TEM characterization of dislocation loops in irradiated bcc Fe-based steels

In this study, we describe a methodology to examine dislocation loops in irradiated steels based on a combination of crystallographic information and g⋅b invisibility criteria. Dislocation loops in transmission electron microscope (TEM) images can be conveniently analyzed using this method. Through this analysis approach, dislocation loops in reduced activation ferritic/martensitic (RAFM) steels irradiated at 400 °C have been examined. The predominant types of loops found in irradiated RAFM steels were 〈1 0 0〉{2 0 0} and 1/2〈1 1 1〉{1 1 1}. The size, density, and density anisotropy of these two types of dislocation loops were quantified. It was observed that the 〈1 0 0〉{2 0 0} loop density is more than twice that of 1/2〈1 1 1〉{1 1 1} loops. A large density anisotropy of 〈1 0 0〉{2 0 0} loops was identified.