Morphological, Microstructural and Magnetic Characteristics of Electrodeposited Ni-Fe-W-Cu Alloy Powders

Nanostructured Ni-Fe-W-Cu alloy powders were electrodeposited from an alkaline ammonium citrate solution on a titanium cathode. Powder particles were dendrite- and cauliflower-shaped. The dendritic particles had a high density of branches made up of interconnected globules. XRD analysis showed that the powder contained an amorphous matrix and FCC nanocrystals of the solid solution of Fe, W and Cu in Ni. As the deposition current density increased, the mean nanocrystal size decreased, and the mean value of internal microstrain and the total weight percent of Fe and Ni in the alloy increased. The powders deposited at higher current densities exhibited higher magnetization. During annealing at temperatures up to 460 degrees C, the powders underwent short-range ordering, which caused an increase in magnetization, whereas at temperatures above 460 degrees C, the magnetization decreased due to the formation of large FCC crystalline grains.