Effect of nitrogen addition on structural, mechanical, and corrosion properties of FeCoCrMnNiNx high entropy nitride ceramics thin films

The FeCoCrMnNiNx high entropy nitride ceramics thin films were prepared using the magnetron sputtering method, and the effects of nitrogen on the thin film properties were later examined. The addition of N2 affected the microstructure and its mechanical and corrosion properties. The addition of 2 and 3 sccm N2 by as much as 4.16 and 5.45 at% compared to the FeCoCrMnNi and 1 sccm N2 thin films changed the solid solution's crystalline structure (BCC+FCC) into an amorphous structure. The addition of nitrogen caused drastic changes to the surface morphology, creating a smoother and more uniform surface without cauliflower units. The AFM image analysis indicated that adding nitrogen reduced the surface roughness from 5.807 to 2.448 nm. Adding N2 to the CoCrFeMnNi thin film helped increase mechanical properties such as hardness, elasticity modulus, and strength. The FeCoCrMnNi thin film with a hardness of 8.75±0.5 GPa and an elasticity modulus of 257.37±11.4 GPa reached 12.67±1.2 and 194.39±12.4 GPa at 1 sccm N2. The applying coating of the CoCrFeMnNi thin film on the 304SUS increased corrosion resistance, while the addition of nitrogen to the CoCrFeMnNi thin film also improved corrosion resistance compared to the CoCrFeMnNi thin film.