Structural gradient induced novel deformation mechanisms. BCDs in GNT Cu at 1% strain, indicated by the white arrows (A), which are identified by two-beam diffraction using vectors of g _M = 200 (B). Highly dense micrometer-length SF bundles in the GDS HEA at 3% strain (C), which are composed of numerous sub-10 nanometer SFs and tiny TBs (D). The inset in (C) is the corresponding selected area electron diffraction patterns containing parallel streaks from SFs. (A, B) adapted with permission from Ref. [ 10], AAAS; (C, D) adapted with permission from Ref. [ 11], AAAS.