E. Maire - Academia.edu (original) (raw)

Papers by E. Maire

Acta Materialia, 2011

In situ tensile tests were carried out during X-ray microtomography imaging of three steels: a si... more In situ tensile tests were carried out during X-ray microtomography imaging of three steels: a single phase ferritic steel, a dual phase steel and a fully martensitic steel. Cavity growth was first quantified in the different samples as a function of strain and triaxiality. The Rice and Tracey model, a version of this model corrected by Huang, and a third version accounting for the cavity shape were then used to predict void growth evolution. It was experimentally demonstrated that for steels Huang's correction is a real improvement to the original Rice and Tracey model. Some differences in the void growth kinetic are discussed, accounting for the microstructure and the mechanical behavior of each steel.

Acta Materialia, 2013

The freezing of colloidal suspensions is encountered in many natural and engineering processes su... more The freezing of colloidal suspensions is encountered in many natural and engineering processes such as the freezing of soils, food engineering, and cryobiology. It can also be used as a bio-inspired, versatile, and environmentally-friendly processing route for porous materials and composites. Yet, it is still a puzzling phenomenon with many unexplained features, due to the complexity of the system and the space and time scales at which the process should be investigated. We demonstrate here the interest of fast X-ray computed tomography to provide time-lapse, three-dimensional, in situ imaging of ice crystal growth in a colloidal silica suspension. The experimental measurements show that the local increase of colloid concentration does not affect the growth kinetics of the crystals, until the colloidal particles become closely packed. For particles much smaller than ice crystals, the concentrated colloidal suspension is equivalent to a simple liquid phase with higher viscosity and a freezing point determined by the concentration of colloidal particles.

Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, 2012

ABSTRACT In this paper, the effect of the resolution on damage characterization in a Dual-Phase s... more ABSTRACT In this paper, the effect of the resolution on damage characterization in a Dual-Phase steel was investigated. In situ and ex situ tensile tests were carried out on two synchrotron tomographs achieving a voxel size of 1.6μm and 100nm. A higher volume fraction of cavity was first qualitatively observed on three-dimensional views and confirmed by quantitative analysis: a large number of cavities not seen at low resolution is detected with a finer voxel size. On the other hand, void growth characterization seems not to be affected: in this studied case, the low resolution is sufficient. The effect of the underestimation of the number of voids is illustrated with the calculation of the mean distance between cavities, this information being a key parameter of void coalescence.

This paper investigates the behaviour of colloidal suspensions of alumina particles during direct... more This paper investigates the behaviour of colloidal suspensions of alumina particles during directional solidification, by in situ high-resolution observations using X-ray radiography and tomography. This second part is focussed on the evolution of ice crystals during steady state growth (in terms of interface velocity) and on the particles redistribution taking place in this regime. In particular, it is shown that diffusion cannot determine the concentration profile and the particles redistribution in this regime of interface velocities (20-40 microns/s); constitutional supercooling arguments cannot be invoked to interpret particles redistribution. Particles are redistributed by a direct interaction with the moving solidification interface. Several parameters controlling the particles redistribution were identified, namely the interface velocity, the particle size, the shape of the ice crystals and the orientation relationships between the crystals and the temperature gradient.

The control of the growth morphologies of ice crystals is a critical issue in fields as diverse a... more The control of the growth morphologies of ice crystals is a critical issue in fields as diverse as biomineralization, medicine, biology, civil or food engineering. Such control can be achieved through the ice-shaping properties of specific compounds. The development of synthetic ice-shaping compounds is inspired by the natural occurrence of such properties exhibited by antifreeze proteins. We reveal how a particular zirconium acetate complex is exhibiting ice-shaping properties very similar to that of antifreeze proteins, albeit being a radically different compound. We use these properties as a bioinspired approach to template unique faceted pores in cellular materials. These results suggest that ice-structuring properties are not exclusive to long organic molecules and should broaden the field of investigations and applications of such substances.

Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, 2003

X-ray tomography is a non-destructive technique which provides 3D information of materials. It is... more X-ray tomography is a non-destructive technique which provides 3D information of materials. It is consequently very attractive in Materials Science since the relation between macroscopic properties and the micro-structure of a material is very frequently required. The aim of this paper is to present selected results obtained in various investigations of metallic materials such as superplastic deformation, materials in the semi-solid state and metallic foams. Depending on the studied features, several tomography analysis modes were used: conventional absorption mode, phase contrast and holotomography, a new technique, which provides the 3D distribution of the electron density in the bulk of the material. Furthermore micro-tomography enables one to perform in situ experiments either by using a mechanical test machine or a furnace.

Metallurgical and Materials Transactions A, 2000

In the present work we report the processing of the WC-based and ZrO 2 -doped cermets with the ad... more In the present work we report the processing of the WC-based and ZrO 2 -doped cermets with the addition of oxides of 6 wt% through sinter/HIP routine. Microstructural characterization of the final products has been conducted with the help of XRD-analysis and scanning electron microscopy combined with energy dispersive spectroscopy. Influence of the binder metal on the developed microstructure and possibility to sinter a fully dense bulk cermet with zirconia is discussed in detail.

Ironmaking & Steelmaking, 2010

X-ray tomography has been applied for the estimation of iron ore sinter porosity. Procedures to d... more X-ray tomography has been applied for the estimation of iron ore sinter porosity. Procedures to distinguish open and closed pores and to estimate the volume and the equivalent diameter of each pore were developed, providing the possibility to calculate the amount of porosity considering open and closed pores separately. The effect of the sinter mixture composition on the porosity parameters was investigated, and a comparison with a mercury intrusion measurement is also presented. Reducibility tests were performed for the samples, the porosity of which had been previously identified by tomography. The fact that samples with a premeasured porosity could be analysed with other characterisation methods opens new possibilities to understand the effect of the porosity on the properties of the sinter.

