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In this paper, detailed properties of Ti-Al-Si-N nanocomposite films doped with Cu additive at various concentrations are studied and followed with careful discussion. Deposited on high speed steel substrates with the assistance of vacuum cathode arc ion plating, the film composition and crystallinity can be controlled by changing the target composition. Then the film structure, chemical and phase composition, mechanical and tribological properties are characterized by X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), field emission scanning electron microscope (FESEM) and high resolution transmission electron microscopy (HRTEM), atomic force microscopy (AFM), nanoindentation and Rockwell indenter. The results indicate that with increasing copper content in the film systems, a reduction of the grain size and a deterioration of the preferred orientation were detected by XRD and HRTEM. Furthermore the film hardness H and the elastic modulus E decrease from 35 +/- 6 to 13 +/- 1 GPa and from 286 +/- 26 to 163 +/- 13 GPa, respectively. The ratio H-3/E-2 is calculated on basis of measurements of hardness H and Young's modulus E. The adhesive strength between the film and the substrate is strongly improved, compared to others without Cu additive, as well as the tribological performance of the films. This whole study implies that these Cu-doped nanocomposite films deserve some cautiousness before its application for wear resistance. (C) 2011 Elsevier B.V. All rights reserved.