orientations of the high-temperature body-centered cubic prior-β grains. The combination of these data has been used to gain an understanding of the role of the prior-β grain structure in the formation of specific morphologies and spatial misorientation distributions observed in the transformed α colony structures. It is hoped that this understanding can be used to develop transformation structures optimized for specific applications and to produce more physically realistic synthetic microstructures for use in simulations.

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