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Effective strategies to improve the tarnishing resistance of the 18 K (karat) gold-based bulk glass-forming composition Au49Ag5.5Pd2.3Cu26.9Si16.3 were recently found, with the addition of Ga at the expense of Cu and a sufficient reduction of Si. However, the modification of the alloy is accompanied by a reduction of the glass-forming ability (GFA) from 5 to 2 mm in terms of the critical casting thickness, and eventually collapses for Ga contents higher than about 9 at%. In this work, thermodynamic and kinetic studies of the newly discovered 18 K Au-Ag-Pd-Cu-Ga-Si system shed light on the reason for the loss in GFA with increasing Ga content. Investigations of the liquid kinetics in terms of viscosity and transition time, assessed by three-point beam bending and the Tg-shift method, reveal an unexpected change of the fragility to stronger liquid kinetics with increasing Ga concentration, which is usually attributed to an increase in the GFA. Thermodynamic considerations based on specific heat capacity measurements reveal, in contrast, an ascending driving force for crystallization with an increasing Ga-content, accountable for the drop in GFA. Therefore, a Ga-rich melt beyond the threshold concentration of 9 at% is not desirable for the production of bulk metallic glasses (BMGs) from the liquid state. With the intention to outrun this barrier, while preserving the amorphous structure, Ga-ion implantation with a liquid metal focused ion beam source is used as a post-processing routine for a cast Ga-containing 18 K Au-BMG. Hence, the thermodynamic borderline concentration is successfully crossed with additional tremendous improvement of the tarnishing resistance in the Ga-enriched areas.

Metal-organic framework (MOF) glasses provide new perspectives on many material properties due to their unique chemical and structural nature. Their mechanical properties are of particular interest because glasses are inherently brittle, which limits their applications as structural materials. Here we perform strain-rate-dependent uniaxial micropillar compression experiments on agZIF-62, agZIF-UC-5, and agTIF-4, a series of MOF glasses with different substituting linker molecules, and find that these glasses show substantial plasticity, at least on the micrometer scale. At a quasi-static strain rate of 0.001 s-1, the micropillars yielded at approximately 0.32 GPa and subsequently deformed plastically up to 35% strain, irrespective of the type of substituting linker. With increasing strain rate, the yield strength of agZIF-62 evolved with the strain-rate sensitivity m = 0.024 to reach a yield strength of 0.44 GPa at a strain rate of 510 s-1. On the basis of this relatively low strain-rate sensitivity and the absence of serrated flow, we conclude that structural densification is the predominant mechanism that accommodates such extensive plasticity.

Pyrolytic carbon (PyC) plays a critical role in many applications for its unique properties. In ceramic composite systems, the elastic properties of PyC at the fiber/matrix interface drive toughening mechanisms, enabling structural performance at increased operating temperatures. PyC expresses a wide range of crystallographic texture depending on fabrication parameters. As a result, modelling and optimization requires direct understanding of the texture-property relationships at the relevant length scales. This research leverages high-resolution transmission electron microscopy (HRTEM) to link the PyC microstructure to the elastic response observed via digital image correlation (DIC) during micropillar compression. The HRTEM and DIC results quantitatively resolve a gradient for microstructural texture and Young's modulus respectively, showing that disordered texture increases compressive stiffness normal to the average orientation of the PyC basal planes. The values for modulus ranged from 55 to 150 GPa, which are large compared to most experimental methods, but may be more realistic considering the uniaxial stress state and length scale. The behavior supports findings from numerical homogenization models, suggesting that this advanced technique may provide a path forward for optimization and validation of these nanoscale elasticity models.

Low-dimensional Ge is perceived as a promising building block for emerging optoelectronic devices. Here, we present a wafer-scale platform technology enabling monolithic Al-Ge-Al nanostructures fabricated by a thermally induced Al-Ge exchange reaction. Transmission electron microscopy confirmed the purity and crystallinity of the formed Al segments with an abrupt interface to the remaining Ge segment. In good agreement with the theoretical value of bulk Al-Ge Schottky junctions, a barrier height of 200 ± 20 meV was determined. Photoluminescence and μ-Raman measurements proved the optical quality of the Ge channel embedded in the monolithic Al-Ge-Al heterostructure. Together with the wafer-scale accessibility, the proposed fabrication scheme may give rise to the development of key components of a broad spectrum of emerging Ge-based devices requiring monolithic metal-semiconductor-metal heterostructures with high-quality interfaces.

The interest in using high vacuum-compatible time-of-flight secondary ion mass spectrometry (TOF-SIMS) detectors integrated within focused ion beam instruments (FIB) has increased due to the possib...

State-of-the-art atomic layer deposition (ALD) thin-film technology which is well-integrated with microelectronics and beyond is currently strongly extending toward hybrid materials where organic fragments are inserted within the inorganic matrix through so-called molecular layer deposition (MLD) cycles. This allows the fabrication of nanoscale inorganic-organic superlattices and multilayers directly from the gas phase. These materials are particularly promising for enhancing the mechanical flexibility of rigid inorganics. Here we demonstrate for ALD/MLD-grown ϵ-Fe2O3/Fe-terephthalate superlattice structures that nanoscale (1-10 nm) Fe-terephthalate interlayers significantly improve the flexibility of ϵ-Fe2O3 thin films without sacrificing their unique high-coercive-field magnetic characteristics. Nanoindentation evaluation indicates that the elastic modulus can be reduced by a factor of 2 down to 70 ± 20 GPa, while in situ tensile fragmentation testing demonstrates that the crack onset strain and critical bending radius can be tuned by a factor of 3. Modeling of the tensile fragmentation patterns through Weibull statistics shows that cohesive and interfacial shear strain, following the trend for crack onset strain, increase with increasing organic content, while gains for the respective strengths are limited by the simultaneous reduction in elastic modulus. The Fe-terephthalate film exhibits high interfacial shear strain/strength and low tendency for buckling, which highlights its potential to act as an adhesion layer for the ferrimagnetic ϵ-Fe2O3 layers. The results are particularly interesting for magnetic recording applications in sustainable next-generation flexible electronics.

Atomic force microscopy (AFM) is a well-known tool for studying surface roughness and to collect depth information about features on the top atomic layers of samples. By combining secondary ion mass spectroscopy (SIMS) with focused ion beam (FIB) milling in a scanning electron microscope (SEM), chemical information of sputtered structures can be visualized and located with high lateral and depth resolution. In this paper, a high vacuum (HV) compatible AFM was installed in a TESCAN FIB-SEM instrument that was equipped with a time-of-flight SIMS (ToF-SIMS) detector. To calibrate the sputtering rate and measure the induced roughness caused by the ToF-SIMS analysis, subsequent AFM measurements were performed on an inorganic multilayer vertical cavity surface-emitting laser sample. Normalized sputtering rates were used to aid the accurate three-dimensional reconstruction of the sputtered volume's chemical composition. Achievable resolution, surface roughness during sputtering, and surface oxidation issues were analyzed. The integration of complementary detectors opens up the ability to determine the sample properties as well as to understand the influence of the Ga+ ion sputtering method on the sample surface during the analysis.

