Effects of RF magnetron sputtering power on the structure and nanohardness of high-entropy alloys (TiVCrNbSiTaBY)N hard coatings

High-entropy alloys (TiVCrNbSiTaBY)N hard coatings were deposited on silicon wafers and stainless steel plates using radio-frequency (RF) magnetron sputtering. The effects of RF power on the elemental composition, morphology, structure and nanohardness of coatings are evaluated. The coatings exhibit smooth surface with low roughness less than 1 nm. Higher RF power introduces more silicon into coatings and densifies the columnar structure. The coatings present nanocomposite structure of face-centered cubic phase and amorphous Si3N4. With increasing RF power, the content of amorphous phase rises and crystal grains are refined. The changes in structure lead to a tendency for nanohardness and elastic modulus of coatings to first increase and then decrease. The coating grown at 800 W has the highest nanohardness and highest elastic modulus of ∼38.1 GPa and ∼451.2 GPa, respectively. The strengthening mechanism is explained by the nanocrystal-TiN/amorphous-Si3N4 model. The annealing treatment in air demonstrates that the coating exhibits excellent oxidation resistance at 800 °C.