Microstructural response of He⁺ irradiated FeCoNiCrTi_0.2 high-entropy alloy

In the He⁺ irradiated FeCoNiCrTi_0.2 high-entropy alloy (HEA), radiation-induced defects including helium bubbles and faulted dislocation loops were characterized by transmission electron microscopy. Compared with other face-centered cubic alloys irradiated in similar conditions, we found that the faulted loops in the FeCoNiCrTi_0.2 HEA have a much large size, whereas the perfect loops were rarely detected. Our results reveal that the faulted-type defect structure is more energetically favorable in the FeCoNiCrTi_0.2 HEA, whereas the transformation of the faulted to perfect dislocation loops was suppressed. For the underlying mechanism, we propose that the low stacking fault energy can stabilize the faulted planar defects during irradiation.