Brug, A. Resume : Modern electron microscopes provide an ideal platform for in situ mechanical testing and manipulation of materials at small length scales owing to high flexibility in realizing special sample geometries and loading scenarios without compromising microscope performance. This holds true for both, combined focused ion beam scanning electron microscopes FIB-SEM as well as transmission electron microscopes TEM with the former providing highest flexibility and the latter highest resolution.
Examples include sliding friction experiments and defect manipulation in layered crystals and 2D materials, combined mechanical testing and 3D characterization of nanoporous metals as well as new preparation routines for in situ compression and tensile testing of glass structures.
Wherever possible, modeling simulation aspects are also addressed. Resume : A novel method was developed for the preparation of thin film microtensile specimens. Unlike other techniques, it does not rely on expensive cleanroom photolithographic equipment, but it is based on a combination of focused ion beam FIB milling and electron-beam-assisted etching with xenon difluoride precursor gas.
The new method furthermore ensures that the area of interest is never exposed to ion beam irradiation so that a pristine microstructure is preserved. This is achieved by using a special shadow milling geometry with a thin silicon membrane simultaneously serving as a substrate and protective layer for the thin film of interest.
A further advantage of the new method is that it enables the target preparation and mechanical testing of individual microstructural defects. The method was applied to nanotwinned Cu-Al as well as Au thin films. The fabricated tensile specimens were mounted on a push-to-pull mechanical conversion device and subsequently tested in-situ in the transmission electron microscope TEM. Ultramicroscopy, Resume : The size dependent plastic behavior of micro and nano-scaled non-organic materials has attracted enormous interest during the last decade.
When the object size becomes comparable to intrinsic length scales, finite-size and quantum size effects occur influencing the physical properties. For complete understanding of the deformation process in-situ experiments are necessary. Resume : Interfacial properties of thin films on compliant substrates are important to understand in order to design reliable flexible electronic devices.
Due to the compliance of the substrates, measuring the adhesion energies of these systems is difficult with existing techniques and models. A new method and mechanics-based model have been developed to measure the adhesion energy of metal films on compliant substrates using an in situ uniaxial tensile test inside a scanning electron microscope.
Surface Phenomena in the Structural and Mechanical Behaviour of Solid Polymers
With this technique, the initial fracture and buckling of the film can be observed and correlated to the strain. Once buckling of the film has been achieved, the height and width of the buckles are then used in the new model to calculate the adhesion energy. To demonstrate the technique and model, titanium films on polyimide are studied before and after annealing.
It will be shown that annealing decreases the adhesion because the interface structure changes. Resume : The oxidation of Fe-based alloys in liquid Pb-Bi eutectic, with oxygen dissolved in liquid phase, leads to oxide formation on the surface.
Surface Phenomena in the Structural and Mechanical Behaviour of Solid Polymers - CRC Press Book
These structures are primarily determined by oxygen concentration and diffusion properties of cations from solid and oxygen anion from liquid phase. In this work, the influence of temperature and oxygen concentration on oxides growth dynamics and their diffusion properties is examined in oxidation of ferritic Fe-Cr-Al-alloys in liquid lead-bismuth at high temperatures.
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The order of oxide phases, and their structure, determined by XRD, EDS, TEM and Raman spectroscopy, are correlated with model predictions of dynamics of their formation and degradation. The ultimate goals have been to determine the oxide phases present in the scales, and to understand their evolution as a function of temperature and oxygen concentration and origins of strain induced in oxide and in bulk. Resume : Layered materials present a promising route for achieving attractive combinations of properties, e.
In this work, we evaluate the mechanical moduli of an Al2O3-TiO2 superlattice using effective elastic constants as well as a a more advanced direct ab initio approach which involves calculations of stress-strain curves of the superlattice. The effective elasticity is derived by means of the Grimsditch-Nizzoli  method, which allows to estimate the elasticity of a superlattice from the elasticity of the constituents. The ab initio calculations are performed in the framework of density functional theory, using the structural information epitaxial relationships and interface structure obtained in our previous work .
We compare the outcomes of the two approaches and discuss the performance of the Grimsditch-Nizzoli method when evaluating the bulk, Young's, and shear moduli. In particular, we demonstrate that the transverse Young's modulus obtained in the Grimsditch-Nizzoli method gives reasonable results, while a reliable description of the shear modulus is only obtained when applying the direct ab-initio approach.
References:  Abadias, G. B 33,  Popov, M. B 86, However, a high sintering temperature above K is required to obtain dense TiB2 specimens.
Grain growth occurs by the sintering at such high temperatures which causes the degradation of the mechanical properties. In order to obtain dense and hard TiB2 based materials by the sintering at lower temperatures, sintering of TiB2 with various intermetallics as sintering aid has been investigated. In the present study, it has been shown that AlTi-TiB2 composites in which sub-micron sized TiB2 particles are dispersed in AlTi matrix can be formed by the reaction sintering of Al, Ti and boron powders using the spark plasma sintering method at K.
No crack has been observed near the corners of the Vickers indentation indicating excellent fracture toughness of composites of sub-micron sized TiB2 particles. The latter characterizes graphene on Ni , where the hexagonal carbon network accommodates onto a square surface lattice. Ab-initio density functional theory DFT simulations well reproduce the observed STM images and shed further light on the spatial corrugation of graphene and the interfacial interactions, indicating that, depending on the misorientation angle, graphene can be alternately physi- and chemisorbed or uniformly chemisorbed.
