Notch insensitive strength and ductility in gold nanowires

The initially defect-free nanowires were nanostructured with well-defined circular holes in the 19-62 nm regime by a He ion beam. The resulting flaw insensitivity and the effect of notches in single crystalline < 110 > oriented Au nanowires on strength and ductility is demonstrated by in-situ tensile testing. Both, the atomistic simulation and transmission electron microscopy analysis, elucidated the mechanistic origin of the flaw-insensitivity, i.e. plastic flow initiation at the hole with the nucleation, propagation and interaction of Shockley partial dislocations, resulting in unique defect morphologies. The unique defect signature of post-mortem defects show in conjunction with accompanying large-scale atomistic simulation the build-up of an internal microstructure at the notch, which rationalizes the observed strain hardening and therefore allowed the unexpected extended ductility in notched nanowires. (C) 2016 Acta Materialia Inc. Published by Elsevier Ltd. All rights, reserved.