Characterization of nanocrystalline Co-W coatings on Cu substrate, electrodeposited from a citrate-ammonia bath

► Lower deposition current density results higher percentage of W in Ni-W coatings. ► Higher W content in Ni-W coatings results higher microhardness and wear resistance. ► The highest corrosion resistance belongs to the coating with the lowest W content. ► At lower current densities, W codeposition proceeds via reduction of its oxide film. ► At higher current densities, reduction of ternary complexes is the prevailing mechanism.