Radiation defects-induced plastic flow localization is the origin of loss of ductility in irradiated metals. Defect-free channels (DFCs) are a typical form of strain localization that lead to crack initiation and premature failure. A comprehensive understanding of the DFC dynamics is key to managing radiation boosted property degradation. Despite great research efforts, a clear mechanism of DFC remains unknown. Here, our in-situ tests on irradiated Ni pillars provide a real-time observation of the dynamics of DFCs, including DFC initiation, extension and thickening. The merging and spreading of dislocation loops serve as an alternative mechanism of dislocation sources that emit massive dislocations and initiate nano-thick DFCs inside the grain. Nano-thick DFCs were formed through chopping up or sweeping away of loops by mobile dislocations. Annihilation of opposite loops and interactions between loops and vacancies accelerate DFC extension. Activation of multiple dislocation sources and dislocation cross-slips are the mechanisms for DFC thickening.

辐射缺陷引起的塑性流动局部化是被辐射金属失去延展性的根源。无缺陷通道（DFC）是应变局部化的一种典型形式，会导致裂纹萌生和过早失效。全面了解DFC动力学是管理辐射增强的性能退化的关键。尽管进行了大量的研究，但DFC的明确机制仍然未知。在这里，我们对被辐照的镍柱进行的原位测试可实时观察DFC的动力学，包括DFC的引发，延伸和增稠。位错环的合并和扩散是位错源的另一种机制，位错源发出大量的位错并在晶粒内引发纳米级DFC。纳米级DFC通过移动位错将回路切碎或清除而形成。反向循环的灭以及循环与空位之间的相互作用会加速DFC扩展。多个位错源的激活和位错错位是DFC增厚的机制。