Influence of Beam Divergence on Pseudo-Strain Induced in Time-of-Flight Neutron Diffraction

2014 ◽  
Vol 777 ◽  
pp. 105-111 ◽  
Author(s):  
Hiroshi Suzuki ◽  
Stefanus Harjo ◽  
Jun Abe ◽  
Koichi Akita
Keyword(s):  
Neutron Diffraction ◽  
Steel Plate ◽  
Surface Effect ◽  
Time Of Flight ◽  
Incident Beam ◽  
Surface Strain ◽  
Beam Divergence ◽  
Coarse Grain ◽  
Attenuation Effect ◽  
Neutron Attenuation

Effects of beam divergence on pseudo-strains observed in time-of-flight (TOF) neutron diffraction, which overlapped with the neutron attenuation effect and the surface-effect, were investigated. The through-surface strain scanning on an annealed steel plate was performed in different instrument resolutions by controlling the incident beam divergence. Typical pseudo-strain distributions were observed, but they showed different trend according to the beam divergence. Furthermore, it was demonstrated that the pseudo-strains induced in strain scanning measurements of coarse grain materials can be suppressed by controlling the incident beam divergence. Therefore, the incident beam divergence must be carefully considered to reduce pseudo-strains in time-of-flight neutron diffractometry.

Rapid Measurement of Texture of Metals by Time-of-Flight Neutron Diffraction at iMATERIA and its Applications

2016 ◽  
Vol 879 ◽  
pp. 1426-1430 ◽  
Author(s):  
Yusuke Onuki ◽  
Akinori Hoshikawa ◽  
Shigeo Sato ◽  
Toru Ishigaki
Keyword(s):  
Neutron Diffraction ◽  
Measurement System ◽  
Life Science ◽  
Time Of Flight ◽  
Incident Beam ◽  
High Flux ◽  
Experimental Facility ◽  
Texture Measurement ◽  
Rapid Measurement ◽  
Time Of Flight Method

The authors have developed the texture measurement system at iMATERIA, which is the neutron diffractometers built in Materials and Life Science Experimental Facility (MLF) at J-PARC, Japan. The high flux of the incident beam and Time-Of-Flight method enabled the complete texture measurement within several minutes in case of steels. Since the neutron beam can transmit most of the materials, the measured texture represents the state of whole exposed volume. The multi-histogram analysis also enables to determine phase fractions in a multiphase material as well as the texture of each phase.

scholarly journals Phase imaging using time-of-flight neutron diffraction

2006 ◽  
Vol 39 (1) ◽  
pp. 82-89 ◽  
Author(s):  
M. J. Gutmann ◽  
W. Kockelmann ◽  
L. C. Chapon ◽  
P. G. Radaelli
Keyword(s):  
Neutron Diffraction ◽  
Phase Distribution ◽  
Tomographic Reconstruction ◽  
Time Of Flight ◽  
Incident Beam ◽  
Phase Imaging ◽  
Data Set ◽  
Sample Position ◽  
Scattering Material ◽  
Experimental Geometry

A technique that allows the spatial distribution of crystallographic phases in the interior of an object to be reconstructed from neutron time-of-flight (TOF) diffraction is described. To this end, the shift of the Bragg peaks due to the so-called `geometrical aberration' is exploited. A collimated incident white beam is used to perform a translational or rotational scan of the object whilst collecting a TOF data set for each sample position or orientation. Depending on the location of any scattering material along the line of the incident beam path through the object, the measuredd-spacings of the corresponding Bragg peaks are shifted with respect to their nominal values, which are attained only at the geometrical centre of the instrument. Using a formula that is usually employed to correct for sample offset, the phase distribution along the incident beamline can be directly reconstructed, without the need to perform a tomographic reconstruction. Results are shown from a demonstration experiment carried out on a cylindrical Al container enclosing an arrangement of Cu and Fe rods. On the basis of this formalism, an optimized experimental geometry is described and the potential and limits of this technique are explored, as are its applicability to X-ray and constant-wavelength neutron diffraction.

Effect of Neutron Attenuation on Strain Measurement with Large Gauge Volume

2013 ◽  
Vol 772 ◽  
pp. 33-38 ◽  
Author(s):  
Hiroshi Suzuki ◽  
Jinya Katsuyama ◽  
Koichi Akita
Keyword(s):  
Neutron Diffraction ◽  
Strain Measurement ◽  
Normal Strain ◽  
Structural Components ◽  
Diffraction Intensity ◽  
Butt Weld ◽  
Attenuation Effect ◽  
Neutron Attenuation ◽  
Gauge Volume ◽  
Apparent Strain

When measuring residual strain distributions of thick structural components such as thick butt-welds using neutron diffraction, it is required to make a gauge volume larger as well as to shorten neutron path length in a material to obtain sufficient diffraction intensity. In this study, neutron attenuation effect on the strain measurement with a large gauge volume was discussed on the normal strain measurement of a thick butt-weld. Influences of neutron attenuation like an apparent strain change were observed, and it was more noticeable when the gauge volume becomes larger. Therefore, the neutron attenuation effect should be considered in the strain measurement with a large gauge volume, and the neutron absorption corrections certainly play an important role for improvement of reliabilities of strain measurement using neutron diffraction with a large gauge volume.

