Determination of crystallographic texture in polycrystalline materials from wavelength-resolved neutron transmission experiments: application to high-symmetry crystals

M. A. VICENTE ALVAREZ; F. MALAMUD; J. R. SANTISTEBAN

Journal of Applied Crystallography

International Union of Crystallography

Año: 2023 vol. 56 p. 1721 - 1731

Wavelength-resolved neutron transmission experiments are useful for characterizingthe microstructure of macroscopic specimens with 2D spatialresolution perpendicular to the beam direction. The crystallographic texturecan affect the neutron transmission in the thermal neutron energy range, whichmanifests as changes in the shape and height of Bragg edges as a function ofneutron wavelength. Models have been proposed to predict the transmission oftextured polycrystalline materials from knowledge of the material texture andhave proved to accurately predict the observed transmission data. In recentwork, a novel method was described and tested for obtaining texture integralparameters from the combined analysis of transmission data measured alongseveral directions of a specimen in a hexagonal crystal Zr alloy. However, thisprocedure has limitations when dealing with high-symmetry crystal structures.In this work, a generalization of such a method based on the expansion of theorientation distribution function (ODF) in symmetric generalized sphericalharmonics that is applicable to all crystal and sample symmetries is presented.Using this method, the low-order Fourier coefficients of the ODF can beestimated by analyzing transmission data obtained for a reduced set of beamdirections. This method was verified using a cubic Cu sample, for whichtransmission data were available along five different directions. Two samplesymmetries were assumed to reduce the number of Fourier coefficients of theODF. In the case of cylindrical symmetry (fiber-type texture), the results weregood; but in the case of orthorhombic symmetry, some bias was observed whichwas attributed to the reduced number of beam directions used to perform theevaluation.