Mechanical properties of nanocomposite and multilayered Cr–Si–N sputtered thin films

We have investigated the structural and mechanical properties of polycrystalline Cr–Si–N thin films of different morphologies. The films were deposited by reactive magnetron sputtering at 510 K using two confocal targets of Cr and Si. The structure and mechanical properties of co-deposited Cr–Si–N films depend on their silicon content. Films with silicon content lower than 3 at.% are fcc Cr1−xSixN compounds with a maximum hardness of 22 GPa. On the contrary, films containing more than 3 at.% of silicon show the segregation of a SiNx amorphous phase and highly columnar morphology. These samples have low hardness values (14 GPa). The alternating deposition of CrN and a-SiNx layers disrupts this columnar structure and leads to nanocomposite films. The hardness of these films varies when the multilayer period is changed, i.e. the CrN crystallite size. A maximum hardness value (26 GPa) has been found for a nanocomposite structure composed of 4 nm CrN crystallites embedded in amorphous SiNx.