Comparison of crystal orientation mapping-based and image-based measurement of grain size and grain size distribution in a thin aluminum film

Crystal orientation maps of a nanocrystalline Al film were obtained using precession electron diffraction in a transmission electron microscope. The orientation maps were then subjected to a series of well-defined clean-up procedures for removal of badly indexed points and pseudosymmetry boundaries. The mean grain size and grain size distribution were obtained from the reconstructed boundary network. The grain size and grain size distribution were also measured by the conventional transmission electron microscopy bright-field-imaging-based hand-tracing methodology, and were compared quantitatively with the orientation mapping results. It was found that the mean grain size from the two methodologies agree within experimental error. On the other hand, the orientation mapping methodology produced a somewhat different grain size distribution compared with the distribution obtained by the hand-tracing methodology. The reasons for the differences in the distributions are discussed.