Dealloying is a corrosion process where an alloy is "parted" by the selective dissolution of electrochemically active elements, leading to the formation of a nanoporous sponge composed mainly of noble alloy components. This process involves the aggregation of noble atoms into two-dimensional clusters via spinodal decomposition at the solid-electrolyte interface, resulting in nanoporosity. The surface area increases continuously due to etching, and these processes evolve a characteristic length scale predicted by a continuum model. Nanoporous metals have significant applications, such as in sensor technology due to their high surface area. Selective dissolution has a long history, with examples like depletion gilding, where a non-gold element is selectively dissolved from an alloy surface, leaving pure gold. In modern times, selective dissolution has been studied in corrosion contexts, particularly in alloys like brasses and stainless steels. The mechanical properties of porous overlayers differ from the bulk alloy, leading to brittle fracture and other material failures. The formation of porosity during dealloying is a complex process involving dissolution kinetics, surface diffusion, and mass transport. A kinetic Monte Carlo (KMC) model was developed to simulate Ag-Au dealloying, reproducing experimental trends. Simulations showed that gold adatoms coalesce into clusters, leading to the formation of nanoporous structures. The process starts with the dissolution of silver atoms, leaving terrace vacancies that are filled by gold atoms. These gold atoms diffuse and agglomerate into clusters, which passivate the surface. As silver dissolves, more gold adatoms are released, leading to the formation of pits and full-blown porosity. The coalescence of gold adatoms into clusters is driven by spinodal decomposition, a process where composition fluctuations lead to lower free energy. The spacing between these clusters corresponds to the characteristic length scale of the porous structure. The motion of the alloy-electrolyte interface is described by the flux of diffusing adatoms, interface velocity, and concentration accumulation rate. The Cahn-Hilliard equation models the diffusion during spinodal decomposition, and the interface response function describes the velocity of the interface based on gold concentration and overpotential. The results show that the characteristic length scale of porosity decreases with increasing driving force, consistent with both simulations and experiments. The analysis also highlights the analogy between this process and two-dimensional island nucleation during vapor phase deposition, where adatoms agglomerate into islands. The study provides insights into the mechanisms of nanoporosity formation and the role of spinodal decomposition in dealloying processes.Dealloying is a corrosion process where an alloy is "parted" by the selective dissolution of electrochemically active elements, leading to the formation of a nanoporous sponge composed mainly of noble alloy components. This process involves the aggregation of noble atoms into two-dimensional clusters via spinodal decomposition at the solid-electrolyte interface, resulting in nanoporosity. The surface area increases continuously due to etching, and these processes evolve a characteristic length scale predicted by a continuum model. Nanoporous metals have significant applications, such as in sensor technology due to their high surface area. Selective dissolution has a long history, with examples like depletion gilding, where a non-gold element is selectively dissolved from an alloy surface, leaving pure gold. In modern times, selective dissolution has been studied in corrosion contexts, particularly in alloys like brasses and stainless steels. The mechanical properties of porous overlayers differ from the bulk alloy, leading to brittle fracture and other material failures. The formation of porosity during dealloying is a complex process involving dissolution kinetics, surface diffusion, and mass transport. A kinetic Monte Carlo (KMC) model was developed to simulate Ag-Au dealloying, reproducing experimental trends. Simulations showed that gold adatoms coalesce into clusters, leading to the formation of nanoporous structures. The process starts with the dissolution of silver atoms, leaving terrace vacancies that are filled by gold atoms. These gold atoms diffuse and agglomerate into clusters, which passivate the surface. As silver dissolves, more gold adatoms are released, leading to the formation of pits and full-blown porosity. The coalescence of gold adatoms into clusters is driven by spinodal decomposition, a process where composition fluctuations lead to lower free energy. The spacing between these clusters corresponds to the characteristic length scale of the porous structure. The motion of the alloy-electrolyte interface is described by the flux of diffusing adatoms, interface velocity, and concentration accumulation rate. The Cahn-Hilliard equation models the diffusion during spinodal decomposition, and the interface response function describes the velocity of the interface based on gold concentration and overpotential. The results show that the characteristic length scale of porosity decreases with increasing driving force, consistent with both simulations and experiments. The analysis also highlights the analogy between this process and two-dimensional island nucleation during vapor phase deposition, where adatoms agglomerate into islands. The study provides insights into the mechanisms of nanoporosity formation and the role of spinodal decomposition in dealloying processes.