Increase in rate of electrodeposition and in Ni(II) concentration in the bath as a way to control grain size of amorphous/nanocrystalline Ni-W alloys

Calculations based on the equilibria involved have been carried out to find the conditions of the highest possible solubility of Ni(II) in an ammonia-citrate bath for the electrodeposition of amorphous/ nanocrystalline Ni-W alloys. The appropriate increase in the concentration of citrate, followed by the corresponding increase in the concentration of Ni(II), has led, under the conditions of constant current, to the increase in the efficiency of the electrodeposition and therefore the rate of electrodeposition by 3.2 times. The amorphous alloys obtained in solutions of different Ni(II) concentrations had different sizes of nanocrystals (15-100 Angstrom), as determined from X-ray diffractograms, and different alloy compositions (10-19.5 at% of W), but were of similar high hardness.