Cascade debris overlap mechanism of 〈100〉 dislocation loop formation in Fe and FeCr

¹ Department of Physics, University of Helsinki - P. O. Box 43, FIN-00014 Helsinki, Finland
² CCFE, Culham Science Centre - Abingdon, Oxon, OX14 3DB, UK

Received: 18 July 2017
Accepted: 12 October 2017

Abstract

Two types of dislocation loops are observed in irradiated α-Fe, the 1/2〈111〉 loop and the 〈100〉 loop. Atomistic simulations consistently predict that only the energetically more favourable 1/2〈111〉 loops are formed directly in cascades, leaving the formation mechanism of 〈100〉 loops an unsolved question. We show how 〈100〉 loops can be formed when cascades overlap with random pre-existing primary radiation damage in Fe and FeCr. This indicates that there are no specific constraints involved in the formation of 〈100〉 loops, and can explain their common occurrence.