Helium ion irradiation induced swelling and hardening in commercial and experimental ODS steels

The radiation resistance of two promising ferritic ODS steels, PM2000 and 15CRA-3, is studied. More specifically, the effect of helium on these materials is studied by examining the swelling and hardening after He+ implantation to similar to 1 dpa at 4000 appm/dpa. White light interferometry is used to measure the post-irradiation surface displacement whereas mirco-hardness measurements are carried out to determine the radiation hardening. These methods prove to be very efficient and fast working, thus making good statistics obtainable in a reasonable time. Low swelling is found in both alloys, although the PM2000 shows a lower resistance, with an increased swelling of similar to 0.8% dpa(-1) at 600 degrees C, while the 15CRA-3 presents an almost constant swelling of around 0.4% dpa(-1) throughout the complete temperature range. Radiation hardening follows a similar trend, whereby hinting towards an annealing mechanism taking place at the interfaces between the very fine distribution of Y2O3 nanoparticles and the matrix, interfaces which act as sites of enhanced point defect recombination as well as traps for the implanted helium. (C) 2013 Elsevier B.V. All rights reserved.