Tailoring the amorphous-nanocrystalline structures of TiNbZrN_x films towards improving the anti-corrosion and mechanical properties by controlling nitrogen flow ratio

Multi-principal element alloy (MPEA) films demonstrate superior corrosion resistance and tribological properties, which have substantial potential for applications in marine engineering equipment. In this study, the TiNbZrNx MPEA nitride films were successfully deposited on 316 L austenitic stainless steel by direct current (DC) magnetron sputtering at various nitrogen flow ratio (R-N2). The phase, composition, microstructure, corrosion and mechanical behaviors were investigated in detail. The results showed that the phase transitioned from amorphous to amorphous/nanocrystalline as R-N2 increased. The TiNbZrNx films deposited at R-N2 = 0.15-0.4 exhibited better corrosion performance in the electrochemical and salt spray tests. The R-N2 = 0.4 film presented the optimal corrosion resistance, with the lowest self-corrosion current density (0.249 mu A/cm(2)) and the largest passivation zone (from OCP to >1.2 V-SCE). The amorphous/nanocrystalline film deposited at R-N2 = 0.2 showed a remarkable nanohardness of 7.03 GPa and adhesion strength of 18.86 N. The strengthening effect can be attributed to the interstitial dissolution of nitrogen atoms among the metal atoms. The formation of nitride nanocrystalline phases and the existence of interfaces can effectively improve the plastic deformation ability of amorphous alloy films. This work provides theoretical guidance for the development of MPEA nitride films with tunable properties for key moving parts in marine equipment.