Jean-Marc Joubert

Jean-Marc Joubert
Institut de Chimie et des Matériaux de Paris Est

Doctor of Philosophy

About

200
Publications
16,821
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3,548
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Introduction
Intermetallic compounds, metal hydrides, non-stoichiometry, phase diagrams, DFT calculations, Calphad, thermodynamic modeling, thermodynamics, crystal structure, powder X-ray diffraction, resonant or anomalous diffraction, powder neutron diffraction, Rietveld

Publications

Publications (200)
Article
Full-text available
The aim of this paper is to investigate the contribution of the mixing enthalpy to the stability of the faced-centered cubic (fcc) phase of the Co–Cr–Fe–Mn–Ni system. For this purpose, systematic first principles calculations on Special Quasirandom Structures (SQS) were performed in a comprehensive manner on the fcc solution in every \(\left( {\beg...
Article
Calphad description at high pressure is a very important topic. Several models have been proposed in the literature. The model proposed by Lu et al. (X.-G. Lu, M. Selleby and B. Sundman, Comput. Coupling Phase Diagr. Thermochem., 29 (2005) 49-55) is very convenient in many aspects. But it has been criticized for giving unphysical extrapolations in...
Article
In Part I of this paper, we have described a modification brought to the model of Lu (X.-G. Lu et al., Comput. Coupling Phase Diagr. Thermochem. 29 (2005) 49–55) in order to avoid extrapolation problems at high pressure and temperature. We now extend this approach to the study of a binary system: Os–Pt. For this, a complete description (equation of...
Article
Full-text available
Boron and Silicon site occupancies of the T2 phase in the Cr-Si-B system were investigated experimentally and by first-principles electronic-structure calculations. A sample with nominal composition Cr 0.625 B 0.175 Si 0.2 was arc-melted under argon, encapsulated in a quartz-tube and heat-treated at 1400°C for 96 hours. It was then analyzed using S...
Article
Full-text available
Sm2Fe17 compounds are high-performance permanent magnets. Cobalt substitution allows us to further improve their magnetic properties. Depending on the thermal treatment, cobalt-substituted compounds can be synthesized either in the TbCu7 (disordered) or in the Th2Zn17 (ordered) structure type. Rietveld refinement of the number of transition metal d...
Article
This paper is a comprehensive review of the properties of LaNi5 derivatives and other AB5 compounds with CaCu5 crystal structure (A=Y, lanthanide, Th and B=transition metal, Al, Ge, Si, Sn) and their applications. The crystal structures of the intermetallic compounds are described considering their chemical composition and off-stoichiometry. Same a...
Preprint
Full-text available
Boron and Silicon site occupancies of the T2 phase in the Cr-Si-B system were investigated experimentally and by first-principles electronic-structure calculations within the scope of the Density Functional Theory (DFT). A sample with nominal composition Cr0.625B0.175Si0.2 was arc-melted under argon, encapsulated in a quartz-tube and heat-treated a...
Preprint
Full-text available
Machine learning (ML) methods are becoming integral to scientific inquiry in numerous disciplines, such as material sciences. In this manuscript, we demonstrate how ML can be used to predict several properties in solid-state chemistry, in particular the heat of formation of a given complex crystallographic phase (here the $\sigma-$phase, $tP30$, $D...
Article
Full-text available
This paper is dedicated to the Calphad modelling of the Cr–Fe–Nb–Sn–Zr quinary system. In previous papers, the thermodynamic modelling of the Cr–Nb–Sn–Zr quaternary system, the Fe–Sn–Zr and Fe–Nb–Zr ternary systems as well as the Fe–Nb binary system were carried out. Since no experimental data were available for the Cr–Fe–Sn and Fe–Nb–Sn ternary sy...
Article
Full-text available
High-throughput calculations can be applied to a large number of compounds, in order to discover new useful materials. In the present work, ternary intermetallic compounds are investigated, to find new potentially interesting materials for thermoelectric applications. The screening of stable nonmetallic compounds required for such applications is p...
Article
Phase equilibria data from ternary Cr-Nb-X (X = Hf, Ta, Ti, Zr) systems are relevant to the development of Niobium-silicide based composites for use in jet engines. Such systems present at several temperatures a pseudo-binary of Cr2Nb-Cr2X Laves phases. This work presents the experimentally determined liquidus projection and the 1200 °C isothermal...
