(Fusion Power CDT) Temperature-dependent defects and light gas element loading in beryllium-titanium ordered alloy TiBe12 for neutron breeding (Materials strand project)

About the Project

The MBe12 ordered intermetallic (beryllide) is the main stable component of many Be-transition metal alloy systems that are emerging as strong candidates for neutron breeding to enable on-site tritium replenishment in large fusion reactors such as DEMO and JA-DEMO. This material is considered because at the designed breeder operating temperature of 500-600°C, it does not retain tritium. Above operating temperature, however, this material has been observed to form helium bubbles associated with interphase boundary type crystal defects similar to those found in the nickel superalloy precipitates, but whose structure is as yet unknown. This means the material’s behaviour in an overtemperature situation, e.g. a fire, is not yet predicted, which is unacceptable. The first step in remedying this situation is to find the structure of the defects and understand their relationship with transmutant gas bubbles.

The student in this project would initially work alongside Dr Jo Sharp to compare defect simulations from density functional theory with experimental data from electron microscopy to determine the structure of these defects in the ordered alloy. When a structural model that fits the initial data has been found through team effort, the student will then be able to develop their research and analytical skills in one or a combination of the following areas, dependent on their interest:

• Simulating the effect of adding He and H atoms to the defect structure model – the student would develop expertise in simulation by density functional theory and have opportunities to try other methods
• Making and analysing experimental samples at UKAEA in Culham and the MIAMI-2 ion irradiation facility in Huddersfield, followed by analysing implanted samples using transmission electron microscopy – the student would be trained to a high level in this sophisticated analytical technique and the subsequent data analysis, which is a high- demand research area worldwide
• Implanting samples with helium, hydrogen or deuterium in collaboration with the UK National Ion Beam facilities in Surrey and Cumbria, and carrying out and analysing data from atom-probe tomography and thermal desorption spectroscopy with world-leading scientists in Rouen and at UKAEA Culham.

Within all of these potential avenues there will be scope for the student to propose and carry out their own ideas towards the common aim of understanding defects and ensuring the safety of beryllide-containing test breeder module designs.

The student will also have opportunities to learn to write academic papers, participate in the peer review process, disseminate knowledge via video and animation, and present at conferences to develop their own network. Support will be given to help the student discover and progress to their next career ambitions, including finding mentors and ongoing transferable skills development.

During the first six months of the PhD, materials strand students will typically travel to attend taught modules at all six of the Fusion CDT partner universities.

After the taught programme the project will be based at the University of Sheffield, but depending which aspects of the overarching project the student chooses to participate in and on visa conditions, some of it could be done from other locations.

There are opportunities within the experimental branch of the project to undertake work for up to a week at a time at: MIAMI-2 in Huddersfield; UKAEA in Culham, Oxfordshire; UK National Ion Beam facilities in Cumbria and Surrey; the Université de Rouen for atom-probe tomography.

For further information please contact: Dr Joanne Sharp (joanne.h.sharp@sheffield.ac.uk)