Resume : we developed rubber material that is environment-friendly and superior in mechanical property using rubber-clay nanocomposites. Typical modifiers to enhance dynamical properties of rubber material were carbon black and silica. Recently, nano-clay was popular as modifiers. Many researches on nanocomposites are being actively carried out because they are excellent in modification even with a small quantity of them while nano-clay is difficult to diffuse. Fillers or modifiers used when manufacturing polymer nanocomposites include layered silicate, POSS nanoparticles, CNT and nanoparticles of metal or inorganic matters, among which layered silicate is now being most actively developed as polymer nanocomposites.
The key technology of development of polymer nanocomposites is how to change layered clay so as to easily insert polymers into it. When organic matters are inserted using inorganic material like clay silicate that has a uniform structure with nano scale, in particular, nanocomposites are attracting great concerns in their application. The basic structure of clay, as it is well known, consists of silica tetrahedral and alumina octahedral sheets: it is classified into several groups including vermiculite and montmorillonite depending on its negative charge.
In this study, acrylonitrile butadiene rubber NBR was used as rubber in combination; ZnO and stearic acid were used as vulcanization activators; and 3C was used as an additive; sulfur of purity Polymer layered silicate was made by the melted intercalation method in which polymers in the melted state were inserted between silicate layers: this method is advantageous in mass production and does not need to use solution.
Thermal resistance was estimated through material tests of developed material at room temperature and aged condition. Fatigue durability was estimated after we developed a new method that could estimate fatigue lifetime of rubber parts in a short period in the initial stage. As results, fatigue lifetime evaluation by the fatigue lifetime prediction equation was exactly consistent with that obtained by fatigue tests of actual engine mounts.
In addition, we verified that the developed material was superior in fatigue durability as well as mechanical properties because the lifetime of rubber component made by the developed material was longer than the existing material. Resume : Duo to the unique and highly valuable properties, graphene sheets has attracted increasing attention.
In this paper, the nonlocal elastic theory and classical plate theory CLPT are used to derive the governing equations. The element-free kp-Ritz method is employed to analyze the buckling behaviors of double layer circular graphene sheets DLGSs embedded in an elastic medium. Pasternak-type model is adopted to simulate the functioning of the elastic medium. Then, the effects of boundary conditions, aspect ratio, size of graphene sheets, nonlocal parameters on the buckling behavior of DLGSs are investigated.
Resume : Falls are dangerous for the elderly population; therefore, many fall detection systems have been developed. However, previous methods are bulky for elderly people or only use a single sensor to isolate falls from daily living activities, which makes a fall difficult to distinguish.
Surface phenomena in the structural and mechanical behavior of solid polymers
We present a cost-effective and easy-to-use portable fall-detection sensor and algorithm. Specifically, to detect human falls, we used a three-axis accelerator and a three-axis gyroscope in a mobile phone. We used the Fourier descriptor-based frequency analysis method to classify both normal and falling status. To calculate the classification accuracy, the K-fold cross-validation method was used and K was set as From the results, we noticed that the proposed method detects data falling or walking out of original data falling or walking.
The statistical analysis shows that the resulting accuracy was In this paper, we propose a mobile phone-based falling detection sensor and algorithm. From the experimental results, the proposed method detects falling status with Resume : Single-grain mechanical properties have been measured with the aim of calibrating the material parameters of a crystal plasticity finite element model to a single-crystal response.
Such simulation-oriented experiments allow the investigation of the deformation behaviour of individual grains in plastically deforming metals, which underpins the bridging of scales in multiscale modelling approaches to predict the mechanical behaviour of nuclear structural materials and support the elaboration of materials design rules for nuclear energy applications. On that basis, a series of micropillars have been fabricated by Focused Ion Beam inside single grains of polycrystalline steels, and compressed by a flat punch using a nanoindentation system.
This work will present the results of the combination of compression tests and crystal plasticity finite element simulations. Resume : Hydrophobicity of graphene has been investigated for the first time using multiscale simulation, i. Wettability of graphene was determined by using a concept of work of adhesion; free energy gap of a two-phase system liquid and solid between a sum of each solitary states and a neighbored state. Two phase thermodynamics 2PT analysis was used for free energy calculations. Here, we investigate a consequence of various chemo-physical conditions in graphene such as layer thickness, corrugated structure, and nitrogen doping.
The microscopic wettability of graphene and geometric alignment of waters on the surface were studied.
Resume : While bulk silicon is brittle at temperatures below K, the compression of nanopillars has shown that a decrease of the diameter below few hundreds of nanometers could change the silicon behavior from brittle to ductile . The identification of the parameters governing the brittle to ductile transition in size and the understanding of the mechanisms are the key points to prevent the failure of microelectronic components based on the silicon strained technology.
Nowadays the respective improvements in simulations and experiments allow to investigate the mechanical properties of objects of similar sizes, close to hundreds of nanometers. We considered atomistic simulations based on two different semi-empirical potentials fitted to better reproduce the ductile and brittle properties of bulk silicon.
The simulations under tensile load show the nucleation of perfect dislocations from the surface that can lead to cavity opening when they interact . Second, we show that the brittle to ductile transition is not abrupt and mainly controlled by the diameter of the nanopillars, as observed experimentally in compression. The underlying mechanisms will be detailed, and a criterion based on the quantification of the plastic deformation before cracks opening will be presented to measure the degree of ductility of the breaking.
Oestlund et al. AFM 19 1  F. Resume : The report is devoted to mechanisms that may operate influence of nanoparticles interaction with bulk matrix on phase transformations and in such way — on mechanical properties formation.