Mechanical Properties and Corrosion Resistance of NbTiAlSiZrN_x High-Entropy Films Prepared by RF Magnetron Sputtering

In this study, we designed and fabricated NbTiAlSiZrN_x high-entropy alloy (HEA) films. The parameters of the radio frequency (RF) pulse magnetron sputtering process were fixed to maintain the N₂ flux ratio at 0%, 10%, 20%, 30%, 40%, and 50%. Subsequently, NbTiAlSiZrN_x HEA films were deposited on the 304 stainless steel (SS) substrate. With an increasing N₂ flow rate, the film deposited at a R_N of 50% had the highest hardness (12.4 GPa), the highest modulus (169 GPa), a small roughness, and a beautiful color. The thicknesses of the films were gradually reduced from 298.8 nm to 200 nm, and all the thin films were of amorphous structure. The electrochemical corrosion resistance of the film in a 0.5 mol/L H₂SO₄ solution at room temperature was studied and the characteristics changed. The HEA films prepared at N₂ flow rates of 10% and 30% were more prone to corrosion than 304 SS, but the corrosion rate was lower than that of 304 SS. NbTiAlSiZrN_x HEA films prepared at N₂ flow rates of 20%, 40%, and 50% were more corrosion-resistant than 304 SS. In addition, the passivation stability of the NbTiAlSiZrN_x HEA was worse than that of 304 SS. Altogether, these results show that pitting corrosion occurred on NbTiAlSiZrN_x HEA films.