Mechanical response of nanoporous gold

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We report the results of computational tensile and compressive tests for model bi-continuous nanoporous gold structures using atom-
istic 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  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 sam-
ples 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.

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