Effect of nitrogen flow ratios on microstructure and mechanical properties of nanocomposite Ti-Si-N thin flims

In this study, the nanocomposite Ti-Si-N thin films were prepared by reactive magnetron co-sputtering system. The Ti-Si-N film is a mixed composite consisting of the Ti-Si, Ti-N and Si-N compounds. The TiN phase is polycrystalline while SiNx is amorphous. As Si is added to the Ti-N compound to form Ti-Si-N, the microstructure becomes nanocrystalline grains embedded in an amorphous matrix i.e. nanocomposite quasi-amorphous microstructure, which is also affected by the nitrogen flow ratio (FN₂%) during co-sputtering. Therefore, the aim is to study the evolution of microstucture and mechanical properties of Ti-Si-N at different FN₂%. The thickness, structure, morphology, chemical composition and mechanical properties of films were characterized by alpha-stepper profiler, Grazing Incidence X-ray Diffraction (GIXRD), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS) and nanoindenter, respectively. The experimental result shows that the deposition rate decreased with increasing N₂ flow rate. According to Scherrer´s formula, the grain size of films was below 5 nm. The surface morphology each film was very smooth due to fine grains. The maximum hardness was 21.5 GPa and H³/E*² ratio was 0.321 at 7 FN% which was found at the transformation between polycrystalline and amorphous phases.