Production of high-entropy TiAlVNi-(N) coatings, investigation of their structural, mechanical, tribological, and corrosion properties

High entropy alloys (HEA), also known as multi-component alloys, have attracted great attention in recent years due to their unique compositions, microstructural properties, and tunable characteristics. Within the scope of this thesis study, TiAlVNi-(N) high entropy alloy films were produced by using the closed-field unbalanced magnetron sputtering method with the Taguchi L9 (3³) experimental design. The structural, mechanical, tribological, adhesion, and corrosion properties of TiAlVNi-(N) HEA films were investigated. The chemical compositions of the produced TiAlVNi-(N) films were determined to be in the range of 8.3–30.1%. It was also determined that the film structure of the TiAlVNi-(N) films was dense and homogeneous, and the film thicknesses varied between 1.538–1.971 µm. The produced TiAlVNi-(N) HEA films were found to be amorphous in structure, and heat treatment was applied at 850 °C for transformation into a crystalline structure. After heat treatment, strong TiN and VN phases and, in addition to these, the presence of intermetallic phases were observed in the XRD analyses of TiAlVNi-(N) HEA films. XPS results confirmed that TiN and VN phases were present in the film structure. After heat treatment, TiAlVNi-(N) HEA films exhibited high mechanical properties with the highest hardness value of 27.6±1.4 GPa and an elastic modulus of 438.1±30.7 GPa. Tribological test results showed that after heat treatment, the wear rates of TiAlVNi-(N) HEA films were at the levels of 10-5–10-6, providing high resistance to wear. In addition, the adhesion values of TiAlVNi-(N) HEA films, which reached the highest level with a critical load value of 89 N after heat treatment, revealed the positive effect of heat treatment on the films. When the corrosion properties were examined, after heat treatment, TiAlVNi-(N) HEA films reached the lowest corrosion rate of 0.248x10-6 mm.yr-1 and the highest polarization resistance value of 1,039,402 Ω.cm2.