Microstructural and elasto-plastic material parameters identification by inverse finite elements method of Ti(1−x)AlxN (0<x<1) sputtered thin films from Berkovich nano-indentation experiments (original) (raw)
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Philosophical Magazine A
A procedure to obtain the elasto-plastic mechanical properties of strainhardening materials from indentation tests, based on dimensional analysis and ®nite-element techniques, is proposed. The method is applicable to homogeneous materials and to coatings deposited on substrates of known mechanical properties. The Young's modulus of the material is extracted from the initial slope of the unloading indentation curve and the yield strength and strainhardening exponent are obtained from the maximum indentation load and the contact area after unloading. The method is used to obtain the properties of a high-alloy steel and Mo and AlSi coatings deposited on a steel substrate by plasma spraying. The sensitivity of the measurement to the depth of indentation is discussed.
The Hardness and Elastic Modulus of TiN Films as Determined by Ultra-Low Load Indentation
MRS Proceedings, 1990
The mechanical properties of a series of titanium nitride films on stainless steel substrates have been evaluated using an indentation technique with a mechanical properties microprobe (MPM). The MPM makes possible measurement of film properties without contribution by the substrate material. The titanium nitride films were deposited with a PVD technique known as sputter ion plating (SIP). Deposition substrate bias was varied from 0 to −120 V, while keeping other deposition parameters constant. With increasing negative substrate bias, dramatic increases in hardness and elastic modulus have been observed.
RELATION BETWEEN HARDNESS OF MULTILAYERED (Ti, Al)N BASED COATINGS AND PERIODS OF THEIR STACKING
2019
This study aims to model, by using a finite element method, the relationship between the hardness and the period Λ of metal/nitride multilayer coatings (Ti0.54Al0.46/Ti0.54Al0.46N)n in order to understand the increase of the hardness at the low periods [1] and then optimise the multilayer coating architecture to obtain the best mechanical properties. A 2D axisymmetric finite element model of the Berkovich nanoindentation test was developed. The coating was designed as a stacking of Ti0.54Al0.46 and Ti0.54Al0.46N nanolayers with, in the first hypothesis, equal thickness and perfect interface. The elastoplastic behaviours of the metal and nitride layers were identified by Berkovich nanoindentation experiments and inverse analysis on thick monolayer samples. The indentation curves (P-h) obtained by this model depend on the period Λ of the stacking. Simulated (P-h) curves were compared with experimental data on 2 μm thick films with different periods Λ ranging from 10 to 50 nm deposited...
Thin Solid Films, 2011
Titanium and aluminium nitride Ti 1 − x Al x N films deposited by radiofrequency magnetron reactive sputtering onto steel substrate are examined by transmission electron microscopy over all the range of composition (x = 0, 0.5, 0.68, 0.86, 1). The deposition parameters are optimised in order to grow nitride films with low stress over all the composition range. Transmission electron microscopy cross-section images of Vickers indentation prints performed on that set of coatings show the evolution of their damage behaviour as increasing x Al content. Cubic Ti-rich nitrides consist of small grains clustered in rather large columns sliding along each other during indentation. Hexagonal Al-rich films grow in thinner columns which can be bent under the Vickers tip. Indentation tests carried out on TiN and AlN films are simulated using finite element modelling. Particular aspects of shear stresses and displacements in the coating/substrate are investigated. The growth mode and the nanostructure of two typical films, TiN and Ti 0.14 Al 0.86 N, are studied in detail by combining transmission electron microscopy cross-sections and plan views. Electron energy loss spectrum taken across Ti 0.14 Al 0.86 N film suggests that a part of nitrogen atoms is in cubic-like local environment though the lattice symmetry of Al-rich coatings is hexagonal. The poorly crystallised domains containing Ti and N atoms in cubic-like environment are obviously located in grain boundaries and afford protection of the coating against cracking.
RELATION BETWEEN HARDNESS OF (Ti, Al)N BASED MULTILAYERED COATINGS AND PERIODS OF THEIR STACKING
Acta Polytechnica CTU Proceedings, 2020
This study aims to model, by using a finite element method, the relationship between the hardness and the period Λ of metal/nitride multilayer coatings (Ti0.54Al0.46/Ti0.54Al0.46N)n in order to understand the increase of the hardness at the low periods [1] and then optimise the multilayer coating architecture to obtain the best mechanical properties. A 2D axisymmetric finite element model of the Berkovich nanoindentation test was developed. The coating was designed as a stacking of Ti0.54Al0.46 and Ti0.54Al0.46N nanolayers with, in the first hypothesis, equal thickness and perfect interface. The elastoplastic behaviours of the metal and nitride layers were identified by Berkovich nanoindentation experiments and inverse analysis on thick monolayer samples. The indentation curves (P-h) obtained by this model depend on the period Λ of the stacking. Simulated (P-h) curves were compared with experimental data on 2 μm thick films with different periods Λ ranging from 10 to 50 nm deposited...
