Extended Data Fig. 4: Dislocations, nanocracks, and boundary disordering associated with ITB transitions.

a, HAADF-STEM image of the ITB displayed in Fig. 2d−f, after further STEM scanning. b–e, A sequence of individual HAADF-STEM images (selected from the cyan box in a) after FFT filtering by choosing {111} diffractions (enclosed red circles in the inset FFT), showing the gradual generation of a dislocation loop. The red ⊥ symbols mark two cutoff points of this dislocation loop. The Burgers circuits are also drawn in c and e, indicating a vector of \(1/2[0\bar{1}\bar{1}]\) or \(1/2[\bar{1}0\bar{1}]\) that can be identified only by projected on the \((1\bar{1}0)\) plane. f–i, Raw HAADF-STEM images corresponding to those displayed in b−e, respectively, overlapped with the corresponding ε_yy mapping from GPA, revealing a mixed feature of this dislocation loop (the Burgers vector is not lying on the plane where the dislocation loop lies on). j, A HAADF-STEM image shows a VI-variant {112} ITB, which obliquely connects to a {111} twin at its left end. k, HAADF-STEM image of j acquired after 20 sec of STEM scanning. The left half of the ITB displays blurry and disordered features (cyan rectangle), and the rest of the ITB transforms into a mixture with structural units of configurations I, IV, and V. A nano crack can be developed at the ITB/CTB junction (red arrow). CTBs and SFs are labeled in both images with red solid and dash lines, respectively.