Structure of nanocrystalline arc-PVD (Ti, Al)N coatings modified with nickel

The introduction of nickel into the composition of ion-plasma vacuum-arc (Ti, Al)N coatings refines nitride-phase crystallites from 100–120 to 15–18 nm when the nickel content is varied from zero to 12 at %. The size of nitride blocks is in agreement with that of ceramic-phase grains. Some (Ti, Al)N grains grow with the nickel content up to 30–35 nm. The structure changes from columnar to equiaxed during modifying the (Ti, Al)N coatings with nickel. Nickel in a coating is in an amorphous state (detected by X-ray diffraction) when its content is no more than 12–13 at %. A further increase in its content leads to the formation of the TiNi intermetallic compound, which results in structure porosity in the deposited coating. A transition zone forms at the boundary between a (Ti, Al)N–Ni coating and the VK6-alloy substrate, which is characterized by an element concentration gradient from the coating to the substrate and vice versa. © 2015, Pleiades Publishing, Ltd.