Supervisor: Robert Harrison (University of Manchester)
Fusion -specific radiation damage in silicon carbide has not been investigated sufficiently to qualify components for use in reactor . Specifically, transmutation effects in a fusion neutron spectrum are significantly different to those in a fission spectrum, with high energy fusion neutrons causing production of helium, hydrogen, and metallic Mg, Be, and Al species. The synergistic effects of these transmutation products with radiation defects and their effect on the materials performances must be understood before silicon carbide can be deployed as a structural material in advanced reactor breeder blankets.
This project will combine multi-scale atomistic modelling with advanced characterization methods to correlate the formation and evolution of radiation defects that may form in SiC in a fusion reactor environment. For example, He atoms have the propensity to bind to vacancies within the radiation damage cascade which may result in defect survival and evolution . First principles modelling has identified the formation and migration energy of point defect configurations in SiC. The student will begin by extending the modelling length scale to nanometres using kinetic Monte Carlo methods to assess evolution of point defects to larger extended defects such as voids, dislocations and precipitates, at which point it can be correlated to experimental techniques transmission electron microscopy and atom probe tomography . Ion implantation experiments are being performed by UKAEA on “fusion grade” silicon carbide composites as well as model single crystals to simulate the effects of transmutation. These samples will be made available to the student on this project, and the student will be supported in designing their own irradiation experiments.
Transmission electron microscopy (TEM) and atom probe tomography (APT) will be used to yield information of dislocation type and nature, image voids/bubbles and map chemical element and phase distribution in materials via spectroscopy techniques (e.g. EDS, EELS and MS) to develop detailed understanding of the material at the nanoscale and correlate to modelling results. MRF has capability to handle and prepare neutron activated samples for TEM equipped with EDS and UoM has a range of TEM capabilities with chemiSTEM EDS, EELS and aberration corrected systems which the student will be trained on – APT at the University of Oxford will be access through the Henry Royce Institute user access scheme. In-situ observation of radiation defect formation and mobilities will can also be conducted using the MIAMI facility at the University of Huddersfield through the EPSRC National Ion Beam Centre. Advanced total scattering X-ray diffraction methods may also be applied in this project . The combination of modelling and characterization will provide a full picture of defect formation, and evolution mechanisms during the operational lifetime of a fusion reactor.
This PhD will integrate with ongoing and planned work at UKAEA, Uuniversity of Manchester and partners, including studies on nano-scale thermophysical properties of irradiated SiC. The TEM analysis in this PhD will help to explain develop mechanistic understanding of measurements such as thermal conductivity, defect annealing and mechanical properties measured using new capabilities developed at the Materials Research Facility, and by a UKAEA supported PhD student at University of Bristol. Physical properties can also be calculated from the atomic structures predicted in the modelling work package to help link experiments with models. The student will be based at University of Manchester with opportunity to work at UKAEA Culham site and work with partners at Oxford, Bristol and in MIT, USA.
This project is offered by University of Manchester. For further information please contact: Robert Harrison (r.w.harrison@manchester.ac.uk)
This project may be compatible with part time study, please contact the project supervisors if you are interested in exploring this.