Characterization of crystallographic texture of Zirconium alloy components by neutron diffraction

Abstract

The reproducibility of the determination of crystallographic texture of Zr-based components by neutron diffraction has been studied through a small round-robin exercise, with the participation of texture and residual stress diffractometers from five international laboratories. Both constant-wavelength and polychromatic neutron beams have been used to define the texture of specimens from a warm-rolled and annealed Zircaloy-4 plate, and from a Zr-2.5%Nb pressure tube. Measurements were also compared to synchrotron high energy X-ray diffraction experiments, as a complementary volumetric technique with much shorter data collection times compared to neutrons. Results are qualitatively consistent and reproducible in terms of pole figures and orientation distribution function, underlining the suitability of neutrons for bulk texture measurements. Expected uncertainty of measurements has been quantified by global parameters such as texture indexes and Kearns factors, and local parameters associated to the main texture components (volume fraction, centroids, and widths of fiber components). The typical uncertainties found for these parameters are compared to spatial differences found in a small batch of cold-rolled Zr-2.5%Nb pressure tubes.