High angular resolution electron backscatter diffraction (HR-EBSD) was coupled with focused ion beam (FIB) slicing to characterize the shape of the plastic zone in terms of geometrically necessary dislocations (GNDs) in W single crystal in 3 dimensions. Cantilevers of similar size with a notch were fabricated by FIB and were deformed inside a scanning electron microscope at different temperatures (21$^{\circ}$C, 100$^{\circ}$C and 200$^{\circ}$C) just above the micro-scale brittle-to-ductile transition (BDT). J-integral testing was performed to analyse crack growth and determine the fracture toughness. At all three temperatures the plastic zone was found to be larger close to the free surface than inside the specimen, similar to macro-scale tension tests. However, at higher temperature, the 3D shape of the plastic zone changes from being localized in front of the crack tip to a butterfly-like distribution, shielding more efficiently the crack tip and inhibiting crack propagation. A comparison was made between two identically deformed samples, which were FIB-sliced from two different directions, to evaluate the reliability of the GND density estimation by HR-EBSD. The analysis of the distribution of the Nye tensor components was used to differentiate between the types of GNDs nucleated in the sample. The role of different types of dislocations in the plastic zone is discussed and we confirm earlier findings that the micro-scale BDT of W is mainly controlled by the nucleation of screw dislocations in front of the crack tip., Comment: accepted (Acta Materialia)

Nanoparticle-reinforced thin films synthesis is often limited by precipitation thermodynamics and kinetics to certain material combinations and nanoparticle size distributions. We demonstrate a new method that allows direct co-deposition of mono-sized nanoparticles with various matrix materials, independent particle size and composition control, yielding flexible material selection, and nanoparticle density spatial variations laterally and depth-wise. Tungsten nanoparticles were co-deposited into magnetron-sputtered copper, giving a uniform distribution of nanoparticles in transmission electron microscopy. To demonstrate the application potential, W nanoparticles stabilized nanograined Cu at 500 °C; pure Cu reference showed significant grain growth. This method opens new possibilities in tailored nanocomposite fabrication.

In this work, we present a comprehensive comparison of time-of-flight secondary ion mass spectrometry (TOF-SIMS) and scanning transmission electron microscopy combined with energy-dispersive X-ray spectroscopy (STEM/EDX), which are currently the most powerful elemental characterization techniques in the nano- and microscale. The potential and limitations of these methods are verified using a novel dedicated model sample consisting of Al nanoparticles buried under a 50 nm thick Cu thin film. The sample design based on the low concentration of nanoparticles allowed us to demonstrate the capability of TOF-SIMS to spatially resolve individual tens of nanometer large nanoparticles under ultrahigh vacuum (UHV) as well as high vacuum (HV) conditions. This is a remarkable achievement especially taking into account the very small quantities of the investigated Al content. Moreover, the imposed restriction on the Al nanoparticle location, i.e., only on the sample substrate, enabled us to prove that the measured Al signal represents the real distribution of Al nanoparticles and does not originate from the artifacts induced by the surface topology. The provided comparison of TOF-SIMS and STEM/EDX characteristics delivers guidelines for choosing the most optimal method for efficient characterization of nano-objects.

Structural colours have received a lot of attention regarding the reproduction of the vivid colours found in nature. In this study, metal–anodic aluminium oxide (AAO)–Al nanostructures were deposited using a two-step anodization and sputtering process to produce self-ordered anodic aluminium oxide films and a metal layer (8 nm Cr and 25, 17.5 and 10 nm of Au), respectively. AAO films of different thickness were anodized and the Yxy values (Y is the luminance value, and x and y are the chromaticity values) were obtained via reflectance measurements. An empirical model based on the thickness and porosity of the nanostructures was determined, which describes a gamut of colours. The proposed mathematical model can be applied in different fields, such as wavelength absorbers, RGB (red, green, blue) display devices, as well as chemical or optical sensors.

Microfabrication of synthetic single crystal diamond using accelerated helium ions beams has significant potential for functional applications, such as high precision optical devices, through tailoring of the optical properties via diamond graphitization. The use of helium ion microscopes (HIM) with nano-scaled focused ion beam spot sizes also allows for precision nano-patterning of the diamond surface through post-exposure selective etching of the generated graphitic phase. Here, single-crystalline diamonds with ⟨100⟩, ⟨110⟩, ⟨111⟩ and ⟨123⟩ orientations are exposed to He ion radiation from a HIM at a range of acceleration voltages and fluences. It is observed that ⟨123⟩ orientation was notably more sensitive to ion irradiation as sp3 bonds transition to sp2 bonds at lower fluence (1015 ions/cm2) compared to other orientations. In situ uniaxial compression of SC diamond micro-pillars revealed the strength of ⟨123⟩-oriented pillars is strongly dependent on the ion fluence, and thus is tunable by ion irradiation. Notably, ⟨100⟩-oriented pillars exhibit a better damage resistance as a small strength degradation due to its higher ion channeling efficiency. The irradiation damage of energetic helium ions on the structure and strength of diamond is therefore highly orientation-dependent. Such results provide the critical knowledge for precise patterning and designing of diamond-based functional structures in nano-fabrication.

The matrix effect, i.e. the dependence of element ion yield on the surrounding chemical state, is very often considered as a negative and limiting factor in elemental characterization. In fact, it is the main reason making Time-of-Flight Secondary Ion Mass Spectrometry (TOF-SIMS) a non-quantitative technique as element ionization efficiency can span over several orders of magnitude depending on the matrix. Despite that, even small chemical variations of an experimental setup can cause interpretation of TOF-SIMS depth profiles a challenging task. However, the sensitivity of element ionization to the neighboring atoms can also be very beneficial as ion yields can be enhanced in the presence of particular species such as oxygen, cesium, water and fluorine. In this work, we make an attempt to estimate the matrix effect in two-element Zr-containing alloys using TOF-SIMS. The Zr ionization efficiency as well as its response to the surface and interface contaminants was investigated depending on Al, Si and Cu matrices. It was observed that Zr ionization efficiency is over four times higher in the Si matrix than in the Cu matrix and over two times higher when compared to the results obtained in the Al matrix.

