Characterization of W–Ge–N coatings deposited by sputtering

In this work, the effect of the addition of increase Ge concentrations to W–N thin films, with different nitrogen contents, is investigated. For this purpose, W–Ge–N thin films were deposited by reactive r.f. magnetron sputtering onto Fecralloy® substrates from a W target embedded with Ge pieces in mixed Ar/N2 discharge atmospheres. The nitrogen partial pressure and the number of Ge pieces were varied, while the total pressure was kept constant at 0.7 Pa. dified surfaces were characterised in the as-deposited state. It was found that the highest hardness (43 GPa) was obtained for the W–N film with the highest nitrogen percentage (60 at.%) which presented a mixture of cubic β-W2N and hexagonal δ-WN phases. The presence of Ge induced a decrease in the hardness, independently of the nitrogen content of the films. Further, the hardness could also be correlated with the residual stress of the coatings, regardless of their chemical composition, showing different behaviours according to their crystalline or amorphous nature.