Preparation,friction And Corrosion Properties Of CrNbSiTiZr High Entropy Alloy Films

In this paper,CrNbSiTiZr high-entropy alloy film was the main research object.Firstly,effects of substrate bias voltage on the morphology,microstructure,phase structure,chemical composition,mechanical properties,tribological performance,and corrosion resistance of the CrNbSiTiZr films were investigated.Secondly,the formation possibility of high-entropy alloy（CrNbSiTiZr）C was accurately predicted by analyzing thermodynamics parameters through first-principles calculation.The（CrNbSiTiZr）C high-entropy alloy film was successfully prepared using reactive radio-frequency magnetron sputtering technology.Effects of C doping on the structure,friction and corrosion properties of CrNbSiTiZr high-entropy alloy films were studied.The main conclusions were as follows:（1）Research on the influences of different substrate bias on the structure,tribological performance and corrosion resistance of CrNbSiTiZr high-entropy alloy film shows that:As the substrate bias increases,the deposition rate decreases,the mobility of surface atoms increases,the voids and pores decrease,and the film transforms from columnar to dense structure.The large atomic size difference results in severe lattice distortion,and the film exhibit an amorphous phase structure.The film deposited at the bias of–50 V reaches the maximum hardness value of 12.4±0.3GPa,and its comprehensive mechanical properties were the best.The residual compressive stress was 0.82±0.04 GPa,and the elastic modulus was 182.32±3.2 GPa.The wear mechanism of the film deposited at low negative bias（0,–50,and–100 V）was adhesive and slightly abrasive,and the friction coefficient was 0.53.The film deposited at high negative bias（–150 and–200 V）had wear-out failure during the friction process,resulting in a friction coefficient as high as 0.6,and the wear mechanism was severe abrasive.This is mainly due to lower hardness,H/E and H³/E²values of the film.All films exhibit superior corrosion resistance than AISI304L stainless steel in 3.5 wt.%Na Cl solution.This result may be due to the amorphous structure of the film and the formation of a Cr-containing passivation layer on the surface.The best was the film deposited at the bias of-50 V.The values of E_OC,E_corr,i_corr,and R_po of this film were-198.2 m V,-283 m V,0.0178μA/cm²,and 2.084×10⁶Ω?cm²,respectively.This result is due to the film has a transition structure between columnar and fine fiber structure,which can delay the corrosion solution to reach the film substrate interface.（2）Research on the effects of C doping on the on the structure,tribological performance and corrosion resistance of CrNbSiTiZr high-entropy alloy film shows that:Thermodynamic analysis and first-principles calculations obtained the mixing enthalpy and entropy values of（CrNbSiTiZr）C system were 20.29 k J/mol and 0.805 R,respectively,indicating that（CrNbSiTiZr）C is thermodynamically stable above the temperature of 3038 K.C-doped lead CrNbSiTiZr film transition from an amorphous structure to an FCC structure of Na Cl type,and the grain size of about 5 nm.The hardness of（CrNbSiTiZr）C film was as high as 32.9±0.7 GPa,and the elastic modulus was 218.7±4.3 GPa.This is because the hard binary carbide phases Ti C and Zr C were formed,and the nanocrystalline nanostructure can significantly increase the hardness,but the elastic constant was not sensitive to the structure,resulting in relatively small elastic constant.The friction coefficient of（CrNbSiTiZr）C film was as low as 0.3,and the wear rate was as low as 4.2×10^–6 mm³/N·m.This is because the transfer film was formed on the surface of GCr15 dual ball,which reduces the friction coefficient,and the high hardness,high H/E and H³/E² can reduce the wear rate values.The（CrNbSiTiZr）C film also has excellent corrosion resistance in a 3.5 wt.%Na Cl solution.The corrosion resistance of（CrNbSiTiZr）C film in 3.5 wt.%Na Cl solution was better than that of CrNbSiTiZr film.The values of E_OC,E_corr,i_corr,and R_po of this film were–28.8 m V,–189 m V,0.0026μA/cm²,and 7.72×10⁶Ω·cm,respectively.The denser structure was the main reason for the superior corrosion resistance.