Monte Carlo modelling of damage accumulation in metals under cascade irradiation

The Monte Carlo (MC) method is used to study cascade damage effects in damage accumulation in pure metals at temperatures below stage III, when vacancies and their clusters are immobile. The irradiation is modelled by sequential introduction of collections of defects representing the primary damage state of cascades placed randomly in the simulation volume. The cascades generated in molecular dynamics (MD) simulations for recoil energies from 2 to 10 keV are used. Concentrations of point defects as well as defect cluster densities are monitored as a function of dose up to 0.02 dpa. The results are compared with those obtained in the mean-field (MF) approximation. Factors responsible for the difference in damage accumulation under homogeneous and cascade irradiation conditions are revealed. Problems in using MC modelling to study damage accumulation when interstitial clusters move one-dimensionally are investigated and discussed.