Evaluation of Dislocation Character in Eurofer97 around the Ductile-to-Brittle Transition Temperature

The characterisation and development of structural materials for nuclear fusion reactors poses a significant challenge to the adoption of fusion energy. Eurofer97 (E97) is a front running reduced activation ferritic martensitic steel candidate in this area. It is important that candidate materials maintain their structural properties, and a comprehensive understanding of the ductile to brittle transition (DBT) is therefore desirable. This work will utilise in-situ neutron diffraction of E97 tensile samples at temperatures around the DBT to evaluate changing dislocation behaviour. Through analysis of shifting peak position and width, the dislocation density and character, as well as the elastic properties and yield flow stress of E97 around the DBT will be established. Dislocation character is strongly linked to embrittlement, and this work represents a novel means of evaluating the DBT.