Deformation mechanisms and scaling relations in the mechanical response of nano-porous Au

We report a series of atomistic virtual mechanical tests on digitally created samples of nanoporous gold with 60% porosity, and average ligament diameters varying from 5.5 nm to 14.4 nm. Corresponding tests were also conducted for nanowires of equivalent surface to volume ratio and crystalline orientation. The validity of the Gibson-Ashby (G-A) scaling relations for the elastic and plastic behavior of the NP-Au structures is discussed. Tension/compression asymmetry in the plastic behavior was observed in both the nanoporous samples as well as the nanowires. Consistent with previous experimental and computational studies, the asymmetry becomes increasingly evident for the smaller ligament diameters, clearly pointing to capillary effects for large surface to volume ratios. Based on the present simulation results, a simple analytical model is presented for predicting the tension/compression asymmetry. The effects of internal ligament stresses on the deformation mechanisms and dislocation activity in the NP-Au structures are also discussed.