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

材料在高放射性环境中，如核反应堆中发现的，会产生缺陷，随后会合并成复杂的结构。因此，这些材料的性能可能会发生深刻的变化，包括但不限于：形状和体积的变化，严重降低的延展性和对环境引起的开裂的敏感性。虽然这些影响是有据可查的，但这些现象背后的机制仍在调查中。这项工作将集中在辐照的单晶薄膜合成使用直流磁控溅射设备在布里斯托大学，特别强调的金属：铁，钒，铜，钨，钽和U。样品将在道尔顿坎布里亚工厂和GANIL工厂接受辐照，并将暴露于模拟各种高放射性环境的质量和能量范围内的粒子。使用近理想的单晶样品允许一个精确地描述缺陷传播的性质，确定材料内的固有应变，并通过X射线反射率和高角度X射线衍射的组合来研究晶体结构的影响。将使用透射电子显微镜对缺陷结构形成的机制进行调查，包括使用该大学的扫描电子显微镜套件开发和改进样品制备技术。与实验工作并行的是，将开发计算模拟，以努力扩展当前的方法并指导该项目的实验流。在整个工作过程中，将与赞助公司原子武器研究所保持密切合作，以指导材料和条件的选择，这些材料和条件对样品制备和辐射损害的影响具有科学和技术上的重要性。

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.