The energy and stability of helium-related cluster in nickel: A study of molecular dynamics simulation

Using molecular dynamics simulation, we investigated the energy and stability of helium-related cluster in nickel. All the binding energies of the He-related clusters are demonstrated to be positive and increase with the cluster sizes. Due to the pre-existed self-interstitial nickel atom, the trapping capability of vacancy to defects becomes weak. Besides, the minimum energy configurations of He-related clusters exhibit the very high symmetry in the local atomistic environment. And for the HeN and HeNV1SIA1 clusters, the average length of He-He bonds shortens, but it elongates for the HeNV1 clusters with helium cluster sizes. The helium-to-vacancy ratio plays a decisive role on the binding energies of HeNVM cluster. These results can provide some excellent clues to insight the initial stage of helium bubbles nucleation and growth in the Ni-based alloys for the Generation-IV Molten Salt Reactor.