Fabrication and characterization of electrodeposited nanocrystalline Ni–Fe alloys for NiFe2O4 spinel coatings

Abstract

Nanocrystalline Ni–Fe FCC alloy coatings with Fe content of 1.3%–39% (mass fraction) were fabricated on the nickel substrates using a DC electrodeposition technique. The crystal structure, lattice strain, grain size and lattice constant of the Ni–Fe alloy coatings were studied by X-ray diffraction technique. The chemical composition and surface morphology of the FCC Ni–Fe alloy coatings were investigated with the energy dispersive X-ray spectroscopy (EDS) and atomic force microscopy (AFM). The results show that the Fe content of the Ni–Fe alloy coatings has a great influence on the preferred orientation, grain size, lattice constant and lattice strain. FCC Ni–Fe alloy coatings exhibit preferred orientations of (200) or (200)(111). With an increase of Fe content, the preferred growth orientation of (200) plane is weakened gradually, while the preferred growth orientation of (111) increases. An increase of the Fe content in the range of 1.3%–25% (mass fraction) results in a significant grain refinement of the coatings. Increasing the Fe content beyond 25% does not decrease the grain size of FCC Ni–Fe alloys further. The lattice strain increases with increasing the Fe content in the FCC Ni–Fe alloys. Since the alloys with Fe content not less than 25% has similar grain size (∼11 nm), the increase in the lattice strain with the increase of Fe content cannot be attributed to the change in the grain size.