Structure and properties of duodenary (TiVCrZrNbMoHfTaWAlSi)N coatings by reactive magnetron sputtering

Abstract

The influence of the N2-to-total (N2+Ar) ratio (RN) on the structure and properties of duodenary (TiVCrZrNbMoHfTaWAlSi)N coatings with markedly high mixing entropy is investigated. The coatings are deposited by DC reactive magnetron sputtering with an equimolar TiVCrZrNbMoHfTaWAlSi target. No external bias and heating are applied to the substrate. An increase in RN contributes to an increase in N concentration, residual stress, and lattice parameter. At low RN, the coatings have an amorphous structure. When RN is 15%, an FCC nanocrystal structure with (200)-preferred orientation appears. When RN increases to 20%, HCP nitride nanocrystals coexist with coarse columnar grain FCC structures with (111)-preferred orientation. As RN increases to 50%, the grain size decreases, and their preferred FCC orientation returns to (200). Given that the mechanical and electro-optical properties are strongly correlated with RN, the hardness of the coatings is enhanced up to 34.8 GPa. However, the electrical conductivity and light reflectivity at 0.62 eV deteriorate from 5319 S/cm to 62.1 S/cm and from 71.2% to 42.8%, respectively. These results provide a valuable basis for the future development of high-entropy nitrides.