Synthesis and mechanical properties of Mo-Al-Si-N films deposited by direct current magnetron sputtering

Mo-Al-Si-N films were deposited on Si (100) wafers and hot working steel substrates by direct current magnetron sputtering using composite targets consisting of Mo, Al and Si. The chemical composition, crystalline microstructure, surface morphology and mechanical properties of films were investigated by energy dispersive spectroscopy, X-ray diffraction, field emission scanning electron microscopy, nanoindentation and wear test. The results indicate that Mo-Al-Si-N films are composed of grains with mixed crystallographic orientations. With increasing Si content from 0 to 18 at.%, the growth of (200) orientation in Mo-Al-Si-N films is promoted and that of (220) orientation is restrained, while the grain size decreases from 24.3 to 16.8 nm. At Si content of 12 at.%, the hardness and elastic modulus of films reach the maximum values of 38.2 and 390 GPa, respectively, which are due to the grain-size refinement, amorphous SiNx phase and mixed crystallographic orientations. With increasing Si content from 0 to 29 at.%, the friction coefficient of films decreases from 0.55 to 0.32 due to the grain-size refinement and amorphous SiNx phase.