Imaging the deformation-induced accumulation of defects in nanoporous gold

Abstract

Nanoporous gold (NPG) provides a model material for studying small-scale deformation and the mechanical behavior of network solids. We report a transmission electron microscopy study of the defect structure in electron-transparent NPG leaf deformed by rolling. The results confirm that plastic deformation significantly enhances the defect density. Specifically, twins are formed on several sets of crystallographic planes, and their interaction forms Lomer-Cottrell locks. This inhibits dislocation escaping from NPG, thus avoiding the dislocation starvation scenario that is often considered in the ‘smaller is stronger' context of small-scale plasticity. Instead, strain hardening is apparently linked to accumulation and interaction of twins.IMPACT STATEMENT: This paper provides a direct observation of the lattice defects in plastically deformed nanoporous gold, confirming the contribution of accumulation and interaction of defects to the strain hardening rate.