Thermomechanical properties and oxidation resistance of Ce–Si alloyed Ti–Al–N thin films. (August 2019)

• Record Type: Journal Article
• Authors: Asanuma, H.; Klimashin, F.F.; Polcik, P.; Kolozsvari, S.; Riedl, H.; Mayrhofer, P.H.
• Is Part Of: Vacuum. Volume 166(2019)
• Page Start: 231
• Page End: 238
• Publication Date: 2019-08
• Subjects: Ti1–xAlxN -- Cerium -- Silicon -- Thermal stability -- Oxidation resistance; Vacuum -- Periodicals; 621.55
• DOI: 10.1016/j.vacuum.2019.05.016
• Languages: English
• ISSNs: 0042-207X

Abstract

Abstract: Within this study, we show that single-phase face centered cubic (fcc) Ti0.47 Al0.46 Ce0.02 Si0.05 N coatings (sputtered from Ti0.37 Al0.57 Ce0.02 Si0.04 targets plus the addition of Ti) outperform their single-phase fcc Ti0.49 Al0.51 N counterparts (sputtered from Ti0.40 Al0.60 targets plus the same addition of Ti). The deposition rate increases by more than 43% and also the hardness of as-deposited Ti0.47 Al0.46 Ce0.02 Si0.05 N coatings is with 39.9 ± 1.2 GPa (on sapphire) 13% higher. Furthermore, this Ce–Si alloyed coating shows a remarkably higher thermal stability, represented by a higher annealing temperature (1200 °C instead of 900 °C) after which hexagonal structured wurtzite-type AlN (w-AlN) can be detected. They also show a more parabolic like oxide growth rate (4.13·10 −7 and 1.13·10 −5 μm 2 /s at 850 and 950 °C) during the 10-h-oxidation experiment, whereas that of Ti0.49 Al0.51 N is close to linear already at 850 °C (especially after ∼2 h). The postponed w-AlN formation guarantees that the hardness of Ti0.47 Al0.46 Ce0.02 Si0.05 N is still 40.8 ± 1.6 GPa even after annealing at 1100 °C. Our results clearly demonstrate that the addition of 2 mol% CeSi2 to Ti–Al targets allows to increase the sputter rate and leads to Ce–Si alloyed nitride coatings with improved thermomechanical properties and oxidation resistance. Highlights: Alloying Ti–Al targets with 2 mol% CeSi2 allows to increase the sputter rate. The Ce–Si alloyed Ti–Al–N coating shows a significantly higher thermal stability. The hexagonal AlN formation upon annealing, is postponed from 900 to 1200 °C when Ti–Al–N is alloyed with Ce–Si. The oxidation resistance of Ce–Si alloyed Ti–Al–N is considerably higher than that of Ti–Al–N.