Inverse pole figure mapping of bulk crystalline grains in a polycrystalline steel plate by pulsed neutron Bragg-dip transmission imaging

A new mapping procedure for polycrystals using neutron Bragg-dip transmission is presented. This is expected to be useful as a new materials characterization tool which can simultaneously map the crystallographic direction of grains parallel to the incident beam. The method potentially has a higher spatial resolution than neutron diffraction imaging. As a demonstration, a Bragg-dip neutron transmission experiment was conducted at J-PARC on beamline MLF BL10 NOBORU. A large-grained Si–steel plate was used. Since this specimen included multiple grains along the neutron beam transmission path, it was a challenging task for existing methods to analyse the direction of the crystal lattice of each grain. A new data-analysis method for Bragg-dip transmission measurements was developed based on database matching. As a result, the number of grains and their crystallographic direction along the neutron transmission path have been determined.

Download Full-text

Time-of-flight neutron transmission of mosaic crystals

Journal of Applied Crystallography ◽

10.1107/s0021889805028190 ◽

2005 ◽

Vol 38 (6) ◽

pp. 934-944 ◽

Cited By ~ 19

Author(s):

Javier R. Santisteban

Keyword(s):

Crystal Orientation ◽

Average Rate ◽

Time Of Flight ◽

Incident Beam ◽

Linear Increase ◽

Reflection Index ◽

Neutron Transmission ◽

Mosaic Crystals ◽

Definition Of

The energy-dispersive neutron transmission of mosaic crystals presents a series of dips in intensity as a result of reflection in the crystal planes. The positions of these dips can be exploited for the definition of the crystal orientation with a resolution of 1 min of arc. The widths of these dips depend on crystal orientation, on the reflection index, on the mosaicity, and on the incident-beam divergence. The capability of the technique to define the orientation and mosaicity of a Cu crystal has been assessed through time-of-flight experiments. A Cu monochromator has been plastically deformed by uniaxial tensionin situ, and the evolution of crystal orientation and mosaicity was tracked using the technique. Several crystal reflections at different locations of the sample were simultaneously studied during the experiment. A linear increase of mosaicity on deformation at an average rate of ∼5 min per percentage of shear strain was observed. The reorientation of the crystal as a result of the applied load showed variations across the specimen.

Download Full-text

Multi-Capillary and Conic Optical Elements for Parallel Beam Production

Advances in X-ray Analysis ◽

10.1154/s0376030800022461 ◽

1995 ◽

Vol 39 ◽

pp. 73-79

Author(s):

C. M. Dozier ◽

D. A. Newman ◽

M. I. Bell ◽

Qi-Fan Xiao ◽

S. L. Espy

Keyword(s):

Incident Beam ◽

X Rays ◽

Large Area ◽

Incident Intensity ◽

Cross Sectional ◽

Optical Elements ◽

Rocking Curve ◽

Beam Production ◽

Diffraction Imaging ◽

Beam Signal

Large area, parallel beams of x-rays are potentially useful in many diffraction, imaging and other x-ray analysis applications. Diffraction, in typical experiments, uses only a small portion of the incident beam that is within a limited “rocking curve” of the crystal capable of diffracting, although the whole crystal may be illuminated by the incident beam. Signal intensity can be increased if the ”whole” crystal can be made to diffract simultaneously. Similarly for imaging, improved results also are possible if divergent beams are replaced with nearly parallel ones. Production of parallel beams of large areal extent has not been simple. Often this meant that the source had to be placed at great distances from the sample, reducing the incident intensity. Sometimes, asymmetric cuts of crystals can be used to increase beam cross-sectional areas.Production of parallel beams of large area! extent has not been simple. Often this meant that the source had to be placed at great distances from the sample, reducing the incident intensity. Sometimes, asymmetric cuts of crystals can be used to increase beam cross-sectional areas.

Download Full-text

The Determination of Rotation Axis in the Rotation Electron Diffraction Technique

Microscopy and Microanalysis ◽

10.1017/s1431927613012749 ◽

2013 ◽

Vol 19 (5) ◽

pp. 1276-1280 ◽

Cited By ~ 3

Author(s):

Mika Buxhuku ◽

Vidar Hansen ◽

Peter Oleynikov ◽

Jon Gjønnes

Keyword(s):

Electron Diffraction ◽

Rotation Axis ◽

Incident Beam ◽

Zone Axis ◽

Crystallographic Direction ◽

Accurate Knowledge ◽

Electron Diffraction Technique ◽

Diffraction Patterns

AbstractMethods to determine the rotation axis using the rotation electron diffraction technique are described. A combination of rotation axis tilt, beam tilt, and simulated experimental diffraction patterns with nonintegers zone axis has been used. Accurate knowledge of the crystallographic direction of the incident beam for deducing the excitation error of reflections simultaneously near Bragg positions is essential in quantitative electron diffraction. Experimental patterns from CoP3 are used as examples.

Download Full-text

Optimization of x-ray Techniques for Nondestructive Characterization of Single Crystal Turbine Blades

MRS Proceedings ◽

10.1557/proc-591-3 ◽

1999 ◽

Vol 591 ◽

Cited By ~ 1

Author(s):

J.M. Winter ◽

K.G. Lipetzky ◽

R.E. Green

Keyword(s):

Single Crystal ◽

Turbine Blades ◽

Crystalline Perfection ◽

X Ray ◽

Diffraction Imaging ◽

Nickel Based Alloy ◽

Beam Transmission ◽

Nondestructive Characterization

ABSTRACTThis paper describes nondestructive x-ray characterization techniques which detect macroscopic and microscopic defects, determine the overall crystallographic perfection, and detect any unwanted secondary crystals both on the external surface as well as in the interior of single crystal blades. The method of Asymmetric Crystal Topography for diffraction imaging the surfaces of single crystal turbine blades and the method of White Beam Transmission Topography for diffraction imaging through the thickness of single crystal turbine blades are both discussed and illustrated with representive diffraction images (topographs). It is clear that the images gained from these methods have a capability for providing information about the details of crystalline perfection (or lack thereof) in nickel-based alloy single crystal turbine blades. Such information can provide considerable leverage for the crystal grower to help in adjusting processing variables to enhance quality of a critical product. And the same methods of topography can conceiveably provide tools for evaluating the finished product in a way which has not been available to date.

Download Full-text

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

Materials Science Forum ◽

10.4028/www.scientific.net/msf.777.105 ◽

2014 ◽

Vol 777 ◽

pp. 105-111 ◽

Cited By ~ 1

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.

Download Full-text