Structure, composition and mechanical properties of reactively sputtered (TiVCrTaW)Nx high-entropy films

Abstract

Nitride and metallic films multi-element (TiVCrTaW)Nx high-entropy alloy were deposited on silicon wafers by pulse DC magnetron sputtering. The microstructure and mechanical properties of the films prepared with different nitrogen gas flow ratios were studied. The results show that the concentration of nitrogen approached the stoichiometric composition at nitrogen gas ratio RN ≥ 33.3 %. The alloy film deposited with pure argon atmosphere exhibited a BCC structure and a very smooth surface, while an FCC with (111) or (200) preferred orientation and granular surface morphologies was observed in those films prepared with introduction of nitrogen gas. The (TiVCrTaW)Nx films exhibited enhanced hardness upon the addition of nitrogen probably due to the solid-solution strengthening effect and grain refinement. The nitride film achieved the highest hardness and Young’s modulus of 38 GPa and 340 GPa, respectively. The results show that the deposition atmosphere plays a vital rule in the structure and the properties of the (TiVCrTaW)Nx high-entropy films.