Molecular layer deposition (MLD) is a strongly emerging thin-film technique for deposition of ultra-thin inorganic-organic hybrid ("metalcone") coatings directly from the gas phase, even on complex three-dimensional surfaces. In particular alucones (Al-based hybrids) have been found interesting e.g. for Li-ion battery and gas-barrier applications owing to the promise for enhanced mechanical performance provided by the organic fragments in the materials' structure. However, the metalcones based on short/small organic fragments are relatively brittle from the mechanical perspective. Here, we demonstrate an efficient approach for tailoring mechanical properties of MLD-fabricated hybrid inorganic-organic thin films through control over the organic precursor chain length. The proof-of-concept data is presented for alucones prepared using trimethyl aluminum together with 1,6-hexanediol or 1,10-decanediol as the precursors. Tensile testing coupled with in situ optical microscopy reveals a gradual increase in stretchability with the increasing chain length, such that the crack onset strain value of 9.9 ± 0.2% is obtained for the 1,10-decanediol-based 100 nm-thick film. Through the demonstration of substantially suppressed crack propagation-as a sign of brittle-to-ductile transition-and the decrease in the elastic modulus value down to 4.6 ± 2.1 GPa, the mechanical performance of the alucone family is extended to the polymeric regime. The substantial increase in the mechanical performance within the metalcone material family makes the results particularly interesting for high-capacity high-volume-change battery electrodes requiring mechanically highly robust coatings.

Enhancing the spatial resolution of Time-Of-Flight Secondary Ion Mass Spectrometry (TOF-SIMS), which provides 3D elemental distribution in combination with high sensitivity and molecular information, is currently one of the hottest topics in the field of chemical analysis at the nanoscale. As the efficiency of the ionization process determines the possibility of imaging a sample's elemental structure in 3D, methods for enhancing secondary ion generation are of particular interest. Recently, a novel approach of combining a high-vacuum compatible compact TOF-SIMS detector with a Gas Injection System (GIS) integrated within a Focused Ion Beam (FIB) instrument has been demonstrated on pure metals. In this work, we present a comprehensive study on water vapor and fluorine gas-assisted TOF-SIMS conducted on dedicated Zr-based model samples (ZrAl, ZrSi and ZrCu) to verify whether the application scope of this method can be expanded to more complex alloys. The main concerns of potential preferential sample sputtering and sample isotope abundance content degradation caused by the introduced gas were excluded. Moreover, fluorine gas improved the accuracy of the measured Zr isotope contents. In most cases, the ion yields were significantly increased. Furthermore, gas co-injection seemed to mitigate variations in element ionization along the thin film, allowing us to obtain more representative TOF-SIMS data regarding sample composition. Compared to the results obtained under standard vacuum conditions, the alloys' sputtering rates decreased by up to 46% when using water vapor and almost doubled in the case of fluorine gas.

Zircaloy-4 (Zr-1.5%Sn-0.2%Fe-0.1%Cr wt%) is used as nuclear fuel cladding materials and hydride embrittlement is a major failure mechanism. To explore the effect of δ-hydride on plastic deformation and performance of Zircaloy-4, in situ high angular resolution electron backscatter diffraction (HR-EBSD) was used to quantify stress and geometrically necessary dislocation (GND) density during bending tests of hydride-free and hydride-containing single crystal Zircaloy-4 microcantilevers. Results suggest that while the stress applied was accommodated by plastic slip in the hydride-free cantilever, the hydride-containing cantilever showed precipitation-induced GND pile-up at hydride-matrix interface pre-deformation, and considerable locally-increasing GND density under tensile stress upon plastic deformation.

Nanocrystalline (nc) alloys are stronger than their coarse-grained versions. Here, we report ultrastrong alloys, discovered via high-throughput screening of the nc CoCr33-69 materials library. The nc materials library was fabricated using magnetron co-sputtering. The alloys consist of textured, columnar structures with grain size in the nanometric regime. We found that the texture and phase composition can be tailored by changing the Cr concentration. In the investigated region of the nc CoCr system, a relatively broad spectrum of yield strength, determined via micropillar compression tests, was found ranging from 1.41 GPa up to 3.64 GPa. The remarkable strength increment was caused by a chemically- and thermally-driven phase and microstructure evolution of the system. The strongest alloys were found in the regions containing the δCoCr phase, which was considered previously as metastable. Density functional calculations revealed that the δCoCr phase is more energetically favourable in Cr-rich regions compared to single-phase simple solid solutions (HCP, BCC). Experimental results showed that the range of its occurrence is wider than previously thought, i.e. after annealing the δCoCr phase was found above 44 at. % of Cr. We demonstrate that systematic screening of materials libraries can boost the discovery of new materials with outstanding properties.

Garnet Li7La3Zr2O12 (LLZO) is a promising solid-state electrolyte due to its wide electrochemical stability window and high Li-ion conductivity. This electrolyte has potential to be employed in the form of thin films for solid-state batteries, a promising approach in the quest for safer batteries with higher energy densities at lower fabrication costs. In this study, we use a scalable cosputtering process to fabricate LLZO thin films with subsequent postannealing at a temperature of 700 °C, significantly below the sintering temperatures employed in ceramic pellet processing. We investigate the roles that Li excess and incorporation of Al play in the film’s crystalline phase, microstructure, phase stability, and, ultimately, ionic conductivity. Our results reveal that improving the conductivity of LLZO thin films requires not only the stabilization of the cubic phase but especially the densification of the film and the minimization of the proton exchange degradation mechanism in the presence of moisture an...

Combining a Gas-Injection System (GIS) with the Focused Ion Beam (FIB) has a broad scope of applications in sample preparation such as protective layer deposition, increasing material sputtering rates, and reducing FIB-related artifacts. On the other hand, injecting certain specific gases during a Time-of-Flight Secondary Ion Mass Spectrometry (TOF-SIMS) analysis can significantly increase element ionization probability and, therefore, improve the quality of 3D representation of a sample elemental structure. In this work, for the first time, the potential of GIS for enhancing secondary ion signals acquired using a TOF detector incorporated into a commercial Ga

Free-standing solid-state ion conducting thin film membranes are key components in micro-energy conversion devices such as micro-solid oxide fuel cells or electrolyzers. Through this work, we explore the design and fabrication of thin film architectures with either straight, zigzag or spiral-shaped columnar grain nanostructures of 8 mol% doped Yttria stabilized zirconia (8YSZ) in order to modify the ceramics elastic properties and mechanical stability for MEMS integration. We report that the zigzag and spiral-shaped nanomorphologies' can be engineered with a ∼44% reduced elastic modulus. Ultimately, this results in an increased fabrication yield when the thin ionic conductor thin film structures are turned into free-standing membranes as required for different micro energy converter applications. Raman spectroscopy reveals that the symmetry is lowered by the existence of monoclinic distortions in the cubic phase which modifies the elastic moduli of films with straight columnar structures. Fundamentally, we show here evidence that for yttria-stabilized zirconia modifications in membrane nano-architectures and strain can lead to phase changes, which agrees well with findings published in the 1970s based on applied external stress's on macroscopic structures (i.e. pellets). The influence of the change in nano-morphology on the cross-plane ionic conductivity is minor. The oxygen ion conducting thin film nanomorphology design exhibits potential to optimize grain connectivity and tortuosity by growth as either columnar, zigzag or spiral-shaped morphologies, in order to obtain membranes with controllable phases and elastic moduli for micro-energy conversion devices.

