Super-hard and anti-corrosion (AlCrMoSiTi)N_x high entropy nitride coatings by multi-arc cathodic vacuum magnetic filtration deposition

Super-hard and corrosion-resistant (AlCrMoSiTi)N_x high-entropy nitride coatings were prepared using a novel multi-arc cathodic vacuum magnetic filtration deposition at different N₂ gas flow rates (R_N) of 0, 20, 50 and 70 sccm. The influence of R_N on the element composition, phase structure, mechanical, tribological and corrosion properties of the coatings were systematically studied. Higher R_N promoted higher N contents in the coatings that resulted in a transformation from an amorphous to face-centered-cubic (FCC) phase. At a high N content of 49 at. % (R_N = 70%), the coating exhibits a simple FCC structure, and offers a superior combination of super-hardness, excellent wear and corrosion resistance. The exceptional hardness of the (AlCrMoSiTi)N coating (41.6 GPa) that surpasses most high-entropy ceramics is underlain by the formation of strong metal-nitride phase, the solid-solution strengthening and the fine grain strengthening. Therefore, (AlCrMoSiTi)N_x nitride coating presents a potential application in protective coating owing to its extraordinary mechanical properties and corrosion resistance.