Comparison of mechanical properties of TiN thin films using nanoindentation and bulge test
Thin Solid Films, 1998
Two experimental techniques including the bulge test and depth sensing nanoindentation measurements were used to describe mechanical properties of titanium nitride (TiN x ) thin ®lms in terms of their growth morphology. Thin layers of titanium nitride (t 400±700 nm) were deposited in a RF magnetron sputtering system on the Si(100) wafers containing a layer of low stress (LPCVD) silicon nitride. Variation of the Young's modulus, hardness, and residual stresses of the TiN x ®lms versus deposition parameters such as the substrate bias voltage and nitrogen partial pressure was investigated. It was found that, in particular, the tensile residual stress of the ®lms ®rst increases with the substrate bias to a maximum, then drops to zero and converts to the compressive stress, that grows again with the negative bias. At the same time, both modulus and hardness monotonously rise with the substrate bias without any abrupt changes. The nanoindentation data extracted from dynamically loading±unloading of TiN ®lms converged to the bulge test measurements for compact coatings, but diverged from the bulge test data for porous coatings. The morphology of the ®lms were observed using scanning electron microscopy and the relationships between microstructural evolution of columns and mechanical properties of coatings are discussed in terms of deposition parameters. q 1998 Elsevier Science S.A. All rights reserved.
The effect of the substrate on the mechanical properties of TiN coatings
Surface & Coatings Technology, 2003
TiN coatings are commonly used in industry to impart improved friction and wear performance. It is widely recognised that the substrate plays an important role in determining the mechanical properties and wear resistance of such coatings. TiN coatings are usually applied to hard tool steels where there is substantial load support from the substrate. However, there are many applications where it may be desirable to apply the coatings to substrates with lower hardness or stiffness values than the conventional, hard tool-steel substrates that are commonly used. Coatings can still be effectively used in these applications. However, it is then critical to understand the transitions between where the deformation is contained solely in the coating and where it is a combination of coatingysubstrate properties that are important in determining the overall mechanical response of the system. This paper therefore reports on a systematic investigation of the effect of the substrate on the mechanical response using a range of mechanical testing techniques. A TiN coating was deposited using ion-assisted PVD onto a number of substrates with differing combinations of modulus and hardness wi.e. a range of Young's modulus (E) to yield stress (Y) EyY ratiosx. The mechanical properties of these coatings have been investigated using nanoindentation, microindentation and scratch testing, and the deformation was observed using scanning electron microscopy. In the microindentation tests, nested cracks were observed around the indentations. In the nanoindentation tests, the indentation response was found to be plasticity-dominated, with little evidence of cracking. The scratch tests showed that the scratch response was controlled by plastic deformation in the substrate, and that the friction coefficient increased as the depth of penetration into the sample increased. For the coatings here, it was observed that the indentation depthycoating thickness ratio required for the deformation to be contained within the coating was less than the usual ty10 ratio. ᮊ
Finite element modeling of nano-indentation technique to characterize thin film coatings
Journal of King Saud University - Engineering Sciences, 2017
Thin films and coatings are increasingly being used almost in every engineering field. Many properties such as tribological, strength and magnetic can be improved by application of thin film. Especially in mechanical they are being applied in engines parts, prone to worn out and corroded parts, biomedical implants and cutting tools. Under service life, these coatings may incur failure thereby resulting in loss of the system as a whole. Therefore, it is unavoidable to investigate the critical loads that lead to ultimate fracture. Among many techniques available to assess the service performance of coatings, nanoindentation technique is a versatile nondestructive and has been applied frequently for this purpose. Further, it is imperative to simulate nanoindentation by powerful FEM software to extract plenty of mechanical properties like hardness, elastic modulus, endurance loads and various parameters like optimal thickness and optimal critical load, stress distribution and contact pressure between substrate and layer can be obtained through load-displacement curve. In this article review, a detailed procedure of nanoindentation experiment and its finite element analysis have been presented and latest development in this area has been provided while keeping focus on thin films.
materials Nanohardness and Residual Stress in TiN Coatings
TiN films were prepared by the Cathodic arc evaporation deposition method under different negative substrate bias. AFM image analyses show that the growth mode of biased coatings changes from 3D island to lateral when the negative bias potential is increased. Nanohardness of the thin films was measured by nanoindentation, and residual stress was determined using Grazing incidence X ray diffraction. The maximum value of residual stress is reached at −100 V substrate bias coinciding with the biggest values of adhesion and nanohardness. Nanoindentation measurement proves that the force-depth curve shifts due to residual stress. The experimental results demonstrate that nanohardness is seriously affected by the residual stress.
Evaluation of nano-mechanical properties of hard coatings on a soft substrate
Thin Solid Films, 2012
The present study focuses on the manifestation of substrate effect while characterizing films of different hardness using nanoindentation technique. Nanoindentation tests were carried out on hard TiN and (Ti, Al)N coatings deposited on soft D9 steel substrates. Hardness of coatings was extracted from different indentation depths for revealing the substrate effect. For both coatings, hardness was found to decline with increasing indentation depths indicating the severity of substrate effect at higher depths. However, the decline in hardness was much steeper in case of (Ti, Al)N film than TiN film. Also, discontinuities (pop-ins), signature of film cracking, were observed on the load-displacement curves. Using a scanning electron microscope, surface cracks were observed near the indentation edge and inside indentation zone in both coatings. To understand the observed behavior, 2-D Finite element analysis was used to simulate the indentation process. Plastic deformation in the substrate was found to take place in the early stages in both cases resulting in an earlier decline of hardness. However, the critical depth, at which substrate started deforming plastically, was 8% and 11% of the total film thickness for (Ti, Al)N and TiN films, respectively. Interestingly, pop-ins were found to appear on the load-displacement curves only after the occurrence of yielding of the substrate in both cases. Film cracking is explained on the basis of stress distribution in the coatings during the indentation process. It is concluded that substrate effect becomes more pronounced in the case of harder films and manifests itself at early stages of indentation.