Cluster dynamics modeling of helium irradiation and accumulation near aluminum surface

We study the defect dynamic and aggregation behavior of helium in aluminum under keV-He ion irradiation by using a cluster dynamics model (IRadMat). Through the quantitative analysis of the concentration of He by different traps (clusters, grain boundaries and dislocations) we find that most of He atoms are absorbed by grain boundaries, which is the main contribution to embrittlement of Al under low irradiation fluence. With irradiation energy increasing, the position of He retention peak becomes deeper. However, with ion fluence increasing, the amount of He retention in Al becomes more, while the position of retention peak remains unchanged. The results show that the effect of grain boundaries plays a key role in the distribution of He retention and the behavior of embrittlement in Al, which is also helpful for understanding the dynamic behavior of He and the distribution of damages in metals. (authors)