(TiVCrZrHf)N coatings were deposited on Si substrates by reactive magnetron sputtering system. Their oxidation behaviors and structure were studied after static oxidation tests in air at different temperatures. The evolution of the chemical composition, microstructure, nanohardness, and electrical resistivity of these coatings after annealing at different temperatures in air was systematically analyzed. The as-deposited coating showed continued variation in structure from amorphous to columnar with the face-centered cubic crystal phase, but had no significant change in structure with increased annealing temperature to 300 °C. The hardness of the coating was stable at a high value of 31.24 GPa up to an annealing temperature of 300 °C. However, a thin oxide overlayer was observed at 400 °C, which increased in thickness at 500 °C and thus drastically decreasing the hardness to 11.85 GPa. Above 600 °C, the coating was almost fully oxidized and became quite porous and loose. Accordingly, a very low hardness of only 2.3 GPa was obtained. The electrical resistivity of the coatings followed the same trend as the hardness. The electrical resistivity of the as-deposited coating was about 144 μΩ-cm, followed by an apparent increase to 100 Ω-cm due to the formation of oxide phases.
