Fig. 3: Characterization of secondary GB dislocations and their linkage to segregation patterns in the Fe-1 at% W specimen.

a Compositional mapping of W at a resolution of 0.5 × 0.5 × 0.5 nm³ per voxel, enabling visualization of volume-specific variations. Parts of the grains and GBs have been labeled, with identities ranging from grain α₁ to grain α₅ and from GB1 to GB2 (see all labels in Supplementary Fig. 7). The X-axis represents the thin film growth direction in the same coordinate system in Supplementary Fig. 1. Correlative crystallographic and compositional quantitative analysis for two GBs GB1: b–e and GB2: f–i. Each set includes: b, f orientation mappings of the local normal to the GB plane between adjacent grains (rendered in translucent gray), with two mappings provided for each GB, referenced to the respective grain involved. Cubic symbols in indicate the orientation of the grains and the red arrow indicates the misorientation rotation axis. c, g 4DSTEM virtual dark-field images; d, h atom maps of Fe (colored red) and W (colored cornflower blue), with superimposed isosurfaces at 2.5 at% W and 4.0 at% W, respectively; e, i W profiles along the red arrows shown in (e, i). The insert images in (c, g) display the nanobeam diffraction patterns with the vectors \({{{\bf{g}}}}=[{{{\bf{12}}}}\bar{{{{\bf{1}}}}}]\) for grain α₂ and \({{{\bf{g}}}}=[\bar{{{{\bf{2}}}}}{{{\bf{11}}}}]\) for grain α₅ (highlighted by red circles), which were used to generate the virtual dark-field images shown in (c, g). Two perspectives (90^∘ rotated clockwise from left to right) in (d, h) are shown to illustrate the segregation patterns in 3D.