Ion irradiations of fusion reactor materials

Lead Research Organisation: University of Oxford
Department Name: Materials

Abstract

To optimise materials for operation in a fusion environment, we need to develop a mechanistic understanding of their mechanical properties and of the changes in mechanical properties induced by irradiation. An ongoing project at Oxford has concentrated on developing an understanding of the mechanical properties of unirradiated materials and on studies of the evolution of radiation damage in thin electron microscope specimens by 50-100keV heavy-ion irradiation. There are difficulties with using thinned specimens, in that defects can relatively easily escape from the free surfaces of the specimens; the damage observed may not be typical of that introduced by cascades initiated by neutron irradiation deep within a material. Hence we now need to study materials irradiated with MeV heavy ions in the bulk.The feasibility of using the Surrey University facility for such studies has been demonstrated in a trial implantation of FeCr alloys. Our first microscopy experiments have shown a high density of resolvable dislocation loops, qualitatively similar to the microstructures seen in neutron-irradiated FeCr alloys. We now need to carry out a set of systematic irradiation experiments, where we will irradiate a wider range of materials, and study the resultant radiation damage and its effects on mechanical properties. We will include both TEM and microbeam specimens of Fe, FeCr (up to 12% Cr), RAFM and ODS steels. The experiments will also be extended to materials pre-implanted with He+ immediately before Fe+ irradiation, so as to simulate the effects of transmutation gases. Transmission electron microscopy will be used to study irradiation damage and post-damage and deformation dislocation structures in each of the materials, including specimens cut from the microbeams before and after deformation. The aim will be a complete microstructural characterisation of dislocations, dislocation loops and voids using a full range of TEM techniques, including both standard diffraction-contrast and high-resolution methods and novel techniques developed by M.L. Jenkins and co-workers. Advanced analytical techniques will be used to study local chemistry, for example at the interfaces of ODS particles. Micro-beams will be used to study the elastic, plastic and fracture behaviour of irradiated materials. We will study the bulk properties of the materials, by cutting specimens within single grains. Grain boundary segregation and embrittlement will be studied as a function of grain boundary crystallography, local chemistry and radiation damage. Slip transmission through boundaries will be studied by loading of microbeams containing a boundary and an indentation as a local dislocation source. Fracture strength of boundaries will be studied by notching of boundaries within bend specimens.

Publications

10 25 50

publication icon
Armstrong D (2013) Hardening of self ion implanted tungsten and tungsten 5-wt% rhenium in Journal of Nuclear Materials

publication icon
Hardie C (2013) Nanoindentation of model Fe-Cr alloys with self-ion irradiation in Journal of Nuclear Materials

publication icon
Grieveson E (2012) Compression of self-ion implanted iron micropillars in Journal of Nuclear Materials

publication icon
Robertson I (2011) Towards an integrated materials characterization toolbox in Journal of Materials Research

publication icon
Xu S (2009) TEM characterisation of heavy-ion irradiation damage in FeCr alloys in Journal of Nuclear Materials

publication icon
Yao Z (2008) Preparation of TEM samples of ferritic alloys. in Journal of electron microscopy

 
Description This was an "underpinning resources" grant, aimed at giving access to heavy-ion irradiation facilities for research students and poctdoctoral researchers using ion-irradiation to emulate the radiation damage produced by neutrons in fission and fusion reactors. It enabled these researchers to perform characterisation of radiation damage and its effects on mechanical properties in model Fe-based alloys, steels, and tungsten alloys.
Exploitation Route The methods and findings from this project have already been carried forward into a much large portfolio of projects on radiation damage in power reactor materials, where teh team at Oxford is collaborating with academic researchers in the USA, Japan and Europe, and with nuclear industries; Rolls Royce, Areva, Westinghouse, CCFE.
Sectors Energy

URL Http://mffp.materials.ox.ac.uk
 
Description The work supported by this project was a contributing factor o the research association with CCFE that led to the establishment of the NNUF (National Nuclear User Facility) Materials Research Facility at CCFE. This is an open facility for (academic and) industrial nuclear materials research.
First Year Of Impact 2013
Sector Energy
Impact Types Economic

 
Description EPSRC
Amount £5,810,166 (GBP)
Funding ID EP/G050031/1 
Organisation Engineering and Physical Sciences Research Council (EPSRC) 
Sector Public
Country United Kingdom
Start  
 
Description EPSRC
Amount £5,810,166 (GBP)
Funding ID EP/G050031/1 
Organisation Engineering and Physical Sciences Research Council (EPSRC) 
Sector Public
Country United Kingdom
Start  
 
Description European Commission (EC)
Amount £18,000 (GBP)
Funding ID SPIRIT 041 & 042 (2009) 
Organisation European Commission 
Sector Public
Country European Union (EU)
Start  
 
Description European Commission (EC)
Amount £18,000 (GBP)
Funding ID SPIRIT 041 & 042 (2009) 
Organisation European Commission 
Sector Public
Country European Union (EU)
Start  
 
Description European Union Framework 7
Amount £48,792 (GBP)
Funding ID FEMas - CA 
Organisation European Commission 
Department Seventh Framework Programme (FP7)
Sector Public
Country European Union (EU)
Start  
 
Description European Union Framework 7
Amount £48,792 (GBP)
Funding ID FEMas - CA 
Organisation European Commission 
Department Seventh Framework Programme (FP7)
Sector Public
Country European Union (EU)
Start