Article
Full-text available
New face-centered cubic (FCC) multicomponent alloys designed through the high-entropy (HEA) concept and strengthened with L1 2 ordered precipitates are promising material solutions for high temperature (HT) structural applications. However, as the design strategy is based on multi-principal elements, the research of alloy compositions exhibiting a...
Article
In hypothetical accidental conditions, zirconium-based nuclear fuel claddings can absorb high hydrogen contents (up to several thousand wppm) and be exposed to high temperatures (βZr phase temperature range) before being cooled. This paper thoroughly investigates the microstructural and microchemical evolutions that take place in such conditions. T...
Article
Full-text available
Aiming at increasing the yield strength of transformation and twinning induced plasticity (TRIP and TWIP) titanium alloys while maintaining a good work-hardening, a dual-phase α/β alloy is designed and studied. The composition Ti – 7 Cr – 1.5 Sn (wt.%) is proposed, based on an approach coupling Calphad calculations and classical Bo-Md design tool u...
Article
Full-text available
Triggering transformation induced plasticity (TRIP) and twinning induced plasticity (TWIP) mechanisms in metastable β titanium alloys (bcc, body centered cubic) have helped reaching unprecedented mechanical properties for Ti-alloys, including high ductility and work-hardening. Yet the yield strength of such alloys generally remains rather low. So f...
Article
The case of the substitutional solid solutions based on elements possessing several crystallographic sites is discussed. It is concluded that, at least in some cases, especially when the solution domain is large and when strong differences of site occupancies are observed between the different sites, the sublattice model should be used as it is the...
Preprint
Full-text available
High-throughput calculations are a very promising tool for screening a large number of compounds in order to discover new useful materials. Ternary intermetallic are thus investigated in the present work to find new compounds potentially interesting for thermoelectric applications. The screening of the stable non-metallic compounds required for suc...
Article
The Fe–Sn–Zr system has been studied by first principles calculation and modelled with the Calphad method using the literature and new experimental data. The work includes a revision of Fe–Sn and Fe–Zr systems. Our experimental study has confirmed that the W5Si3 phase (stoichiometry Zr5Sn2,3Fe0,7) is stable at 1350 °C but also down to 1000 °C. More...
Preprint
Aiming at increasing the yield strength of transformation and twinning induced plasticity (TRIP and TWIP) titanium alloys, a dual-phase $\alpha$/$\beta$ alloy is designed and studied. The composition Ti 7Cr 1.5Sn (wt.%) is proposed, based on an approach coupling Calphad calculations and classical Bo-Md design tool used in Ti-alloys. Its microstruct...
Article
The mechanical properties due to solid solution strengthening are explored within the single phase face-centered cubic (fcc) domain of the Co–Cr–Fe–Mn–Ni high entropy alloy (HEA) system. This is achieved by combining an efficient and reproducible metallurgical processing of alloys to X-ray diffraction and nanoindentation characterization techniques...
Article
This work focuses on interstitial solid solutions of hydrogen in the face-centred cubic (fcc) host lattice of palladium and nickel, using a first-principles based approach. Cluster Variation Method (CVM) and Monte Carlo simulation algorithms were especially designed, allowing a coupled use of both techniques, to study hydrogen–vacancy interactions...
Article
Full-text available
The C15 phase (\(Fd\bar{3}m\)) has been extensively studied by several methodologies to evaluate its atomic interactions. Ideally ordered at the \(AB_2\) composition, this Laves phase is known to present a non-stoichiometry domain accommodated by substitutional atomic disorder at high temperature. With the Cu–Mg system as an example, a cluster expa...
Article
Full-text available
Magnesium hydride owns the largest share of publications on solid materials for hydrogen storage. The “Magnesium group” of international experts contributing to IEA Task 32 “Hydrogen Based Energy Storage” recently published two review papers presenting the activities of the group focused on magnesium hydride based materials and on Mg based compound...
Article
This work reports the Calphad modelling of the Cr–Nb–Sn–Zr quaternary system. In a previous paper, the thermodynamic modelling of the Cr–Nb–Sn system was presented. Since no experimental data were available for the Cr–Sn–Zr ternary system, new experimental data are provided, within this study, on the isothermal section at 900 °C. A ternary C14 phas...
