Investigations of structure, energetics, thermodynamics and kinetics of copper-vacancy clusters in bcc-Fe

The irradiation-enhanced formation and evolution of Cu-rich precipitates in reactor pressure vessel steels are multiscale phenomena. These processes can be effectively investigated by rate theory using thermodynamic parameters which must be obtained from atomistic simulations. The present work reports on the structure, energetics, thermodynamics and kinetics of nanoclusters consisting of vacancies and/or Cu. The most recent Fe-Cu interatomic potential by Pasianot and Malerba is used. A combination of Metropolis Monte Carlo and Molecular Dynamics simulation is applied to determine the most stable configurations the Cu-rich nanoclusters. The phonon contributions to the free formation energies of the clusters are evaluated from vibrational density of states obtained using dynamical matrix method. The absolute value of the total free binding energy decreases for vacancy clusters with increasing temperature while the increase is observed for pure Cu clusters. Mixed vacancy-Cu defect clusters show non-uniform behaviour in the absolute value of total free binding energy.