The Strength of Gold Nanowires

Atomistic simulations are used to investigate the yield strength of experimentally observed atomic and nanometer scale gold wires. The atomistic predictions of strength are quantitatively consistent with discrete experimental measurements and they reveal the mechanisms for increasing nanowire strength with decreasing dimensional scale. Distinct transitions in yield strength and yield mechanism are discovered. At nanometer scales (diameter > 1 nm), the mechanism for strengthening involves the scarcity and low mobility of dislocations coupled with constraint from tensile surface stresses. As the wires approach the atomic scale (diameter < 1 nm), an increase in strength occurs concurrent with a surface-stress-induced change in the stable structure of the nanowires and the absence of dislocation-mediated yield. The results constitute a new fundamental understanding of strength in metallic nanowires spanning technologically relevant dimensional scales.