Strength recovery in self-healed nanoporous gold

Abstract

Nanoporous gold (np-Au) is an open-cell structured material with nanoscale pores and ligament introducing high surface area and high surface curvature. Np-Au shows mechanical fragility with low strength and brittleness due to its irregular porous structure introducing catastrophic failure under tensile stress. During failure, deformed ligaments are localized near fracture surface and each ligament on fracture surface failed by necking. Recent studies have suggested cold-welding behavior of gold nanowires with diameter of sub10 nm at room temperature. Two nanowires could be welded by surface diffusion because surface diffusion rate is increased by reducing diameter of nanowires. Based on this, fracture surface of np-Au could be self-healed while it consists of very thin fractured ligament like nanowires. Here, self-healing ability of np-Au is suggested in terms of strength recovery. Np-Au samples are fabricated free-corrosion dealloying and mechanical properties before and after self-healing are investigated by in-situ tensile test in SEM chamber.