Cross-sectional Nanoindentation Research Articles

Nano-, micro- and macro-indentation tests of thermal spray WC-Ni coatings with lamellar microstructure at different particle deposition temperatures

The mechanical properties of WC-Ni coatings by HVOF thermal spraying were comprehensively evaluated by indentation tests at a wide load range of 10−1-103 N, i.e. nano-, micro- and macro-indentations. The correlation between process parameters and coating microstructure and mechanical properties was characterized via particle deposition temperature. The coating microstructure changes in reduced porosity, enhanced WC phase decomposition and better splats flattening were correlated to the particle deposition temperature rising. A porosity divergence between coating surface and cross-section was found as a quantitative anisotropy indicator to coating intrinsic lamellar microstructure formed by the splats flattening and piling up. Considering the lamellar microstructure, indentation responses on coating surface and cross-section were compared for hardness and elastic modulus evaluation below 3 N. The surface hardness is higher than that of cross-section, and both increased correlatively to the particle deposition temperature rising except for the almost constant surface hardness below 1 N. An analogous particle temperature-dependent behavior was also manifested for the elastic modulus by nano-indentation below 1 N. Interestingly, the elastic modulus by coating surface micro-indentation at 30 N presented identical particle temperature dependence to that by coating cross-section nano-indentation, both consistently representing the overall coating elastic modulus change trend verified by non-destructive ultrasonic test. Indentation fracture toughness on coating surface under 1.96 kN and on coating cross-section under 49 N was comparatively evaluated, and the values had a reverse trend of dependence on the particle deposition temperature. The particle-deposition-temperature dependent mechanical properties were interpreted by the coating intra-splats and inter-splats defects reduction with enhanced carbide-metal bonding essentially determined by the melting state of the metal binder phase, providing an insight to utilize indentation tests for characterizing thermal spray coatings.

Adhesion strength of ductile thin film determined by cross-sectional nanoindentation

Cross-sectional nanoindentation (CSN) is a powerful tool for measuring the adhesion strength of thin films. However, a quantitative assessment of interfacial properties for metal thin films on brittle substrates remains a challenge due to thin film ductility. In this work, we present a hierarchical analysis method to account for plastic dissipation during delamination. According to our observations, the CSN-induced wedge geometry is more complex than what is currently presented in literature. Therefore, we develop a three-dimensional finite element (FE) modelling strategy to simulate CSN-induced delamination. Furthermore, we present the mode mixity distribution during CSN measurement based on our simulation results. We find that a purely experimental assessment of adhesion strength by CSN for ductile thin films is imprecise due to the adhesion strength-dependent stress-state in this characterization technique. By using our combined experimental and numerical approach, the adhesion strength of EBPVD-deposited Al thin film on SiO2/Si substrate is determined as 0.577 J/m2 and an additional 20 nm thick Ti adhesion layer enhances its adhesion strength to 16.4 J/m2.

Preparation of silicon carbide and tantalum carbonitride composite with high hardness and moderate elastic modulus by laser chemical vapor deposition for anti-erosion protective coatings

Maintaining the harness of silicon carbide (SiC), while reducing Young's modulus of ceramic coatings is crucial for developing highly durable coating systems. This study demonstrated the growth of SiC and tantalum carbonitride (TaCN) composite films with high hardness and low modulus using laser-assisted chemical vapor deposition (CVD) with metal-organic precursors. The effects of deposition temperature on phases, chemical compositions, binding states, microstructures and mechanical properties were investigated. The film prepared at a deposition temperature of 1100 °C were grown at a deposition rate of 81.8 μm h−1, which comprised low-crystallinity SiC and TaCN grains smaller than 10 nm finely mixed and dispersed each other, forming a nanometric mosaic structure. The cross-sectional nanoindentation tests revealed a reduced Young's modulus (E*) of 238.2 GPa and a hardness (H) of 30.4 GPa, corresponding to H/E* and H3/E*2 values of 0.127 and 0.493 GPa, respectively. The SiC–TaCN nanocomposite film exhibited superior durability in erosion tests using a zirconia slurry at 20 kPa, compared with a monolithic SiC film and a silicon nitride substrate.

