Tribo-corrosion behavior of VAlTiCrCu high-entropy alloy film

Highlights: • BCC VAlTiCrCu HEA films were successfully synthesized by DC magnetron sputtering. • A specific spliced target with a certain order of different single metal blocks were used. • Tribo-corrosion behavior of HEA films in NaCl, H₂SO₄ and NaOH were discussed in detail. -- Abstract: In recent years, high-entropy alloy (HEA) films, with excellent comprehensive performance due to their unique structure, have received wide attention from scientists and engineers all over the world. In this work, the VAlTiCrCu HEA films with different deposition temperatures (100 °C–400 °C) were synthesized successfully on 304 stainless steel using a facile splicing target technology by magnetron sputtering. The microstructure, mechanical properties and tribo-corrosion behavior were studied in detail. It was found that the VAlTiCrCu HEA films with different deposition temperatures were all composed of a single BCC phase, which was in good agreement with the thermodynamic calculation. The VAlTiCrCu HEA films deposited at 300 °C have the best mechanical properties and corrosion-resistance. In the tribo-corrosion test, the HEA films behaved differently in NaCl, H₂SO₄ and NaOH solutions. In NaCl solution, the HEA films were seriously corroded due to the strong pitting corrosion of Cl⁻ ions despite the formation of tribo-corrosion products, while in NaOH solution, the HEA films suffered the most serious wear due to the oxidation film and corrosion products were washed away. The lowest friction coefficient and wear area were found in H₂SO₄, showing the best tribo-corrosion resistance, which was attributed to the hindering effect of SO₄²⁻ on pitting nucleation and the protection provided by the formation of tribo-corrosion products.