C. Toffolon-Masclet

• Dr
• Senior expert at Atomic Energy and Alternative Energies Commission

The exploration of archaeological heritage aims at understanding past societies through the study of ancient materials. While archaeometric analysis provides valuable insights, invasive sampling raises ethical concerns and is often restricted, necessitating the development of non-invasive techniques. This study presents a methodology based on X-Ray...

In the context of the heat treatment optimisation of steels used for nuclear reactor pressure vessel, the carbide precipitations in three model alloys: Fe-0.2 %C-1 %Mn, Fe-0.2 %C-1.5 %Mo and Fe-0.2 %C-1 %Mn-1.5 %Mo have been experimentally investigated and modelled. The precipitation sequences for times up to 2 months at 650 and 700°C have been de...

Chromium coated zirconium based nuclear fuel claddings are studied within the CEA-Framatome-EDF French nuclear fuel joint program as a short-term “Enhanced Accident Tolerant Fuel” (EATF) concept. It has already been demonstrated that, in hypothetical accident conditions such as Loss-of-Coolant-Accident (LOCA), 10-20 µm thick Cr coating slows down t...

Based on the M5Framatome alloy metallurgy, several Zr1NbxSnyFe alloys were developed to make structural components, with ultra-low tin addition and slightly increased iron content (Sn = 0, 0.3, and 0.5 wt.%; Fe = 1,000 and 2,000 wt. ppm). This paper details the microstructure of five different alloys, including M5Framatome and Q12, and their micros...

The paper aims at understanding the nature of ferrous alloys used for the fabrication of Renaissance armour in a Nuremberg workshop, owned by Valentin Siebenbürger. Noninvasive techniques such as X-ray diffraction (XRD) using synchrotron radiation (SR) are well suited to identify the different crystalline phases, characteristic of ancient ferrous a...

Low-alloy 16 to 20MND5 steels are used for the production of nuclear reactor components. During manufacturing, austenitization is followed by a quench; different types of microstructures are formed during this step. Characterizing the impact of Mo and Mn and of cooling rate on these microstructures can help understand how mechanical properties will...

Description Featuring 37 peer-reviewed and award-winning papers from industry experts that were presented at this 2019 symposium held in Manchester, United Kingdom. Topics covered include Sponsored by ASTM International Committee B10 on Reactive and Refractory Metals and Alloys and its subcommittee Zirconium and Hafnium.

Oxide Dispersion Strengthened (ODS) steels are candidate materials for both fission and fusion nuclear reactors. In this study, the microstructure of ferritic (Fe-14Cr-1W) and ferritic / martensitic (Fe-9Cr-1W) ODS steels has been characterized after two different processing routes: Hot Extrusion (HE) and Hot Isostatic Pressing (HIP). Transmission...

This study aims at identifying and quantifying the rate-limiting steps of the hydrogen desorption process from unoxidized M5Framatome alloy. Gaseous deuterium charging, Thermal Desorption Spectrometry (TDS), Differential Scanning Calorimetry (DSC) and finite elements simulations of TDS results reveal that hydrogen desorption kinetics from the metal...

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...

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...

The oxidation of chromium-coated zirconium-based alloys is studied under steam at temperatures ranging from 800°C up to 1500°C and for oxidation times ranging from a few minutes up to a few hours. For oxidation temperatures up to 1300°C, the overall oxidation kinetics is nearly parabolic at the beginning of oxidation, when the Cr outer layer is pro...

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...

In-situ time-resolved Synchrotron X-ray diffraction analyses were performed on zirconium alloy (Zircaloy-4) sheet samples, during their heating, isothermal oxidation at 700, 800 and 900°C under a flowing mixture of He and O2 and cooling. The oxide growth and the evolution of the oxide structure as a function of time and temperature were studied wit...

The effect of strengthened elements (Y 2 O 3 and TiO 2 ) on the microstructure has been investigated in Fe-14Cr-1 W based ferritic steels. Titanium content and/or volume fraction of yttria range between ∼0 up to 0.3 wt%. The volume fraction of nanoparticles is shown to control the grain size whereas titanium content has a sig- nificant influence on...

Coatings with thicknesses between a few microns and ~10mm deposited on a Zircaloy-4 substrate havebeen studied with the objective to provide a significant reduction in the oxidation-induced embrittle-ment of the nuclear fuel cladding, especially in accidental conditions, such as LOss-of-Coolant-Accident(LOCA) conditions. This paper deals with the e...

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...

Coatings with thicknesses between a few microns and ~10μm deposited on a Zircaloy-4 substrate have been studied with the objective to provide a significant reduction in the oxidation-induced embrittlement of the nuclear fuel cladding, especially in accidental conditions, such as LOss-of-Coolant-Accident (LOCA) conditions. This paper deals with the...