International Materials Reviews, 2014

$Research paper thumbnail of A study of fracture of unidirectional composites using in situ high-resolution synchrotron X-ray microtomography$

Composites Science and Technology, 2006

Fibrous arrays and composites are among the strongest structures created by man or found in natur... more Fibrous arrays and composites are among the strongest structures created by man or found in nature. Such materials often fail in a slow, cumulative fashion, suppressing the sudden occurrence of rapid structural collapse. Our classical understanding of the statistical tensile strength and failure of unidirectional composites is usually based on a stochastic model where the key predictor is the size (N*) of a critical cluster of adjacent broken fibres, which inevitably leads to final composite failure. Here we show, via direct measurements using high-resolution synchrotron X-ray tomography, that in a quartz-epoxy composite the classical stochastic theory underpredicts -by a factor 3-5 -the size N* of the critical Ôfailed-fibreÕ cluster. A simple fracture mechanics argument which relates the critical fibre cluster size to the material strength is proposed to account for our data.

$Research paper thumbnail of The effect of fibre fractures in the bridging zone of fatigue cracked Ti–6Al–4V/SiC fibre composites$

Acta Materialia, 2004

The aim of the paper is to study the partitioning of stress between bridging and broken fibres an... more The aim of the paper is to study the partitioning of stress between bridging and broken fibres and the nearby matrix in the region around a fatigue crack in the matrix of a Ti-6Al-4V/SCS-6 SiC fibre composite. This was achieved by using synchrotron X-ray radiation to perform a combination of high spatial resolution tomographic imaging and strain mapping. The average elastic fibre strain for each ply was mapped with distance from the crack, ply by ply. Two samples were examined; one in which there were no broken fibres and one in which some fibres in ply 1 had broken. The contributions of broken and bridging fibres were separated using a double peak fitting routine. The interfacial stress variation and the extent of interfacial debonding were deduced from the fibre strain profiles. Contrary to most micromechanical models the interfacial frictional sliding stress was not found to be constant along the fibre length, but to decrease approximately linearly towards the crack plane. Upon unloading the fibres were found to undergo reverse sliding at the interface.

Acta Materialia, 2008

In situ tensile tests have been carried out on a high-strength, dual-phase steel. These experimen... more In situ tensile tests have been carried out on a high-strength, dual-phase steel. These experiments show that it is possible to follow and quantify the evolution of damage nondestructively and in three dimensions in this type of material. The measurements were analyzed in terms of density, size, aspect ratio of the cavities but also of the local deformation and the stress triaxiality in the sample. It was found that damage initiation is progressive with the applied tensile strain and that the initiation of new small cavities reduces the average diameter while the growth of the previously created ones increases the average diameter. This information was used to develop a new model for void growth based on the classical Rice and Tracey approach. This simple approach was modified to account for progressive damage initiation. The results of the proposed model are in good agreement with the measurements.

Acta Materialia, 2001

X-ray synchrotron radiography and high spatial resolution strain measurements have been combined ... more X-ray synchrotron radiography and high spatial resolution strain measurements have been combined to build-up a picture of the micromechanics of the damage that occurs, and the internal stress that causes it, within a Ti/SiC monofilament composite test-piece that was progressively strained in situ on the beam-line. The sample was designed to include a row of fibre ends within the test-piece. The radiographs show that fibre breakages occur during straining, even in the vicinity of the fibre ends. Axial and transverse strain measurements were made along each fibre in the composite as the load was progressively increased using a small X-ray spot size. In the present case interfacial sliding is believed to occur by slipping in or near the 4 µm carbon coating of the SCS-6 fibres. In order to interpret the strain measurements the predictions of a simple axi-symmetric finite element model of the composite are compared with the measured strains.

Acta Materialia, 2007

Syntactic foams (hollow glass microspheres embedded in a polymeric matrix) are being used increas... more Syntactic foams (hollow glass microspheres embedded in a polymeric matrix) are being used increasingly for thermal insulation purpose in ultra-deep water. A better understanding of the damage mechanisms of these materials under such a hydrostatic loading condition would be useful in determining actual material limits, improving phenomenological modeling and developing novel formulations in the future. To achieve this goal, a

Journal of Quantitative Spectroscopy and Radiative Transfer, 2008

The aim of this study is to determine the radiative properties, which are the extinction coeffici... more The aim of this study is to determine the radiative properties, which are the extinction coefficient, the scattering albedo and the scattering phase function, of highly porous open-cell aluminium foam, using more-or-less simple predictive models, and to compare all these models. The radiative properties are predicted using geometric optics laws to model the interaction of radiation with the particles forming the foam. Moreover, the particles forming the foam are large compared with the considered wavelength and are supposed to be sufficiently distant from each other to scatter radiation independently. Thus, the radiative characteristics of the foam can be determined by adding the contributions of each particle. A particular attention is paid on microstructure analysis and modelling. We considered different kinds of cell shapes and struts cross-section, using microscopic and tomographic analysis. Furthermore, a new phase function modelling is presented. Finally, we compare the results of each method with the radiative properties obtained from experimental measurements of directional and hemispherical transmittances and hemispherical reflectance. r