Wear Mechanisms of Cold-Sprayed Stellite-6 During Reciprocated Dry Sliding Under Different Sliding Speeds

Cobalt–chromium alloys are often employed in those environments that require reliable wear and friction properties. Cold Gas Dynamic Spray offers the opportunity to obtain good quality deposits of Stellite-6, that can be successfully used in harsh environments, where good surface performance, in terms of wear resistance, is required. It is also well-known that Stellite-6 is subjected to several physical changes at the interface during dry sliding, that are often related to the loading conditions. As a consequence, wear behavior of this alloy can undergo some variations that linear models are not able to capture, since micro-structural modifications occur during operation. To better understand the wear mechanisms of cold-sprayed Stellite-6 coatings together with the occurring physical phenomena, a systematic experimental study was performed, in fact, to date, no such in-depth tribological studies have been performed. Tests were conducted under combinations of two sliding speeds (0.1 and 0.5 m/s) and four contact pressure in the range of 2-5 MPa. In low-speed tests, abrasive wear is evident, where detachment and pull-out phenomena mainly affect the worn surface of coatings. On the other hand, subsurface cracking was observed in high-speed tests, as well as evidence of plastic deformation on the wear surface. These results suggest that observed wear mechanisms are more likely a consequence of adhesive wear. Unique to this study, the cross-sectional nano-indentation tests showed how the stiffness of the coating, near to wear interface, increases significantly in the case of the lowest value of sliding speed (i.e., v = 0.1 m/s), whereas tends to decrease at high speeds, i.e., v = 0.5 m/s, as a consequence of the formation of subsurface cracks into the coating.

The Effect of Nanosilver Sodium Fluoride on the Mechanical and Physiochemical Properties of Artificially Demineralised Dentin.

To synthesise and characterise nanosilver sodium fluoride (NSSF) and assess the effect of applying this formulation in vitro on artificially demineralised root dentin lesions, compared with the application of silver diamine fluoride (SDF), sodium fluoride (NAF) or no treatment, in terms of mechanical, chemical and ultrastructural properties. NSSF was prepared using 0.5 wt% chitosan solution. On 40 extracted human molars, the buccal aspect of the cervical thirds of roots were prepared and divided into 4 groups of 10 each: control (no treatment), NSSF, SDF and NaF (n = 10). The specimens were examined using scanning electron microscopy (SEM), atomic force microscopy (AFM), and x-ray photoelectron spectroscopy (XPS). Fourier transform infrared spectroscopy (FTIR), surface and cross-sectional microhardness and nano-indentation tests were performed to determine the mineral and carbonate content, microhardness, and nanohardness, respectively. Statistical analysis was performed to determine the differences between the different treatment groups for the set parameters using parametric and non-parametric tests. Tukey's and Dunnet's T3 post-hoc tests were further used for multiple comparisons between groups (α = 0.05). The control group (no treatment) was found to have statistically significantly lower mean scores for surface and cross-sectional microhardness compared with all other test groups (NaF, NSSF and SDF) (p < 0.05). Spearman's rank correlation test showed statistically insignificant differences between the mineral-to-matrix ratio (M:M) and carbonate content of all groups (p < 0.05). Treatment of root lesions with NSSF yielded comparable results to SDF and NaF under in-vitro conditions.

Delamination Criteria for SiN/TiW Interfaces Tested by Cross-Sectional Nanoidentation and by Four Point Bending

Interfaces between different material layers are potentially weakest links of microelectronic devices. Therefore, reliable criteria for delamination of structures are required as prerequisite of design optimization. In the present article, delamination of adjacent material layers is studied experimentally and by FEM simulation. An interface between SiN and TiW was delaminated by Cross-Sectional Nanoindentation (CSN) and by Four Point Bending. The adhesion energy observed during CSN is determined by FEM simulation using a method of equivalent loads, which compares CSN with a peel test. In a second approach, delamination during Four Point Bending is simulated by Mixed Finite Elements based on Strain Gradient Elasticity. The Mixed Elements were implemented in ABAQUS with user subroutine UEL. In this approach, the delamination criterion can be defined with use of a critical elastic energy density. The accordance between experiments and theoretical models is demonstrated.

