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Maire E.,CNRS Laboratory for Materials: Engineering and Science | Withers P.J.,Manchester X ray Imaging Facility | Withers P.J.,Rutherford Appleton Laboratory
International Materials Reviews | Year: 2014

X-ray computer tomography (CT) is fast becoming an accepted tool within the materials science community for the acquisition of 3D images. Here the authors review the current state of the art as CT transforms from a qualitative diagnostic tool to a quantitative one. Our review considers first the image acquisition process, including the use of iterative reconstruction strategies suited to specific segmentation tasks and emerging methods that provide more insight (e.g. fast and high resolution imaging, crystallite (grain) imaging) than conventional attenuation based tomography. Methods and shortcomings of CT are examined for the quantification of 3D volumetric data to extract key topological parameters such as phase fractions, phase contiguity, and damage levels as well as density variations. As a non-destructive technique, CT is an ideal means of following structural development over time via time lapse sequences of 3D images (sometimes called 3D movies or 4D imaging). This includes information needed to optimise manufacturing processes, for example sintering or solidification, or to highlight the proclivity of specific degradation processes under service conditions, such as intergranular corrosion or fatigue crack growth. Besides the repeated application of static 3D image quantification to track such changes, digital volume correlation (DVC) and particle tracking (PT) methods are enabling the mapping of deformation in 3D over time. Finally the use of CT images is considered as the starting point for numerical modelling based on realistic microstructures, for example to predict flow through porous materials, the crystalline deformation of polycrystalline aggregates or the mechanical properties of composite materials. © 2014 Institute of Materials, Minerals and Mining and ASM International.

Tournus F.,University Claude Bernard Lyon 1 | Sato K.,Tohoku University | Epicier T.,CNRS Laboratory for Materials: Engineering and Science | Konno T.J.,Tohoku University | Dupuis V.,University Claude Bernard Lyon 1
Physical Review Letters | Year: 2013

The atomic structure of CoPt and FePt nanoparticles (with a diameter between 2 and 5 nm) has been studied by transmission electron microscopy. The particles have been produced by a laser vaporization cluster source and annealed under vacuum in order to promote chemical ordering. For both alloys, we observe a coexistence of crystalline and multiply twinned particles with decahedral or icosahedral shapes. In addition to particles corresponding to a single L1 0 ordered domain, we put into evidence that even small particles can display several L10 domains. In particular, the chemical order can be preserved across twin boundaries which can give rise to spectacular chemically ordered decahedral particles made of five L10 domains. The stability of such structures, which had been recently predicted from theoretical simulations, is thus unambiguously experimentally confirmed. © 2013 American Physical Society.

Delgado L.F.,CNRS Laboratory for Materials: Engineering and Science | Charles P.,CIRSEE | Glucina K.,CIRSEE | Morlay C.,CNRS Laboratory for Materials: Engineering and Science
Science of the Total Environment | Year: 2012

This paper provides a review of recent scientific research on the removal by activated carbon (AC) in drinking water (DW) treatment of 1) two classes of currently unregulated trace level contaminants with potential chronic toxicity-pharmaceutically activate compounds (PhACs) and endocrine disrupting compounds (EDCs); 2) cyanobacterial toxins (CyBTs), which are a group of highly toxic and regulated compounds (as microcystin-LR); and 3) the above mentioned compounds by the hybrid system powdered AC/membrane filtration. The influence of solute and AC properties, as well as the competitive effect from background natural organic matter on the adsorption of such trace contaminants, are also considered. In addition, a number of adsorption isotherm parameters reported for PhACs, EDCs and CyBTs are presented herein. AC adsorption has proven to be an effective removal process for such trace contaminants without generating transformation products. This process appears to be a crucial step in order to minimize PhACs, EDCs and CyBTs in finished DW, hence calling for further studies on AC adsorption removal of these compounds. Finally, a priority chart of PhACs and EDCs warranting further study for the removal by AC adsorption is proposed based on the compounds' structural characteristics and their low removal by AC compared to the other compounds. © 2012 Elsevier B.V.

Delgado L.F.,CNRS Laboratory for Materials: Engineering and Science | Charles P.,CIRSEE | Glucina K.,CIRSEE | Morlay C.,CNRS Laboratory for Materials: Engineering and Science
Water Research | Year: 2012

Recent studies have demonstrated the presence of trace-level pharmaceutically active compounds (PhACs) and endocrine disrupting compounds (EDCs) in a number of finished drinking waters (DWs). Since there is sparse knowledge currently available on the potential effects on human health associated with the chronic exposure to trace levels of these Emerging Contaminants (ECs) through routes such as DW, it is suggested that the most appropriate criterion is a treatment criterion in order to prioritize ECs to be monitored during DW preparation. Hence, only the few ECs showing the lowest removals towards a given DW Treatment (DWT) process would serve as indicators of the overall efficiency of this process and would be relevant for DW quality monitoring. In addition, models should be developed for estimating the removal of ECs in DWT processes, thereby overcoming the practical difficulties of experimentally assessing each compound. Therefore, the present review has two objectives: (1) to provide an overview of the recent scientific surveys on the occurrence of PhACs and EDCs in finished DWs; and (2) to propose the potential of Quantitative-Structure-Activity-Relationship-(QSAR)-like models to rank ECs found in environmental waters, including parent compounds, metabolites and transformation products, in order to select the most relevant compounds to be considered as indicators for monitoring purposes in DWT systems. © 2012 Elsevier Ltd.

