Micromechanical Testing of Irradiated Nuclear Fusion Materials

Lead Research Organisation: University of Oxford
Department Name: Materials

Abstract

Understanding how irradiation damage from neutrons affects the mechanical properties of structural materials is a key step towards realising nuclear fusion as a sustainable power source. However, working on irradiated materials is costly, and generating mechanical data from them is difficult. Neutron damage can be simulated with ion irradiations but the damage layers are thin - 200 nm to 100 microns. As such traditional mechanical testing methods cannot be used and novel micro-mechanical tests must be conducted. This leads to difficulties in interpreting the results due to size effects inherent in testing small material volumes.

This project will utilise the newly opened Materials Research Facility (MRF) at the Culham Centre for Fusion Energy to study the effects of ion irradiation on fusion materials and correlate this with the defect populations produced. This will then be used to develop methods to use small scale mechanical tests to aid engineering design of future fusion systems. Materials of interest include iron, chromium, vanadium and tungsten based alloys and this programme will initially focus on iron - chromium alloys.

Ion irradiations will be carried out using protons and heavy ions at a range of international irradiation facilities, at fusion reactor relevant doses and temperatures. Advanced electron microscopy at the Department of Materials, University of Oxford will be used to characterise the damage and defect types produced. Micromechanical tests will be performed at the MRF to understand how these defects affect mechanical behaviour, such as ductility, work hardening, and flow localisation. Tests conducted will involve micro-scale tensile or compression testing including testing in situ in the scanning electron microscope at the MRF. Digital image correlation will be used to quantify the pattern of plastic slip that develops during deformation with particular focus on how irradiation decreases the deformation homogeneity and increases the local strain intensities in slip bands. High resolution EBSD will be used to map the dislocation density and stress distributions at intermittent intervals throughout such tests. Finite element modelling will be used to help interpret the results and capture our understanding of the deformation patterning.

The project is in collaboration with the Culham Centre for Fusion Energy and the DPhil student will be part of the EPSRC CDT on the Science & Technology of Fusion.

The research programme aligns with the EPSRC portfolio themes of both 'Energy' and the sub-themes 'Fusion' and 'Nuclear Power'. The 'Engineering' theme is also relevant through the 'Materials Engineering - Metals and Alloys' research area.

Publications

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Studentship Projects

Project Reference Relationship Related To Start End Student Name
EP/R512060/1 01/10/2017 30/09/2022
1921700 Studentship EP/R512060/1 01/10/2017 30/09/2021 Shahnaz Hoque
 
Description Beyond Boundaries Outreach Competition 
Form Of Engagement Activity Engagement focused website, blog or social media channel
Part Of Official Scheme? No
Geographic Reach Regional
Primary Audience Schools
Results and Impact The Mathematical, Physical and Life Sciences Division of the University of Oxford launched the Beyond Boundaries competition. This science-inspired art competition is for Oxfordshire state school students in Years 5, 6, 7, and 8 to create art inspired by research from six Black, Asian and Minority Ethnic (BAME) scientists. The Beyond Boundaries project, originally funded by the University of Oxford Diversity Fund, aims to increase the visibility of Oxford's Black, Asian and Minority Ethnic scientists and mathematicians, bridge the perceived divide between science and art, and further connect schools and local communities with the University. This year, my story and research are one of the 6 stories featured on the website. Children from local state schools will produce art based on my research, with winners receiving awards at an awards ceremony at the Ashmolean museum. Their art will then be exhibited at the museum for several weeks.
Year(s) Of Engagement Activity 2020
URL https://www.oxfordsparks.ox.ac.uk/content/shahnaz-shaz-hoque
 
Description Fusion Film Event and Panel Discussion 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? No
Geographic Reach Local
Primary Audience Postgraduate students
Results and Impact 60/60 free tickets booked for a public viewing of the acclaimed nuclear fusion documentary 'Let There Be Light.' There were 297 views on the event page. I organised a viewing of the film in Oxford, open to any audience but mainly students and local academics attended, as well as those who work at Culham Centre for Fusion Energy. I organised and chaired a panel discussion and Q&A after the film, with an ITEr scientist from the film Mark Henderson and Sir Steven Cowley who was the head of UKAEA at the time. Much discussion was sparked and many people outside of fusion materials research were interested. An undergraduate student told me he wanted to pursue fusion research after he graduated and felt inspired by the event.

I organised the event alone, producing a poster, Facebook event and Eventbrite booking page. These resources were used to advertise within the Materials, Engineering and Physics departments as well as several Oxford colleges. I organised for the panel discussion to be filmed and this is available on Youtube.
Year(s) Of Engagement Activity 2018
URL https://www.youtube.com/watch?v=f2L0ifxdPao