The effect of triple ion beam irradiation on cavity formation on pure EFDA iron

Abstract

Pure EFDA Iron was irradiated under triple ions beam (Fe + He + H) at 350 °C, 450 °C and 550 °C respectively to a nominal 40 dpa with a uniform He concentration of ∼14 appm He/dpa and H content of ∼50 appm H/dpa at depth between 1 and 2 μm. Cavity characteristics (size, morphology, distribution and population) at each irradiation temperature have been thoroughly studied by TEM using FIB lamellae, showing bubble formation at all irradiation temperatures with several differences between one to another experimental condition. At 350 °C homogeneous distribution of small cavities with sizes in the range of 2–4 μm was observed. However, irradiations at 450 °C and 550 °C led to non-homogeneous distribution of cavities with a wide range of sizes. Additionally, it was detected at these temperatures, preferential nucleation of bubbles within the ferritic grains exhibiting rounded and faceted shapes. Faceted cavities with sizes larger than 16 nm were detected at 450 °C and 550 °C.