Micro-pillar splitting at temperatures up to 500 °C was used to evaluate the toughness for a series of thin physical vapour deposited ceramic-nitride coatings. When compared to ion beam notched geometries, this testing approach reduces the likelihood of ion impregnation within a material volume where fracture may initiate. A toughness increase with elevated temperature was observed for the nanostructured ceramic coatings; the magnitude of which varied between the coatings. A transmission electron microscopy investigation showed deposition-specific periodic nano-layering within the films as a result of the deposition process, which may explain the observed differences in the toughness trends.

The distribution of strain in hard mode oriented lamellar stacks of the two-phase γ-TiAl/α2-Ti3Al alloy Ti-45Al-2Nb-2Mn (at.%)-0.8 vol% TiB2 was measured at several temperatures up to 633 °C by in situ micropillar compression, complemented by electron backscatter diffraction orientation mapping and digital image correlation strain mapping of a thermally stable surface Pt speckle pattern. Post-mortem transmission electron microscopy further identified the finest scale deformation structures. It was found that slip and twinning transverse to the lamellae operates within discreet bands that zigzag across the lamellar structure. The shear strain within each band is approximately constant across the pillar width. This is inconsistent with current energetic models for transverse twin formation in γ-TiAl, which assume independent, non-interacting twins. This is explained using a mathematical formulation for the stress required to operate this transverse mechanical twinning as a function of strain. This study has elucidated how the multi-scale combination of several transverse twinning systems on different {111} planes in γ-TiAl lamellae can relieve the elastic stresses generated at a lamellar interface by the primary (highest Schmid factor) twinning system. It is thought that the facilitation of this mechanism will promote the ductilisation of lamellar γ-TiAl alloys. This is crucial for an increased damage tolerance and ease of component manufacture, leading to a more widespread use of γ-TiAl alloys.

Secondary ion mass spectrometry (SIMS) is a well-known technique for 3D chemical mapping at the nanoscale, with detection sensitivity in the range of ppm or even ppb. Energy dispersive X-ray spectroscopy (EDS) is the standard chemical analysis and imaging technique in modern scanning electron microscopes (SEM), and related dual-beam focussed ion beam (FIBSEM) instruments. Contrary to the use of an electron beam, in the past the ion beam in FIBSEMs has predominantly been used for local milling or deposition of material. Here, we review the emerging FIBSIMS technique which exploits the focused ion beam as an analytical probe, providing the capability to perform secondary ion mass spectrometry measurements on FIBSEM instruments: secondary ions, sputtered by the FIB, are collected and selected according to their mass by a mass spectrometer. In this way a complete 3D chemical analysis with high lateral resolution We first report on the historical developments of both SIMS and FIB techniques and review recent developments in both instruments. We then review the physics of interaction for incident particles using Monte Carlo simulations. Next, the components of modern FIBSIMS instruments, from the primary ion generation in the liquid metal source in the FIB column, the focussing optics, the sputtered ion extraction optics, to the different mass spectrometer types are all detailed. The advantages and disadvantages of parallel and serial mass selection in terms of data acquisition and interpretation are highlighted, while the effects of pressure in the FIBSEM, acceleration voltage, ion take-off angles and charge compensation techniques on the analysis results are then discussed. The capabilities of FIBSIMS in terms of sensitivity, lateral and depth resolution and mass resolution are reviewed. Different data acquisition strategies related to dwell time, binning and beam control strategies as well as roughness and edge effects are discussed. Data analysis routines for mass identification based on isotope ratios and molecular fragments are outlined. Application examples are then presented for the fields of thin films, polycrystalline metals, batteries, cultural heritage materials, isotope labelling, and geological materials. Finally, FIBSIMS is compared to EDS, and the potential of the technique for correlative microscopy with other FIBSEM based imaging techniques is discussed.

Multiphase titanium alloys are critical materials in high value engineering components, for instance in aero engines. Microstructural complexity is exploited through interface engineering during mechanical processing to realise significant improvements in fatigue and fracture resistance and strength. In this work, we explore the role of select interfaces using in-situ micromechanical testing with concurrent observations from high angular resolution electron backscatter diffraction (HR-EBSD). Our results are supported with post mortem transmission electron microscopy (TEM). Using micro-pillar compression, we performed in-depth analysis of the role of select {\beta}-titanium (body centred cubic) ligaments which separate neighbouring {\alpha}-titanium (hexagonal close packed) regions and inhibit the dislocation motion and impact strength during mechanical deformation. These results shed light on the strengthening mechanisms and those that can lead to strain localisation during fatigue and failure.

The occurrence of plasticity below the macroscopic yield stress during tensile monotonic loading of nearly lamellar Ti-45Al-2Nb-2Mn(at%)-0.8 vol% TiB2 at both 25 °C and 700 °C, and in two conditions of lamellar thickness, was measured by digital image correlation strain mapping of a remodelled Au surface speckle pattern. Such initial plasticity, not necessarily related to the presence of common stress concentrators such as hard particles or cracks, could occur at applied stresses as low as 64% of the general yield stress. For a same applied strain it was more prominent at room temperature, and located as slip and twinning parallel to, and near to or at (respect.) lamellar interfaces of all types in soft mode-oriented colonies. These stretched the full colony width and the shear strain was most intense in the centre of the colonies. Further, the most highly operative microbands of plasticity at specimen fracture were not those most active prior to yielding. The strain mapping results from polycrystalline tensile loading were further compared to those from microcompression testing of soft-mode stacks of lamellae milled from single colonies performed at the same temperatures. Combined with post-mortem transmission electron microscopy of the pillars, the initial plasticity by longitudinal dislocation glide was found to locate within 30–50 nm of the lamellar interfaces, and not at the interfaces themselves. The highly localised plasticity that precedes high cycle fatigue failure is therefore inherently related to the lamellar structure, which predetermines the locations of plastic strain accumulation, even in a single loading cycle.

