Energetics, kinetics and dynamics of self-interstitial clusters in bcc tungsten

JL Wang and BL He and W Song and WQ Dang, MOLECULAR SIMULATION, 45, 666-671 (2019).

DOI: 10.1080/08927022.2019.1578356

The configuration, slipping and rotation of self-interstitial atoms cluster along crystal orientation with different sizes in a tungsten are investigated systematically with molecular dynamics. It is found that (I) the SIA clusters with high symmetry are always favoured; (II) the SIA clusters can undergo one-dimensional fast migration along direction, and their migration barriers are no more than 0.07 eV, which is expected due to the strong interaction in the SIA clusters; (III) the rotation energy barriers of the SIA clusters are rather high and they are basically positively correlated with the size of the cluster. For example, the reorientation barrier is 0.66 eV for 1 SIA, 1.2-1.8 eV for SIA(n) (2 <= n <= 5) clusters and over 2.7 eV for SIA(n) (6 <= n <= 7) clusters. Compared with slipping of SIA clusters, is an infrequent event, especially for larger SIAs cluster, the vast majority SIAs cluster would have already recombination with vacancies or annihilates at surface and grain boundary through slipping before rotation, which explained that there are very low density of SIAs cluster found in the experiment.

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