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Irradiation Effects on Deformation Behaviour of Additively Manufactured Steels for Fusion Applications – Materials Strand Project

Supervisors: Dr Xingzhong Liang & Prof Christopher Truman (University of Bristol), Dr Rhys Thomas (Henry Royce Institute), Dr David Lunt (UKAEA).

The materials used in a fusion reactor must tolerate intense neutron exposure over long periods. To minimise irradiation damage, reduced activation ferritic martensitic (RAFM) Eurofer 97 steel is a promising structural candidate for future fusion systems due to their low activation behaviour and high temperature performance. Understanding their irradiation response is essential for predicting component lifetime and supporting future fusion demonstration in the UK.

Additive manufacturing provides rapid prototyping and enables components with complex geometry that are difficult to produce through conventional routes. In fusion environments, these capabilities are valuable for parts requiring tailored geometry for thermal and mechanical performance. However, the microstructure generated by additive manufacturing often differs from that produced by traditional processing, with features such as anisotropic grains, cellular structures and process related defects. Irradiation can further modify this microstructure and affect deformation and failure behaviour. The combined influence of irradiation and additive manufacturing on mechanical performance remains insufficiently understood.

Powder metallurgy with hot isostatic pressing (PM-HIP) offers an alternative route for near net shape components. HIP typically produces a more uniform microstructure with lower porosity and distinct grain size, precipitation behaviour and residual stress compared with conventional manufactured materials. These differences are likely to influence irradiation response. Direct comparison between additively manufactured and PM-HIP Eurofer 97, will provide insight into how processing route affects irradiation induced microstructural evolution and mechanical behaviour.

This project combines experimental work with modelling. Existing additively manufactured 316L data sets with ion irradiation and in situ digital image correlation (DIC) measurements will first be used to establish a crystal plasticity finite element modelling (CPFEM) framework. These data provide a well characterised face centred cubic reference that supports calibration of irradiation hardening, defect influenced slip and strain localisation. The model will then be extended to the ferritic martensitic microstructure in Eurofer 97, capturing the slip behaviour, defect interactions and irradiation effects characteristic of RAFM steels. This will create a unified framework describing irradiation modified behaviour in additively manufactured fusion materials.

Irradiation of additively manufactured and PM-HIP Eurofer 97 will be carried out at the Dalton Cambrian Facility (DCF). Characterisation by X-ray diffraction (XRD) and transmission electron microscopy (TEM) will quantify irradiation induced defects for model input and validation. The student will receive training in crystal plasticity modelling, irradiation science, mechanical testing and microscopy, and will further develop scientific writing, communication and analytical skills through activities within the University of Bristol and the Southwest Nuclear Hub. The project provides a strong foundation for careers in fusion materials research, nuclear modelling and structural integrity analysis.

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. This project will be based at the University of Bristol.

The project will be mainly based in Bristol, but will collaborate with Manchester, Henry Royce Institute and Dalton Cumbrian Facility for experiments and conferences.

This project is offered by University of Bristol as part of the Fusion CDT Community Studentship scheme. For further information and details of how to apply please contact: Dr Xingzhong Lian (xingzhong.liang@bristol.ac.uk).