Misorientations across etched boundaries in deformed rocksalt: a study using electron backscatter diffraction

Automated electron backscatter diffraction (EBSD) in the scanning electron microscope has been used to collect crystallographic orientation and misorientation data from etched surfaces of deformed synthetic rocksalt. By comparing the misorientation across individual boundaries to the intensity of etching, we have assessed the effectiveness of the etching procedure. High angle (>10°) grain boundaries are typically etched significantly more than low angle subgrain boundaries, and thus they can be easily identified using reflected light microscopy. However, there exists considerable variation in the intensity of etching of subgrain boundaries, independent of their misorientation. The intensity of intragranular boundary etching is controlled by the crystallographic orientation of the etched surface: surfaces close to {100} faces are only lightly etched, while surfaces close to {111} faces are heavily etched. Therefore, whilst reflected light microscopy of etched surfaces of deformed rocksalt remains extremely useful for general microstructural characterisation, fully quantitative techniques such as EBSD are ideal for more detailed microstructural analyses.