India - UK Civil Nuclear Collaboration: Development of Radiation Damage Resistant High Entropy Alloys for Advanced Nuclear Systems

Lead Research Organisation: University of Oxford
Department Name: Materials


High entropy alloys (HEAs) are a novel and recently developed class of materials that do not contain one dominant element. Rather, four or more elements are combined together in equal or near equal measures with each element being randomly arranged. They have been reported to have a large number of desirable properties, including high strengths at high temperatures, good corrosion resistance and ability to withstand irradiation damage. These properties make HEAs strong candidate materials for use as structural materials in future nuclear fission and fusion reactors. These reactors are being designed to operate at higher temperatures, use less fuel and can be made safer and more efficient than current reactors.

For HEAs to be utilised in this highly harsh and demanding environment there are three key needs that must be addressed.

First, we must identify promising alloys, have them manufactured on a small scale, and characterise their mechanical behaviour and the stabilities of their microstructures. This will be carried out using advanced microscopes capable of studying the chemistry and structure of these alloys at the atomic level.

Second, the underlying materials physics of HEAs that provide the excellent resistance to irradiation damage need to be fully understood. To assess radiation damage resistance, we will perform ion implantations rather than using neutrons. This allows us to perform a large number of experiments and the samples are not radioactive so can be easily handled in a laboratory. The damage caused will be studied using mechanical testing methods capable of probing the small damage regions produced by these heavy ions. Results from experiments, combined with computational modelling of damage effects in these novel alloys, will allow us to describe radiation damage accumulation and recovery mechanisms in these materials, which can be used to design even more advanced alloys.

Finally, we must determine how well the materials will behave in service by assessing how they react when placed under load at high temperatures for long periods of time. We will work with Indian partners, utilising their unique facilities, to perform these tests on our most promising compositions. These compositions will be manufactured in large-scale quantities, tested, and returned to the UK for further study.