Developing understanding of the creep mechanisms in CuCrZr under fusion specific operating conditions

Copper-based alloys are candidate heat sink materials for the divertors in fusion devices. The heat sinks used to keep divertor temperatures under control will be subjected to high thermal loads, neutron irradiation, and high stress levels for extended durations, thus subjecting the heat sink material to conditions where creep deformation is a potential service life-limiting factor. Copper-chromium-zirconium (CuCrZr) alloys are a prime candidate due to an acceptable trade-off between mechanical and thermal performance, however they are still very much in the developmental phase in the creep regime, with a lack of long-term experimental data for the alloy in fusion-relevant environments. Furthermore, the predictive models that will be used to certify fusion require an understanding of the creep deformation mechanisms prevalent in the alloy is of pivotal importance. This proposal aims to build on investigations into the dislocation and dynamic recrystallization-based creep behaviour of the CuCrZr. Changes in creep mechanism, from dislocation-based to a dynamic recrystallization-based, make simulating creep strain significantly more complex and pose a significant hurdle in the fulfilment of data collection to support modelling activities. In situ neutron diffraction offers the potential to pinpoint the onset of recrystallisation and to quantify the influence this recrystallisation has on dislocation density and intergranular stress.