Primary radiation damage characteristics in displacement cascades of FeCrAl alloys

Abstract

Displacement cascades in FeCrAl alloys are simulated by molecular dynamics using a recently fitted embedded atom method (EAM) potential. The threshold displacement energy of the atoms in FeCrAl is firstly computed and then the evolution of displacement cascades is quantitatively analyzed with the recoil energy ranging from 0.5keV to 15keV, and the results are compared with Fe. The influence of temperature and the direction of the primary knock-on atom (PKA) are also investigated. The results show that temperature decreases the number of surviving Frenkel pairs, but the PKA direction has very little effect on them, similar to other materials. The cluster fraction and size for interstitials increase with both irradiation temperature and PKA energy, but the increase of vacancy clusters is smaller due to their lower mobility. Compared to the case of Fe, the presence of Cr and Al in FeCrAl slightly increases the surviving FPs in FeCrAl but reduces the number of clusters formed at the annealing phase. Cr can reduce the mobility of nearby Fe and thus the surviving interstitials are mostly in the form of relatively stable Fe-Cr dumbbells. Al has little influence on surviving FPs but will restrain the formation of clusters. The proportion of Cr in clusters is largely in excess of its atomic fraction in FeCrAl, while Al takes a tiny proportion.