NONUNIFORM MICRODISTRIBUTION OF SOME ALLOYS AND THEIR COMPONENTS ON SHAPED AND ROUGH CATHODE SURFACES

Some features of microdistribution of copper-based binary alloys and t heir components have been studied. If the codeposition rate of the mor e electropositive component (copper) is at least partially controlled by diffusion, antilevelling takes place for the alloy as a whole. Cons iderable enrichment of the deposit with respect to the more electropos itive component is observed on micropeaks, provided the electrodeposit ion rate of the more electronegative component is nearly constant at a ll points of the microprofile (electrodeposition of Cu-Ni alloy from p yrophosphate solution). If the more electropositive component produces a depolarizing effect on the deposition of the more electronegative c omponent, microdistribution of the latter also becomes non-uniform in spite of the absence of diffusion control (Cu-Cd and Cu-Zn alloys). In this case an overall alloy microdistribution shows stronger antilevel ling; however, the composition of the deposit becomes more uniform ove r the microprofile.