The potential of a novel caesium evaporator for enhancing negative secondary ion yields during Focused Ion Beam Time-Of-Flight Secondary Ion Mass Spectrometry (FIB-TOF-SIMS) elemental analysis is presented. The design of the lab prototype Cs evaporator is based on alkali metal dispensers containing a stable Cs salt and therefore it can be safely used for FIB-TOF-SIMS measurements under high vacuum conditions. Continuous in-situ Cs0 deposition on an Au sample surface has allowed the TOF-SIMS signal to be increased by a factor of 260, which confirms the functionality of the technique. A series of tests were conducted in positive and negative ion detection modes to study the response of the system to currents applied on Cs dispensers and generated Joule heating. A stable Cs flux (represented by a Cs+ signal measured with the TOF-SIMS) was achieved over around 1.5 h when using two Cs dispensers simultaneously. Moreover, the presence of Cs0 has enabled the stability of an enhanced Si− signal measured by the TOF-SIMS to be maintained over several hours. This time is much longer than a typical duration of FIB-TOF-SIMS depth profiling, thus the presented method exhibits the potential for studying heterogeneous and multi-layer structures in a three-dimensional space.

We report on the effect of aging on the mechanical properties of molecular layer–deposited (MLD) thin films. We studied the mechanical failure of the films during uniaxial tensile testing and observed a sixfold difference in the crack-onset strain (COS) and related flexibility within the first two days after the samples were exposed to ambient air. The MLD films made using trimethylaluminum and ethylene glycol are notorious for exhibiting structural changes after the fabrication; we show that these changes are detrimental for mechanical robustness of the films. This information aids to plan the handling or the protection of these films to achieve better performance with these materials. The interfacial shear strains and COSs of the shortly air-exposed 300-nm-thick films were observed to be roughly 0.3% and 1.8%, respectively. These values are the highest reported so far for hybrid organic–inorganic MLD thin films and would extrapolate to about 14% COS for 5-nm-thick film, indicating potential applications as interfacial adhesion layer for films on polymer substrates and as a protective coating in battery applications.

Tungsten carbide cobalt hardmetals are commonly used as cutting tools subject to high operation temperature and pressures, where the mechanical performance of the tungsten carbide phase affects the wear and lifetime of the material. In this study, the mechanical behaviour of the isolated tungsten carbide (WC) phase was investigated using single crystal micropillar compression. Micropillars in two crystal orientations, 1-5 ${\mu}$m in diameter, were fabricated using focused ion beam (FIB) machining and subsequently compressed between room temperature and 600 {\deg}C. The activated plastic deformation mechanisms were strongly anisotropic and weakly temperature dependent. The flow stresses of basal-oriented pillars were about three times higher than the prismatic pillars, and pillars of both orientations soften slightly with increasing temperature. The basal pillars tended to deform by either unstable cracking or unstable yield, whereas the prismatic pillars deformed by slip-mediated cracking. However, the active deformation mechanisms were also sensitive to pillar size and shape. Slip trace analysis of the deformed pillars showed that {10-10} prismatic planes were the dominant slip plane in WC. Basal slip was also activated as a secondary slip system at high temperatures., Comment: accepted version - International Journal of Refractory Metals and Hard Materials (2021)

In this work, we present the potential of high vacuum-compatible time-of-flight secondary ion mass spectrometry (TOF-SIMS) detectors, which can be integrated within focused ion beam (FIB) instruments for precise and fast chemical characterization of thin films buried deep under the sample surface. This is demonstrated on complex multilayer systems composed of alternating ceramic and metallic layers with thicknesses varying from several nanometers to hundreds of nanometers. The typical problems of the TOF-SIMS technique, that is, low secondary ion signals and mass interference between ions having similar masses, were solved using a novel approach of co-injecting fluorine gas during the sample surface sputtering. In the most extreme case of the Al/Al2O3/Al/Al2O3/.../Al sample, a

Recent progress in manufacturing now enables the efficient fabrication of complex oxide-glass components at the micrometer– to sub-micrometer scale. This benefits both the industry and fundamental research as such miniature glass parts have numerous applications. However, at these length-scales, the mechanical properties of glasses can no longer be predicted based on bulk material characteristics. Here it is shown that fused silica micro-pillars fabricated by laser-assisted etching are almost ten times stronger than their bulk-sized counterparts. The relatively rough surface typical for this process does not much impair this strength. Additionally, it is demonstrated that annealing of the as-fabricated structures at 1200 °C in air results in significantly smoother surfaces. The accompanying increase in mechanical strength from approximately 8 GPa to 10 GPa is due to the reduction of stress concentrations at the surface, as demonstrated by finite element simulations. It is also demonstrated that the gain in mechanical resistance of glass components due to downsizing occurs already for parts as large as almost 20 µm – orders of magnitude above the critical size reported for other micro-mechanical effects. These micro-mechanical properties of selective laser-assisted etching structured fused silica components are key to a reliable use of glass micro-components.

Due to excellent electric conductivity and chemical inertness, Au can be used in new microdevices for energy applications, microelectronics, and biomedical solutions. However, the chemical analysis of Au-containing systems using time-of-flight secondary ion mass spectrometry (TOF-SIMS) can be difficult because of the negative ionization of Au, as most metals form positive ions, and therefore cannot be detected from the same analytical volume. In this work, we present the potential of fluorine gas coinjection for altering the polarity, from the negative to positive, of Au secondary ions generated under Ga+ beam bombardment. The importance of detecting Au+ ions and representing their spatial distribution in nanoscale was demonstrated using a novel solid electrolyte for Li-ion solid-state batteries, amorphous Li7La3Zr2O12 (aLLZO). This allowed for assessing the migration of mobile Li+ ions outside the aLLZO layer and alloying the Au layer with Li, which explained the presence of an internal electric field observed during the polarization measurements. Remarkably, during fluorine gas-assisted TOF-SIMS measurements, the trace amount of Au content (5 ppm) was detected in a Pt layer (unattainable under standard vacuum conditions). In conclusion, fluorine gas-assisted TOF-SIMS can help understanding operation mechanisms and potential degradation processes of microdevices and therefore help optimizing their functionality.

Journal of materials research 36(11), 2325 - 2336 (2021). doi:10.1557/s43578-021-00187-5, High strain rate micromechanical testing can assist researchers in elucidating complex deformation mechanisms in advanced material systems. In this work, the interactions of atomic-scale chemistry and strain rate in affecting the deformation response of a Zr-based metallic glass was studied by varying the concentration of oxygen dissolved into the local structure. Compression of micropillars over six decades of strain rate uncovered a remarkable reversal of the strain rate sensitivity from negative to positive above ~ 5 s$^{���1}$ due to a delocalisation of shear transformation events within the pre-yield linear regime for both samples, while a higher oxygen content was found to generally decrease the strain rate sensitivity effect. It was also identified that the shear band propagation speed increases with the actuation speed, leading to a transition in the deformation behaviour from serrated to apparent non-serrated plastic flow at ~ 5 s$^{���1}$., Published by Cambridge Univ. Press, Cambridge [u.a.]

