Alexis Deschamps

Alexis Deschamps
Grenoble Institute of Technology | Grenoble INP · Filière Science et Ingénierie des Matériaux

Ph.D., Professor, Grenoble Institute of technology

About

248
Publications
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Publications

Publications (248)
Article
The composition dependence of ferrite growth kinetics in Fe-C-X ternary alloyed steels, where X=Ni, Mn, Mo, Cr, Si, was investigated using a high-throughput approach. Compositionally graded samples were subjected to in situ time- and space-resolved X-ray diffraction during intercritical annealing. To this end, diffusion couples were created between...
Article
The growth kinetics of ferrite during intercritical annealing of steel has been investigated using in situ high energy X-ray diffraction with a specially designed furnace allowing highly quantitative measurements of phase volume fractions. Kinetics have been obtained at 730∘C, 750∘C and 775∘C in different ternary Fe-C-X (where X : Mn, Ni, Mo and Cr...
Article
Full-text available
The unique combination of very large strains, high temperatures and high strain rates inherent to friction stir welding (FSW) and friction stir processing (FSP) and their dependency on the processing parameters provides an opportunity to tailor the microstructure, and hence the performance of welds and surfaces to an extent not possible with fusion...
Article
Full-text available
Combining submicrometer grain size with nanoscaled precipitation is an attractive approach to achieve high yield stress with reasonable ductility in aluminum alloys. The control of super saturated solid solutions decomposition in ultrafine grain structure during precipitation annealing treatments is however a huge challenge. It raises indeed the ge...
Article
Fe-Cr unmixing in stainless steels is an issue of great importance in industry restricting the use of these materials at middle range temperatures (around 300 °C–500 °C). The study of this phenomenon is difficult due to its very small scale (a few tenth to a few nanometers) and the fact that Fe and Cr have very similar crystallographic structures a...
Article
Full-text available
The natural aging (NA) response of a commercial Al-Zn-Mg alloy has been tracked to investigate the effects of solute clusters on its mechanical properties. It has been observed that the increase of yield strength during NA is not accompanied by the degradation of uniform elongation due to the simultaneously enhanced strain hardening ability. As a c...
Article
Full-text available
Oxide Dispersion Strengthened (ODS) steels are candidates for nuclear applications. ODS are produced by mechanical alloying of Fe-14Cr, Y2O3 and TiH2 powders and consolidation at 1100°C, resulting in finely dispersed nano-oxides. Their precipitation kinetics has been quantitatively determined by in-situ Small Angle X-ray Scattering during continuou...
Article
Full-text available
The unique combination of very large strains, high temperatures and high strain rates inherent to friction stir welding (FSW) and friction stir processing (FSP) and their dependency on the processing parameters provides an opportunity to tailor the microstructure and hence the performance of welds and surfaces to an extent not possible with fusion...
Article
Full-text available
Wrought aluminum alloys are an attractive option in the quest for lightweight, recyclable, structural materials. Modern wrought aluminum alloys depend on control of complex microstructures to obtain their properties. This requires an understanding of the coupling between alloy composition, processing, and microstructure. This paper summarizes recen...
Article
The mechanical behavior of micro-composites Duplex Stainless steels (DSS) produced by Accumulative re-Bundling and Drawing (ABD) has been investigated. We evidenced a systematic increase in the yield strength, as a function of the manufacturing step, independently from the phases' volume fraction. A simple rule of mixture (ROM) successfully predict...
Article
Full-text available
Increasing demand for a reduction in fuel emissions in passenger vehicles has generated the need for lighter weight materials to be used in automobile manufacture for body-in-white applications. Aluminium alloys in the 6000-series, containing Mg and Si are ideal candidates for these applications but lack the formability found in commonly used steel...
Article
When subjected to long-term aging at intermediate temperatures, the 15–5PH precipitation hardening martensitic stainless steel is subject to a complex evolution of its microstructure that impacts its service mechanical properties. This evolution includes possible evolution of minor austenite phase, of the copper-rich precipitates, as well as unmixi...
Article
Full-text available
This study allowed to understand the influence of severe plastic deformation by High Pressure Torsion (HPT) on an Al-Zn-Mg-Cu alloy and more especially the influence on precipitation mechanisms thanks to the correlation between DSC, SAXS and STEM data. A shear strain of γ ≈ 200 was first applied to the alloy. This deformation leads to nanostructura...
Article
Full-text available
In-situ high energy X-Ray diffraction (HEXRD) was used on compositionally graded steels to study the effect of substitutional elements on ferrite growth kinetics in Fe–C–X and Fe–C–X–Y systems. Two systems were selected to illustrate the applicability of the combinatorial approach in studying such transformations, Fe–C–Mn and Fe–C–Mn–Mo. Comparison...
