LAUSR

Abstract Mechanically robust nanoscale metallic materials are highly desirable in many miniaturized devices. However, the lack of strain hardening and controllable plasticity plagues such small-volume metals. Using Al-4Cu alloy as an example, here we show that a submicron-sized metallic material with ultrathin native oxide shell exhibits a high degree of deformation controllability, unprecedented strain hardening, size strengthening and toughness, in uniaxial tensile deformation. The metal/native oxide “composite” is easy to make, and the emergent properties extend well beyond the benchmark range known for metals in a normalized (i.e., dimensionless) strength-toughness plot. The origin of the combination of strengthening and plastic stability is that an intact ultrathin native oxide shell exerts a strong confinement on dislocation movement and annihilation, thereby breaking the envelope on dislocation storage and strain hardening achievable in small-volume metals.