LAWS GOVERNING THE SELECTIVE DISSOLUTION OF ALLOYS

Quantitative data on laws governing the initial stages of the selective dissolution of an alloy are obtained using potentiostatic, galvanostatic, and potentiodynamic methods. It is established with an example of alloys of the Sn-In system that the kinetics of the dissolution of the alloy's negative component in the initial period determines strictly the electrochemical reaction, and thereafter, the diffusion of its atoms in the solid phase, for whose description the bulk-diffusion mechanism is valid. Its characteristic features are examined as a function of the concentration of the negative component, the duration of selective dissolution, and the melting point of the alloy. Electrochemical indications of dissolution are established. It is demonstrated that the positive component, which is accumulated on the surface, determines the stationary corrosion-electrochemical behavior of the alloy, and also that it participates in the formation of new phases.