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.

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.

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

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.

Investigation of Residual Strains of the Second Kind in Plastically Deformed Metallic Materials

1994 ◽  
Vol 376 ◽  
Author(s):  
M. Vrána ◽  
P. Klimanek ◽  
T. Kschidock ◽  
P. Lukáš ◽  
P. Mikula
Keyword(s):  
High Resolution ◽  
Neutron Diffraction ◽  
Stacking Faults ◽  
Metallic Materials ◽  
Line Broadening ◽  
X Ray Diffraction ◽  
X Ray ◽  
Neutron Diffractometer ◽  
Residual Strains ◽  
Good Agreement

ABSTRACTInvestigation of strongly distorted crystal structures caused by dislocations, stacking-faults etc. in both plastically deformed f.c.c. and b.c.c. metallic materials was performed by the analysis of the neutron diffraction line broadening. Measurements were realized by means of the high resolution triple-axis neutron diffractometer equipped by bent Si perfect crystals as monochromator and analyzer at the NPI Řež. The substructure parameters obtained in this manner are in good agreement with the results of X-ray diffraction analysis.

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

High-resolution diffraction using Larmor precession of polarized neutrons

2002 ◽  
Vol 35 (1) ◽  
pp. 28-33 ◽  
Author(s):  
M. Theo Rekveldt ◽  
Wicher Kraan ◽  
Thomas Keller
Keyword(s):  
High Resolution ◽  
Neutron Diffraction ◽  
Small Angle ◽  
Angular Resolution ◽  
Lattice Plane ◽  
Larmor Precession ◽  
Neutron Diffractometer ◽  
Diffraction Mode ◽  
Angle Scattering ◽  
Collimated Beam

A new Larmor precession device, consisting of two separate precession modules, is introduced. It operates as a high-resolution neutron diffractometer, without the need for a highly collimated beam, necessary in conventional high-resolution neutron diffraction. The same instrument operates in different modes as an effective small-angle scattering device or accurately determines the line profile, the lattice plane orientation or the angular spread in crystal orientations. A dramatic intensity gain can be obtained in all applications discussed, compared with the conventional analogues, owing to the possibility to use a relaxed wavelength and angular resolution. Experiments in the high-resolution diffraction mode on Si and Al are discussed.

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