Interfacial adhesion strength of III-N heterostructures

Wide bandgap semiconductors such as group III-nitrides and SiC are considered as key materials for the fabrication of smaller, more reliable and efficient power electronics. Fabrication of robust and durable power devices requires an optimized design based on the understanding of the interfacial adhesion properties of the constituent thin-film heterostructures. In this study, the adhesion properties of GaN/AlN layers grown on Si substrates were investigated. Particularly, the influence of the AlN buffer layers, necessary for GaN growth on Si, on the delamination response was determined. The interfacial adhesion strength was obtained using cross-sectional nanoindentation (CSN) and four-point bending (4PB) tests. Analytical models based on beam- and elastic plate theory which were applied respectively to calculate the interfacial fracture energy (Gic) for both methods are found to be in good agreement provided the loading conditions are similar. Detailed transmission and scanning electron microscopy investigations prior and subsequent to delamination reveal the microstructural details of the relevant interfaces and provide insights into the encountered mechanisms of interfacial failure. Finally, the probability of delamination along the weakest interface is discussed based on a fracture mechanics model.

Microstructure and wear behavior of inductive nitriding layer in Ti–25Nb–3Zr–2Sn–3Mo alloys

In human implant materials, beta (β) titanium alloys have been extensively used because of their excellent biocompatibility and lower elasticity modulus; however, they have poor hardness and wear resistance. Herein, vacuum induction nitriding technology is used to strengthen the surface of a Ti–25Nb–3Zr–2Sn–3Mo (TLM) alloy. The nitriding layer microstructure is characterised using X-ray diffraction (XRD), scanning electron microscopy (SEM)–energy dispersive spectrometry (EDS) and optical microscopy (OM). The mechanical properties of nitriding layer are tested using cross-sectional hardness gradient and nano-indentation. Furthermore, the wear resistance and mechanism of nitriding layer are examined using a self-made reciprocating wear tester, a three-dimensional (3D) profilometer and SEM, respectively. The results demonstrate that an approximately 30-μm thick nitriding layer is formed on the TLM alloy surface after induction nitriding treatment. Interestingly, it forms a gradient structure that can improve the hardness and wear resistance of samples. Moreover, at a maximum test load of 10 N, the abrasion loss of the raw sample is 463 times that of the nitriding sample. Furthermore, the friction coefficient of the raw sample significantly exceeds that of the nitriding sample at three test loads. The wear mechanism between the friction pair Al 2 O 3 ball and the raw sample is primarily a combination of abrasive and adhesive wear, whereas that of the nitriding sample is primarily abrasive wear. The results demonstrate that the nitriding layer significantly improves the wear performance of TLM alloys. • The surface of TLM alloy can be rapidly strengthened by induction nitriding. • The gradient strengthening layer can be formed by induction nitriding. • The formation of gradient structure has excellent performance in improving the wear resistance of TLM alloy.

An Analytical Model for Oblique Cross Section Nanoindentation of Ion‐Irradiated Metallic Alloys Based on Studies of Oxide Dispersion Strengthened Steel MA957

Herein, oblique cross section (OCS) nanoindentation is used to measure the hardness changes in He2+ ion‐irradiated oxide dispersion strengthened (ODS) steel MA957, to obtain the hardness profile through the thickness, and correlate it with the damage dose profile. Following this, the dispersed barrier hardening (DBH) model is implemented to calculate the hardness of each layer of the irradiated material, based on the displacement damage and He concentration from simulations. Next, a simplified analytical model for the measured hardness at different depths is developed with the assumption that the plastic zone under the indenter is hemispherical and the hardness measured at any given depth depends on the average hardness of the plastic zone volume. This analytical model is implemented with the help of a program written in MATLAB. The calculated hardness profile is compared with the experimental profile, and it is found to be in reasonably good agreement for different energies of the irradiating He ions. This model can be used not only for ion‐irradiated materials with varying doses in different layers but also for other metallic materials with surface layers having diffuse interfaces.

Adhesion Properties of Thin Film Multilayers: Comparison of Nanoindentation and Four-Point-Bending Techniques

In this study, we investigated the adhesion strength of SiO2/SiN/TiW/Cu film stacks on silicon by the use of cross-sectional nanoindentation (CSN) technique. The delamination occurred along the SiN/TiW interface as determined by means of SEM and EDX analysis. The critical energy release rate was determined as a quantitative measure of the adhesion strength by application of analytical models as well as Finite Element Method (FEM). Comparative measurements on samples of the same layer composition using the well-established four-point bending (4PB) technique were performed to validate the results of the CSN measurements. FEM was performed to calculate the loading conditions and stress distribution in the samples. The calculations also allowed separating the contribution of plastic and elastic energy in the metallization layers during delamination testing and thereby estimating the value of the interfacial adhesion energy. The experimental results show the good applicability of both the 4PB and CSN method for determining quantitative values of the fracture toughness of thin-film interfaces found in microelectronic components and indicate a good agreement between the two methods.

