Behaviors of bubble-loop complexes in He-irradiated CLAM steels at elevated temperatures

Formation of Bubble-Loop Complexes During Helium Radiation in Fe-9Cr Steel

“…As can be seen from Table 4, bubble-loop complexes usually appeared under irradiation conditions with relatively high temperatures. The experiment results of Li et al (2020) also indicated that bubble-loop complexes were easily formed at a high temperature. Besides, a high He/dpa ratio is also believed to contribute to the formation of bubble-loop complexes.…”

“…The density of bubble-loop complexes in region 2 is about three times as large as that in region 1, which is consistent with the trend of change of bubble density along with the depth. Bubble-loop complexes have been observed in pure Fe and Fe-Cr-based steels irradiated by dual-beam ions (Fe ion + He ion) and single-beam He ions (Brimbal et al, 2014;Chen et al, 2008;Brimbal et al, 2011;Bhattacharya et al, 2019;Zhang et al, 2018;Li et al, 2020). Chen et al (2008) 4.…”

“…Because He atoms are insoluble in the Fe matrix, these clusters are stable and can grow by further absorbing He atoms or vacancies until they are observed in TEM as bubbles inside the loop plane. Based on the atomistic simulations (Yang et al, 2013;Li et al, 2020), a different mechanism was proposed by Li et al (2020). In the process of He + irradiation, the selfinterstitial atoms (SIAs) are attached to the He-Vac clusters to form the initial He-Vac-SIA complexes.…”

“…On the other hand, He atoms can reduce the loops' mobility so that loops are left to absorb additional interstitials to further grow (Brimbal et al, 2014). Especially, it is also found that the He ion injection can lead to the heterogeneous nucleation of cavities or bubbles inside the plane of the dislocation loops in Fe-Cr alloys or ferritic-martensitic steels (Chen et al, 2008;Brimbal et al, 2011;Brimbal et al, 2014;Zhang et al, 2018;Bhattacharya et al, 2019;Li et al, 2020). This special structure between bubbles and loops was called "bubble-loop complexes" in some papers (Chen et al, 2008;Zhang et al, 2018;Li et al, 2020).…”

“…Especially, it is also found that the He ion injection can lead to the heterogeneous nucleation of cavities or bubbles inside the plane of the dislocation loops in Fe-Cr alloys or ferritic-martensitic steels (Chen et al, 2008;Brimbal et al, 2011;Brimbal et al, 2014;Zhang et al, 2018;Bhattacharya et al, 2019;Li et al, 2020). This special structure between bubbles and loops was called "bubble-loop complexes" in some papers (Chen et al, 2008;Zhang et al, 2018;Li et al, 2020). Zhang et al (2018) believed that this special structure can promote the growth of dislocation loops.…”