Thermal dissolution mechanisms of AlN/CrN hard coating superlattices studied by atom probe tomography and transmission electron microscopy

Tytko, Darius; Choi, Pyuck‐Pa; Raabe, Dierk

doi:10.1016/j.actamat.2014.11.004

Cited by 28 publications

(15 citation statements)

References 47 publications

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“…Furthermore, layer pinch-off at GB junctions leads to the formation of h-AlN predominantly at GB triple junctions, as verified in Ref. [19]. A high angle annular dark (HAADF) STEM image of an in-plain section of annealed c-AlN/CrN multilayers shows the microstructural changes described (see Fig.…”

Section: Resultssupporting

confidence: 70%

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Oxidation behavior of AlN/CrN multilayered hard coatings

2017

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We report on the oxidation behavior of AlN/CrN multilayers at 900 °C, deposited by radio frequency magnetron sputtering. It is shown that oxidation in this system is controlled by diffusion of Cr towards the surface and formation of Cr 2 O 3 . Cr diffusion is found to mainly occur along grain boundaries. Thus, coherent cubic AlN/CrN multilayer regions with coarse columnar grain structures are found to be oxidation resistant, whereas regions decomposed into hexagonal AlN/cubic CrN are prone to oxidation.

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Section: Resultssupporting

confidence: 70%

“…As GB triple junctions promote the formation of the h-AlN phase [19], regions with a high number of GBs enable a faster transport of Cr towards the surface. Consequently, such regions exhibit thicker oxide layers as compared to regions with lower GB density.…”

Section: Resultsmentioning

confidence: 99%

Oxidation behavior of AlN/CrN multilayered hard coatings

2017

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“…This could be due to precipitation at grain boundaries or triple junctions as has been observed during decomposition of CrN/AlN superlattices [71]. This verifies the unprecedented thermal stability increase of a metastable coating by point defect engineering.…”

Section: Resultsmentioning

confidence: 87%

Unprecedented thermal stability of inherently metastable titanium aluminum nitride by point defect engineering

Baben

Hans

Primetzhofer

et al. 2016

Materials Research Letters

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Extreme cooling rates during physical vapor deposition (PVD) allow growth of metastable phases. However, we propose that reactive PVD processes can be described by a gas-solid paraequilibrium defining chemical composition and thus point defect concentration. We show that this notion allows for point defect engineering by controlling deposition conditions. As example we demonstrate that thermal stability of metastable (Ti,Al)N x , the industrial benchmark coating for wear protection, can be increased from 800°C to unprecedented 1200°C by minimizing the vacancy concentration. The thermodynamic approach formulated here opens a pathway for thermal stability engineering by point defects in reactively deposited thin films. IMPACT STATEMENTA novel thermodynamic methodology to predict stoichiometry of coatings is utilized to increase thermal stability of today's industrial benchmark hard coating TiAlN from 800°C to 1200°C by point defect engineering. ARTICLE HISTORY

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“…The chemistry of the superlattice was investigated by atom probe tomography (APT) using a LEAP TM 3000X-HR system. Details on the experiments are given in [25]. The hardness and reduced elastic modulus of the superlattice were determined by nanoindentation at constant load of 6 μN using a Hysitron Triboindenter with a Berkovich tip.…”

Section: Methodsmentioning

confidence: 99%

Synergy of atom-probe structural data and quantum-mechanical calculations in a theory-guided design of extreme-stiffness superlattices containing metastable phases

et al. 2015

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A theory-guided materials design of nano-scaled superlattices containing metastable phases is critically important for future development of advanced lamellar composites with application-dictated stiffness and hardness. Our study combining theoretical and experimental methods exemplifies the strength of this approach for the case of the elastic properties of AlN/CrN superlattices that were deposited by reactive radio-frequency magnetron sputtering with a bilayer period of 4 nm. Importantly, CrN stabilizes AlN in a metastable B1 (rock salt) cubic phase only in the form of a layer that is very thin, up to a few nanometers. Due to the fact that B1-AlN crystals do not exist as bulk materials, experimental data for this phase are not available. Therefore, quantum-mechanical calculations have been applied to simulate an AlN/CrN superlattice with a similar bilayer period. The ab initio predicted Youngʼs modulus (428 GPa) along the [001] direction is in excellent agreement with measured nano-indentation values (408±32 GPa). Aiming at a future rapid high-throughput materials design of superlattices, we have also tested predictions obtained within linear-elasticity continuum modeling using elastic properties of B1-CrN and B1-AlN phases as input. Using single-crystal elastic constants from ab initio calculations for both phases, we demonstrate the reliability of this approach to design nano-patterned coherent superlattices with unprecedented and potentially superior properties.

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Thermal dissolution mechanisms of AlN/CrN hard coating superlattices studied by atom probe tomography and transmission electron microscopy

Cited by 28 publications

References 47 publications

Oxidation behavior of AlN/CrN multilayered hard coatings

Oxidation behavior of AlN/CrN multilayered hard coatings

Unprecedented thermal stability of inherently metastable titanium aluminum nitride by point defect engineering

Synergy of atom-probe structural data and quantum-mechanical calculations in a theory-guided design of extreme-stiffness superlattices containing metastable phases

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