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Table of Contents
FitAllB
FitAllB is tailored to do centre-of-mass (COM) refinements of grain orientations, positions and strain tensors from far-field images of a polycrystalline material. The name FitAllB originates because the routine fits all Bi (1), the grain specific reciprocal space metrics, which contain information about the strain states of the individual grains.
It was written by Jette Oddershede, formerly at DTU in Denmark and now working for Xnovo Technology ApS. The source code, along with a complete manual is available online at https://github.com/FABLE-3DXRD/FitAllB.
Jette Oddershede, Søren Schmidt, Henning Friis Poulsen, Henning Osholm Sørensen, Jonathan Wright and Walter Reimers, Determining grain resolved stresses in polycrystalline materials using three-dimensional X-ray diffraction, J. Appl. Cryst. 43, 539-549 (2010) doi: 10.1107/S0021889810012963
Capabilities
Taken from the manual:
The aim is to be able to handle several hundred illuminated grains and obtain the strain tensors to an accuracy of 10−4. The strain tensors are output both in the Cartesian grain coordinate system relative to the grain orientation and in the sample system for overall comparisons, and if the components of the stiffness tensor C are provided, the stress tensors in the same two representations will also be output.
FitAllB includes an error estimation routine to give standard deviations of all refined parameters. In addition the relative volumes of the grains (from the peak intensities with the possibility to take absorption effects into account) are refined, so in principle a 3D orientation and stress/strain map of the polycrystal can be obtained using tessellation.
Lately an algorithm to extract the peak widths(median 2θ and η) for each grain has been added as an indicator of intragranular orientation and/or strain gradients.
Application to DAC experiments
In DAC experiments, FitAllB is a second stage refinement. You use FitAllB after finding and indexeding your grains with another piece of software.