Article
Full-text available
Mechanical alloying is widely used for the synthesis of hydrogen storage materials. However, amorphization and contamination triggered by long-time milling are serious drawbacks for obtaining efficient hydrogen storage. In this work, short-time ball milling synthesis is explored for a representative hydride forming compound: TiNi. Through structura...
Article
A series of Mg–Ni or Mg–Cu alloys with Mg content comprised between 55 and 77 at% Mg was prepared by mechanical alloying with the aim of synthesizing Mg2Ni and Mg2Cu phases, respectively. Their morphology and structural properties were characterized by scanning electron microscopy (SEM) and X-ray Diffraction (XRD). High Pressure Differential Scanni...
Article
Previous experimental studies in the Mo-Si-Ti system have shown the existence of a ternary phase around the composition Mo4Si9Ti7. No crystal structure was indicated for this phase. In the frame of a complete DFT study of phase stability in this system, we have discovered that this compound could have the V6Si5-type structure. The synthesis of the...
Article
Thermodynamic stability of the MoNi2 and MoNi8 compounds has been discussed in detail, and decision about their inclusion in thermodynamic assessment of the Mo–Ni system has been made. Enthalpies of formation of all Mo–Ni intermetallic compounds have been determined with the help of DFT calculations whereas enthalpies of mixing in the solid solutio...
Preprint
Full-text available
Within 4 different crystal structures, 2280 ternary intermetallic configurations have been investigated via high-throughput density functional theory calculations in order to discover new semiconducting materials. The screening is restricted to intermetallics with the equimolar composition TMX, where T is a transition metal from the Ti, V, Cr colum...
Article
The present study focuses on the impact of the vibrational frequencies on the thermodynamic behavior of hydrides, deuterides and tritides, using high scale harmonic phonon calculations based on first-principle calculations. 115 MHy hydrides were considered, for y={0.5, 1, 2} with M among 30 metallic elements. The results were found in excellent agr...
Article
Full-text available
This study aims to clarify the influence of the Spark Plasma Sintering (SPS) method on structural morphology, mechanical properties and also functional characteristics, such as hydrogen absorbing properties, for titanium-iron intermetallic compounds. We could synthesize B2-TiFe phase using mechanical alloying (MA) during 3 h and SPS treatment of 5...
Chapter
This chapter provides the ageing properties of AB5 compounds relevant for hydrogen storage.
Chapter
In this chapter the synthesis and crystal structure of AB5 phase intermetallic compounds are discussed in detail.
Chapter
This chapter provides an introduction to metal hydrides of AB5 compounds.
Chapter
This chapter provides an overview to AB5 phase metal hydrides that can be used for hydrogen storage.
Chapter
This chapter provides the electrochemical properties of AB5 compounds relevant for hydrogen storage.
Chapter
In this chapter the synthesis and crystal structure of AB5 phase hydrides are discussed in detail.
Chapter
This chapter contains tabular compilation of thermodynamic properties of AB5 compounds relevant for hydrogen storage.
Article
The high temperature oxidation behavior of two highly alloyed refractory austenitic steels is studied at 1000 °C under air. Both short-term oxidation kinetics and long-term oxidation products are investigated. Structural, elemental and morphological analyses are coupled to characterize the oxide phases' formation. Chromia and spinel are the main ph...
Conference Paper
Full-text available
The paper presents the investigation of a new three component (HF, AgNO 3 and H 2 O 2) metal assisted etching treatment on Si. Future possible applications are in particular the texturization of multicrystalline Si substrates. Currenttreatments of these substrates are known to be complex and moderately effective, especially when diamond wire saws a...
Article
The Cr-Nb-Sn system has been studied experimentally, by first principles calculation and finally modeled with the Calphad method. The experimental study has been carried out on the Cr-Sn binary system to determine the solubility of Sn in the A2 (Cr) solid solution, but also in the Cr-Nb-Sn ternary system in order to determine phase equilibria of th...
Article
Metal–silicon alloys have been extensively studied due to their potential as high temperature structural materials. In this sense, information from accurate phase diagram becomes important. The niobium–silicon–titanium system has been studied experimentally and thermodynamically assessed by different authors, resulting in contradictory isothermal s...
