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Binding of He$_n$V Clusters to $α$-Fe Grain Boundaries

The objective of this research is to explore the formation/binding energetics and length scales associated with the interaction between He$_n$V clusters and grain boundaries in bcc $α$-Fe. In this work, we calculated formation/binding energies for 1-8 He atoms in a monovacancy at all potential grain boundary sites within 15 Å of the ten grain boundaries selected (122106 simulations total). The present results provide detailed information about the interaction energies and length scales of 1--8 He atoms with grain boundaries for the structures examined. A number of interesting new findings emerge from the present study. First, the $\Sigma3$(112) `twin' GB has significantly lower binding energies for all He$_n$V clusters than all other boundaries in this study. For all grain boundary sites, the effect of the local environment surrounding each site on the He$_n$V formation and binding energies decreases with an increasing number of He atoms in the He$_n$V cluster. Based on the calculated dataset, we formulated a model to capture the evolution of the formation and binding energy of He$_n$V clusters as a function of distance from the GB center, utilizing only constants related to the maximum binding energy and the length scale.