Morphology and microstructure of hard and superhard Zr-Cu-N nanocomposite coatings

In the present article, we compare the morphology and microstructure of hard (<40 GPa) and superhard (>40 GPa) Zr-Cu-N nanocomposite films. It is shown that the morphology strongly depends on the Cu content in the film. The film with a low (1-2 at.%) Cu content exhibits a columnar structure. In contrast, films with a higher (>5-6 at.%) Cu content have a globular structure. The hardness of films depends on both the Cu content in the film and the structure of individual phases of the nanocomposite. The nanocomposite film of type nc-/nc-exhibits higher hardness than that of type nc-/a-; here "nc-" and "a-" denote the nanocrystalline and amorphous phases, respectively. The film of type nc-ZrN/nc-Cu with a low (1-2 at.%) Cu content exhibits the highest hardness of 50 GPa.