Microstructure and mechanical properties of reactively sputtered Ti–Si–N nanocomposite films

A series of Ti–Si–N nanocomposite films with different Si content were deposited by reactive sputtering in a gas mixed with Ar, N2 and SiH4. Energy dispersive spectroscope, X-ray diffraction, transmission electron microscope and nanoindentation technique were employed to characterize the microstructure and mechanical properties of the films. The results reveal that Ti–Si–N nanocomposite films with different Si content can be easily obtained by controlling SiH4 partial pressure in the mixed gas. With Si content ranging from 4 at.% to 9 at.%, the films are strengthened and reach the highest hardness and elastic modulus of 34.2 GPa and 398 GPa, respectively. With a further increase of Si content, the mechanical properties of films decrease gradually. The microstructure of Ti–Si–N films with high hardness shows the existence of TiN nanocrystals surrounded by Si3N4 interphase. The grain size of TiN is about 20 nm and the thickness of Si3N4 interphase is less than 1 nm.