Molecular dynamics simulation of displacement cascades in U–Mo alloys

Abstract

Molecular dynamics simulations are employed to investigate the displacement cascades in U–Mo alloys. The cascade process is analyzed in detail. The effects of initial directions of primary knock-on atom (PKA), Mo content and PKA energies on the final damage state are evaluated. The results suggest that the direction of the PKA has no effect on the final primary damage state. A high content of Mo will raise the number of defects and the probability of Mo replacement. Most of the sizes of defects cluster are no larger than three and the probabilities of producing larger interstitial and vacancy clusters are increased with higher PKA energy. The fractions of Mo interstitial in clusters with size larger than three and isolated Mo interstitials is low, while more than half the total Mo interstitials are contained in dumb-bells. Finally, it is found that the number of U–U dumb-bells is the highest and the number of Mo–Mo dumb-bells is the lowest in both alloys. The number of Mo–Mo dumb-bells seems to be independent of Mo content but the numbers of U–U and U–Mo dumb-bells decline with the increase of Mo content in alloys.