Influence of modulation ratio on the structure and mechanical properties of TiB2/TiAlN multilayered coatings

TiB₂/TiAlN multilayered coatings with various modulation ratios (t_TiB2:t_TiAlN) were grown using radio-frequency magnetron sputtering at room temperature. Nanoindentation, tester for material surface properties, and XRD were used to investigate the influence of modulation ratio on microstructure and properties of the multilayers. All multilayers showed improved mechanical properties, compared with the average value of the monolithic TiB₂ and TiAlN coatings. The multilayer with modulation ratio of 5:2 displayed the highest hardness (36 GPa) and longest time to crack during wear. A marked layer structure with the strong mixture of TiAlN (111), AlN (111), and TiB₂ (001) textures with smaller grain sizes was responsible for the enhanced hardness.