Konstrukcijski deli v konvencionalnih in jedrskih elektrarnah so pogosto izdelani iz močno legiranega Cr-Ni nerjavnega jekla. Raziskali smo staranje nerjavnega jekla tipa 258 (ASTM A351). Vzorce jekla smo izotermno žarili 10.000 ur pri temperaturi 350 °C. Za določanje vsebnosti δ-ferita in orientacijskega razmerja do austenita, strjenega na že form...

One-sided steam oxidation tests have been conducted at various temperatures between 1000 and 1500°C on several facilities on 12-15µm thick Cr-coated M5 claddings. Microstructural observations and micro-chemical analysis have been performed after oxidation and quenching. Some post-quenching ring compression tests have been also carried out to assess...

The numerical tool EKINOX-Zr has been upgraded to simulate oxygen tracer experiments during the high-temperature oxidation of a metal with a high oxygen solubility limit. The penetration of ¹⁸O tracer is calculated during the dynamic evolution of the ZrO2-x/αZr(O)/βzr system. The numerical approach allows to explicitly take into account the variati...

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...

Austenite grain size has been experimentally determined for various austenitization temperatures and times in a 2.25Cr-1Mo vanadium-free steel. Three grain growth regimes were highlighted: limited growth occurs at lower temperatures [1193 K (920 °C) and 1243 K (970 °C)]; parabolic growth prevails at higher temperatures [1343 K (1070 °C) and 1393 K...

The purpose of this work is to study the effect of prior plastic deformation on the precipitation mechanisms of MgxSiy in an AA6061 alloy. Differential scanning calorimetry (DSC), tensile testing and transmission electron microscopy (TEM) were used to characterize the precipitation sequence in samples that were isothermally aged at 180 °C with and...

The effect of the tempering heat treatment, including heating prior to the isothermal step, on carbide precipitation has been determined in a 2.25 Cr-1 Mo bainitic steel for thick-walled applications. The carbides were identified using their amount of metallic elements, morphology, nucleation sites, and diffraction patterns. The evolution of carbid...

This paper gives an overview of a multi-scale experimental study of the secondary hydriding phenomena that can occur in nuclear fuel cladding materials exposed to steam at high temperature (HT) after having burst (loss-of-coolant accident conditions). By coupling information from several facilities, including neutron radiography/tomography, electro...

An overview of the R&D carried-out at CEA since the nineties on the nuclear fuel claddings (Zircaloy-4, M5...) behavior upon DBA (and slighlty beyond) LOCA conditions, with a special focus on the relationship betwen phase transformation, O and H diffusion and partitioning and the actual and resultant thermomechanical nuclear fuel cladding propertie...

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,...

Previous experiments showed that the thickness of a thick prior-oxide layer formed on Zircaloy-4 fuel cladding can decrease during the first seconds at very high-temperature, before re-growing. We confirmed these results with oxidations performed at 1200. °C on prior-oxidized Zircaloy-4. The initial reduction of the prior-oxide was explained by the...

This work focuses on the effects of tempering conditions on the microstructure and consequently on the mechanical properties of a forged 2.25Cr-1Mo bainitic steel, for tempering temperatures between 650°C and 725°C and times up to 24 hours. Carbide precipitation sequences have been investigated by means of quantitative TEM characterizations of carb...

Sigma-phase precipitation in a 316Nb “stabilized” austenitic stainless steel was studied through complementary CALPHAD-based and dedicated experimental investigations. Thermokinetic calculations performed using Thermo-Calc (with the DICTRA module) and MatCalc software showed that the sigma phase (σ) precipitated directly at γ-austenite grain bounda...

1. Introduction 2. State of the Art 2.1 Materials and their Thermodynamic Properties 2.2 Growth Mechanism of Oxide Layers Formed on Zirconium Alloys 2.3 Oxidation Kinetics of Zirconium Alloys and Oxide Layer Microstructures 3. Influence of Water Vapor on Titanium Oxidation 3.1 Morphology 3.2 Kinetics 3.3 Limiting Process during the Parabolic Stage...

Specimens of duplex stainless steel (DSS, the 258-alloy type) were isothermally annealed (aged) at 300 °C and 350 °C for 10000 h and 30000 h. Spinodal decomposition of the solid solution in ferrite occurs during the thermal ageing of this material with a redistribution of mainly Cr and Ni and a formation of nanocellular domains. This causes signifi...

This study is focused on the hydrogen-induced dimensional change or ”growth” of zirconium alloys. Dilatometric experiments were performed on samples taken from a unirradiated Zircaloy-4 (Zy-4) fuel cladding loaded up to 940 wppm hydrogen. Samples were taken in the axial direction of the tube or at 45° to the axial and transverse directions. The res...