Article
Precipitation in Duralumin, a historic quaternary alloy of the type: Al–Cu–Mg–Si, was never fully studied nor observed by current electron microscopy techniques. This article presents the full characterization and comparison of two alloys: a Duralumin (A-U4G) from the 1950s collected on a vintage aircraft and its modern equivalent: a 2017A alloy. T...
Article
The spatial distribution of the strengthening precipitates in stationary shoulder friction stir welds (SSFSW) of the AA2050 Al-Cu-Li alloy has been characterized by small-angle X-ray scattering (SAXS), combined with micro-hardness mapping and transmission electron microscopy (TEM). It is shown that welding the alloy before ageing (T3WT8) leads to a...
Article
Ultrafine-grained aluminum alloys offer interesting multifunctional properties with a combination of high strength, low electrical resistivity, and low density. However, due to thermally induced grain coarsening, they typically suffer from an intrinsic poor thermal stability. To overcome this drawback, an Al-2%Fe alloy has been selected because of...
Article
Development and characterization of clad-to-plug resistance upset welds is presented for two oxide dispersion strengthened steels candidates for sodium-cooled fast reactors fuel cladding: 9Cr ferrito-martensitic steel and 14Cr ferritic steel. A comparative approach is adopted regarding these two materials implying weldability studies and weld mecha...
Article
The design of duplex stainless steels (DSS) with strain induced martensite (SIM) transformation relies on the optimization of austenite stability. The goal is to achieve a distribution of SIM over a wide range of strain so as to get the best combination of strength and ductility. A systematic study of plastic deformation mechanisms, of the link bet...
Article
Full-text available
In this paper are reviewed some recent progress on the understanding and simulation of aluminum alloy age hardening. The main phenomena governing the formation of precipitate microstructures in aluminum alloys are presented; they provide a qualitative understanding of the relationship between alloy chemistry, processing and final precipitate micros...
Article
Full-text available
Deformation and damage mechanisms of Fe-14Cr based oxide dispersion strengthened (ODS) steels have been investigated through a multi scale approach on model materials elaborated by powder metallurgy Uniaxial tensile behavior was studied from room temperature to 800 °C at several strain rates. Furthermore, the plasticity of Fe-14Cr ODS steels has be...
Article
Full-text available
The design of new metallic alloys is faced with the challenge of an increasing complexity of the alloys composition, processing and resulting microstructures necessary to answer to multiple property targets, together with a requirement that the design stage be faster and less expensive. This paper shows that combinatorial methods, combining numeric...
Article
The aging response of two Al-3Mg alloys with Cu addition < 1 wt% has been tracked under simulated automotive paint bake conditions ($ 20 min, 160 and 200 C) to quantify the processes controlling hardening. The decomposition of the solid solution, observed by atom probe tomography, has been interpreted using a novel pair correlation function approac...
Article
The aging response of two Al-3Mg alloys with Cu addition < 1 wt% has been tracked under simulated automotive paint bake conditions ($ 20 min, 160 and 200 C) to quantify the processes controlling hardening. The decomposition of the solid solution, observed by atom probe tomography, has been interpreted using a novel pair correlation function approac...
Article
The effect of Mg content on the natural ageing of Al-Cu-Li-(Mg) alloys has been investigated on a compositionally graded material made by linear friction welding, allowing to probe Mg contents between 0 and 0.4 at.%. High throughput time- and space-resolved characterization of natural ageing kinetics has been achieved using small-angle X-ray scatte...
Conference Paper
Full-text available
Increased demand for light-weighting in passenger vehicles has created a need for strong, light, ductile materials to be used in body-in-white applications. The AA6xxx-series of aluminum alloys are suitable candidates meeting most requirements but can fall short of the formability demands of designers, necessitating an understanding of what control...
Preprint
The effect of Mg content on the natural ageing of Al-Cu-Li-(Mg) alloys has been investigated on a compositionally graded material made by linear friction welding, allowing to probe Mg contents between 0 and 0.4 at.%. High throughput time-and space-resolved characterization of natural ageing kinetics has been achieved using small-angle X-ray scatter...
Article
The corrosion and microstructure of the Al-Cu-Li alloy AA2050 were investigated as a function of artificial ageing. The work herein seeks to provide a consolidated overview of the corrosion of AA2050, in particular the influence of T1 (Al2CuLi) precipitates on the observed behaviour. Transmission electron microscopy (TEM) and scanning electron micr...
