Super-hard and well-tough (TiZrVCrCoNi)Nx high entropy nitride coatings with biphasic nanocomposite structure

High entropy nitride (HEN) coating is a new choice to replace traditional nitride as a protective coating. Through rational composition design, (TiZrVCrCoNi)Nx HEN coatings under different N2 gas flow rates (RN) were fabricated by multi-target magnetron co-sputtering deposition. The increasing RN enhanced N content in the HEN coatings, which influences the structural, mechanical, and corrosion characteristics of the coatings. The increase of N content caused the phase structure to transform from an amorphous phase to a face-centered-cubic (FCC) phase in the coatings. At a high N content of 47.7 at.% (RN = 15 sccm), the coating with a biphasic nanocomposite structure exhibits a high-quality combination of super-hardness, good toughness, anti-friction property, and excellent corrosion resistance. While the hardness can reach the super-hard level (40.9 ± 0.75 GPa), the toughness is not decreased much (3.35 ± 0.08 MPa m1/2). Besides, the corrosion current density of it (1.86 × 10−8 A/cm2) is nearly two orders of magnitude lower than 304 stainless steel (1.24 × 10−6 A/cm2). Therefore, (TiZrVCrCoNi)Nx HEN coatings present outstanding mechanical properties and corrosion resistance, which have potential applications in various fields.