Selective dissolution (dealloying) of homogeneous metallic A,B-alloys consists in ionization and transition into electrolyte of only component - electronegative metal A. Investigation of dealloying kinetics promotes development of the anodic dissolution theory and ways of protection against corrosion of multicomponent metal systems. Dealloying leads to enrichment of dissolving alloy surface layer by the second component B and to its saturation by nonequilibrium vacancies. Non-stationary character of the process determines a choice of chrono-methods for the establishment of its rate and mechanism. In the present work selective dissolution of binary alloys is investigated at potentiodynamic (chronovoltammetric) polarization. The problem of anodic selective dissolution in the assumption that rates of diffusive mass-transport of ions in a solution and atoms in an alloy are comparable is theoretically solved. Expressions for voltammograms calculation of A,B-alloy selectively dissolving in a mixed-kinetic mode are obtained. Realization conditions of especial solid-phase diffusion transport are found. Kinetics of Ag,Au-alloys (atomic fraction of gold jcAu = 0.15-0.60) anodic dealloying in acidic nitrate environment is experimentally studied. It is found that at high potential scan rate (v) and initial concentration of silver ions in a solution (c) the kinetic mode of the process is mixed. Decrease of v and c, as well as increase of xAu promote the transition of the process from mixed into the solid-phase diffusion mode. The role of the surface segregation, initial electrode roughness and nonequilibrium vacancy subsystem relaxation in Ag,Au-alloys selective dissolution kinetics is discussed.
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