Fig. 16: The atomic force microscope (AFM) and SKPFM mappings of two inclusions at different hydrogen charging times.

a “mosaic” inclusion morphology of SKPFM scanning and potential mappings before and after hydrogen charging. b Line scanning potential results along the blue arrow in (a). c “core-shell” inclusion morphology of SKPFM scanning and potential mappings before and after hydrogen charging. d Line scanning potential results along the blue arrow in (c).