Plastic deformation in crystalline materials consists of an ensemble of collective dislocation glide processes, which lead to strain burst emissions in micro-scale samples. To unravel the combined role of crystalline structure, sample size and temperature on these processes, we performed a comprehensive set of strict displacement-controlled micropillar compression experiments in conjunction with large-scale molecular dynamics and physics-based discrete dislocation dynamics simulations. The results indicate that plastic strain bursts consist of numerous individual dislocation glide events, which span over minuscule time intervals. The size distributions of these events exhibit a gradual transition from an incipient power-law slip regime (spanning ≈ 2.5 decades of slip sizes) to a large avalanche domain (spanning ≈ 4 decades of emission probability) at a cut-off slip magnitude 𝑠�c. This cut-off slip provides a statistical measure to the characteristic mean dislocation swept distance, which allows for the scaling of the avalanche distributions vis-à-vis the archetypal dislocation mechanisms in face-centered cubic (FCC) and body-centered cubic (BCC) metals. Our statistical findings provide a new pathway to characterizing metal plasticity and towards comprehension of the sample size effects that limit the mechanical reliability in small-scale structures., Scientific Reports, 10 (1), ISSN:2045-2322

Mechanical fracture properties were studied for the common atomic-layer-deposited Al2O3, ZnO, TiO2, ZrO2, and Y2O3 thin films, and selected multilayer combinations via uniaxial tensile testing and Weibull statistics. The crack onset strains and interfacial shear strains were studied, and for crack onset strain, TiO2/Al2O3 and ZrO2/Al2O3 bilayer films exhibited the highest values. The films adhered well to the polyimide carrier substrates, as delamination of the films was not observed. For Al2O3 films, higher deposition temperatures resulted in higher crack onset strain and cohesive strain values, which was explained by the temperature dependence of the residual strain. Doping Y2O3 with Al or nanolaminating it with Al2O3 enabled control over the crystal size of Y2O3, and provided us with means for improving the mechanical properties of the Y2O3 films. Tensile fracture toughness and fracture energy are reported for Al2O3 films grown at 135 &deg, C, 155 &deg, C, and 220 &deg, C. We present thin-film engineering via multilayering and residual-strain control in order to tailor the mechanical properties of thin-film systems for applications requiring mechanical stretchability and flexibility.

Physical vapor deposition (PVD) is a well-known route for manufacturing hard coatings. In recent years, PVD has also been applied to create high-entropy alloy (HEA) thin films. HEAs are multicomponent alloys with nearly equal atomic fractions. To achieve the desired composition, typically alloy targets are used in the deposition process. The present work demonstrates that HEA thin films can also be processed using a multiple beam sputtering system in PVD, which does not require preliminary manufacturing of HEA targets, but rather uses commercially pure metal targets. The effectivity of this technique was demonstrated on a nanocrystalline CoCrNiFe HEA film with a thickness of about 1 μm. A part of the compositional gradient sample exhibited equal elemental fractions. The microstructure and the hardness of this part of the PVD film were studied in detail, and the results were compared with those obtained on a bulk nanocrystalline sample having the same chemical composition, but was prepared by the high pressure torsion (HPT) technique. The crystallite size and the texture were characterized by X-ray diffraction, while the hardness was measured by nanoindentation. The PVD film exhibited an exceptionally high hardness of 9.8 ± 0.3 GPa, a value that was notably higher than that determined for the HPT sample (7.3 ± 0.3 GPa). This study also demonstrated the capability of this new multiple beam sputtering technique for the production of compositional gradient samples with a wide range of elemental concentrations, enabling combinatorial analysis of multiple elements high-entropy alloy.

An initial study to investigate the effect of controlled deposition of nanoparticles at multilayer interfaces was conducted to explore the mechanical effect of particles on laminate structures. Nanoparticles with diameter of about 4.5 nm were specifically deposited at the interface between Cu and Ni laminates by forced agglomeration of magnetron sputtered ions using a Mantis Ltd. Nanogen50 nanoparticle generator and the hardness of these films were measured using the nanoindentation technique. Cu/Ni laminates without W nanoparticles have an average modulus value of approximately 120 ± 3.7 GPa and hardness value of 2.23 ± 0.07 GPa, while the hardness values of the particle-containing films are greater, regardless of particle density. The areas with the lowest particle density at the interfaces (0.9 at.% W) show the greatest increase in hardness, with an increase of about 1.3 GPa greater than the particle-free sample. However, as the particle density increases, there is a corresponding decrease in hardness. In-situ x-ray diffraction of these films was also conducted to observe the annealing behavior of these films. For all samples, the Cu and Ni layered structure remained intact; however, there is evidence of Ni diffusion along grain boundaries and interaction with the oxygen, likely creating NiO. After annealing, a significant number of the W nanoparticles dissolved into the Ni matrix to create NiW solid-solution. The ability to deposit particles with such precise control has the potential to open up an exciting new field of research. publishedVersion

The development of new, efficient, chemoselective, and seemingly stable catalysts to rapidly convert 4-nitrophenol into 4-aminophenol, which is a particularly valuable chemical within multiple industries, is highly required. The use of non-toxic and non-corrosive chemicals for 4-aminophenol synthesis presents further challenges. We show a simple and scalable shape-controlled electrodeposition using a dual-template method for the synthesis of well-defined porous Au micropillar array electrodes to enhance electrocatalyst stability, efficiency, and durability during the electroreduction of 4-nitrophenol. Consequently, we avoid the use of toxic and aggressive chemical reducing agents and minimize the production of residues. Surface areas up to 55.2 m2 g−1 are achieved, which represent a substantial improvement over non-architectured Au film electrodes. Porous Au micropillars exhibit excellent yields (100 %), chemoselectivity (other byproducts are not detected), and a high kinetic constant of 2.5 × 10-2 min−1, which is impressively higher than those reported recently for Au thin films or Au-based electrocatalysts.

