Enhanced mechanical properties and corrosion resistance of (TiAlTaCrZr)N coating via amorphous-nanocrystalline heterostructure design

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An amorphous-nanocrystalline dual-phase multilayer structure was designed to overcome the columnar grain structure of high-entropy nitride coatings by regulating the structural evolution of TiAlTaCrZr/(TiAlTaCrZr)N multilayers with different modulation periods and ratios. Compared with the monolithic (TiAlTaCrZr)N coating, the multilayer coating exhibits a maximum toughness improvement of 38.9% while maintaining a low wear rate of 1.987 × 10 −6 mm 3 ·N −1 ·m −1 . In a 3.5% NaCl solution, the corrosion current density decreases from 3.186 × 10 −7 A·cm −2 to 6.75 × 10 −8 A·cm −2 . The amorphous TiAlTaCrZr layer suppresses the V-shaped growth of columnar grains in the high-entropy nitride layer and promotes significant grain refinement through interface-mediated growth regulation. The restriction of dislocation motion by grain boundaries, together with the strengthening effect arising from refined grains, synergistically enhances the toughness of the coating without compromising its hardness. In addition, the abundant grain boundary interfaces and the disordered structure of the amorphous layer effectively hinder the diffusion of oxygen atoms and corrosive ions, thus enhancing the oxidation resistance and corrosion resistance of the coating. This study provides a novel materials design strategy for high-performance protective tool coatings.