Microstructure, mechanical and corrosion properties of TiN/Ni nanomultilayered films

Nanomultilayered TiN/Ni thin films with different bilayer periods (57.8–99.7 nm) and Ni single-layer thickness (3.9–19.2 nm) were prepared by alternatively sputtering Ti and Ni targets in N 2 gas atmosphere. The microstructure, mechanical and corrosion properties of the multilayer films were investigated by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), X-ray photoelectron spectroscopy (XPS), nanoindenter and electrochemical technologies. The multilayer films are fine with a mean grain size of ~ 8–9 nm independent of the bilayer period. However, the smoothness and compactness seem to decrease with the bilayer period increasing. The hardness ( H ) and elastic modulus ( E ) of the multilayer films gradually decrease as the bilayer period increases, and the multilayer film with bilayer period of 57.8 nm exhibits higher H , ratios of ( H / E ∗ and H 3 / E ∗ 2 ) ( E ∗ is effective Young’s modulus) than the monolithic TiN film and the other multilayers. The multilayer films exhibit an obvious passivation phenomenon in 10% H 2 SO 4 solution, and the passive current and corrosion current densities decrease, whereas the corrosion potential increases when the bilayer period or Ni single-layer thickness decreases. It is found that the passivating behavior and corrosion potential of the multilayers are more sensitive to Ni single-layer thickness than the bilayer period. More corrosion pits and lamellar flaking could be found on the films with larger bilayer period or Ni single-layer thickness.