Observation of speeding growth of metal nanowires by ultra-low frequency micro-vibration assisted superplastic nanomolding

Abstract

Superplastic nanomolding (SPNM), a method to directly form nanostructures in metal surface through contact deformation by using a hard mold, provides a toolbox to mold essentially any metals on the nanoscale. Here, by superimposing an ultra-low frequency micro-vibration to the molding pressure, it is interesting to find that the molding efficiency can be drastically increased. Specifically, the length of molded Ag nanowires increased by 20% when a micro-vibration (with a frequency as low as 100 Hz) is exerted. The speeding growth of the Ag nanowires during SPNM is attributed to the interfacial friction reduction and material softening induced by vibration according to the experimental results. Based on the thermal activation theory, a theoretical model is developed, which predicts that the micro-vibration accelerated deformation increases as the vibration frequency, agreeing with experiments well. These findings are expected to facilitate the wide application of SPNM in the quick fabrication of metal nanostructures.