Defect Formation and Migration in Single Crystal Thin Films Exposed to High Radiation Levels

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Materials subjected to highly radioactive environments such as thosefound in a nuclear reactor develop defects that subsequently coalescenceinto complicated structures. As a result, such materials can sufferprofound changes to their properties, including but not limited to: changesin shape and volume, severely reduced ductility and a susceptibility toenvironmentally induced cracking. While these effects are quantitativelywell documented, the mechanisms underlying such phenomena are stillunder investigation. This work will focus on the irradiation of single crystalthin films synthesised using DC Magnetron Sputtering equipment at theUniversity of Bristol with particular emphasis on the metals: Fe, V, Cu, W,Ta and U. Samples will be irradiated at both the Dalton Cumbria Facilityand the GANIL facility and will be exposed to particles over a range ofboth mass and energy simulating a variety of highly radioactiveenvironments. The use of near-ideal single crystal samples allows one toprecisely characterise the nature of defect propagation, determineinherent strain within the material and investigate the effect of crystalstructure all via a combination of x-ray reflectivity and high angle x-raydiffraction. Investigation of the mechanisms underpinning the formation ofdefect structures will be conducted using Transmission ElectronMicroscopy involving the development and refinement of samplepreparation techniques using the university's suite of scanning electronmicroscopes. Parallel to experimental work, computational simulations willbe developed in an effort to expand on current methods and direct theexperimental stream of the project. Throughout this work closecollaboration will be maintained with the sponsoring company, The AtomicWeapons Establishment, in order to guide the selection of materials andconditions that are of both scientific and technical importance with relationto sample preparation and the effects of radiation damage.