Neutron diffractometer using Bragg diffraction optics for high-resolution strain/stress measurements

1997 ◽  
Author(s):  
Pavel Mikula ◽  
Petr Lukas ◽  
Jan Saroun ◽  
Pavel Strunz ◽  
Miroslav Vrana ◽  
...  
Keyword(s):  
High Resolution ◽  
Bragg Diffraction ◽  
Stress Measurements ◽  
Neutron Diffractometer ◽  
Strain Stress ◽  
Diffraction Optics

High-Resolution Neutron Diffraction for Nondestructive Analysis of Residual Stresses in Polycrystalline Materials

2006 ◽  
Vol 3-4 ◽  
pp. 331-336
Author(s):  
Pavol Mikula ◽  
Petr Lukáš ◽  
Miroslav Vrána
Keyword(s):  
High Resolution ◽  
Neutron Diffraction ◽  
Bragg Diffraction ◽  
Polycrystalline Materials ◽  
Nondestructive Analysis ◽  
Strain Measurements ◽  
Neutron Diffractometer ◽  
Stress Studies ◽  
Strain Stress ◽  
Diffraction Optics

The performance of an unconventional high-resolution neutron diffractometer using Bragg diffraction optics that can be efficiently employed in strain/stress diffractometers are reported. Presented results demonstrate their experimental abilities for powder diffraction, namely for residual strain/stress measurements. In addition to the macrostrain scanning capability, the device can also be used for microstrain/stress studies by suitable analysis of the diffraction profiles. Two examples of the strain measurements are presented.

High-Resolution Neutron Diffraction Employing Bragg Diffraction Optics: A Tool for Advanced Nondestructive Testing of Materials

2008 ◽  
Author(s):  
Pavol Mikula ◽  
Miroslav Vra´na ◽  
Lubos Mra´z ◽  
Leif Karlsson
Keyword(s):  
High Resolution ◽  
Neutron Diffraction ◽  
Nondestructive Testing ◽  
Bragg Diffraction ◽  
Internal Stresses ◽  
Material Research ◽  
Neutron Sources ◽  
Neutron Diffractometer ◽  
Strain Stress ◽  
Diffraction Optics

The present paper deals with an efficient use of high-resolution neutron diffraction for material research studies, namely for studies of internal stresses. It is demonstrated that a conventional neutron diffractometer equipped with focusing elements can be used as neutron strain/stress scanner with medium power neutron sources. Principles of this enhanced technique are introduced and an example of internal strain/stress measurements in the vicinity of welds is presented.

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.

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.

High-resolution neutron diffractometer for internal stress measurements

1995 ◽  
Vol 213-214 ◽  
pp. 803-805 ◽  
Author(s):  
M. Ceretti ◽  
R. Coppola ◽  
A. Lodini ◽  
M. Perrin ◽  
F. Rustichelli
Keyword(s):  
High Resolution ◽  
Internal Stress ◽  
Stress Measurements ◽  
Neutron Diffractometer

High resolution neutron diffraction techniques for strain/stress measurements at a steady state reactor

1994 ◽  
Vol 75 (1-4) ◽  
pp. 305-310
Author(s):  
M. Vrána ◽  
P. Mikula ◽  
P. Lukáš ◽  
J. Šaroun ◽  
P. Strunz
Keyword(s):  
Steady State ◽  
High Resolution ◽  
Neutron Diffraction ◽  
Stress Measurements ◽  
Strain Stress

Investigation of multiple Bragg reflections and their possible exploitation

2021 ◽  
Vol 23 (1) ◽  
pp. 29-51
Author(s):  
Pavol Mikula ◽  
Jan Šaroun ◽  
Pavel Strunz ◽  
Vasyl Ryukhtin
Keyword(s):  
Experimental Study ◽  
High Resolution ◽  
Single Crystals ◽  
Multiple Reflection ◽  
Bragg Diffraction ◽  
Multiple Reflections ◽  
Diffraction Geometry ◽  
Diffraction Optics

This paper summarizes recent results of an exhaustive experimental study of multiple Bragg reflections accompanying allowed as well as forbidden reflections. The multiple reflection observations were carried out in the frame of Bragg diffraction optics experiments on cylindrically bent perfect single crystals. It has been found that depending on the thickness and curvature of the crystal slabs and the diffraction geometry (reflection, transmission), many strong multiple reflections can be excited which can also be used as a source of highly monochromatic and highly collimated beams for further experiments requiring extremely high resolution.

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