Dresden 2011 – wissenschaftliches Programm
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MM: Fachverband Metall- und Materialphysik
MM 15: Computational Materials Modelling IV
MM 15.4: Vortrag
Dienstag, 15. März 2011, 11:45–12:00, IFW B
Structure and energetics of nanoclusters in bcc-Fe containing copper, nickel and vacancies — •Ahmed Tamer Al-Motasem1, Matthias Posselt2, Frank Bergner1, and Uwe Birkenheuer1 — 1Institute of safety research — 2Institute of Ion Beam and Materials Research, Helmholtz-Zentrum Dresden-Rossendorf
Reactor pressure vessel (RPV) steels consist of polycrystalline bcc-Fe containing Cu, Ni and other foreign atoms. The continuous irradiation by fast neutrons leads to supersaturation of vacancies and self-interstitials and enhances the diffusion of Cu and Ni which occurs via the vacancy mechanism. These processes favor the formation of nanoclusters consisting of vacancies, Cu and Ni. The interaction of dislocations with these precipitates is considered to be the main cause of hardening and embrittlement of the RPV steels. In order to model the evolution of the precipitates under irradiation by rate theory, the energetics and thermodynamics of the clusters must be known. These data are hardly obtainable by experiments, however, they can be provided by atomic-level computer simulations. In the present work a combination of on-lattice Monte Carlo simulations and off-lattice Molecular Dynamics calculations is employed to determine structure and energetics of the nanoclusters. The atomistic simulations show that ternary clusters exhibit a shell structure with a core consisting of vacancies followed by a shell of Cu and an outer shell of Ni. Binary vacancy-Cu and Ni-Cu clusters show a similar shell structure, whereas the atomic configuration of vacancy-Ni agglomerates is completely different.