Mechanical response of nanoporous gold

D Farkas and A Caro and E Bringa and D Crowson, ACTA MATERIALIA, 61, 3249-3256 (2013).

DOI: 10.1016/j.actamat.2013.02.013

We report the results of computational tensile and compressive tests for model bi-continuous nanoporous gold structures using atomistic simulations with empirical many-body potentials and molecular dynamics. The results are compared with the predictions of scaling laws for coarser-scale foams and with available experimental data. We find a surprising substantial tension/compression asymmetry in yield due to the surface stress that sets the filament under compression, providing a bias favoring yielding in compression. We provide a model for our results based on a ligament strength value close to the theoretical strength of Au, and the surface stress. The model predicts a significant tension/compression asymmetry for ligament sizes below, similar to 10 nm and pore collapse for ligament sizes below 1 nm. We also observe an unexpected compaction tendency under tension characterized by a decrease in the total volume of the sample of 15% for samples deformed under tension by 30%. The mechanism of the compaction involves a decrease in the average pore size and pore collapse resulting from plasticity within the ligaments. (C) 2013 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Return to Publications page