b'Figure 3. STEM BF (a) and HAADF (b) images show the overall microstructure of the Cr diffusion barrier after micro-tensile testing. The gauge section shows several Cr crystals, with sizes ranging from hundreds of nanometers to around 2 m (a). The STEM images (c)(d) and EDS elemental maps (e)-(f) of a selected area highlighted in green rectangle in (a). The STEM BF image (d) shows a high density of cavities which appear to be closely associated with the Fe element in (e). (g) and (h) TEM selected area diffraction patterns taken from the top shoulder denoted by the as red circle in (a)2023|AFC ACCOMPLISHMENTS 167'