Structure and properties of arc evaporated nanoscale TiN/MoN multilayered systems

Using vacuum-arc evaporation method we fabricated periodic multilayered TiN/MoN structures with different bilayer periods λ ranging from 25 to 100 nm. Rutherford backscattering (RBS), X-ray diffraction (XRD), scanning electron microscopy (SEM) as well as transmission electron microscopy (TEM) and microhardness measurements were used for investigations of composition, structure and mechanical properties of the multilayered coatings. We found that molybdenum nitride and titanium nitride layers grown on steel show local partial epitaxy and columnar growth across interfaces. A molybdenum-titanium carbide interlayer was evidenced between the substrate and the multilayer. Molybdenum nitride and titanium nitride layers contain small (5-30 nm) grains and are well crystallized with (100) preferred orientation. They were identified as stoichiometric fcc TiN and cubic γ-Mo2N. Non-cubic molybdenum nitride phases were also detected. The hardness of the obtained structures achieved great values and maximal hardness was 29-31 GPa for multilayered structure with 50 nm period. Hardness of the obtained coatings is 25% higher in comparison with initial single-layer nitride coatings, wherein plasticity index (H/E) of multilayered structure is 0.075.