Influences of displacement damage due to heavy ion irradiation on deuterium retention in CLF-1 steel

In this study, the structure damage and its influence on deuterium retention in the reduced-activation ferritic martensitic (RAFM) steel were investigated using heavy ions to simulate the displacement damage caused by neutron irradiation. Iron (Fe) and nickel (Ni) ions were applied as self-ions and other ions to irradiate steel samples. After Fe or Ni heavy ion irradiation, some amorphous cluster structures were evident, especially at the peak displacement damage region located at a depth of around 1.0 mu m in the CLF-1 steel. When the displacement damage was higher than 2.0 dpa, the grain boundaries or boundary structures became obscured by the formation of other defects, such as dislocation clusters for samples irradiated by either Fe or Ni ions. The damaged samples irradiated by Fe or Ni heavy ions were exposed to deuterium plasma, and the deuterium release and retention behaviors were measured. The results showed that after being irradiated by Ni ions, the deuterium release peak increased with no changes of the release temperature. However, after Fe ions irradiation, the deuterium release peaks shifted to lower temperatures corresponding to an increase in the number of the low-energy capture sites, such as dislocations. The increase in the total deuterium retention in CLF-1 steel after heavy ion irradiation was less than 56%, which was much lower than those of tungsten materials.