Nano-structural investigation of Ti-Al-N/Mo-Si-B multilayer coatings: A comparative study by APT and HR-TEM. (November 2018)

• Record Type: Journal Article
• Authors: Aschauer, E.; Sackl, S.; Schachinger, T.; Wojcik, T.; Bolvardi, H.; Arndt, M.; Polcik, P.; Riedl, H.; Mayrhofer, P.H.
• Is Part Of: Vacuum. Volume 157(2018)
• Page Start: 173
• Page End: 179
• Publication Date: 2018-11
• Subjects: Hard coatings -- Ti-Al-N -- Mo-Si-B -- Atom probe tomography (APT) -- HR-TEM -- Spatially resolved analysis; Vacuum -- Periodicals; 621.55
• DOI: 10.1016/j.vacuum.2018.08.037
• Languages: English
• ISSNs: 0042-207X

Abstract

Abstract: Nano-composites often represent a challenge for spatially resolved analysing methods. The overlap of specific signals, for example in the mass-to-charge spectrum during atom probe tomography (APT) analysis or the intersection of electron energy loss edges in electron energy loss spectroscopy (EELS), leads to highly challenging results. Therefore, a complementary use of different techniques is essential to fully characterise a given system. Within this work, we studied our Ti-Al-N/Mo-Si-B multilayer (comprising alternating 31 nm thin arc evaporated fcc-Ti0.57 Al0.43 N layers and amorphous 6 nm thin Mo0.58 Si0.28 B0.14 layers), by high-resolution transmission electron microscopy, EELS as well as APT and completed the results by comprehensive X-ray diffraction measurements. We focused on the microstructure and crystallographic evolution during thermal loading - up to 1400 °C - and hence a detailed analytical description applying a wide set of high resolution techniques. When exposed to high temperatures, the as-deposited amorphous MoSiB layers form the oxidation resistant, intermetallic phases T1 -Mo5 Si3 and T2 -Mo5 SiB2 . The layered arrangement between Ti-Al-N and Mo-Si-B allows to postpone the formation of the comparative soft, hexagonal wurtzite type AlN (due to the decomposition of fcc-Ti1-x Alx N layers) up to 1200 °C, which is by ∼200–300 °C above the typical formation temperature of w-AlN in homogeneously grown single phase fcc-Ti1-x Alx N thin films. Highlights: Nano-layered PVD deposited Ti-Al-N/Mo-Si-B multilayer coating. Comparative use of APT, EELS and EDXS in the nm-scale range. Highly spatially resolved analysis. Retarded spinodal decomposition of fcc-TiAlN up to 1200 °C. Interrupted column boundaries of fcc-TiAlN.