Ti-Si-N films with about 10 at.% Si were deposited onto silicon (100) substrates using inductively coupled plasma-assisted dc magnetron sputtering of Ti80Si20 target in a mixture of argon and nitrogen. X-ray diffraction, transmission electron microscopy, scanning electron microscopy, X-ray photoelectron spectroscopy and nanoindentation analysis were employed to investigate the effects of ion flux and ion energy on the structure and hardness of as-deposited films. It was found that (i) high-flux ion irradiation with energy of 20 eV caused microstructure to change from non-assisted amorphous columnar form to one where there are globular nanocrystallites of TiN (nc-TiN) embedded in amorphous Si3N4 (a-Si3N4) network; (ii) the hardness of this nc-TiN/a-Si3N4 nanocomposite film was approximately 35 GPa, significantly higher than that of monolithic TiN film of approximately 20 GPa; (iii) upon increasing ion energy the structure of Ti-Si-N film became columnar again and the hardness of film decreased markedly. (C) 2007 Elsevier B.V. All rights reserved.