Insights into fracture mechanisms in nanoporous gold and polymer impregnated nanoporous gold

Nanoporous metals have favourable characteristics for many applications. These materials have, however, failed to show suitable attributes in tension: showing an extremely weak and brittle response. This issue has been addressed through the impregnation of a polymer constituent into the nanoporous ligament network, creating a strong and malleable material in both tension and compression. In this work, this improvement is investigated by comparing nanoporous gold and its polymer filled nanocomposite counterpart using computational microspecimen compact-tensile tests. We examine crack initiation and propagation within these materials. The micromechanical response is also explored to reveal the influence of the polymer impregnation on fracture mechanisms. It is shown that, in agreement with the findings in the literature, the failure of a few gold ligaments in nanoporous gold leads to the complete failure of the material with a relatively small resistance to failure and a characteristically brittle fracture. Polymer impregnation, on the other hand, effectively delays the complete material failure as the polymer stabilizes the individual ligaments. This results in a significantly increased ductility under tension which is vital for it to be considered for use in structural applications.