Role of Trapping Impurities on He Desorption and Clustering in Irradiated a-Fe
- Departamento de Fisica Aplicada, University of Alicante, E-03690 Alicante, Alicante (Spain)
- Service de Recherches Metallurgiques, CEA/Saclay, F-91191 Gif-sur-Yvette (France)
It is well-known that impurities affect the migration of intrinsic point defects in metals. For instance, carbon is a common impurity in Fe that significantly retards diffusion of vacancies. Under fusion irradiation conditions, high levels of He are produced by transmutation reactions. This element strongly interacts with vacancies produced during irradiation and agglomerate into stable He-vacancy clusters that can deteriorate the mechanical properties of the material. A physically-based model accounting for the interactions between He, point defects (interstitials and vacancies) and trapping impurities is therefore necessary to understand and predict damage evolution in Fe. We have used a multi-scale approach to predict the evolution of He in the presence of impurities in irradiated Fe. Density Functional Theory (DFT) calculations were performed to investigate the migration mechanisms and to determine the activation energies of the different atomistic processes. The influence of impurities - such as carbon - on the binding energies of small He-vacancy clusters was also studied. Using the information obtained by DFT a physically-based model was developed and implemented in a kinetic Monte Carlo (kMC) code to follow the evolution of He in Fe. In addition, a model based on the rate theory (RT) was developed in order to achieve larger simulation times and volumes. Results obtained with this model, which is based on a mean field approximation are compared to those obtained with kMC. Using this multi-scale approach, the simulation results are used to interpret the different stages of thermal He desorption experiments and to determine the predominant migration mechanism. The influence of impurities which affect the diffusion of point defects or modify the binding energies of He-vacancy type clusters is also studied. (authors)
- Research Organization:
- Materials Research Society, 506 Keystone Drive, Warrendale, PA, 15086-7573 (United States)
- OSTI ID:
- 21091559
- Resource Relation:
- Conference: Symposium on Structural and Refractory Materials for Fusion and Fission Technologies, Boston, MA (United States), 28-30 Nov 2006; Other Information: Country of input: France; Related Information: In: Proceedings of the Symposium on Structural and Refractory Materials for Fusion and Fission Technologies, by Aktaa, J. [ed. Forschungszentrum Karlsruhe GmbH, Institute for Materials Research II, Postfach 3640, 76021 Karlsruhe (Germany)]; Samaras, M. [ed. Paul Scherrer Institute, Nuclear Energy and Safety, CH-5232 Villigen PSI (Switzerland)]; Serrano de Caro, M. [ed. Lawrence Livermore National Laboratory, Chemical Biology and Nuclear Science Division, L-632, P.O. Box 808, Livermore, CA 94550 (United States)]; Victoria, M. [ed. Polytechnic University of Madrid, Instituto de Fusion Nuclear, J. Gutierrez Abascal 2, 28006 Madrid (Spain)]; Wirth, B. [ed. University of California-Berkeley, Nuclear Engineering Dept., Berkeley, CA 94720-1730 (United States)], v. 981E, 112 pages.
- Country of Publication:
- United States
- Language:
- English
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