scholarly journals Through-Thickness Microstructure Characterization in a Centrifugally Cast Austenitic Stainless Steel Nuclear Reactor Primary Loop Pipe Using Time-of-Flight Neutron Diffraction

2021 ◽  
Vol 5 (2) ◽  
pp. 12
Author(s):  
Matthew M. Schmitt ◽  
Daniel J. Savage ◽  
James J. Wall ◽  
John D. Yeager ◽  
Chanho Lee ◽  
...  
Keyword(s):  
Stainless Steel ◽  
Austenitic Stainless Steel ◽  
Neutron Diffraction ◽  
Time Of Flight ◽  
Radial Distance ◽  
Ultrasonic Waves ◽  
Science Center ◽  
Los Alamos ◽  
Inspection Method ◽  
Centrifugally Cast

The US code of Federal Regulations mandates regular inspection of centrifugally cast austenitic stainless steel pipe, commonly used in primary cooling loops in light-water nuclear power plants. These pipes typically have a wall thickness of ~8 cm. Unfortunately, inspection using conventional ultrasonic techniques is not reliable as the microstructure strongly attenuates ultrasonic waves. Work is ongoing to simulate the behavior of acoustic waves in this microstructure and ultimately develop an acoustic inspection method for reactor inspections. In order to account for elastic anisotropy in the material, the texture in the steel was measured as a function of radial distance though the pipe wall. Experiments were conducted on two 10 × 12.7 × 80 mm radial sections of a cast pipe using neutron diffraction scans of 2 mm slices using the HIPPO time-of-flight neutron diffractometer at the Los Alamos Neutron Science Center (LANSCE, Los Alamos, NM, USA). Strong textures dominated by a small number of austenite grains with their (100) direction aligned in the radial direction of the pipe were observed. ODF analysis indicated that up to 70% of the probed volume was occupied by just three single-grain orientations, consistent with grain sizes of almost 1 cm. Texture and phase fraction of both ferrite and austenite phases were measured along the length of the samples. These results will inform the development of a more robust diagnostic tool for regular inspection of this material.

Analytical model for neutron diffraction peak shifts due to the surface effect

2013 ◽  
Vol 46 (3) ◽  
pp. 628-638 ◽  
Author(s):  
Jan Šaroun ◽  
Joana Rebelo Kornmeier ◽  
Michael Hofmann ◽  
Pavol Mikula ◽  
Miroslav Vrána
Keyword(s):  
Neutron Diffraction ◽  
Analytical Model ◽  
Surface Effect ◽  
Perfect Crystal ◽  
Optimum Configuration ◽  
Gauge Volume ◽  
Spurious Peak ◽  
Incomplete Filling ◽  
Broad Variety ◽  
Residual Strains

Residual strains measured by neutron diffraction near sample boundaries can be biased by the surface effect as a result of incomplete filling of the instrumental gauge volume. This effect is manifested as anomalous shifts of diffraction lines, which can be falsely interpreted as a lattice strain unless appropriate data corrections are made. A new analytical model for the surface effect has been developed, which covers a broad variety of instrumental arrangements, including flat mosaic and bent perfect crystal monochromators, narrow slits, and Soller and radial collimators. This model permits the spurious peak shifts to be predicted quantitatively, and also allows the optimum configuration parameters, such as curvature of a focusing monochromator, which lead to suppression of the surface effect, to be calculated. The model has been thoroughly validated by comparisons with Monte Carlo simulations and experiments on a stress-free calibration sample. Predictions of the model proved to be very accurate, often within the interval of experimental errors, which makes it suitable for use in data analysis.

Time-of-flight neutron diffraction of nanocrystalline powders of nonstoichiometric niobium carbide NbC0.77

2017 ◽  
Vol 59 (3) ◽  
pp. 607-612 ◽  
Author(s):  
A. S. Kurlov ◽  
A. I. Gusev ◽  
V. S. Kuznetsov ◽  
I. A. Bobrikov ◽  
A. M. Balagurov ◽  
...  
Keyword(s):  
Neutron Diffraction ◽  
Niobium Carbide ◽  
Time Of Flight ◽  
Nanocrystalline Powders

Dynamical diffraction peak splitting in time-of-flight neutron diffraction

2006 ◽  
Vol 89 (23) ◽  
pp. 233515
Author(s):  
E. Üstündag ◽  
R. A. Karnesky ◽  
M. R. Daymond ◽  
I. C. Noyan
Keyword(s):  
Neutron Diffraction ◽  
Time Of Flight ◽  
Diffraction Peak ◽  
Dynamical Diffraction ◽  
Peak Splitting

Imaging crystallographic phases using time-of-flight neutron diffraction

2006 ◽  
Vol 385-386 ◽  
pp. 1203-1205 ◽  
Author(s):  
Matthias Gutmann ◽  
Winfried Kockelmann ◽  
Laurent Chapon ◽  
Paolo G. Radaelli
Keyword(s):  
Neutron Diffraction ◽  
Time Of Flight
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