2014 Volume 55 Issue 3 Pages 443-446
In-situ observations of ferritic/martensitic steels by electron irradiation with a 1.25 MeV high voltage microscope at 573 K were carried out to study damage evolution in the steels. The development of interstitial type loops and cavities in both of the two steels, F82H-IEA and F82H-ODS, showed smaller and more numerous defects in the ODS steel. The cavities were formed preferentially at the interface between oxide particles and matrix. The results suggest that ODS particles may function to suppress the nucleation and growth of loops and cavities arising from irradiation. The effect of pre-implanted helium was also studied. The pre-implanted helium led to a homogenous distribution of black dots and cavities in the steels, and these may act as sinks for point defects arising from irradiation, causing a suppression of the subsequent growth of loops and cavities. The hardening corresponding to the microstructural evolution was estimated by assuming parameters extracted from the ion irradiation.