One of our lab group's major research interests is understanding the fundamentals of dealloying and using this knowledge to fabricate and process new materials. Dealloying has received renewed recent attention due its re-invention as a nanoscale processing tool to fabricate ultra-high surface area materials for catalysis, sensing, and optical applications. A peculiar aspect to porous metals is that all of the nanoscale features are easily controlled by bulk processes, such as alloy composition and dissolution potentials.

The formal definition of dealloying is the selective dissolution of one of more components of an alloy.  What this means is we start with an alloy (and ingot made of two or more metals) and remove one of the elements in a controlled manner such that we are left with a nano-scale structure.  Below is a cartoon of our process as well as an SEM image of a porous structure.

In order to fully understand the atomic level mechanisms involved we have developed simulation code, MESOSIM, that relies only on surface diffusion and dissolution events.  Below is a video of dealloying.  The aspects of note are that the silver atoms dissolve layer by layer and gold atoms clump together and form "clusters."