Size-dependent ion-induced densification of nanoporous gold
Relative density is a major factor governing the mechanical properties of (nano-)porous materials. In nanoporous gold, a correlation between relative density and the ligaments aspect ratio was recently reported as the result of a meta-study that measured hundreds of published images. The effects of ion-irradiation on nanoporous structures however are not yet well explored. We irradiated samples of nanoporous gold of two different initial characteristic lengths with 30 keV Ga + ions. The degree of densification was found to be higher for the samples with finer ligaments and to proceed by thickening of ligaments besides the reduction in length also observed in the coarser samples. The proportionality between relative density and aspect ratio in the ion irradiated samples was found to agree well with the previously reported results from specimens of various processing and coarsening routes. The present study points at ion irradiation as a tool to tune these parameters in nanoporous structures and suggests that the correlation between relative density and aspect ratio may be involved in the volume contraction observed during the formation of nanoporous samples by dealloying.