Article
Room temperature solute clustering in aluminium alloys, or natural ageing, despite its industrial relevance, is still subject to debate, mostly due to its experimentally challenging nature. To better understand the complex multi-constituents' interactions at play, we have studied ternary and quaternary subsystems based on the Al-Cu alloys, namely A...
Article
In this work we propose a top-down strategy in which an austenitic stainless steel (type AISI 316L) and a ferritic stainless steel (type AISI 430LNb) are mechanically alloyed by Severe Plastic Deformation (SPD) to elaborate an architectured duplex stainless steel. This proposed strategy serves two main objectives: i) enhancing the properties by mic...
Article
A new methodology for the characterization of solute clusters leading to compositional fluctuations is presented and discussed. The methodology makes use of contrast variation arising from a combination of small-angle scattering using neutrons and X-rays, and adapts a model for solute correlation to extract the chemistry and length scale of cluster...
Article
Precipitation in structural alloys is one way of controlling the mechanical strength of structural materials. Taking the example of a stainless steel used in aircraft manufacturing, it is shown that "macro"-scale design often involves extensive "nano"-scale studies that require the use of advanced instruments. The mastery of each of these technique...
Article
Full-text available
The landscape of energy production and use is facing great challenges in the transportation sectors. The two main means of transportation, automobiles and airplanes, are mainly made from metals. The necessity of reducing their carbon emission translates into major stakes for weight reduction, which can only be the result of an interplay between imp...
Article
Full-text available
The use of high strength Al-Zn-Mg-Cu alloys in automotive components is restricted by their low formability. Warm forming in the under-aged state improves formability, but induces a strain-dependent microstructure evolution due to dynamic precipitation. We present a new methodology to quantitatively evaluate the dynamic precipitation strain depende...
Article
The influence of minor solute additions of Mg, Ag and Zn and their combinations on the precipitation kinetics and strengthening of an Al-Cu-Li alloy has been systematically investigated. Combining differential scanning calorimetry (DSC) and small-angle X-ray scattering (SAXS) provides information on how alloy chemistry changes the precipitation seq...
Article
The microstructure of a 6061-T6 Al alloy subjected to ion irradiation at 95 and 165 displacements per atom (dpa) has been evaluated by transmission electron microscopy and atom-probe tomography. The initial microstructure of the alloy is dominated by needle-shaped β’’ precipitates. After 95 dpa irradiation, the β’’ precipitates display a slight lat...
Article
The effect of microstructural parameters on the microstructure, tensile properties from room temperature to 800 °C and creep properties at 650 °C has been investigated in a 14%Cr oxide dispersion strengthened (ODS) steel. Combining a control of oxide addition, consolidation route and thermo-mechanical processing, the different parameters of the mic...
Article
The evolution of microstructure during long-term ageing (LTA) up to 3000 h at 85 °C following a T8 heat treatment has been characterised in three Al[single bond]Cu[single bond]Li[single bond]Mg alloys of variable Mg and Li content. A combination of transmission electron microscopy, differential scanning calorimetry and small-angle X-ray scattering...
Article
Full-text available
The influence of the martensitic transformation on microscale plastic strain heterogeneity of a duplex stainless steel has been investigated. Microscale strain heterogeneities were measured by digital image correlation during an in situ tensile test within the SEM. The martensitic transformation was monitored in situ during tensile testing by high-...
Article
The fine microstructure obtained by unmixing of a solid solution either by classical precipitation or spinodal decomposition is often characterized either by small angle scattering or atom probe tomography. This article shows that a common data analysis framework can be used to analyze data obtained from these two techniques. An example of the appl...
Article
The processing of oxide dispersion strengthened (ODS) steels involves ball milling, where the oxide forming species are driven in solid solution. Precipitation of the nanometre-scale oxides occurs during subsequent annealing and consolidation. This paper reports in-situ Small-Angle X-ray Scattering measurements of the formation of these precipitate...
Article
The GP(I) zone formation during quench is simulated in an industrial Aluminum alloy AA7449 75 mm thick plate by using a multi-class precipitation model. For this purpose, results of in situ SAXS experiments are reported. A methodology is presented that takes advantage of the collected data to derive i - a thermodynamic description for GP(I) zones f...
Article
In irradiated material, cavities result from the condensation of vacancies induced by collision cascades. The study of their formation is a relevant topic since a high density of cavities may alter significantly the material performance. In this work, a simplified version of in line holography was successfully applied for imaging cavities in ion-ir...
