Nanoporous metallic structures can be formed via a process called dealloying. This term refers to the removal of the more active element from an alloy system when exposed to a suitable reagent. The residing noble element diffuses and agglomerates to form a bi-continuous porous structure on the nano-scale. The length scale can be increased (coarsened) by increasing the amount of exposure time to the dealloying solution or post formation heat treatments. A variety of techniques have been used to characterise these materials e.g. FEGSEM, TEM and SANS.
In this study SAXS and XRD have been used, alongside FEGSEM microstructural analysis, to study nanoporous Au formed via the selective dissolution of Ag from a Ag-Au alloy. The porous system is formed by free corrosion when floated on concentrated HNO3. The ligament width and spacing are increased by longer exposure time to the solution. SAXS data allow us to estimate the ligament spacing at various exposure times. The data are also used to produce representative 2-D and 3-D morphologies. XRD is shown to give an insight in to the strain development associated with the formation and following coarsening of the nanoporous material.