The widespread use and negative environmental effects of antibiotics have made their removal from aqueous media essential in terms of wastewater treatment. Accordingly, a hybrid helical Cu@Cu2O@CuO–microalgae photocatalyst for antibiotic photodegradation was synthesized in this study by a simple, inexpensive, and scalable process based on electroless Cu deposition and soft thermal treatment. The hybrid photocatalyst was more competitive for the photocatalytic degradation of tetracycline, especially in terms of mineralization and energy consumption, than state-of-the-art photocatalysts. The excellent photocatalytic performance is attributable to the effective formation of onion-like Cu@Cu2O@CuO heterojunctions, which synergistically lower the electron–hole recombination rate, promote the utilization of light and photogeneration of charge carriers, and decrease the photocorrosion activity. All these effects result in the enhanced photocatalytic degradation and mineralization of tetracycline. The high photocatalytic performance of the Cu@Cu2O@CuO–microalgae hybrids under LED irradiation resulted in a significantly lower electrical energy per order—i.e., the electrical energy required to diminish the tetracycline concentration by one order of magnitude in a unit of volume—of 57 kW h m−3 order-1. Importantly, the Cu@Cu2O@CuO–microalgae hybrids can easily be recycled after reaching their effective lifetime to fabricate competitive microalgal pellets, then integrated into a circular process in an environment–energy nexus to minimize the generation of residues.

Two-photon lithography (TPL) enables the fabrication of metamaterials exhibiting unprecedented mechanical performance. Such lattice structures consist of micron-scale geometric features and are designed to achieve their envisioned properties through stretching and bending of individual trusses. Here, we present for the first time a comprehensive study of the effect of temperature and strain rate on the mechanical properties of micron-sized 3D printed polymers made by TPL using Nanoscribe's negative tone photoresist IP-Dip. A strong strain rate dependency was identified for the yield strength, which increased fourfold in compression from 68 MPa to 230 MPa as the strain rate was raised from 7e−4 s−1 to 600 s−1. This trend was also seen in tension. The elastic modulus was found to increase with strain rate in the quasistatic regime but was constant at 3.2 GPa for strain rates of 0.7 s−1 and above. Even slightly elevated temperatures of 80°C led to a significant drop in the yield strength and elastic modulus, though the observed reduction was less severe at higher strain rates. Further, a model based on the strain rate-temperature superposition principle is reported that allows the extrapolation of the mechanical properties even beyond the conditions tested here.

A Zr-based bulk metallic glass produced using selective laser melting (SLM) was compared to the same alloy fabricated using traditional suction-casting. Analysis of the fracture toughness through single edge notched beam bending experiments showed a significantly reduced damage tolerance for the laser-processed material (KQ ~ 138.0 ± 13.1 → 28.7 ± 3.7 MPa √m), even though X-ray diffraction and microhardness responses were identical. Using uniaxial quasistatic micro-pillar compression, it was found that as-cast samples more readily underwent shear transformations (evidenced through discrete load drops) below the nominal 0.2% yield stress, which was connected to the higher macroscopic toughness. Differential scanning calorimetry demonstrated that the increased barrier to shear transformation for the SLM material could not be explained by the relative relaxation states. Rather, it was attributed to the greater dissolved oxygen concentration in the laser-processed material, which is postulated to decrease atomic mobility in the structure and thereby increase the activation energy required to initiate shear transformations.

Optimally, hard protective coatings should effectively absorb impact energy to reduce the likelihood of failure events. In this work, an arc-PVD approach was utilised for the deposition of thick ceramic multilayer AlCrTiN/CrN-based coatings containing a distribution of metallic nickel inclusions throughout sequential CrN-based interlayers. The aim of such coatings is to provide resistance to impact loading in intensive application environments, such as drop forging of steel and turbine blades exposed to abrasive particles. The structure and micro-structural development of the ceramic was first investigated using transmission electron microscopy, where discrete Ni inclusions were observed as both larger discs (d ~ 600–800 nm, h ~ 200 nm) and smaller (d ~ 50 nm) nanoclusters. Confirmation of the distribution and nanocluster chemistry was achieved using atom probe tomography. For mono-block coatings, XRD data showed drastically reduced internal stresses as a result of the Ni inclusions, enabling the creation of thicker protective coatings which minimise substrate stress concentration upon loading. Nickel inclusion additionally provides a softening of the containing hard ceramic layer, allowing for tuning of mechanical properties. Supporting this idea, in situ micropillar compression measurements of the multi-layered coating systems showed that Ni clusters hindered crack propagation through the coating during failure, while the fracture strength could be increased by incorporating both Ti and Ni in the softer CrN-based layer. High-load impact testing highlighted the influence of Ni ‘shock absorbers’ in reducing circumferential cracking, which was further confirmed by an industrial die forging test that demonstrated a 15–22% life-time increase compared to a much thicker hard-chrome plated reference. The results of this study demonstrate an exciting way to produce Ni nanocluster integrated hard ceramic multi-layers using arc-PVD in a single processing step. Such tuneable thin-film composite systems show great promise in minimising damage from impact loading, even under severe working conditions such as in hot forging.

The measuring of internal stress has not only a great scientific aspect, but is particularly important for nondestructive description of component or products in industry. It is expected that exceeding of local mechanical limits in the material can have catastrophic consequences. In this paper is mapped the deformation field of amorphous material under the nanoindenter tip using diffraction in Debye-Scherrer geometry. Using the FEM analysis, it was modeled the deformation field in such material. There is a great match in between measured and calculated data. The result is pointing out on large limits of internal stresses measuring by conventional standard methods.

Time-of-flight secondary ion mass spectrometry (TOF-SIMS) detectors have been intensively developed in recent decades due to their unprecedented capability of representing a sample elemental composition in a three-dimensional space from nano- to submilliscale with high spatial resolution and mass resolution. A compact high-vacuum-compatible version of these detectors can be integrated into a focused ion beam (FIB) system which, assembled with scanning electron microscopy (SEM), is the most popular tool used in nanotechnology and material science. This gives a new opportunity for combining TOF-SIMS analysis with other instruments within the same analytical chamber. In this work we present the results of conducting elemental characterization of a dedicated model multilayer sample composed of 100 nm thick thin films of Cu, Zr, and ZrCuAg alloy in a fluorine gas atmosphere provided by an in situ gas injection system (GIS). In general, the secondary ion signals were significantly enhanced by up to 3 orders of magnitude, leading to much higher spatial resolution. The quality of elemental images and depth profiles was improved during a single measurement (which usually cannot be obtained at standard vacuum conditions) at a high beam energy of 20 keV. Moreover, fluorine assistance has enabled a mass interference between

