Extended Data Fig. 2: Safe analysis region for the 6 MeV Au ion irradiation.

a, SRIM simulation (using the Kinchin-Pease method56,57) showing the radiation damage (dpa) profile and injected ion distribution along the ion penetration depth for 6 MeV Au3+ with a dose of 3×1017 cm−2. Inset is the corresponding cross-sectional HAADF-STEM image of the Au ion-irradiated superlattice steel. b, Energy dispersive X-ray spectrometer (EDS) profiles along radiation depth of the samples subjected to 84, 840 and 2350 dpa at 500 °C. The error bars are the standard deviation of the mean. c, Enlarged EDS profiles’ image labeled by violet dashed rectangle. d, The temperature-dependent void denuded zone near the surface and the injected ion-affected region for the 6 MeV Au ion-irradiated superlattice steel. Safe analysis region for void swelling is shown between two regions.