Transmission Kikuchi diffraction versus electron back-scattering diffraction: A case study on an electron transparent cross-section of TWIP steel.

The present case study compares transmission Kikuchi diffraction (TKD) with electron back-scattering diffraction (EBSD) on the same area of an electron transparent cross-section of a twinning induced plasticity steel. While TKD expectedly provides better clarity of internal defect substructures in the band contrast map, EBSD returns orientation data that approaches the quality of the TKD map. This was rationalised by Monte Carlo simulations of the electron energy spreads, which showed that due to the geometry-based compromises associated with adapting a conventional EBSD detector (which is off-axis with respect to the incident electron beam) to TKD, a broadening in the electron energy distribution of the forward-scattered electrons collected on the detector phosphor screen, is unavoidable. In this circumstance, the values of the full-widths at half-maximum of the energy distributions for TKD and EBSD are of the same order. It follows that EBSD on electron transparent cross-sections may be a viable alternative to TKD when: (i) conventional EBSD detectors are adapted to TKD and, (ii) sample microstructures comprise features whose sizes do not mandate the application of TKD.