Superlattice effect for enhanced fracture toughness of hard coatings

Hahn, Rainer; Bartosik, Matthias; Soler, Rafael; Kirchlechner, Christoph; Dehm, Gerhard; Mayrhofer, P.H.

doi:10.1016/j.scriptamat.2016.06.030

Cited by 154 publications

(54 citation statements)

References 17 publications

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“…Furthermore, it was shown that in superlattice structured coatings a significant fracture toughness enhancement can be achieved (for e.g. by factor of two for the TiN/CrN system) in a way similar to the superhardening effect reported for these structures [17]. With the introduction of the novel High Power Impulse Magnetron Sputtering (HIPIMS) technique, very dense and defect free nanoscale multilayer coatings with high adhesion can be deposited.…”

Section: Introductionmentioning

confidence: 84%

“…The nanoscale multilayer structure restrains the mobility of the dislocations; hence, limited plastic deformation occurs. Additionally, the enhanced toughness of the superlattice structured coatings can also contribute to better resistance to cavitation impulse [16,17]. As the stress waves propagate through the coatings and reach the interface, they would be partially transmitted and partially reflected.…”

Section: Incubation Periodmentioning

confidence: 99%

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Cavitation erosion performance of CrAlYN/CrN nanoscale multilayer coatings deposited on Ti6Al4V by HIPIMS

Harvey

Wellman

et al. 2019

Journal of Alloys and Compounds

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Water droplet erosion (WDE) protection of Ti6Al4V turbofan blades is of paramount importance to the aviation industry. A novel CrAlYN/CrN nanoscale multilayer coating deposited by the HIPIMS technique was evaluated as a potential candidate for this application. Literature suggests a strong correlation in performance ranking under WDE and cavitation erosion (CE) tests. Hence, the WDE performance of the CrAlYN/CrN coating on Ti6Al4V was investigated with an ultrasonic cavitation device. The results show excellent adhesion and superior erosion resistance of the CrAlYN/CrN coating (erosion rate lower by a factor of 14 compared to the bare Ti6Al4V substrate) and compared to coatings reported in the literature with spallation as their main erosion mechanism. Cross-sectional FIB studies revealed formation of substrate cracks underneath 2 the coating when CE generated stresses exceeded the fatigue strength of the Ti6Al4V alloy.The interfaces of the nanoscale multilayers protected the substrate by forming an effective barrier against shock waves, delayed fatigue crack formation, deflected and arrested any cracks formed impeding the overall coating damage. The research shows that the CE resistance is influenced by the coating's texture and elastic properties, (Young's modulus).The paper discusses the erosion mechanisms of the coating and the excellent CE protection it offers.

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Section: Introductionmentioning

confidence: 84%

Section: Incubation Periodmentioning

confidence: 99%

Cavitation erosion performance of CrAlYN/CrN nanoscale multilayer coatings deposited on Ti6Al4V by HIPIMS

Harvey

Wellman

et al. 2019

Journal of Alloys and Compounds

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“…Beam width is measured at the top surface along the notch, and depth measured to the highest point of the bottom surface (i.e. as small a value as possible), as the beams show a small, but common [15], deviation from a perfect rectangle. The cantilever with a fracture toughness closest to the average value was designated as a representative beam for each material, and used for the subsequent FEM analysis.…”

Section: Micro-mechanical Testing and Dftmentioning

confidence: 99%

“…Using data from micro-cantilever bending allows the accurate determination of the CZ parameters, and additionally has been shown to be effective in the determination of fracture behaviour in TiN/CrN superlattice thin films [15]. The damage behaviour and intergranular fracture of such hard coatings was reproduced by comparing calibrated CZ simulations with coating morphologies deformed during nanoindentation [16].…”

Section: Introductionmentioning

confidence: 99%

From quantum to continuum mechanics: studying the fracture toughness of transition metal nitrides and oxynitrides

Gibson

Rezaei

Rueß

et al. 2017

Materials Research Letters

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We show here, based on VAlN, TiAlN and the related oxynitrides, that the (brittle) fracture and elastic properties may be consistently modelled from quantum-to continuum mechanics using micromechanical testing to link both scales. The measured elastic moduli match closely with those predicted by density functional theory calculations. Good agreement was also observed between the microcantilever bending experiments and cohesive-zone-finite element modelling. These scale-bridging data serve as a baseline for future improvements of the fracture toughness of these coating systems based on microstructure and coating architecture optimization. IMPACT STATEMENTWe link ab initio calculations with finite element modelling using micro-mechanical testing to consistently model the elastic and fracture behaviour of transition metal nitrides and oxynitrides. ARTICLE HISTORY

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“…Interface-induced enhancement of mechanical and/or tribologic performance beyond the limits of its individual components was further achieved for TiN/MoN, TiN/NbN, TiN/TaN, and TiN/CrN SL coatings 13,14 . Hahn et al 15 further showed that fracture toughness and hardness of TiN/CrN exhibit almost the same dependence on the bilayer period, Λ, with the fracture toughness peak at Λ ≈ 6 nm coinciding with the hardness peak.…”

Section: Introductionmentioning

confidence: 96%

Point-defect engineering of MoN/TaN superlattice films: A first-principles and experimental study

et al. 2020

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Superlattice architecture represents an effective strategy to improve performance of hard protective coatings. Our model system, MoN/TaN, combines materials well-known for their high ductility as well as a strong driving force for vacancies. In this work, we reveal and interpret peculiar structure-stability-elasticity relations for MoN/TaN combining modelling and experimental approaches. Chemistry of the most stable structural variants depending on various deposition conditions is predicted by Density Functional Theory calculations using the concept of chemical potential. Importantly, no stability region exists for the defect-free superlattice. The X-ray Diffraction and Energy-dispersive X-ray Spectroscopy experiments show that MoN/TaN superlattices consist of distorted fcc building blocks and contain non-metallic vacancies in MoN layers, which perfectly agrees with our theoretical model for these particular deposition conditions. The vibrational spectra analysis together with the close overlap between the experimental indentation modulus and the calculated Young's modulus points towards MoN0.5/TaN as the most likely chemistry of our coatings. arXiv:1905.04155v1 [cond-mat.mtrl-sci]

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Superlattice effect for enhanced fracture toughness of hard coatings

Cited by 154 publications

References 17 publications

Cavitation erosion performance of CrAlYN/CrN nanoscale multilayer coatings deposited on Ti6Al4V by HIPIMS

Cavitation erosion performance of CrAlYN/CrN nanoscale multilayer coatings deposited on Ti6Al4V by HIPIMS

From quantum to continuum mechanics: studying the fracture toughness of transition metal nitrides and oxynitrides

Point-defect engineering of MoN/TaN superlattice films: A first-principles and experimental study

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