Microstructural investigations of polycrystalline Ti2AlN prepared by physical vapor deposition of Ti-AlN multilayers

Ti2AlN is a prominent ternary nitride and belongs to the class of nanolaminated Mn + 1AXn phase materials which combine metallic and ceramic properties. In this work we report on the successful synthesis of polycrystalline Ti2AlN thin films with a preferential (000l) orientation on a polycrystalline Al2O3 substrate by depositing multiple Ti-AlN double layers and applying a subsequent annealing step. Investigations with scanning electron microscopy (SEM), X-ray diffraction (XRD), electron back scatter diffraction (EBSD) and Raman spectroscopy reveal a successful transformation of the multilayer system into a polycrystalline and dense Ti2AlN coating with a thickness of 2.7 mm. The observed grains are plate-like shaped with an in-plane size of about 100 to 300 nm and a thickness of 30 to 60 nm. Furthermore EBSD measurements proof that these macroscopic grains have a preferred orientation in the [000l] direction. We believe that a (000l)-textured microstructure will lead to new applications for protective coatings on polycrystalline substrates.