EFFECT OF SYMMETRICAL TILT GRAIN BOUNDARIES ON DISPLACEMENT CASCADES IN FE-CR-AL ALLOYS BASED ON ATOMIC SIMULATIONS

Nuclear fuel cladding is subjected to neutron irradiation in a high-temperature stress environment, and the structural integrity of the cladding is very important for safe operation. The irradiation performance of Fe-Cr-Al alloy is significant for the development of multi-scale modeling and a deeper understanding of defect production. In this work, displacement cascade behaviors of Fe-Cr-Al crystal with a grain boundary (GB) are investigated by molecular dynamics (MD) simulations. Four grain boundaries, namely ∑3{111}, ∑5{120}, ∑9{221}, ∑11{113}, with misorientation angle varying from 38.9° to 129.5° were considered. It is found that the formation energy of point defects close to the boundary is much lower than that in the grain according to molecular static simulation results. The presence of GB reduces the maximum temperature of the thermal spike in the displacement cascade, which leads to the increase of FPs in the displacement spike and the delay of the time. The absorption bias of GBs on interstitials and vacancies results in more surviving FPs, but the majority of the defects are in the GB, and FPs in the bulk region are significantly lower. Of the four types of GBs studied, ∑3{111} has a high attraction to interstitials and vacancies, but essentially does not affect vacancy formation energy, leading to the most surviving FPs.