Positron annihilation spectroscopic study of intrinsic and ion-irradiation induced vacancy defects in Zr-containing ODS steels with and without Al

The oxide dispersion strengthened (ODS) ferritic steels containing Zr are synthesized with and without Al addition and found to possess homogeneous distribution of nanoprecipitates and nanometric grain sizes. Positron lifetime measured in both alloys indicate trapping in dislocations and vacancy clusters respectively. Room temperature irradiations with 1.6 MeV Fe( )(+)ions induced stable vacancy type defects in both the alloys whereas high temperature irraditaions at 340 degrees C show the recombination of vacancies and interstitials. In room-temperature irradiated specimens, the onset of defect production in Zr-ODS is delayed owing to its superior sink strength caused by the smaller sized, higher number densities of dispersoids compared to Al-ODS. (C) 2022 Published by Elsevier B.V.