Micromechanical Testing of Irradiated Nuclear Fusion Materials

了解中子辐照损伤如何影响结构材料的机械性能是实现核聚变作为可持续能源的关键一步。然而，在辐照材料上工作是昂贵的，并且从它们生成机械数据是困难的。中子损伤可以用离子辐照来模拟，但损伤层很薄- 200 nm至100微米。因此，传统的力学测试方法无法使用，必须进行新的微观力学测试。这导致难以解释的结果，由于尺寸效应固有的测试小材料volumes.This项目将利用新开放的材料研究设施（MRF）在卡勒姆中心聚变能研究离子辐照对聚变材料的影响，并与产生的缺陷人口。这将用于开发使用小规模机械测试的方法，以帮助未来聚变系统的工程设计。感兴趣的材料包括铁、铬、钒和钨基合金，该方案最初将侧重于铁铬合金。离子辐照将在一系列国际辐照设施中使用质子和重离子，在聚变反应堆的相关剂量和温度下进行。牛津大学材料系的先进电子显微镜将被用来鉴定所产生的损伤和缺陷类型。将在MRF进行微观力学测试，以了解这些缺陷如何影响机械性能，如延展性，加工硬化和流动局部化。所进行的测试将涉及微尺度拉伸或压缩测试，包括在MRF的扫描电子显微镜中进行的原位测试。将使用数字图像相关性来量化变形过程中产生的塑性滑移模式，特别关注辐照如何降低变形均匀性并增加滑移带中的局部应变强度。高分辨率EBSD将被用来映射位错密度和应力分布在间歇性间隔在整个这样的测试。有限元建模将被用来帮助解释结果，并捕捉我们的变形模式的理解。该项目是在与卡勒姆中心的聚变能源和哲学博士的学生将是EPSRC CDT的融合科学与技术的一部分。该研究计划与EPSRC的组合主题“能源”和子主题“聚变”和“核能”保持一致。“工程”主题也与“材料工程-金属和合金”研究领域相关。

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.