The challenging conditions in next-generation fission and fusion plants, including extremes with respect to temperatures, corrosion, stress and neutron flux, require new advanced engineering structural materials. Compositionally complex alloys (CCAs) are interesting candidates for these applications, because they combine high strength at high temperatures, good structural stability, wear, corrosion and oxidation resistance with promising irradiation properties. A further point of consideration with respect to materials selection is that no long-lived radionuclides are produced by transmutation, and components made from such materials can be classified as low-level waste post-use. Therefore, the radiation behaviour of a reduced activation body-centred cubic CCA containing Ta-V-Ti in equal amounts with smaller additions of W and Fe was investigated after homogenisation and an ageing treatment. In a first instance, heavy ion implantation at 500°C conducted at the Ion Beam Centre HZDR in Germany was used to assess the radiation response without rendering the resulting material radioactive.

In this study, results from atom probe tomography (APT) of both heat treatment conditions before and after irradiation will be presented. Alongside identification of secondary phases formed during aging, APT can also provide unique insights into the radiation responses of this novel class of materials. Observing the elemental distribution and intrinsic and implantation-induced defect structures enables us to understand defect formation and evolution mechanisms. Furthermore, identifying the role of secondary phases in the delay of defect accumulation is essential for the potential future application of CCAs in nuclear applications.