Superior mechanical properties of GNS materials. Tensile engineering stress-strain relations (A, C) and variation in work hardening rate with respect to true strain (B, D) of GNG IF steel (A, B) and GNT Cu (C, D) samples, compared with their homogeneous components. (A, B) adapted with permission from Ref. [ 9], PNAS; (C, D) adapted with permission from Ref. [ 10], AAAS.