High Resolution Residual Strain/Stress Measurements on Three Axis Neutron Diffractometer

2021 ◽  
Vol 1166 ◽  
pp. 33-40
Author(s):  
Pavol Mikula ◽  
Jan Šaroun ◽  
Vasyl Ryukhtin
Keyword(s):  
High Resolution ◽  
Profile Analysis ◽  
Perfect Crystal ◽  
Polycrystalline Materials ◽  
Line Profile Analysis ◽  
Stress Measurements ◽  
Large Bulk ◽  
Strain Stress ◽  
Set Up

Focusing 3-axis diffractometer set-up equipped with bent perfect crystal (BPC) monochromator and analyzer offers the sensitivity in determination of strains Dd/d < 10-4 in polycrystalline materials which is about one order of magnitude higher with respect to that of conventional 2-axis neutron scanners. It also offers possibility of line profile analysis for reasonable sample volumes and counting times. In this paper, the feasibility of using the 3-axis set-up even for measurements of rather large bulk polycrystalline samples with an acceptable resolution is presented. As the 3-axis set-up exploits focusing in real and momentum space, by a proper adjustment of the curvature of the analyzer, a high-resolution determination of the lattice changes can also be achieved even on large irradiated gauge volumes, though with a slightly relaxed resolution. It can be successfully exploited namely, in the strain/stress measurements on samples exposed to an external load, e.g. in tension/compression rig, in aging machine etc. In addition to the original performance where the analysis is carried out by rocking the BPC analyzer and the neutron signal registered by a point detector, a new alternative is offered which uses a fixed rocking angle position of the analyzer and the detector signal is registered by a one-dimensional position sensitive detector (PSD). This trick makes possible in some cases the elastic strain/stress measurements considerably faster and thus reduces the drawback of the time consuming step-by-step analysis.

scholarly journals High-Resolution Strain/Stress Measurements by Three-Axis Neutron Diffractometer

Materials ◽  
2020 ◽  
Vol 13 (23) ◽  
pp. 5449
Author(s):  
Pavol Mikula ◽  
Vasyl Ryukhtin ◽  
Jan Šaroun ◽  
Pavel Strunz
Keyword(s):  
High Resolution ◽  
Neutron Diffraction ◽  
Perfect Crystal ◽  
Diffraction Profile ◽  
Stress Measurements ◽  
Neutron Diffractometer ◽  
Large Bulk ◽  
Gauge Volume ◽  
Strain Stress ◽  
Point Detector

Resolution properties of the unconventional high-resolution neutron diffraction three-axis setup for strain/stress measurements of large bulk polycrystalline samples are presented. Contrary to the conventional two-axis setups, in this case, the strain measurement on a sample situated on the second axis is carried out by rocking the bent perfect crystal (BPC) analyzer situated on the third axis of the diffractometer. Thus, the so-called rocking curve provides the sample diffraction profile. The neutron signal coming from the analyzer is registered by a point detector. This new setup provides a considerably higher resolution (at least by a factor of 5), which however, requires a much longer measurement time. The high-resolution neutron diffraction setting can be effectively used, namely, for bulk gauge volumes up to several cubic centimeters, and for plastic deformation studies on the basis of the analysis of diffraction line profiles, thus providing average values of microstructure characteristics over the irradiated gauge volume.

Unconventional Performance of a Highly Luminous Strain/Stress Scanner for High Resolution Studies

2011 ◽  
Vol 681 ◽  
pp. 426-430 ◽  
Author(s):  
Baek Seok Seong ◽  
Vyacheslav T. Em ◽  
Pavol Mikula ◽  
Jan Šaroun ◽  
Mi Hyun Kang
Keyword(s):  
High Resolution ◽  
Residual Strain ◽  
Optimization Procedure ◽  
Perfect Crystal ◽  
Polycrystalline Materials ◽  
Good Resolution ◽  
Paper Properties ◽  
Beam Port ◽  
Stress Mapping ◽  
Strain Stress

In this paper properties of the dedicated neutron strain/stress diffractometer installed at the beam port ST-1 of HANARO reactor in KAERI which has been optimized at a small monochromator take-off angle, are described. Thanks to the employment of the horizontally focusing bent perfect crystal monochromator and the optimization procedure good resolution can be achieved and namely, the luminosity of the instrument can be considerably increased which permits us to enlarge the range of the material depth for residual strain/stress mapping. Moreover, new alternative of the diffractometer permits also to investigate some kinetic processes in polycrystalline materials running within few seconds.

