| Abstract Scope |
A multi-phase-field model is proposed to investigate the porous structure evolution during electrochemical dealloying of binary alloys. The Allen-Cahn equations and modified Cahn-Hillard equations are established to govern phase transformation, bulk and surface diffusion, and chemical reactions. It is found that a thermal noise term disturbed the initial stability of the dealloying front by the heterogeneous nucleation of the porous phase. The growth of porous clusters further exposes the interior inert element to the electrolyte, leading to a constant dealloying velocity of porous structural growth. By investigating the effect of dealloying temperature, chemical content of the electrolyte, and precursor alloy composition, we demonstrate the complex pattern evolution of porous structure from the competition between the corrosion-induced surface roughening and diffusion-induced surface smoothing. The characteristics of porous structural evolution, such as dealloying velocity, ligament size, and residual inert element content under different dealloying conditions, are in good agreement with experimental observations. |