Annealing effects on nanostructure and mechanical properties of nanolaminated Ta-Zr coatings

► Ta-Zr multilayer coatings with a cyclical gradient concentration were fabricated. ► Ta-Zr coatings transformed to a t-ZrO2 dominated phase after annealing in 50-ppm O2-N2. ► Buckling and spalling restricted the use of the oxidized (Ta0.49Zr0.51)O2 − x coatings. ► The nanohardness of Ta-Zr coatings was raised from 5 GPa to 17 GPa after annealing. ► Re-annealing was used to evaluate the feasibility of coatings for glass molding.