Determination of lamella thickness distributions in isotactic polypropylene by X-ray line profile analysis

Polymer ◽  
2010 ◽  
Vol 51 (18) ◽  
pp. 4195-4199 ◽  
Author(s):  
Florian Spieckermann ◽  
Harald Wilhelm ◽  
Michael Kerber ◽  
Erhard Schafler ◽  
Gerald Polt ◽  
...  
Keyword(s):  
Line Profile ◽  
Isotactic Polypropylene ◽  
Profile Analysis ◽  
Line Profile Analysis ◽  
X Ray ◽  
Lamella Thickness

An alternative neutron diffractometer performance for strain/stress measurements

2020 ◽  
Vol 35 (3) ◽  
pp. 185-189 ◽  
Author(s):  
Pavol Mikula ◽  
Jan Saroun ◽  
Vasyl Ryukhtin ◽  
James Stammers
Keyword(s):  
Plastic Deformation ◽  
Angular Resolution ◽  
Polycrystalline Sample ◽  
Perfect Crystal ◽  
Line Profiles ◽  
Neutron Diffractometer ◽  
Diffraction Angle ◽  
Strain Stress ◽  
Set Up ◽  
Elastic And Plastic Deformation

An alternative neutron diffractometer performance, which documents the feasibility of using a high-resolution three-axis neutron diffractometer for elastic and plastic deformation studies of bulk metallic polycrystalline samples, is presented. Contrary to the conventional double-axis setting, the suggested alternative consists of an unconventional three-axis set-up employing a bent perfect crystal monochromator and an analyzer with a polycrystalline sample in between. Though the alternative is, for measurements, much more time-consuming, its sensitivity to the change of the diffraction angle of the sample is, however, substantially higher and permits also plastic deformation studies on the basis of analysis of the diffraction line profiles. Moreover, much larger widths (up to 10 mm) of the irradiated gauge volumes can be investigated when just slightly affecting the angular resolution properties of the experimental setting.

Nanostructures and Microhardness in Al and Al–Mg Alloys Subjected to SPD

2008 ◽  
Vol 604-605 ◽  
pp. 179-185 ◽  
Author(s):  
Hans Jørgen Roven ◽  
M. Liu ◽  
Maxim Yu. Murashkin ◽  
Ruslan Valiev ◽  
A.R. Kilmametov ◽  
...  
Keyword(s):  
High Resolution ◽  
High Pressure Torsion ◽  
Profile Analysis ◽  
High Hardness ◽  
Mg Alloys ◽  
Line Profile Analysis ◽  
Dislocation Densities ◽  
Average Grain Size ◽  
Hardness Values ◽  
Al Mg Alloys

Nanostructures and microhardness of a commercial purity Al, three binary Al–Mg alloys and a commercial AA5182 alloy subjected to high pressure torsion (HPT) at room temperature were comparatively investigated using high-resolution transmission electron microscopy, X-ray diffraction (XRD) and high-resolution XRD line profile analysis. The hardness values of HPT samples are twice to three times larger than that of the undeformed counterparts. Grain sizes measured by XRD are in the range 10–200 nm with typical average values ranging from 46 to 120 nm. The hardness values and the dislocation densities increased, whereas, the average grain size decreased significantly with increasing Mg contents. Typical dislocation densities are in the range 1.7 × 1014 m-2 – 2.3 × 1015 m-2. However, local densities in grain boundary and triple junction areas might be as high as 1017 m-2. The strengthening mechanisms contributing to high hardness may primarily be attributed to the cooperative interactions of high dislocation densities, grain boundaries and planar interfaces.

Dislocation Densities, Slip-System Types and Burgers Vector Populationsinhexagonal and Cubiccrystalsfrom X-Ray Line Profile Analysis

2011 ◽  
Vol 702-703 ◽  
pp. 479-484
Author(s):  
Tamás Ungár
Keyword(s):  
Line Profile ◽  
Profile Analysis ◽  
Polycrystalline Materials ◽  
Line Profile Analysis ◽  
X Ray Diffraction ◽  
Burgers Vector ◽  
X Ray ◽  
Diffraction Line Profile ◽  
Vector Population ◽  
Dislocation Densities

X-ray diffraction line profile analysis can be carried out on the hkl planes corresponding to the same texture component or the same crystallographic orientation fiber. It is shown that in textured polycrystalline materials or in thin films or multilayers X-ray line profiles measured on planes corresponding either to the main or the minor texture components can provide the Burgers vector population and dislocations densities in the different texture components separately. The experimental technique is outlined for textured specimens and the multiple convolutional whole profile method, i.e. the CMWP line profile analysis procedure, is presented for its capacity to determine the substructure pertaining to different texture components in textured samples.

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