Reduced interstitial mobility through multicomponent alloying in bcc W

We report the first principles calculations of the defect energetics and dynamics in W ternary alloys. A solute pair of different kinds strongly attracts a W self-interstitial atom, forming a solute-interstitial triple complex. The attractive solute-interstitial interaction can be stronger in ternary than in binary alloys, which works as a primary dissociation barrier to reduce the interstitial mobility. This, in turn, means that a single solute-interstitial pair also attracts a solute atom of a different kind to form a triple complex. The dissociation energy of a triple complex slows the interstitial migration, and increases the odds of vacancy-interstitial recombination in collision cascades. Therefore the reduced interstitial mobility and increased interstitial retention ability of multicomponent alloys may change the fundamental irradiated-damage mechanism in fusion environment.