Metals by Micro-Scale Additive Manufacturing: Comparison of Microstructure and Mechanical Properties.

Many emerging applications in microscale engineering rely on the fabrication of 3D architectures in inorganic materials. Small-scale additive manufacturing (AM) aspires to provide flexible and facile access to these geometries. Yet, the synthesis of device-grade inorganic materials is still a key challenge toward the implementation of AM in microfabrication. Here, a comprehensive overview of the microstructural and mechanical properties of metals fabricated by most state-of-the-art AM methods that offer a spatial resolution ≤10 μm is presented. Standardized sets of samples are studied by cross-sectional electron microscopy, nanoindentation, and microcompression. It is shown that current microscale AM techniques synthesize metals with a wide range of microstructures and elastic and plastic properties, including materials of dense and crystalline microstructure with excellent mechanical properties that compare well to those of thin-film nanocrystalline materials. The large variation in materials' performance can be related to the individual microstructure, which in turn is coupled to the various physico-chemical principles exploited by the different printing methods. The study provides practical guidelines for users of small-scale additive methods and establishes a baseline for the future optimization of the properties of printed metallic objects-a significant step toward the potential establishment of AM techniques in microfabrication.

Chip formation and tribological behavior in high-speed milling of IN718 with ceramic tools

Advanced ceramics exhibit excellent mechanical properties at elevated temperatures suggesting them as plausible cutting tool materials for machining of heat-resistant superalloys. However, despite numerous efforts to date, relative brittleness of ceramic tools can result in chipping or catastrophic failure, especially during an intermittent process where excessive thermo-mechanical alteration occurs, like high-speed face milling. Previous studies by the authors revealed that in high-speed milling of inconel with SiAlON tools, after surpassing a certain cutting speed where extreme levels of strain rates and temperatures exist, the IN718 machinability transforms drastically, showing a significant reduction in cutting force, chipping and tool wear. Following this observation, in the current paper, an attempt has been made to further investigate the phenomena acting at the shear deformation zones through analysis of chip formation mechanisms and tool-workpiece tribosystem. Numerous characterization techniques have been used in this research, such as cutting force measurements, chip cross-section studies, SEM/EDS, TEM, and nanoindentation. Results suggest that a reduction in material flow strength occurs at the extreme conditions of the cut, showing similarities to fluid flow in TEM images of the tool face. Increasing the cutting speed generally facilitates chip formation; However, a rise in cutting force by further increasing the speed, and excessive generation of unstable built-up layers practically limits the cutting speed. Additional XPS studies show that variation in cutting speed also changes the frictional response of the tool-workpiece tribosystem by forming lubricious and thermal-barrier tribofilms.

Cross-sectional nano-indentation of ion-irradiated steels: Finite element simulations based on the strain-gradient crystal plasticity theory

In this work, the cross-sectional nano-indentation of ion-irradiated steels is simulated by the crystal plasticity finite element method. Two dominant features, including the non-uniform irradiation hardening and indentation size effect, are characterized by considering the influence of inhomogeneously distributed irradiation defects and geometrically necessary dislocations within the framework of strain-gradient crystal plasticity theory. The theoretical model is applied for ion-irradiated 304 stainless steel. Both the fitted and predicted macroscopic mechanical responses are compared with experimental data under different irradiation conditions, which include the force-depth (F−h) and hardness-depth (H−h) relationships under surface nano-indentation, and hardness as a function of the distance from the irradiated sample surface (H−x) under cross-sectional nano-indentation. A good agreement is achieved that can validate the rationality and accuracy of the proposed model. Furthermore, the three-dimensional relationship of H−x−h is analyzed under cross-sectional nano-indentation, which indicates that the hardness of ion-irradiated materials depends on both the distribution of defect density in the irradiated layer and indentation position with respect to the irradiated and indented sample surface. Moreover, the evolution of different hardening mechanisms is addressed in details, which can help obtain a sophisticated comprehension of the fundamental mechanisms that result in irradiation hardening and indentation size effect.

