Interface enhanced mechanical and thermal properties of TiSiN/TiAlN multilayers

Multilayer architecture to optimize the properties of TiA1N coating attracts extensive interests in industrial applications. Here, the structure, mechanical and thermal properties of Ti1-xSixN/TiAlN (x = 0.13, 0.17 and 0.22) multilayers consisting of similar to 6.0 nm Ti1-xSixN and -.4.0 nm TiAlN sublayers as well as TiAlN monolithic coating are investigated. Ti1-xSixN/TiAlN multilayers with an epitaxial growth between Ti1-xSixN and TiAlN sublayers exhibit a similar hardness value of similar to 37.6 GPa, corresponding to similar 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 similar to 32.8 GPa at 800 degrees C. The coherent strain between Ti1-xSixN and TiAlN sublayers of Ti1-xSixN/TiAlN multilayers retards the thermal decomposition of TiAlN and thus broadens the temperature range of age-hardening. Therefore, the hardness of Ti1-xSixN/TiAlN multilayers still stay 41.1 +/- 1.4 GPa even after annealing at 1200 degrees C, which corresponds to a low hardness of similar to 22.1 GPa of TiAlN coating. Furthermore, after oxidation of 10 hat 850 degrees C, Ti1-xSixN/TiAlN multilayers exhibit oxide scales of similar to 2.65 mu m for x = 0.13, similar to 2.1 mu m for x = 0.17 and similar to 1.9 mu m for x = 0.22, respectively, whereas TiAlN and Ti1-xSixN coatings have been completely oxidized. (C) 2020 Elsevier B.V. All rights reserved.