Native protective oxide scales offer resistance against corrosion for high temperature materials, which often work in extreme conditions of varying mechanical and thermal loads. The integrity of such layers is of critical importance, since their damage can lead to significant reduction in material life. Mechanical data such as fracture strain and elastic modulus are required to include oxides in material life estimation models for high temperature materials, but there is lack of such data. Their thickness is in the μm range, which makes mechanical testing for property determination difficult. Here we present a micro-mechanical testing method, based on bending of micro-cantilevers produced by focused ion beam milling, capable of circumventing the limitations of conventional approaches. We apply this method to chromia thermally grown on pure chromium, and measure fracture strains at room and high temperatures (600 °C). The measured fracture strains were found to be higher at room temperature, due to a larger fraction of transgranular fracture. Surprisingly, a large fraction of transgranular fracture was seen even in the presence of stress concentrations at grain boundaries. Removal of the stress concentrations accentuated the propensity for transgranular cracking at room temperature. Realistic values of room temperature elastic modulus were obtained as well. The observed mixed trans- and intergranular cracking points towards the need for dedicated investigations of both oxide grain boundary strength and cleavage resistance of single crystals in order to fully understand the failure mechanisms in thermally grown oxide scales. acceptedVersion acceptedVersion

Micromechanical testing is normally limited to the quasi-static strain rate regime: 10−5 to 10−2 s−1. In this work, a nanomechanical testing device has been developed that allows indentation and microcompression at strain rates from the quasi-static regime continuously up to the high strain rate regime. To reach the highest strain rates, the conventional, strain gage-based load cell was replaced with a new piezo-based sensor. The sensor's concept, calibration methods, and measurement strategies are detailed. It is shown, using nanocrystalline Nickel as a case study material, that this new high strain rate device can measure precisely mechanical properties at strain rates up to 1000 s−1 by nanoindentation, and strain rates up to 100 s−1 by microcompression, enabling the device to measure strain rates over 9 orders of magnitude. Keywords: High strain rate, Nanoindentation, Microcompression, Nanocrystalline nickel

International audience; Nano crystalline diamond (NCD) films grown at a temperature below 400°C can open new applications on temperature sensitive substrates such as polymers or low-melting point alloys. One requirement for the applicative use of NCD is the ability of depositing on a structured substrate having high aspect ratio. This work presents a study on the three dimensional (3D) conformity of NCD deposition at low temperature (350°C) and low pressure (30 Pa). Silicon wafers have been structured using a mask-less photolithography and (hardmaskless) Deep Reactive Ion Etching (DRIE) process and seeded with nano-diamond particles. The NCD films were grown on these 3D patterned Si substrates with various trench geometries to provide means of determining the limiting geometries of this technique. By measuring the step coverage with changing trench width, a threshold for conformal NCD growth can be determined. The NCD films at the bottom of the 100 μm deep trenches were continuous down to an aspect ratio of 1:7.

High-impact applications such as forging, punching or fine blanking often utilise hard-coating systems to improve wear and lifetime performance. For rational design of such systems, evaluation after repeated impacts at the application temperature is critical. However, such investigations are time-consuming and costly to perform in-line on an industrial scale. Small-scale impact testing allows for rapid and inexpensive investigation of attractive thin coating designs, which can be performed over a range of controlled temperatures. Here, a novel in situ nanoindentation device was developed, able to perform precise displacement cycles to 1 kHz at temperatures up to 500 °C within a scanning electron microscope. The system is based on a piezoelectric driving tip containing four discrete piezo devices, allowing for the collection of load-displacement data for each individual cycle. Operation of the device at 500 Hz was demonstrated on arc-PVD chromium nitride coated nitrided steel with a diamond flat-punch counter-body, and the effects of temperature and impact number on fatigue deformation studied using electron microscopy techniques. It was found that as the impact number increased as did the residual plastic damage from the impact force. Additionally, the deformation of the tooling was highly dependent on the temperature, which became more strongly apparent with an increased number of impacts. Such testing will be useful for evaluating the lifetime and fatigue properties of potential new thin films and coatings for high-impact operations, where understanding the influence of temperature is crucial.

Metal-anodic aluminum oxide (AAO)−Al nanostructures have been deposited by using sputtering for the metal layer deposition and a two-step anodization process in different electrolytes to produce self-ordered anodic aluminum oxide films. The effect of the morphological parameters of AAO films (such as thickness, pore diameter, interpore distance, and porosity) on the optical properties was studied. The UV−vis reflectance properties as a function of the thickness for the different electrolytes of metal-AAO−Al films were analyzed in order to obtain the color diagrams and the effective refractive indexes of the films. The effective refractive index was found to depend on the thickness and porosity of AAO films. The change in color observed in metalAAO−Al nanostructures is due to the thickness and porosity of the AAO films. In order to verify the experimental results, UV−vis reflectance spectra of AAO− Al films were simulated using commercially available finite element simulation software, The authors would like to acknowledge financial support from Commission for Technology and Innovation (CTI-16977.2 PFNM-NM) of the Swiss Confederation. C.V.M. would like to acknowledge funding from the Marie Curie Actions cofound program of the EU’s Seventh Research Framework Program (FP7).

The ability to determine the radial growth rate of atomic layer deposited (ALD) films on quasi-inert surfaces can enable precise control of decorative particle size or film closure for specific applications. The radial-growth-per-cycle (rGPC) is proposed in this work to quantify how thin films nucleate and grow from defect sites on carbon surfaces until film closure. The ALD of TiO2 on non-functionalized singled-walled carbon nanotubes (SWCNTs) was monitored using in-situ Raman measurements, which collects signal of hundreds of SWCNTs during deposition. The gradual increase of the intensity ratio between the D- and G-band ID/IG from the sp2-to-sp3 hybridization reveals the progression in which TiO2 nuclei grow from surface defects towards the pristine surface until nuclei coalescence. The radial overgrowth of TiO2 along the inert surface is mainly bound by Van der Waals forces. Chemical bonding to the surface only occurred on average every ~12 nm, equivalent to only ~1% of the carbon atoms chemically bonded to the film. The in-situ Raman measurements determined a nuclei rGPC of ~0.19 ± 0.02 nm at temperatures lower than 120 °C, the point of film closure at the SWCNT circumference and axis, and a finite induced compressive stress of ~1 GPa to the nanotubes.

Shear-based material removal processes significantly influence the quality of workpiece surface and implicitly the component functional performance. An in-situ SEM nano-cutting enabled the study of crystal flow and lattice rotation occurring below the cutting edge in a polycrystalline Nickel superalloy. When nano-cutting within single grains a deformed nanolayer appears that consists of a crystal lattice rotated exclusively within the cutting plane which is delimited from the bulk of the grain by high angle boundary (HAB); the depth of deformed nanolayer increases with the material pile-up (nano-chip) caused by the grain shearing. Upon nano-cutting multiple grains, nano-recrystallisation at the HAB occurs, accompanied by the bending of the grain boundary (GB) in the cutting direction, a phenomenon that also significantly influences the deformation behaviour of the grains cut after passing the GB. Clarifying these aspects at the nanoscale is crucial for understanding the formation of workpiece surface damage after material removal operations.