Ratcheting wear of a cobalt-chromium alloy during reciprocated self-mated dry sliding

Cobalt-chromium alloys find usage in environments where reliable wear and friction properties are required. However, the sliding wear particles generated presents significant health risks in nuclear and medical applications. Thus, there is great motivation to develop cobalt-free alternatives. These alloys are known to undergo several physical changes at the interface during dry sliding, sensitive to the loading conditions and environment. Due to these micro-structural alterations, the wear behaviour of the alloy is modified, which linear Archard-like wear models do not capture. To better understand the wear performance a cobalt-chromium alloy in-situ, and to aid their replacement, a mechanistic model of wear would be desirable. To understand the essential physical phenomena required in the modelling of cobalt-chrome systems, a systematic experimental study was performed for a hot-isostatically pressed cobalt-chromium hard-facing alloy. To date, no such in-depth self-mated tribological study has been conducted for this alloy under these processing conditions. Tests were done under combinations of sliding speed (0.02–0.5 m/s) and normal load (40–1000N). Platelet wear and subsurface cracking was seen in all tests, with considerable work-hardening in the subsurface, as well as evidence of plastic deformation at the wear surface. These results suggest the platelet wear observed is more likely a consequence of a plastic ratcheting mechanism, known as ‘ratchetting wear’, and not delamination wear. Unique to this study, the cross-sectional nano-indentation study showed the stiffness of material at and below wear interface to drop significantly. The changes in material properties and a plastically-driven wear mechanism have implications for the development of a mechanistic wear model.

A hardening model for the cross-sectional nanoindentation of ion-irradiated materials

In this paper, a hardening model is developed for the cross-sectional nanoindentation of ion-irradiated materials. The model is based on the derivation of an average defect density within the formed plasticity affected region, which depends on the distribution of defect density in the irradiated region, indentation depth and distance from the irradiated sample surface. A succinct parameter calibration process is proposed by comparing the theoretical results with experimental data at a given indentation depth. A good agreement with experimental data can be achieved for both the fitted relationship between irradiation hardening and indentation distance from the irradiated sample surface under cross-sectional nanoindentation, and predicted hardness as a function of indentation depth under surface nanoindentation. Therefore, the rationality and accuracy of the proposed model are effectively verified. Based on the analysis of this proposed model, it is available to characterize the property of plasticity affected region and irradiation depth of ion-irradiated materials based on the experimental data measured through cross-sectional nanoindentation.

Oblique cross-section nanoindentation for determining the hardness change in ion-irradiated steel

In this study, the authors have applied the “Oblique Cross Section” or OCS method, for the determination of the hardness changes in ion irradiated 316 stainless steel. The steel sample was irradiated with 1, 2 and 3 MeV He2+ ions. The samples were then polished at an angle of ∼15° from the ion irradiated surface, and the hardness on the cross-section was tested using nanoindentation in non-continuous stiffness measurement mode (non-CSM) at various distances from the ion irradiated surface. A profile of the hardness versus depth from the irradiated surface was thus obtained. It is shown that this method is quite suitable for single energy ion irradiation, when the energy is relatively high (≥1 MeV He in stainless steel), as it gives a better match between the damage peak and hardness peak locations than the “Top-down” method. The hardness profiles can be divided into two broad regions, viz. the pre-damage-peak plateau, and the peak hardness region. The results are contrasted with finite element (FE) models. The FE modelling shows formation of a secondary plastic zone in the unirradiated material beyond the irradiated layer, which was verified by cross-sectional transmission electron microscopy (TEM). Other aspects of the deformation below the nanoindents were also studied and illuminated by cross-sectional TEM. Thus, both experimental techniques and theoretical methods are employed here to elucidate the deformation processes and hardness measurement results, thereby establishing a more profound understanding of this relatively uncommon, but potentially powerful method for testing the mechanical property changes in ion irradiated materials, and of thin-layered materials in general.

