Influence of nitrogen implantation on the properties of Ti and substoichiometric TiN_x films deposited on high speed steel

Ti and TiN_x (x < 1) thin films have been deposited on high speed steel (HSS) substrates by reactive sputtering and then N⁺ implanted. The increase of the N/Ti ratio of the films during deposition is related to a decrease in their roughness, and N⁺ implantation produces another additional slight decrease of the roughness. The hardness of samples increases with the nitrogen content in the as-deposited samples; nevertheless, N⁺-implanted Ti coatings show lower values of hardness than reactive sputtered TiN_x films. α-Ti, ∈-Ti₂N, and δ-TiN phases were identified by grazing x-ray diffraction.