The role of alloying element on the behaviors of helium in vanadium: Ti as an example

Using a first-principles method, we present the effect of the alloying element Ti on the behaviors of He in vanadium. Away from Ti atom, He migrates from one tetrahedral site to another with a barrier of 0.06 eV. When He moves towards the Ti, its energy barrier increases to ∼0.19 eV. With the presence of Ti in vacancy vicinity, the binding energies of He to Hen−1-vacancy cluster decrease compared with that in pure vanadium, indicating that the alloying element Ti can diminish the binding of He with vacancy in vanadium. This confirms that the He retention in vanadium can be suppressed by doping Ti in experiments. All the interactions between a tetrahedral He and Hen−1-vacancym (n/m = 1, 2, 3, 4) cluster are attractive in the vicinity of Ti. For a given value of m/n, the He binding energies to the cluster decreases/increases with the increasing number of He/vacancies.