Microstructure evolution of recrystallized Zircaloy-4 under charged particles irradiation

International audienceRecrystallized zirconium alloys are used as nuclear fuel cladding tubes of Pressurized Water Reactors. During operation, these alloys are submitted to fast neutron irradiation which leads to their in-reactor deformation and to a change of their mechanical properties. These phenomena are directly related to the microstructure evolution under irradiation and especially to the formation of -type dislocation loops. In the present work, the radiation damage evolution in recrystallized Zircaloy-4 has been studied using charged particles irradiation. The loop nucleation and growth kinetics, and also the helical climb of linear dislocations, were observed in-situ using a High Voltage Electron Microscope (HVEM) under 1 MeV electron irradiation at 673 and 723 K. In addition, 600 keV Zr+ ion irradiations were conducted at the same temperature. Transmission Electron Microscopy (TEM) characterizations have been performed after both types of irradiations, and show dislocation loops with a Burgers vector belonging to planes close to {101¯0} first order prismatic planes. The nature of the loops has been characterized. Only interstitial dislocation loops have been observed after ion irradiation at 723 K. However, after electron irradiation conducted at 673 and 723 K, both interstitial and vacancy loops were observed, the proportion of interstitial loops increasing as the temperature is increased. The loop growth kinetics analysis shows that as the temperature increases, the loop number density decreases and the loop growth rate tends to increase. An increase of the flux leads to an increase of the loop number density and a decrease of the loop growth rate. The results are compared to previous works and discussed in the light of point defects diffusion

XRD investigation of ion irradiated Ti3Si0.90Al0.10C2

International audienceTi3SiC2 is one of the most promising materials belonging to Mn+1AXn phases, which exhibit good damage tolerance, thermal stability and mechanical properties. Recently, in the frame of research on future gas cooled fast nuclear reactors, Ti3SiC2 has been considered as an innovative candidate material, which could be incorporated in some core components such as fuel cladding. At the present time, however, very few data are available concerning the behaviour of this material after irradiation. In this work, Ti3Si0.90Al0.10C2 samples were irradiated with high energy Kr and Xe ions and characterized by X-ray diffraction. Patterns were analysed in terms of change in peak intensity, peak position and width. Rietveld refinements were also performed. Increase in micro-strains and lattice parameter with irradiation dose was highlighted. The formation of ß-Ti3SiC2, which has never been observed by experimental XRD on non irradiated material, was proposed for the highly irradiated samples. A partial recovery of the microstructure with temperature was found

Impact of Hydrogen Pick-Up and Applied Stress on C-Component Loops: Toward a Better Understanding of the Radiation Induced Growth of Recrystallized Zirconium Alloys

Impact of hydrogen pickup and applied stress on c-component loops: toward a better understanding of the radiation induced growth of recrystallized zirconium alloys, published in ASTM STP 1543 (17th International Symposium on Zirconium in the Nuclear Industry

Experimental study of the nucleation and growth of c-component loops under charged particle irradiations of recrystallized Zircaloy-4

Recrystallized zirconium alloys, used as structural materials for the Pressurized Water Reactor fuel assembly, undergo under neutron irradiation induced stress free growth which accelerates for high irradiation doses. This acceleration is correlated with the formation of c-component vacancy dislocation loops in the basal plane. Since these defects are responsible for breakaway growth of recrystallized zirconium alloys, it is of prime importance to know the various factors that can affect their nucleation and growth. In the present work, two types of charged particle irradiations were conducted on recrystallized Zircaloy-4 samples in order to study c-component loops. A 2 MeV proton irradiation was performed up to a dose of 11.5 dpa at 623 K, and 600 key Zr ion irradiations were carried out at 573 K up to 7 dpa. For the first time after those charged particle irradiations, c-component loops were observed by Transmission Electron Microscopy. It has been shown that under Zr ion irradiation they start to nucleate and grow beyond a threshold dose as for neutron irradiation. The differences in the c-component loop microstructure are discussed for both ion irradiations and compared to the microstructure observed after neutron irradiation. Furthermore, it is shown that after proton irradiation the irradiated layer exhibits a misfit strain which is consistent with the irradiation induced growth of recrystallized zirconium alloys. (c) 2011 Elsevier B.V. All rights reserved

Programme de collaboration franco-suisse pour la création de nouvelles variétés de vigne durablement résistantes au mildiou et à l'oïdium

Une alternative aux traitements phytosanitaires pour lutter contre le mildiou et l'oïdium de la vigne est le développement de variétés résistantes. Leur création doit intégrer non seulement le niveau de résistance mais également sa durabilité, ainsi que les performances agronomiques notamment la productivité et la composition des baies qui doit convenir à la production de vins de haute qualité. L'Inra (France) a engagé le programme de sélection ResDur, basé sur le pyramidage des facteurs de résistance, en 2000. Il a conduit à l'inscription au catalogue français d'une première série de variétés à résistance polygénique – Artaban, Floreal, Vidoc, Voltis – en 2018. Agroscope (Suisse) a démarré la création de variétés résistantes en 1996, en mobilisant les résistances portées par des variétés allemandes, principalement Bronner. Un premier aboutissement a été l'homologation en Suisse de Divico et Divona, respectivement en 2013 et 2018. En 2009 l'Inra et Agroscope ont démarré un programme de sélection commun, visant à combiner les facteurs de résistance aux maladies présents de manière complémentaire dans leurs lignées respectives. Les croisements réalisés ont généré, après sélection assistée par marqueurs, 400 descendants porteurs des facteurs de résistanceRpv1, Rpv10 et/ou Rpv3 ; Run1, Ren3 et/ou Ren3.2. Leur phénotypage agronomique et œnologique est réalisé dans le cadre d'un réseau d'essais situés dans les deux Instituts à Colmar (FR) et à Pully (CH). Les premières observations pluriannuelles, portant sur 80 descendants, ont permis d'étudier leur stabilité phénotypique pour les caractères de résistance, les traits culturaux et la qualité des vins. A l'issue de cette étape, quinze variétés candidates ont été sélectionnées et installées en essais d'évaluation de leur valeur agronomique, technologique et environnementale (VATE) en Valais (CH), ainsi que dans trois régions françaises (Champagne, Val de Loire, Vallée du Rhône). L'inscription au catalogue des premières co-obtentions Inra/Agroscope est prévue à l'horizon 2024–2025

Plastic Deformation of Irradiated Zirconium Alloys: TEM Investigations and Micro-Mechanical Modeling

International audienc