Mechanical properties and high temperature oxidation resistance of (AlCrTiV)N coatings synthesized by cathodic arc deposition

High entropy alloy nitrides (AlCrTiV)N coatings were deposited by cathodic arc evaporation at various deposition bias and temperature. The mechanical properties of the as-deposited coatings and their oxidation resistance after annealing at various temperatures were analysed. X-ray analyses show in all coatings a FCC structure with a (111) preferred orientation up to 750 °C. Up to 600 °C, no oxygen penetration is measured in the films while at 800 °C, critical spalling occurs for all samples. The coating deposited at a temperature of 300 °C and negative bias of 100 V exhibits the most interesting compromise in both oxidation resistance and mechanical performances with a hardness of 40 GPa, a friction coefficient of 0.44 and a wear rate of 5.8 · 10−7 mm3·N−1·m−1. Annealing in air at 600 °C for 2h reduces the wear rate to 2.1 · 10−7 mm3·N−1·m−1 and the surface hardness to 17 GPa. Although annealing forms a thin oxide layer that reduces the hardness on the surface of the coating, it also averages the hardness inside the film to 33 GPa regardless of the deposition bias.