Electroplating of Ni₄W

Nickel-tungsten alloys were electrodeposited on stationary working electrodes from a nickel sulfate, sodium tungstate, and tri-sodium citrate-based bath under different operating conditions. The microstructure of the deposits was studied by X-ray diffraction, the morphology by scanning electron microscopy and atomic force microscopy, and the approximate composition by energy dispersive spectroscopy. Different Ni-W phases, either amorphous or crystalline, were associated with different plating conditions. A body-centered tetragonal Ni₄W phase was formed only at high temperatures and low current density. This is the first time that the formation of this phase by electroplating was observed repeatedly.