Hard yet tough thermodynamics-driven nanostructured (AlCrNbSixTi)N multicomponent nitride hard coating

Breaking the hardness-toughness trade-off has always been a critical issue for hard protective coatings. Rational materials design, which simultaneously incorporate multiple strengthening and toughening me-chanisms, could provide pathways toward hard yet tough materials. In this study, (AlCrNbSixTi)N multicomponent nitride coatings with various Si content are fabricated via magnetron co-sputtering. Multi-dimensional strengthening and toughening mechanisms are found in thermodynamics-driven nanostructured (AlCrNbSixTi)N. Enhanced atomic packing, nanostructure forma-tion, and microstructural modification originate from spinodal decomposition contribute to multiple strengthening and toughening mechanisms after Si incorporation. From atomic-level packing, spinodal-decomposed nanostructure, to microstructure, the evolutions are quantitatively characterized and corre-lated to mechanical properties. With the addition of 4.4 at% of Si, maximum hardness of 27.2 GPa is achieved while maintains high fracture toughness of 3.66 +/- 0.37MPa m. On the other hand, the maximum fracture toughness is found for (AlCrNbSi7.6Ti)N and is attributed to the featureless microstructure, na-nostructure formation and non-complete amorphization. (c) 2023 Published by Elsevier B.V.