Microstructure, mechanical and tribological properties of Hf-Mo-Si-N films with different Si contents.

Hf-Mo-Si-N films with a series of Si contents were prepared by magnetron sputtering in a mixed Ar/N 2 atmosphere. Microstructure and surface morphologies of films were characterized by XRD, XPS, TEM and AFM. Besides, mechanical and tribological properties were evaluated. With increasing of Si addition, the phase of films transforms from single fcc Hf-Mo-N to nanocomposite structure consisted of Hf-Mo-Si-N crystalline and amorphous Si 3 N 4 phases. The Hf-Mo-Si-N film with 5.4 at.% Si content exhibits improved hardness of 38.6 GPa and enhanced toughness of 3.6 MPa·m1/2, which is ascribed to the synergistic effect of the solid solution strengthen, fine grains and interface strengthening in nanocomposite system. The precipitated amorphous Si 3 N 4 phase could hinder the cracks propagation, which results in higher fracture toughness. The low average friction coefficient of 0.37 and wear rate of 1.8 × 10−6 mm3/N are obtained from the Hf-Mo-Si-N film with 5.4 at.% Si, which is also accompanied with high value of H/E (0.14) and H3/E*2 (0.61 GPa). • Quaternary Hf-Mo-Si-N films were synthesized by DC and RF magnetron co-sputtering. • Hard yet tough nanocomposite films with dispersed a-Si 3 N 4 phases can resist crack propagation. • The proper Si-addition greatly improves tribological properties of films. [ABSTRACT FROM AUTHOR]