Simon Hallais's research while affiliated with French National Centre for Scientific Research and other places

Publications (19)

Article
Full-text available
Calcite twinning is a dominant deformation mechanism at low temperatures. It is often used to reconstruct paleostresses: orientations of the principal stress axes, stress ratios and differential stress. Despite numerous studies, on single crystals and aggregates, questions remain about the initiation and evolution of the twinning. In particular, th...
Article
Surface topographies can be reconstructed from backscattered electron (BSE) images captured from different detector orientations. This article presents a very general approach to this problem, in the spirit of photometric stereo methods, allowing for arbitrary BSE detector number (at least 3) and shapes. The general idea is to both determine the (n...
Article
Full-text available
The compressive resistance of truncated nanocone lattices produced by lithography and etching steps on Si or Ge wafers to get superhydrophobic and antireflective light-transmitting windows, as well as the protection efficiency of alumina or diamond coatings, is investigated by numerical simulations of elastic buckling, and nanocompression tests. Th...
Article
Full-text available
Precipitates in an austenitic stainless steel fabricated via any Additive Manufacturing (AM), or 3D printing, technique have been widely reported to be only Mn-Si-rich oxides. However, via Transmission Electron Microscopy (TEM) studies on a 316L stainless steel, we show that non-oxide precipitates (intermetallics, sulfides, phosphides and carbides)...
Preprint
Full-text available
Precipitates in an austenitic stainless steel fabricated via any Additive Manufacturing (AM), or 3D printing, technique have been widely reported to be only Mn-Si-rich oxides. However, via Transmission Electron Microscopy (TEM) studies on a 316L stainless steel, we show that non-oxide precipitates (intermetallics, sulfides, phosphides and carbides)...
Article
Full-text available
The mechanical behaviors of five polyether block amide foams, obtained by mold‐opening foam injection process, were investigated with regard to their microstructures. The materials vary in mass ratios of hard versus soft segments, and/or in process packing time. The resulting microstructures have been characterized in terms of cavity size and shape...
Article
Full-text available
A recently developed atomic force microscope (AFM) process, the Peak- Force Quantitative Nanomechanical Mapping (PF-QNM) mode, allows to probe over a large spatial region surface topography together with a variety of mechanical properties (e.g. apparent modulus, adhesion, viscosity). The resulting large set of data often exhibits strong coupling be...
Article
Scanning Electron Microscopes (SEMs) often generate images with a shaded appearance which gives a natural 3D impression. Ergo, quite a few methods to reconstruct the 3D surface topography from these using shape-from-shading methods are available in the literature. Here, a novel approach is discussed which uses BackScatter Electron (BSE) images from...
Article
Full-text available
Laser Cladding is one of the leading additive manufacturing technologies enabling the repair of metallic components. Their fatigue reliability depends directly on the material microstructure and consequently on the process parameters. This study highlights the influence of the interlayer dwell time on single-track walls for Inconel 718 repaired com...
Article
Laser Cladding is an additive manufacturing technology well suited for the repair of complex metallic components. The repair is a two-step process: first, one removes the worn region and then, the initial geometry is reconstructed locally. The aim of this work is to study the influence of the microstructural gradient on the strain localization in r...
Article
Full-text available
This work focuses on the in-situ characterization of multi-walled carbon nanotube (CNT) motions in thin random networks under strain. Many fine-grain models have been devised to account for CNT motions in carbon nanotube networks (CNN). However, the validation of these models relies on mesoscopic or macroscopic data with very little experimental va...
Article
Full-text available
E-twinning is a common plastic deformation mechanism in calcite deformed at low temperature. Strain rate, temperature and confining pressure have negligible effects on twinning activation which is mainly dependent on differential stress. The critical resolved shear stress (CRSS) required for twinning activation is dependent on grain size and strain...
Article
Full-text available
Laser Cladding is an additive manufacturing technology enabling to repair complex metallic components by removing the worn region and reconstructing locally the initial geometry. The aim of this work is to study the mechanical response of Inconel 718 repaired thin walls. More precisely, we perform an EBSD imaging and in-situ SEM tensile tests on sp...
Article
Full-text available
E-twinning is a common plastic deformation mechanism in calcite deformed at low temperature. Strain rate, temperature and confining pressure have negligible effects on twinning activation that is mainly dependent on differential stress. The critical resolved shear stress (CRSS) required for twinning activation is dependent on grain size and strain...
Article
Full-text available
A previously introduced mathematical framework for full-field X-ray orientation microscopy is for the first time applied to experimental near-field diffraction data acquired from a polycrystalline sample. Grain by grain tomographic reconstructions using convex optimization and prior knowledge are carried out in a six-dimensional representation of p...

