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.

Three-dimensional plastic response in polycrystalline coppervianear-field high-energy X-ray diffraction microscopy

2012 ◽  
Vol 45 (6) ◽  
pp. 1098-1108 ◽  
Author(s):  
S. F. Li ◽  
J. Lind ◽  
C. M. Hefferan ◽  
R. Pokharel ◽  
U. Lienert ◽  
...  
Keyword(s):  
Goodness Of Fit ◽  
Polycrystalline Sample ◽  
High Energy ◽  
Three Dimensions ◽  
X Ray Diffraction ◽  
Orientation Field ◽  
X Ray ◽  
Alignment Procedure ◽  
Polycrystal Plasticity ◽  
Diffraction Microscopy

The evolution of the crystallographic orientation field in a polycrystalline sample of copper is mapped in three dimensions as tensile strain is applied. Using forward-modeling analysis of high-energy X-ray diffraction microscopy data collected at the Advanced Photon Source, the ability to track intragranular orientation variations is demonstrated on an ∼2 µm length scale with ∼0.1° orientation precision. Lattice rotations within grains are tracked between states with ∼1° precision. Detailed analysis is presented for a sample cross section before and after ∼6% strain. The voxel-based (0.625 µm triangular mesh) reconstructed structure is used to calculate kernel-averaged misorientation maps, which exhibit complex patterns. Simulated scattering from the reconstructed orientation field is shown to reproduce complex scattering patterns generated by the defected microstructure. Spatial variation of a goodness-of-fit or confidence metric associated with the optimized orientation field indicates regions of relatively high or low orientational disorder. An alignment procedure is used to match sample cross sections in the different strain states. The data and analysis methods point toward the ability to perform detailed comparisons between polycrystal plasticity computational model predictions and experimental observations of macroscopic volumes of material.

Demonstration of near Field High Energy X-Ray Diffraction Microscopy on High-Z Ceramic Nuclear Fuel Material

2014 ◽  
Vol 777 ◽  
pp. 112-117 ◽  
Author(s):  
Donald W. Brown ◽  
Levente Balogh ◽  
Darrin Byler ◽  
Chris M. Hefferan ◽  
James F. Hunter ◽  
...  
Keyword(s):  
Nuclear Fuel ◽  
Near Field ◽  
Grain Morphology ◽  
High Energy ◽  
X Ray Diffraction ◽  
Boundary Misorientation ◽  
Sintered Ceramic ◽  
X Ray ◽  
Diffraction Microscopy ◽  
Fuel Material

Near-field high energy x-ray diffraction microscopy (nf-HEDM) and high energy x-ray micro-tomography (μT) have been utilized to characterize the pore structure and grain morphology in sintered ceramic UO2nuclear fuel material. μT successfully images pores to 2-3μm diameters and is analyzed to produce a pore size distribution. It is apparent that the largest number of pores and pore volume in the sintered ceramic are below the current resolution of the technique, which might be more appropriate to image cracks in the same ceramics. Grain orientation maps of slices determined by nf-HEDM at 25 μm intervals are presented and analyzed in terms of grain boundary misorientation angle. The benefit of these two techniques is that they are non-destructive and thus could be performed before and after processes (such as time at temperature or in-reactor) or even in-situ.

Tests of microstructure reconstruction by forward modeling of high energy X-ray diffraction microscopy data

2010 ◽  
Vol 25 (2) ◽  
pp. 132-137 ◽  
Author(s):  
C. M. Hefferan ◽  
S. F. Li ◽  
J. Lind ◽  
R. M. Suter
Keyword(s):  
Near Field ◽  
Simulated Data ◽  
Forward Modeling ◽  
High Energy ◽  
Data Sets ◽  
Geometric Accuracy ◽  
X Ray Diffraction ◽  
Detector Resolution ◽  
X Ray ◽  
Diffraction Microscopy

Verification tests of the forward modeling technique for near-field high energy X-ray diffraction microscopy are conducted using two simulated microstructures containing uniformly distributed orientations. Comparison between the simulated and reconstructed microstructures is examined with consideration to both crystallographic orientation and spatial geometric accuracy. To probe the dependence of results on experimental parameters, simulated data sets use two different detector configurations and different simulated experimental protocols; in each case, the parameters mimic the experimental geometry used at Advanced Photon Source beamline 1-ID. Results indicate that element orientations are distinguishable to less than 0.1°, while spatial geometric accuracy is limited by the detector resolution.

Novel Near Field Detector for Three-Dimensional X-Ray Diffraction Microscopy

MRS Advances ◽  
2018 ◽  
Vol 3 (39) ◽  
pp. 2341-2346 ◽  
Author(s):  
Scott Annett ◽  
Sergio Morelhao ◽  
Darren Dale ◽  
Stefan Kycia
Keyword(s):  
New Technologies ◽  
Spatial Information ◽  
Near Field ◽  
Three Dimensional ◽  
High Energy ◽  
Field Of View ◽  
Large Field ◽  
X Ray Diffraction ◽  
Synchrotron Source ◽  
X Ray

AbstractThree dimensional X-ray diffraction (3DXRD) microscopy is a powerful technique that provides crystallographic and spatial information of a large number, of the order of thousands, of crystalline grains in a sample simultaneously. A key component of every 3DXRD microscopy experiment is the near field detector that provides high resolution spatial information of the grains. In this work we present a novel design for a semi-transparent, 16 megapixel near field detector. As opposed to a typical single scintillator phosphor detector, this design, we call the Quad Near Field Detector, uses four quadrants. It has a total field of view is 5.3 mm x 5.3 mm with an effective pixel size of 1.3 µm x 1.3 µm. The detector’s relatively large field of view can be used to obtain higher order diffraction spots which we anticipate will lead to improved spatial resolution in grain reconstructions. The large field of view can also enable the detector to be positioned further from the sample, in this way increasing the working distance and enabling larger environmental cells for in-situ studies. Many alignment parameters can be resolved by careful mechanical design. For this reason a novel translation stage for focusing the microscopes was developed, tested, and implemented. The near field detector was calibrated and characterized at the Cornell High Energy Synchrotron Source. The operational feasibility of such a multi-plate detector demonstrated in this work paves the way for new technologies in instrumentation of 3DXRD microscopy.

Sign in / Sign up

Export Citation Format

Share Document