Micro mechanical testing of candidate structural alloys for Gen-IV nuclear reactors

Ion irradiation is often used to simulate the effects of neutron irradiation due to reduced activation of materials and vastly increased dose rates. However, the low penetration depth of ions requires the development of small-scale mechanical testing techniques, such as nanoindentation and microcompression, in order to measure mechanical properties of the irradiated material. In this study, several candidate structural alloys for Gen-IV reactors (800H, T91, nanocrystalline T91 and 14YWT) were irradiated with 70 MeV Fe9+ ions at 452 °C to an average damage of 20.68 dpa. Both the nanoindentation and microcompression techniques revealed significant irradiation hardening and an increase in yield stress after irradiation in austenitic 800H and ferritic-martensitic T91 alloys. Ion irradiation was observed to have minimal effect on the mechanical properties of nanocrystalline T91 and oxide dispersion strengthened 14YWT. These observations are further supported by line broadening analysis of X-ray diffraction measurements, which show a significantly smaller increase in dislocation density in the 14YWT and nanocrystalline T91 alloys after irradiation. In addition, good agreement was observed between cross-sectional nanoindentation and the damage profile from SRIM calculations.

He ion implantation induced He bubbles and hardness in tungsten

The pure tungsten was implanted with 500 keV helium (He) ions to a fluence of 1.0 × 1017 ions/cm2 at RT and 800 °C. After the implantation, cross-sectional transmission electron microscope (TEM) and nano-indentation measurements were used to investigate the He bubbles and hardness profiles induced by He implantation. Visible He bubbles were observed only in the damage peak region at RT but in the whole damage region at 800 °C. The size of He bubbles at 800 °C increased with increasing depths. With increasing the implantation temperature from RT to 800 °C, the size of He bubbles in the damage peak regions increased. The nano-indentation tests indicated that hardening was induced by He implantation at RT and 800 °C. The implantation induced peak hardness values were the same at both temperatures, but the hardness peaks moved to the surface with increasing temperatures. The formation of He bubbles and the contributions of their distribution and sizes to the hardness were discussed.

Hardness of AISI type 410 martensitic steels after high temperature irradiation via nanoindentation

The hardness of irradiated AISI type 410 martensitic steel, which is utilized in structural and magnetic components of nuclear power plants, is investigated in this study. Proton irradiation of AISI type 410 martensitic steel samples was carried out by exposing the samples to 3 MeV protons up to a 1.0 × 1017 p/cm2 fluence level at a representative nuclear reactor coolant temperature of 350 °C. The assessment of deleterious effects of irradiation on the micro-structure and mechanical behavior of the AISI type 410 martensitic steel samples via transmission electron microscopy-energy dispersive spectroscopy and cross-sectional nano-indentation showed no significant variation in the microscopic or mechanical characteristics. These results ensure the integrity of the structural and magnetic components of nuclear reactors made of AISI type 410 martensitic steel under high-temperature irradiation damage levels up to approximately 5.2 × 10-3 dpa.

Combinatorial refinement of thin-film microstructure, properties and process conditions: iterative nanoscale search for self-assembled TiAlN nanolamellae.

Because of the tremendous variability of crystallite sizes and shapes in nano-materials, it is challenging to assess the corresponding size-property relationships and to identify microstructures with particular physical properties or even optimized functions. This task is especially difficult for nanomaterials formed by self-organization, where the spontaneous evolution of microstructure and properties is coupled. In this work, two compositionally graded TiAlN films were (i) grown using chemical vapour deposition by applying a varying ratio of reacting gases and (ii) subsequently analysed using cross-sectional synchrotron X-ray nanodiffraction, electron microscopy and nanoindentation in order to evaluate the microstructure and hardness depth gradients. The results indicate the formation of self-organized hexagonal-cubic and cubic-cubic nanolamellae with varying compositions and thicknesses in the range of ∼3-15 nm across the film thicknesses, depending on the actual composition of the reactive gas mixtures. On the basis of the occurrence of the nanolamellae and their correlation with the local film hardness, progressively narrower ranges of the composition and hardness were refined in three steps. The third film was produced using an AlCl3/TiCl4 precursor ratio of ∼1.9, resulting in the formation of an optimized lamellar microstructure with ∼1.3 nm thick cubic Ti(Al)N and ∼12 nm thick cubic Al(Ti)N nanolamellae which exhibits a maximal hardness of ∼36 GPa and an indentation modulus of ∼522 GPa. The presented approach of an iterative nanoscale search based on the application of cross-sectional synchrotron X-ray nanodiffraction and cross-sectional nanoindentation allows one to refine the relationship between (i) varying deposition conditions, (ii) gradients of microstructure and (iii) gradients of mechanical properties in nanostructured materials prepared as thin films. This is done in a combinatorial way in order to screen a wide range of deposition conditions, while identifying those that result in the formation of a particular microstructure with optimized functional attributes.