Article
Minor solute additions of Mg, Ag or Zn to AlCuLi alloys are known to promote the formation of the T1-Al2CuLi phase and improve the strengthening of these alloys. In this paper, we use atomic resolution high angle annular dark field scanning transmission electron microscopy (STEM-HAADF) in conjunction with electron dispersive spectroscopy (EDS) mapp...
Article
The mechanical properties of precipitation-hardened stainless steels rely on a complex multi-scale microstructure developed during a sequence of quenching after austenitization, followed by a precipitation heat treatment. Important features of the resulting microstructure include the microstructure of martensite, retained and reverted austenite, na...
Chapter
In the Al-Cu-Li system, the main strengthening precipitate is the T1 phase (Al2CuLi). In order to understand the strengthening related to the formation of this phase, we first present an investigation of the morphology of the T1 phase in an AA2198 alloy using Transmission Electron Microscopy (TEM) and Differential Scanning Calorimetry (DSC) in rela...
Article
This paper presents a systematic study where the distribution of precipitate microstructures is mapped in the cross-section of a friction stir weld made with an AA2050 Al-Cu-Li alloy in the naturally aged temper, as well as the evolution of this microstructure during subsequent post-welding heat treatment (PWHT). This study is carried out using spa...
Article
The development of new engineering alloy chemistries is a time consuming and iterative process. A necessary step is characterization of the nano/microstructure to provide a link between the processing and properties of each alloy chemistry considered. One approach to accelerate the identification of optimal chemistries is to use samples containing...
Article
Nanostructured ferritic steels were mechanically alloyed with various contents of oxide-forming yttrium and titanium (0, 0.05, 0.3 and 1 wt%). The microstructure evolution of the milled powders during non-isothermal annealing treatments was studied using in situ synchrotron X-ray diffraction. Recrystallization and grain growth were quantified upon...
Article
In this study, we demonstrate the feasibility of in-situ combinatorial studies of the effect of alloy composition on precipitation kinetics. We apply the approach to the Cu-Co system which is a classical model system for precipitation kinetics studies. We then use the acquired database as a tool for assessing the capability of a simple precipitatio...
Article
We apply a combinatorial approach to study the influence of Mg concentration on the precipitation kinetics in an Al-Cu-Li alloy using a diffusion couple made by linear friction welding. The precipitation kinetics is monitored in the composition gradient material using simultaneous space and time-resolved in-situ small-angle X-ray scattering measure...
Article
Full-text available
The age hardening 6061-T6 aluminium alloy has been chosen as structural material for the core vessel of the material testing Jules Horowitz nuclear reactor. The alloy contains incoherent Al(Cr, Fe, Mn)Si dispersoids whose characterization by energy-filtered transmission electron microscopy (EFTEM) analysis shows a core/shell organization tendency w...
Article
This work presents a detailed, multiscale, spatially resolved study of the microstructure of an electron beam butt weld of the EN-AW 7020 (Al-Zn-Mg) alloy. Using a combination of optical, scanning and transmission electron microscopy, differential scanning calorimetry, and small-angle X-ray scattering, the distribution of phases in the different ar...
Article
This paper presents an experimental and modeling study of the mechanical behavior of an electron beam welded EN-AW 7020 aluminum alloy. The heterogeneous distribution of mechanical properties is characterized by micro-tensile tests and by strain field measurements using digital image correlation technic. These results are related to the microstruct...
Article
We present a systematic study of the relationship between precipitate microstructure and resulting yield strength in an Al–Cu–Li alloy. By varying the thermomechanical ageing treatments applied to the AA2198 alloy (pre-deformation, heat treatment temperature and duration), T1 microstructural parameters (thickness, diameter and volume fraction) are...
Conference Paper
Full-text available
Dynamic interactions between plastic deformation and precipitation processes in Aluminium alloys can lead to large changes in precipitation kinetics as compared to conventional heat treatments. This can be due to a number of different mechanisms such as changes in vacancy concentrations or movement of structural defects. Understanding the underlyin...
Article
Full-text available
Two examples of precipitation studies (in Al-Li-Cu and Al-Li-Mg alloys) are shown to demonstrate the complementarity of atom probe tomography, small-angle scattering and differential scanning calorimetry for precipitation studies. It will be used to unravel an unexpected two-step precipitation behavior of T1 in Al-Li-Cu and to ascertain precipitate...
Article
Al-Cu-Li alloys are extensively used for aerospace applications. The main hardening phase is the T1 phase that precipitates as thin platelets on {111}Al planes. To facilitate its nucleation, different minor alloying elements are added and dislocations are introduced by cold deformation before the ageing treatment. The impact of these additions in c...