The Phase Structure and Morphology of Electrodeposited Nickel-Cobalt Alloy Powders

摘要

Cobalt and nickel powders of three different compositions: Ni_(0.8)Co_(0.2), Ni_(0.55)Co_(0.45) and Ni_(0.2)Co_(0.8) were obtained by electrodepositionfrom an ammonium chloride-sulphate solution. It was shown that the microstructure and morphology of the powders depended on the deposition current density as well as on the bath composition. Amorphous powder of Ni_(0.8)Co_(0.2) was obtained at the current density higher than 200 mA cm~(-2), but nanocrystalline powders having the same composition were obtained at current densities lower than 200 mAcm~(-2). The nanocrystalline powders with lower Ni contents (0.55 and 0.2) obtained at a current density ranging from 40 mA cm~(-2) to 450 mA cm~(-2) were solid solutions of two phases, FCC (?-Ni) and HCP (á-Co) ones. The increase of the HCP phase in the powder was a result of both the Co content increase in the powder and decrease of the deposition current density.