Elguedj T.,CNRS Contacts and Structural Mechanics Laboratory | Rethore J.,CNRS Contacts and Structural Mechanics Laboratory | Buteri A.,CNRS Laboratory for Materials: Engineering and Science
Computer Methods in Applied Mechanics and Engineering | Year: 2011

In this paper, the potential of isogeometric analysis for strain field measurement by digital image correlation is investigated. Digital image correlation (DIC) is a full field kinematics measurement technique based on gray level conservation principle and the formulation we adopt allows for using arbitrary displacement bases. The high continuity properties of Non-Uniform Rational B-Spline (NURBS) functions are exploited herein as an additional regularization of the initial ill-posed problem. k-Refinement is analyzed on an artificial test case where the proposed methodology is shown to outperform the usual finite element-based DIC. Finally a fatigue tensile test on a thin aluminum sheet is analyzed. Strain localization occurs after a certain number of cycles and combination of NURBS into a DIC algorithm clearly shows a great potential to improve the robustness of non-linear constitutive law identification. © 2010 Elsevier B.V.

Bobina M.,Polytechnic University of Timişoara | Kellenberger A.,Polytechnic University of Timişoara | Millet J.-P.,CNRS Laboratory for Materials: Engineering and Science | Muntean C.,Polytechnic University of Timişoara | Vaszilcsin N.,Polytechnic University of Timişoara
Corrosion Science | Year: 2013

This paper presents the inhibitory properties of l-histidine on the corrosion of carbon steel in weak acid media containing acetic acid/sodium acetate. The inhibition efficiencies obtained by weight loss measurements are in good agreement with values given by Tafel method and electrochemical impedance spectroscopy. The adsorption of l-histidine obeys the Langmuir isotherm and the negative values of Gibbs energy indicate the nature of interactions between inhibitor molecules and metal surface. Further, the inhibition effect was studied using scanning electron microscopy and energy dispersive X-ray analysis. © 2013 Elsevier Ltd.

Palmero P.,Polytechnic University of Turin | Esnouf C.,CNRS Laboratory for Materials: Engineering and Science
Journal of the European Ceramic Society | Year: 2011

Well-dispersed nano-crystalline transition alumina suspensions were mixed with yttrium chloride aqueous solutions, with the aim of producing Al 2O 3-Y 3Al 5O 12 (YAG) composite powders. DTA analysis allowed to highlight the role of yttrium on the α-phase crystallization path. Systematic XRD and HRTEM analyses were carried out in parallel on powders calcined in a wide temperature range (600-1300°C) in order to follow phase and microstructural evolution. A thin, homogeneous yttrium-rich layer was yielded on the alumina particles surface; yttrium diffusion into the alumina matrix was negligible up to 1150°C whereas, starting from 1200°C, aggregates of partially sintered alumina particles appeared, stuck together by yttrium-rich thin films. Moreover, in the yttrium-richer zones, such as alumina grain boundaries and triple joints, yttrium-aluminates precipitated at alumina particles surface. Finally, at 1300°C, alumina-YAG composite powders were produced, in which YAG was homogenously distributed among the alumina grains. © 2010 Elsevier Ltd.

Lame O.,CNRS Laboratory for Materials: Engineering and Science
Macromolecules | Year: 2010

The filler network in filled rubbers exhibits a very disordered structure which is close to a fractal pattern. During mechanical solicitation, the interaction between polymer and the filler network leads to local strong heterogeneous deformation. The question is: How does the fractal structure of the filler network affect these deformations? Direct observation of these microstructures, in particular under an imposed deformation, is difficult; however, AFM phase imaging can fulfill this objective. Local deformation of the filler networks has been observedin situ along two loading sequences. Fracture in the filler network has been observed, strong deformation heterogeneities have been measured.It has been also shown that, from the first loading to the second, the aggregates seem to follow the same path even if the strain heterogeneities increase. Finally, along a current line, the heterogeneities of deformation are self-similar until a maximum size is reached. This size has been determined to be approximately 1 μm, and the return to homogeneity does not occur before 50 μm. © 2010 American Chemical Society.

Blanc N.,CNRS Physics Laboratory of Condensed Matter and Nanostructure | Tournus F.,CNRS Physics Laboratory of Condensed Matter and Nanostructure | Dupuis V.,CNRS Physics Laboratory of Condensed Matter and Nanostructure | Epicier T.,CNRS Laboratory for Materials: Engineering and Science
Physical Review B - Condensed Matter and Materials Physics | Year: 2011

We discuss the possibility of L10 chemical order parameter quantification for an individual particle of CoPt, using transmission electron microscopy. While "usual" approaches are found to be unapplicable for small particles (less than 4 nm in diameter), we present a method based on the comparison between an experimental high-resolution image and simulated ones with various degrees of chemical order. © 2011 American Physical Society.

Boissy C.,CNRS Laboratory for Materials: Engineering and Science | Alemany-Dumont C.,CNRS Laboratory for Materials: Engineering and Science | Normand B.,CNRS Laboratory for Materials: Engineering and Science
Electrochemistry Communications | Year: 2013

The EIS is a useful tool to characterize corrosion behavior of stainless steel, especially when it comes to the properties of the passive film. A specific electrical equivalent circuit was therefore developed to investigate the diffusion/migration of vacancies occurring within this oxide as described in the point defect model. This circuit was used at 20 C, 60 C and 80 C. The vacancy diffusion coefficient calculated was found to be close to 10 - 14 cm2 s- 1. © 2012 Elsevier B.V. All rights reserved.

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