Refinements in phase fraction determination of textured alloys from transmission diffraction data

The use of high-energy synchrotron X-ray diffraction sources has become increasingly common for high-quality phase fraction measurements and microstructural evolution experiments. While the high flux, large volume illuminated and large number of diffraction vectors should reduce common sources of uncertainty and bias, the distribution of the diffraction vectors may still cause bias in the phase fraction measurement. This hypothesis of bias was investigated with example experimental data and synthetic data. The authors found that there may be bias depending on the sample texture, the distribution of diffraction vectors and the hkl planes used in the phase fraction measurement, even for nearly complete coverage of a pole figure. The authors developed a series of geometry-based correction values that reduced the measurement bias due to sampling scheme and texture in the phase fraction measurement by an order of magnitude. The efficacy of these corrections was demonstrated with application to both experimental and synthetic data.