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

• Nitrogen addition transforms the crystalline structure of FeCoCrMnNi thin films into an amorphous structure at higher N2 flow rates, significantly altering their microstructure. • Surface roughness is dramatically reduced from 5.58 nm to 1.82 nm with nitrogen incorporation, leading to smoother and more uniform film surfaces. • Mechanical properties are enhanced: hardness increases from 8.75 GPa to 12.67 GPa, while Young's modulus decreases from 257.37 GPa to 194.39 GPa with 1 sccm N2. • Corrosion resistance of the coatings on 304SUS is improved by nitrogen addition, offering potential for protective applications in corrosive environments.