Fig. 1: Material microstructure with nanoscale chemical inhomogeneity.

a Combined and individual 3D elemental maps of as-deposited O-13 MPEA with chemical composition in atomic percent (at.%) based on APT analysis. b 3D reconstruction map based on APT measurement, illustrating the spatial variation of Cr concentration throughout the sample. c 1D compositional profile along the length direction of the arrow displayed in (b). d Typical BF-STEM image showing the columnar nanocrystal structure. e Grain size (columnar width) distribution of the columnar nanograins. f The SAED pattern acquired from d shows nanocrystalline diffraction rings, corresponding to a mixture of HCP and FCC structures. g Typical STEM-HAADF image taken from the same region as d. h Intensity line profiles of the red and blue square region in (g). i DF-STEM image of the white-dashed square region in d. The red and blue “┴” represent Shockley and Frank partial dislocation, respectively. The inset at the bottom right is the corresponding fast Fourier transform (FFT) image. The inset at the top right is the magnified image of the region corresponding to the black square, showing a Shockley partial dislocation and two adjacent Frank partial dislocations. j Enlarged high-angle GB image corresponding to the white-framed region in (i). k STEM-HAADF image captured from the same region as i. The oxygen-enriched ((Cr, O)-rich) and oxygen-depleted ((Co, Ni)-rich) regions exhibit different interplanar spacings along {111} crystal planes. l EELS mapping collected in the corresponding region of k. The blue and pink dashed frames are (Cr, O)-rich regions in the grain exterior and interior, respectively. Source data are provided as a Source Data file.