Interface enhanced mechanical and thermal properties of TiSiN/TiAlN multilayers.

• TiSiN/TiAlN multilayers exhibit the epitaxial growth with coherent interfaces. • TiSiN/TiAlN multilayers release effectively the stress of TiSiN coatings. • TiSiN/TiAlN exhibit a wide temperature range of age-hardening up to 1200 °C. • TiSiN/TiAlN multilayers reveal better oxidation resistance. ga1 Multilayer architecture to optimize the properties of TiAlN coating attracts extensive interests in industrial applications. Here, the structure, mechanical and thermal properties of Ti 1−x Si x N/TiAlN (x = 0.13, 0.17 and 0.22) multilayers consisting of ~6.0 nm Ti 1−x Si x N and ~4.0 nm TiAlN sublayers as well as TiAlN monolithic coating are investigated. Ti 1−x Si x N/TiAlN multilayers with an epitaxial growth between Ti 1−x Si x N and TiAlN sublayers exhibit a similar hardness value of ~37.6 GPa, corresponding to ~30.9 GPa of TiAlN. Annealing of TiAlN coating induces an age-hardening related to spinodal decomposition, and thus conduces to a peak hardness of ~32.8 GPa at 800 °C. The coherent strain between Ti 1−x Si x N and TiAlN sublayers of Ti 1−x Si x N/TiAlN multilayers retards the thermal decomposition of TiAlN and thus broadens the temperature range of age-hardening. Therefore, the hardness of Ti 1−x Si x N/TiAlN multilayers still stay 41.1 ± 1.4 GPa even after annealing at 1200 °C, which corresponds to a low hardness of ~22.1 GPa of TiAlN coating. Furthermore, after oxidation of 10 h at 850 °C, Ti 1−x Si x N/TiAlN multilayers exhibit oxide scales of ~2.65 µm for x = 0.13, ~2.1 µm for x = 0.17 and ~1.9 µm for x = 0.22, respectively, whereas TiAlN and Ti 1−x Si x N coatings have been completely oxidized. [ABSTRACT FROM AUTHOR]