As the fusion sector advances toward the deployment of fusion power plants (FPPs), the demands on materials performance and lifetime reliability are increasing significantly. Oxford Sigma’s mission is to develop and deploy advanced materials technologies that address these critical challenges, accelerating the commercialisation of fusion energy.
Ceramic materials are expected to play a pivotal role in future fusion reactors, particularly in breeding and shielding applications. However, their behaviour under irradiation remains insufficiently understood, limiting their integration into reactor designs. This project aims to address this knowledge gap of fundamental understanding by investigating the degradation mechanisms and performance of ceramics under fusion-relevant irradiation conditions.
The deployment of ceramic materials in components promises to achieve the demanding requirements associated with commercial power plant design. As fusion enters its ‘delivery era’, there is a need for greater understanding of materials degradation in-service to continue the progress of power plant design maturity.
The focus will be on two key ceramic systems:
- Breeder ceramics such as lithium metatitanate
- Shielding ceramics such as tungsten carbide
These materials will be fabricated with controlled, evaluated and varied microstructures to explore the influence of grain boundaries and defect networks on irradiation response. Irradiation experiments will be conducted using UK-based facilities to simulate fusion-relevant damage. Post-irradiation characterisation will leverage Oxford University’s advanced facilities, including:
- Nano-scale mechanical testing aligned with irradiation length scales
- Transmission electron microscopy (TEM) with newly installed scanning precession electron diffraction (SPED) mapping
- High-resolution imaging and spectroscopy techniques (HR STEM, EELS)
Recent findings suggest that basal grain boundaries in irradiated WC may retain or even enhance ductility, (REF). In combination with the observation that specific high energy GBs allow recovery from irradiation GBs (& REF) this challenges previous assumptions about the detrimental effect of GBs and ceramic brittleness under irradiation. The ability to fully characterize the GB populations that are beneficial or detrimental for performance opens new avenues for microstructural engineering to improve ceramic performance in extreme environments. The project will investigate how grain boundary networks influence key properties such as:
- Tritium release kinetics in breeder ceramics
- Mechanical strength and ductility in both breeding and shielding ceramics
Given the large volume and density of shielding materials required in FPPs, ensuring mechanical integrity is essential to avoid catastrophic failure. This project will also complement research at Oxford University on tritium trapping at microstructural defects, contributing to a holistic understanding of ceramic behaviour in fusion environments.
Beyond the direct investigation of selected ceramics, the project will establish methodologies and expertise for benchmarking alternative fusion materials, supporting broader missions to develop robust, scalable materials solutions for future fusion reactors.
