| Summary: | Compression of nanoporous gold in situ under electrochemical control reveals that its flow stress can be enhanced by surface coverage of monolayer oxide. Here we present a study on the monolayer oxide induced changes in flow stress of an nanoporous gold, while the ligament size is varied by more than 2 orders of magnitude. The increase percentage of flow stress (of nanoporous gold and nano-ligaments) induced by surface monolayer oxide is negligible when the ligament size (L) exceeds ∼2 µm, increases with decreasing L for ∼200 nm < L < ∼2 µm, and then saturates at ∼27% for L < ∼200 nm. These results indicate a transition from bulk-like to surface-mediated deformation behavior of nano-ligaments as L decreases from ∼2 µm to ∼200 nm. Our observation at L < ∼200 nm support the notion that the deformation is dominated by the surface-dislocation-nucleation at this scale.
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