Influence of Dislocations on Positron Lifetime in Iron

Abstract

To clarify `medium' lifetimes of --150 ps in deformed iron, we calculate the positron lifetimes at the core of dislocations and related defects in iron. The calculations are based on an empirical N-body interatomic potential by Finnis and Sinclair for the atomic arrangements and the local-density approximation for the positron--electron correlation. We find the positron lifetime for vacancies associated with edge dislocation to be the medium lifetime, while that for vacancies associated with screw dislocation is almost the same as the single-vacancy value. The positron lifetimes for pure dislocations and for jogged dislocations are close to the perfect-lattice value.