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Postdoc position - Multi-scale modelling the ordering kinetics in Ni-Cr-Fe alloys H/F


Détail de l'offre

Informations générales

Entité de rattachement

Le Commissariat à l'énergie atomique et aux énergies alternatives (CEA) est un organisme public de recherche.

Acteur majeur de la recherche, du développement et de l'innovation, le CEA intervient dans le cadre de ses quatre missions :
. la défense et la sécurité
. l'énergie nucléaire (fission et fusion)
. la recherche technologique pour l'industrie
. la recherche fondamentale (sciences de la matière et sciences de la vie).

Avec ses 16000 salariés -techniciens, ingénieurs, chercheurs, et personnel en soutien à la recherche- le CEA participe à de nombreux projets de collaboration aux côtés de ses partenaires académiques et industriels.  

Référence

2022-19835  

Description du poste

Domaine

Matériaux, physique du solide

Contrat

Post-doctorat

Intitulé de l'offre

Postdoc position - Multi-scale modelling the ordering kinetics in Ni-Cr-Fe alloys H/F

Sujet de stage

Development of a model of the ordering kinetics in Ni-Cr-Fe alloys, combining atomic Monte Carlo simulations and a mesoscopic approach. The model will predict the evolution of the order parameters, the volume fraction and the size of the ordered domains, as well as the effect of Fe content.

Durée du contrat (en mois)

24

Description de l'offre

Scientific and industrial context. Many Pressurized Water Reactors (PWRs) in Europe and the USA are equipped with Alloy 690 steam-generator tubing. Alloy 690 is a Nickel-base alloy containing approximately 60% Ni, 30% Cr and 10% Fe. Alloy 690 was selected for PWR steam-generator tubes thanks to its good thermo-mechanical properties and its excellent resistance to stress corrosion cracking. However, some nickel-chromium alloys may be subject to ordering during thermal aging, resulting in the formation of a Ni2Cr phase. The Ni2Cr phase is a superlattice which can result in significant changes of the physical or mechanical properties compared to those of the disordered alloy. Alloy 690, which usually contains a bit less than two nickel atoms per chromium atom, could potentially develop long-range ordering (LRO) after thermal aging for several years at the high temperatures encountered in PWRs. LRO could be detrimental for the ductility and the resistance to stress corrosion cracking of this alloy. Although some authors conclude that LRO cannot occur within the lifetime of PWRs, such conclusions are based on the extrapolation of experimental results at higher temperatures and highly depend on the activation energies considered. The effects of iron content and stoichiometry on the ordering kinetics is also a matter of debate. Thus, there is a need for more acute understanding and modeling.

Scientific Objectives. The objective of the post-doctoral project is to develop a modelling of ordering kinetics in Ni-Cr-Fe model alloys, combining Atomistic Kinetics Monte Carlo simulations (which will help to understand the mechanisms of ordering) and a more rapid mesoscopic approach (the exact model will depend on the ordering mechanism). These tools should be able to predict time-temperature curves, the evolution of short-range and long-range order parameters, the volume fraction and size of the ordered domains in Ni-Cr alloys, and the effect of an addition of Fe on these evolutions. The post-doctoral researcher will compare the results of the modeling to existing and new experimental results and will interact with experimentalists working on the same topic.

The candidate should hold a recent PhD in Materials Science, a strong expertise in diffusion, thermodynamics or phase transitions in metallic alloys and a good modeling experience in this research area. Interested candidates are invited to submit by email an application letter, a detailed CV including a list of publications and the name and email of two references.

 

Localisation du poste

Site

Saclay

Localisation du poste

France

Ville

Gif-sur-Yvette

Critères candidat

Formation recommandée

PhD in Materials Science

Demandeur

Disponibilité du poste

01/02/2022