Microstructure of Ni-Cu multilayers electrodeposited from a citrate electrolyte

Multilayered nickel-copper deposits were produced on rotating cylinder electrodes from a citrate electrolyte. The modulation was 20 nm and 10 nm for nickel and copper sublayers, respectively. Multilayer deposits of the same modulation were prepared using two different current densities for deposition of the copper sublayer, corresponding to kinetic control or to mixed mass transport and kinetic control of the electrode reaction. The microstructure of the Ni-Cu multilayer deposit was determined using X-ray diffraction, scanning electron microscopy and transmission electron microscopy. Depending on the applied current density for copper deposition a columnar structure of large grains, oriented in the [110] direction, or an equiaxed structure comprised of small non-oriented grains were observed. The results show that by modifying the deposition conditions for copper it is possible to alter the grain size of the multilayered alloy without changing the modulation. (C) 1997 Elsevier Science Ltd.