Fabrication and characterization of CrNbSiTiZr high-entropy alloy films by radio-frequency magnetron sputtering via tuning substrate bias

CrNbSiTiZr high-entropy alloy films with different substrate bias voltages (from 0 V to -200 V) were fabricated on 304 stainless steel and Si substrates by radio-frequency magnetron sputtering. The microstructure, mechanical properties, tribological performance, and corrosion resistance were investigated in detail. Results show that all the as-fabricated films exhibit an amorphous phase. The columnar structure becomes featureless with the increase substrate bias due to re-sputtering effects and densification of the film. The film deposited at the bias of -50 V has a high residual compressive stress of -0.82 +/- 0.04 GPa and a high hardness of 12.4 +/- 0.3 GPa. The wear mechanism of the film is adhesive and slightly abrasive at low negative bias (0, -50, and -100 V), and that at high negative bias (-150 and -200 V) is abrasive. Polarization and electrochemical impedance spectrum measurements reveal that all films have a superior electrochemical corrosion resistance to the 304 stainless steel in 3.5 wt% NaCl solution, which indicates that the film can effectively protect substrate from corrosion. The values of Ecorr, i(corr), and R-po of the film deposited at the bias of -50 V are -283 mV, 0.0178 mu A/cm(2), and 2.084 x 10(6) Omega.cm(2), respectively.