DEN : Thesis SL-DEN-14-0642

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Research field

Solid state physics, surfaces and interfaces / Solid state physics, chemistry and nanosciences

Title

Theoretical study of the role of magnetism on properties of defects in iron based alloys

Abstract

Iron based alloys such as steels, which show a complex structural-magnetic phase diagram,

play an essential role in nuclear technology.

Although their mechanical properties have been investigated intensively,

very little is known on the electronic and magnetic properties at the origin of their

macroscopic behavior. The application of first Principles studies in this field

is relatively new compared to other Solid State Physics and Material Science

disciplines. In light of the magnetic influence on defect properties identified previously:

e.g. dependence of short range order on concentrations of Cr in FeCr alloys and the chnage of diffusion properties of

defects at high temperatures (Gen IV reactors) due to magnetic disorder,

we propose here a theoretical work to investigate such effects.



The aim of this thesis is to understand the interplay between the magnetism and

defects/impurities in an iron matrix:

i.e. how the presence of defects will break the local magnetic order, and how the

magnetism may modify the stability, diffusion and segregation properties of point defect,

defect clusters and nano-precipitates.



To this end, a theoretical approach using multiscale modeling will be

developed. First principles calculations based on Density Functional Theory (DFT)

will be performed to accurately investigate key magnetic properties.

These data will serve to parameterize both Tight Binding and Heisenberg type models.

Semi-empirical Tight Binding schemes will be used to extend the DFT to larger space and

time simulations. The Heisenberg type model results will allow the inclusion of temperature

effects when coupled with Monte Carlo simulations, and therrefore a close comparison between simulation and experiments.



Location

Département des Matériaux pour le Nucléaire
Service de Recherches Métallurgiques Physiques
Service de Recherches de Métallurgie Physique
Centre : Saclay
Starting date : 01/10/2014

Contact person

Chu Chun FU
CEA / DEN/DMN/SRMP/SRMP
CEA/Saclay, Bat. 520, piece 116
Phone : +3 31 69 08 29 32

University / Graduate School

Paris 6 Pierre-et-Marie-Curie
Physique et Chimie des Matériaux - Paris VI -

Thesis supervisor

Cyrille BARRETEAU
CEA / DSM/IRAMIS/SPCSI/LNOSC
CEA/Saclay

F-91191, Gif-sur-Yvettes


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