High-resolution Neutron Diffraction Techniques for Strain Scanning

Abstract

Several high-resolution neutron diffraction techniques using Bragg diffraction optics based on cylindrically bent perfect crystals which have been tested with the aim of their efficient exploitation for strain/stress are summarized. Presented experimental results demostrate their experimental abilities for nondestructive testing and evaluation of a phase and deformation response of polycrystalline materials on residual stress or deformation loading. Due to the unique resolution and good luminosity achieved by focusing in real and momentum space, besides the macrostrain scanning, the presented techniques are also qualified for microstrain/stress studies by an analysis of the diffraction profiles. At the medium flux reactor LVR-15 in NPI Řež there are operating two focusing double axis strain/stress diffractometers. Good luminosity of the diffractometers and a sufficiently high-resolution (FWHM of the instrumental Δd/d-profile can be less than 2×10−3 at d hkl=0.2 nm) permit investigations of both the macro- and microstrains in the sample gauge volumes of several cubic millimetres with a sensitivity in the relative peak shift of several 10−5 rad.KeywordsResidual StressNeutron DiffractionBragg DiffractionDiffraction ProfileInstrumental ResolutionThese keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.