Article
New experimental results on the Fe-Sn-Zr phase diagram at 800 °C are presented, particularly in the central, Fe rich and Sn rich regions of the Gibbs triangle. Seven ternary alloys were designed, produced and examined by different techniques: optical and scanning electron microscopy, semi-quantitative microanalysis, quantitative microanalysis and X...
Article
The phase stability of the fcc solid solution in the Co-Cr-Fe-Mn-Ni system was theoretically and experimentally investigated. Using the Calphad approach and a new database (TCHEA1) devoted to high entropy alloys (HEA), the stable phases of 10 626 compositions could be calculated, depending on the temperature. 11 alloys were also processed and chara...
Article
Hydrogen is the only gas able to dissolve in aluminum. The solubility S of hydrogen in Al obeys the Sieverts' law and S is much larger in the liquid phase (above 660.4 °C) than in the solid one. This might lead to the formation of porosity during aluminum casting. In the present work, the ternary system Al–H–RE (RE = Er, La, Y) is investigated. The...
Article
A Rietveld analysis of neutron powder diffraction patterns obtained in situ during temperature scans shows that Fe 2 VAl crystallizes at room temperature in the fully ordered L2 1 structure and transforms at 1080 C and at 1190 C into partially disordered B2 and fully disordered A2 variants respectively. The low temperature stability of the L2 1 str...
Article
In situ monitoring of isothermal phase transformation in two Nb stabilized austenitic stainless steels (316Nb) by neutron diffraction W. Jolly, C. Toffolon-Masclet, J.-M. Joubert, B. Marini, F. Porcher, G. André, F.Cortial, Ph. Petit, S. Ringeval Journal of Alloys and Compounds (2016), doi:10.1016/j.jallcom.2016.07.244. Abstract In this study,...
Article
Bulk immiscible Pd–Rh nanoalloys supported on carbon are easily formed with tunable compositions and average particle sizes by two different methods: an indirect method (incipient wetness impregnation followed by reduction under H2 at 300 and 500 °C) along with a direct one (one-pot route heat treated at 600 °C under Ar). The main advantage of our...
Article
Full-text available
Ternary intermetallic A-B-C systems sometimes have unexpected behaviors. The present paper examines situations in which there is a tendency to simultaneously form the compounds AB(x), AC(x) and BCx with the same crystal structure. This causes irregular shapes of the phase homogeneity domains and, from a structural point of view, a complete reversal...
Patent
Full-text available
"ZenGen" is a tool which aims to automatically generate first principles input files of all the ordered configurations of a given crystal structure generated by assigning each element to each crystal site. The heat of formation of every end-member can be easily used in the thermodynamic modeling of the considered phase. "ZenGen" is a free and open...
Article
A new thermodynamic assessment of the Ni-H system has been carried out, providing a complete description valid up to 6 × 109 Pa of this system at the center of hydrogen storage issues. The study includes the hydride formation reaction and the presence of a miscibility gap in the fcc interstitial solid solution of hydrogen in nickel. In addition to...
Article
We show the application of the Calphad method to the phase diagram and thermodynamic description of the metal–hydrogen systems. The basics of the technique and selected examples will be presented demonstrating how, specifically, in the case of metal–hydrogen systems, it is able (i) to describe simple systems in a self-consistent way and (ii) to pre...
Article
In order to clarify controversial reports on the Fe–Re phase diagram, a new experimental investigation has been carried out. Three intermetallic phases have been evidenced, including the new report of the P phase found for the first time in a binary system. The phase relations involving the σ phase were established. In parallel, a first-principles...
Article
A comparison has been made between the phase equilibrium calculated within the Calphad method with different thermodynamic databases (TCFE7, TCNI5, TTNI7) and experimental data obtained on a Nb–Ti-modified industrial HP grade. The experimental measurements include phase equilibrium data at different temperatures and liquidus/solidus determination....
Article
The irregular shape of the x phase in the ternary system Re-W-Zr has been investigated. Both experimental measurements (joint Rietveld refinement of neutron and X-ray diffraction data) and density functional theory (DFT) calculations were used in order to obtain the site occupancies and to determine the reason why this phase is so deeply stabilized...
Article
Rhenium (Re) is used as an alloying element in Ni based superalloys but promotes the formation of fragile intermetallic compounds in many systems. The thermodynamic databases that allow the modeling of the properties of Ni based alloys are still incomplete and further data has to be integrated. In this context, we propose a new characterization of...