The erbium–hydrogen (Er–H) binary system has been investigated experimentally. New solubility limits and extensions of the homogeneity domains have been measured, using several experimental techniques, and high purity materials. A thermodynamic assessment of the system using the Calphad method has been performed. The calculated phase diagram shows...

Previous studies have shown that the numerical model EKINOX-Zr was able to simulate with accuracy oxide growth and oxygen diffusion into the matrix during high-temperature oxidation of Zy-4. In this study, the aim of the development was to evaluate if the observed effect of hydrogen cladding content on the increase of oxygen solubility in the high-...

In the purpose of increasing cycle length and/or fuel burn up, several theoretical and experimental studies have been performed at CEA. Among them, prospective neutronic calculations have shown that addition of a few weight percents of erbium into the cladding materials could be a promising alternative to the introduction of the neutronic poison di...

Les transformations de phases dans un acier 2¼Cr – 1 Mo lors de maintiens isothermes et de refroidissements continus ont été étudiées. Les diagrammes TTT et TRC ont été tracés en couplant des études dilatométriques, des observations métallographiques ainsi que des essais de dureté. La transformation par le calcul du diagramme TTT en diagramme TRC a...

The Er-O-Zr ternary system has been investigated experimentally along two isothermal sections at 800 degrees C and 1100 degrees C. In order to obtain pure and homogeneous samples, powder metallurgy has been used. The samples have been synthesized using pure Er and Zr powder obtained by the hydride route. The study has been focused on the Zr rich co...

Understanding the radiation embrittlement of reactor pressure vessel (RPV) steels is required to be able to operate safely a nuclear power plant or to extend its lifetime. The mechanical properties degradation is partly due to the clustering of solute under irradiation. To gain knowledge about the clustering process, a Fe−1.1 Mn−0.7 Ni (at.%) alloy...

The EKINOX numerical code, formerly developed to simulate high temperature oxidation of Ni alloys, has been recently adapted to solve out the issue of high temperature oxidation of Zirconium alloys. This numerical code is a one dimensional model that simulates the growth of an oxide layer using a specific algorithm for moving boundaries problem. In...

Due to their adequate properties, zirconium alloys are the reference materials for the nuclear fuel cladding tubes of Light Water Reactors (LWR). During some hypothetical accidental High Temperature (HT) transients, the materials should experience heavy steam oxidation and deep metallurgical evolutions. This promotes Alpha-Beta phase transformation...

The Zr–Sn binary system has been reinvestigated by several experimental techniques: X-ray diffraction, electron probe micro-analysis, mass density and calorimetry measurements. The existence of a miscibility gap inside the homogeneity domain of the η phase (Zr5Sn3–Zr5Sn4) has been confirmed. It has been also shown that Zr substitution on the Sn sub...

The partial isothermal section of the Fe-Sn-Zr system at 900 degrees C reported in Ref [7] was completed. As compared with this section, three new ternary compounds were evidenced (Y, 06 and Fe(6)Sn(6)Zr), one compound previously reported with a homogeneity domain (X) was shown to consist in fact of two separate compounds with close compositions (X...

Cast duplex stainless steels are frequently used for structural parts of nuclear power plants and other thermo-energetic objects. The ageing behaviour of the cast 258 type stainless steel has been studied in the frame of IMT Slovenia and CEA bilateral cooperation. The results of testing of French and Sloven partners are compared and analysed. The s...

The erbium–zirconium (Er–Zr) system has been completely reinvestigated experimentally. Particular attention was paid to the high purity of the raw materials, to the absence of oxygen contamination and to the control of the high vapor pressure of erbium. Several experimental techniques have been used to measure the solubility limits at different tem...

A new numerical tool has been developed by coupling the diffusion code “EKINOX” (Estimation Kinetics Oxidation) and the thermodynamic database “ZIRCOBASE” using TQ (ThermoCalc program interface). The aim of this tool is to calculate the oxygen diffusion during oxidation of Zr based alloys. The simulation results of the oxide growth kinetics and the...

Description The latest in this popular series provides 44 peer-reviewed papers on the latest international research covering all aspects of zirconium alloy properties and performance relevant to the nuclear industry. Topics address: • All aspects of the fuel cycle • Basic metallurgy • Spent fuel • Corrosion • Mechanical properties • Deformations me...

The Zircobase thermodynamic database for zirconium alloys coupled with Thermo-Calc software represents a powerful tool for prediction of thermodynamic and metallurgical data such as activities, formation enthalpies, phase transformation temperatures, solubility limits, existence temperature range, and chemical compositions of second phase precipita...