Application of quantitative texture analysis to Rietveld profile refinement of neutron diffraction patterns of a zircaloy sample

Abstract

The possibility of extending the Rietveld method to incorporate textured polycrystalline materials is demonstrated with a zircaloy sample. By assigning the pole densities obtained by separate texture analysis to the preferred orientation factors (POFs) in the mathematical model of the Rietveld method, good pro®le re®nement results are achieved with the neutron diffraction patterns. The approach of predetermining the individual POF values from quantitative texture information can be used to improve re®nement of other parameters related to the analysis of composite phases as well as to crystal structure re®nement.

Quantitative phase analysis of strongly textured alloy mixtures using neutron diffraction

“…In line with previous research by Choi et al (1994) and Kim et al (2001), we propose a new method for preferred-orientation correction and apply this method to the Rietveld QPA approach. In contrast to the previous work, the POFs of diffraction peaks were extracted from the inverse pole ®gure calculated from the ODF that was calculated from the averaged pole ®gures measured by the rotating sample stage, providing a faster and simpler texture measurement.…”

“…The POFs P jk can be extracted from the pole density distribution as the result of the texture analysis (Choi et al, 1994;Kim et al, 2001). In this work, the POFs were extracted from the inverse pole ®gures of the radial direction ( = %/2) calculated from the ODFs, which were computed from the averaged complete pole ®gures.…”

“…The March±Dollase function (Dollase, 1986;Howard & Kisi, 2000) is basically used for the correction of preferred orientation, but its application to highly textured samples (e.g. rolled sheets) is generally limited (Kim et al, 2001).…”

“…However, the methods mentioned above require a long measuring time. Recently, Kim et al (2001) reported a less time-consuming method, involving the measurement of neutron diffraction patterns with a multiple-detector and introducing the procedure of extracting the POFs from a number of pole ®gures, recalculated from the ODF that was calculated from several measured complete pole ®gures. In this method, all the {hkl} pole ®gures should be calculated in order to determine the POF of the corresponding individual scattering-vector direction 2 hkl .…”