Citations

... In their study, Parlangeau et al. [24] have deformed samples of Carrara marble in uniaxial compression and at low temperature. The experiments were monitored in situ using a Scanning Electron Microscope and a deformation analysis was performed at regular intervals via image correlation. ...
... However, micropillars are generally obtained by FIB micromanufacturing which allows to produce samples with a controlled shape and above all, a shape in adequation with the load cell used to deform it. In the case of a nanostructure, as the one studied here, the study of the collective behaviour is generally preferred due to the very low stiffness of a single structure [69]. One of the objectives of this work is to reach the behaviour of a single structure. ...
... The influence of other oxide inclusions (summarized in Table 2) on the corrosion performance of LPBF-316L is not discussed in the literature. Besides LPBF, researchers [225] had reported nano-inclusions with different compositions, including sulphur-rich inclusion in 316L manufactured by laser metal deposition (LMD). However, the influence of these inclusions on the corrosion performance of the alloy is not reported in the literature. ...
... The main reason for this is that the mobility of the foam flooding system improves the mobility ratio of the displacing phase and the displaced phase, and its Jamin effect can block large pores and selectively block oil and water. The surfactant in the system can reduce the oil-water interfacial tension and improve the oil washing efficiency [30,31]. ...
... In the present case, the goal is to study the qualitative features of soft MREs and the relative effect of the matrix viscoelasticity upon the coupled magneto-mechanical response. For that reason, we will use in the next section relatively simplified random and periodic particle distributions, as compared to the actual experiments that may exhibit particle clustering (see for instance recent work exhibiting particle clusters in MREs via an AFM surface analysis [61]). ...
... The dwell time also influences the grain morphology and orientation. During L-DED, Guévenoux et al. [347] compared the microstructure of IN718 with and without interlayer dwell time. They reported a highly textured microstructure with a sharp gradient, which consisted of large columnar grains across layers for samples without dwell time. ...
... When metal structures including steel bridges, offshore platforms and high rise steel-concrete composite buildings are in service, local damage such as cracks and local corrosion appear frequently on the surface of these metallic structures, leading to the decrease of the structure's strength and service life [1][2][3][4]. The repair of valuable metallic structures has become a major issue for civil engineering [5]. Additive manufacturing (AM), or 3D printing, has already attracted considerable attention in aerospace and biomedical industries [6], and its application has also been further extended to the field of civil and structural engineering [7], including the construction of new structures and repair of existing structures [8][9][10]. ...
... Perini et al. used steel (C40) as a substrate carbon and irradiated 316L stainless steel powder [9]. Constantinescu et al. studied the localization of plastic strain due to microstructure gradient on LAR structures, using a nickel alloy (Inconel 718) deposited on a wrought Inconel 718 substrate and 316 L stainless steel deposited on 316 substrates [10,11]. These LAR studies were developed using a laser cladding process, also known as direct energy deposition (DED). ...
... According to the Taylor criterion (Taylor 1938), there must be at least five independent systems to accommodate ductility and plastic deformation, thus {10-12}<-1011> extension twinning, and {10-11}<-1012> contraction twins would occur (Nave and Barnett 2004). Plenty of experimental and modeling work has studied the deformation mechanisms of AZ31 alloys (Agnew and Duygulu 2005;Li et al. 2010;Kim et al. 2008;He et al. 2017;Wu et al. 2017;Jiang et al. 2008;Jia and Bai 2016;Kang et al. 2014;Meng et al. 2019;Gzyl et al. 2015;Xu et al. 2015;Koller et al. 2015). ...
... The in-situ characterization of multi-walled carbon nanotube under external strain has uncovered the prominent mechanisms of CNTs motions [62]. Inkjet printing techniques have provided outstanding results for flexible resistance sensors in terms of their resistance reproducibility [68]. The carbon nanotube networks (CNNs) fabricated by inkjet-printing present potential applications for flexible resistance strain sensors [69]. ...