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An ultra-fine-laminated (UFL) Ni sample with a high fraction of low-angle grain boundaries (LAGBs) was produced by dynamic plastic deformation. And self-diffusion behavior was studied in this material by the radio-tracer technique. Significantly enhanced interfacial diffusivity was detected in the UFL Ni in comparison with coarse-grained Ni. Analyses indicated that diffusion along LAGBs in the UFL sample is unexpectedly faster than the typical diffusion rates along conventional grain boundaries in the coarse-grained sample. This behavior is explained by the interaction of LAGBs with numerous extrinsic dislocations, as revealed by high-resolution transmission electron microscopy.