Structure Evolution and Nature of Defects in BCC Iron by Collision Cascade From Molecular Dynamics Simulation

Abstract

The structure evolution and nature of defects in bcc iron by collision cascade from molecular dynamics simulation are investigated. Under irradiation, the collision cascade induces not only self-interstitials, vacancies, <100>, <110>, and <111> dumbbell defects, but also, composite defects, such as, the composite defect of <110> and <111> dumbbell, and composite defect of <110>, <110> dumbbell, and defect clusters. Simulation shows that under the considered energy of primary knock-on atom the higher the energy of a primary knock-on atom (PKA) is, the more the number of producing interstitials is. The size of the region where atoms are displaced by the collision cascade is about 11-15a0. The smaller the energy of PKA is, the smaller the region is. At the same time, it is found that even at the initial stage of 0.0-0.75 ps of collision cascade, there is also some recombination of interstitials and vacancies.