High-Resolution Three-Axis Neutron Diffractometer for Microstructure Investigations of Polycrystalline Materials

Abstract

Recently, focusing 3-axis diffractometer set-up equipped with the bent perfect crystal (BPC) monochromator and analyzer which has offered the sensitivity in determination of strains Δd/d < 10−4 in polycrystalline materials, has been introduced. The resolution determined by FWHM of the diffraction profiles is about one order of magnitude higher with respect to that of conventional 2-axis neutron strain/stress scanners. Therefore, the new set-up also offers possibility of line profile analysis for relatively large irradiated gauge volumes and reasonable counting times, because the 3-axis set-up exploits focusing in real and momentum space simultaneously. As it is demonstrated on several samples, the 3-axis diffractometer can be successfully used in the strain/stress measurements on samples exposed to an external load, studies of diffraction profile affected by plastic deformation, determination of phases having very close values of the lattice spacings etc. The analysis is carried out by rocking the BPC analyzer and the neutron signal is registered by a point detector.