Effect of Al content on the hardness and thermal stability study of AlTiN and AlTiBN coatings deposited by HiPIMS

Abstract

The microstructure, mechanical properties and thermal stability of Al x Ti 1− x N and Al 1 Ti 1-x BN coatings grown by reactive high-power impulse magnetron sputtering (HiPIMS) have been analyzed as a function of Al/(Al + Ti) ratio (x) between 0.5 and 0.8. The coatings were predominantly formed by a face-centered cubic Ti(Al)N crystalline phase, both with and without B, even for x ratios as high as 0.6, which is higher than the ratio typically encountered for Al x Ti 1− x N coatings deposited by reactive magnetron sputtering. B doping, in combination with the highly energetic deposition conditions offered by HiPIMS, results in the suppression of the columnar grain morphology typically encountered in Al x Ti 1− x N coatings. On the contrary, the Al x Ti 1− x BN coatings grown by HiPIMS present a dense nanocomposite type microstructure, formed by nanocrystalline Ti(Al) N domains and amorphous regions composed of Ti(Al)B 2 and BN. As a result, high-Al content (x ≈ 0.6) Al x-Ti 1− x BN coatings grown by HiPIMS offer higher hardness, elasticity and fracture toughness than Al x Ti 1− x N coatings. Moreover, the thermal stability and the hot hardness are substantially enhanced, delaying the onset of formation of the detrimental hexagonal AlN phase from 850 • C in the case of Al 0.6 Ti 0.4 N, to 1000 • C in the case of Al 0.6 Ti 0.4 BN.

Influence of Isothermal Annealing on Microstructure, Morphology and Oxidation Behavior of AlTiSiN/TiSiN Nanocomposite Coatings

“…In the XRD pattern of the as-deposited coating, peaks (111) and (002) corresponding to cubic (Ti,Al)N were identified ( Figure 7 a). The peaks were also found in previous studies [ 21 , 30 , 33 , 34 , 35 , 36 , 37 , 38 , 39 , 40 , 41 ], sometimes with slightly shifted 2θ values. This shift is caused by substitution of Ti by Al, and possibly Si, and also due to the effects of crystallite size and internal stresses [ 30 ].…”

Effects of Al, Ti, and Cr content with different interlayer configurations on tribological behavior of AlCrN and AlTiN multilayer coatings

“…Therefore, hardness reduction didn't occur due to the phase transformation. Mendez et al 37 found that the hardness of AlTiN coatings with high Al concentration is greater than that of AlTiN coatings with low Al content.…”

“…Although the hardness values of coatings B, C, and D were found to be consistent with the literature, coating A's hardness was found to be significantly low. [35][36][37] The Daimler-Benz Rockwell-C adhesion test was used to determine the degree of coating-substrate adhesion. 38,39 The indentation trace was inspected after the adhesion test to identify fractures or delamination surrounding the trace and ranked between HF-1 and HF-6 where the HF-1 to HF-3 accepted adhesion levels for the coatings (see Figure 3).…”

“…Therefore, hardness reduction didn't occur due to the phase transformation. Mendez et al 37 found that the hardness of AlTiN coatings with high Al concentration is greater than that of AlTiN coatings with low Al content. SEM cross-section images were obtained from Coatings A and C, on the other hand, had a higher total coating thickness of 3.37 ± 0.1 µm and 3.54 ± 0.1 µm, respectively, when compared to coatings B and D. Coating D had three AlTiCrN interlayers with a total thickness of 375 nm, whereas coating C had just one AlTiCrN interlayer with a thickness of 1.76 ± 0.1 µm (see Figure 5 (c) and (d)).…”

Selective Metal Ion Irradiation Using Bipolar HIPIMS: A New Route to Tailor Film Nanostructure and the Resulting Mechanical Properties

“…The TiAlN deposition rate is calculated to be approximately 2.5 µm/h. Based on the previous results in the same batch coater, it is assumed that most of the film material would be deposited when the substrate faces the operating magnetron (in this case, the TiAl DCMS), thus, a TiAlN nano-layer of a maximum thickness of 3.3 nm would be deposited on each pass (approximately 8 ML) [12]. Still, it is well known for batch coaters that a certain degree of depositing material reaches the substrate in off-angle positions or at positions very distant from the ignited magnetron, so further investigations to identify the accurate nano-layer thickness should be carried out by, for example, transmission electron microscopy.…”