Effect of pulse plating and additive on phase separation in Cu-Co nano-granular alloys

Pulse electrolysis was employed to deposit heterogeneous Cu-Co alloys from complexed sulphate-citrate electrolyte. The crystal structure, surface morphology and microstructure of the deposited alloys were analysed to understand the effect of process parameters on the deposit. X-ray and selected area electron diffraction (SAED) studies showed that as-deposited films were composed of two phases, a solid solution of face centred cubic Cu-Co phase and a hexagonal close packed Co phase. Pulse electrolysis and addition of saccharine within the electrolyte were found to enhance in forming two-phase structure. Surface morphology of the pulse current (PC) plated alloys was found to be smoother than their direct current (DC) counterparts. Presence of saccharine within the electrolyte led to further improvement in brightness of the deposits top layer. Microstructural investigations revealed that the deposited alloys were nanocrystalline in nature. Further refinement in grain size and increased homogeneity in microstructure were observed in the presence of saccharine.