Orientation mapping of nanostructured materials using transmission Kikuchi diffraction in the scanning electron microscope.

In this study, the new technique of transmission Kikuchi diffraction (TKD) in the scanning electron microscope (SEM) has been applied for the first time to enable orientation mapping of bulk, nanostructured metals. The results show how the improved spatial resolution of SEM-TKD, compared to conventional EBSD, enables reliable mapping of truly nanostructured metals and alloys, with mean grain sizes in the 40-200 nm range. The spatial resolution of the technique is significantly below 10nm, and contrasting examples are shown from both dense (Ni) and lighter (Al-alloy) materials. Despite the burden of preparing thin, electron-transparent samples, orientation mapping using SEM-TKD is likely to become invaluable for routine characterisation of nanocrystalline and, potentially, highly deformed microstructures.