Micron-scale 1D migration of interstitial-type dislocation loops in aluminum

Micron-scale one-dimensional (1D) migration of dislocation loops was discovered by in-situ transmission electron microscope (TEM) observations. Interstitial-type dislocation loops were initially implanted in pure aluminum foils with 30 keV H+. The dynamic behaviour of these loops was investigated in a conventional TEM, operated at 200 kV. During electron irradiation, dislocation loops exhibited super long-range (1.5 μm) 1D migration, featured average speeds over 1 nm/s, and left behind long-lasting tracks up to 60 s. The increase in loop migration speed gave rise to increased track length but showed a subtle impact on the existing time-scale of tracks. Deliberate investigations by varying electron beam positions revealed that the migration distance could be boosted up to micron-scale when exposed to high concentration gradients of self-interstitial atoms built during electron irradiation. Current findings may shed light on the understanding of irradiation damage evolution and bring about new insights into the development of irradiation-resistant materials.