Characterizations of super hard Cu films containing insoluble W prepared by sputter deposition

The microstructure and properties of Cu films containing insoluble W in as-deposited and as-annealed conditions have been studied. The Cu-W films consist of non-equilibrium supersaturated solid solutions of W in Cu with nanocrystalline microstructures. In this study, Cu-W films have been prepared using an RF magnetron sputter deposition technique. As the tungsten content increases, the film crystallites decrease in size, suggesting that the addition of tungsten in the Cu-W films plays an important role in the inhibition of grain growth/coalescence during deposition. Decreasing trend for the deposition rate with the tungsten content in the film is obtained. The film hardness and wear resistance properties correlate well with the microstructure and governed by the impurity effect of tungsten. Hardness and wear resistance results indicate that the strengthening of films is mainly due to the fine structure and presence of tungsten. Compared to other insoluble elements such as Mo, Ta and C, W has resulted in a better wear resistance property when the maximum soluble tungsten content is 11.1 at.% in films. (C) 2001 Elsevier Science B.V. All rights reserved.