Nuclear fusion is a promising energy source with real potential to provide a safe, reliable and virtually inexhaustible base load supply without producing long-lived radioactive waste. Steel will be used to construct the structural components of future nuclear fusion reactors. It maintains favourable mechanical properties even in the harsh operating environments of a reactor, which is characterised by intense high-energy neutron irradiation and elevated temperatures up to 550C. However, the materials will experience microstructural evolution due to the neutron-irradiation-induced cascade damage. Understanding the creation and evolution of the defect population in irradiated steels is crucial for predicting their lifetime and operational limits in a reactor.

Ion-implantation, where self-ions are used to mimic neutron irradiation, provide a more accessible way to study irradiation damage in materials. The characterisation of a range of different material properties is powerful in revealing key insights into the nature and impact of the irradiation-induced defect populations, which often cannot be directly observed with electron microscopy. In my PhD, I have focused on the characterisation of hardness via nanoindentation, thermal and elastic properties through transient grating spectroscopy, and material strain using X-ray diffraction. 

This talk covers several studies conducted at the University of Oxford on ion-irradiated steels:

1. The study of model FeCr binary alloys provides fundamental insights into irradiation damage and defect behaviour without the microstructural complexities of steels. The effect of Cr content and irradiation dose on the irradiation-induced defect population and resultant changes in various material properties were investigated via multi-property characterisation (https://doi.org/10.1016/j.actamat.2020.10.015).
2. A nanoindentation-focused study on the deformation behaviour of irradiated FeCr. Careful analysis allows the distinction of the stages of plasticity initiation from dislocation propagation in the material (https://doi.org/10.1557/s43578-022-00613-2). 
3. Ongoing work with Eurofer-97, a leading candidate for reactor structural steels, which was processed through high-pressure torsion (HPT) to produce severe plastic deformation and grain refinement. The changes in the irradiation resistance of the HPT-processed was investigated by characterising a range of material properties.
   
   

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