Multiscale high-temperature mechanical performance of materials for nuclear fusion

核聚变材料的多尺度高温力学性能

• 批准号: 2743770
• 金额: --
• 依托单位: University of Oxford
• 依托单位国家: 英国
• 项目类别: Studentship
• 财政年份: 2022
• 资助国家: 英国
• 起止时间: 2022 至 无数据
• 项目状态: 未结题
• 来源: https://gtr.ukri.org/projects?ref=studentship-2743770
• 关键词: Multiscale; temperature; mechanical; performance; materials

Nuclear fusion is now being seriously considered as future power source for post 2050, as demonstrated by the recent announcement of the STEP construction in Nottinghamshire. 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. Without understanding the effect that neutron damage has on the materials there is not realistic method of lifing components hence reactors. However we cannot just build a reactor to test materials and 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 um. 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. Mechanical models are being developed that will include the effect of irradiation damage on the evolving mechanical properties, but these require substantial experimental input in the form of characterisation and mechanistic understanding of how different microstructural features (voids, precipitates, loops) control irradiation induced hardening. This project will aim to use micromechanical testing on a series of model alloys to deconvolute the effects of different microstructural features. The alloys will be cast with controlled levels of chromium, carbon, and vanadium, to allow control of solid solution, interstitial and carbide strengthening. Samples will be irradiated with both heavy ions and helium to generate voids and dislocations loops. Hardening will be studied using nanoindentation at both room and operational temperatures. Nanoindentation at room temperature is a standard method of studying irradiation hardening but much less work has been carried out on high temperature irradiation hardening using nanoindentation. We expect that using newly developed computational plasticity finite elements methods developed in oxford we will see the effect off irradiation damage not just on yield tress but also work hardening. To understand both the starting microstructure, the microstructural evolution under irradiation and the interaction of the glissile dislocations with microstructural features advanced electron diffraction imaging will be used. This will include diffraction contrast TEM which is well established for studying such microstructures and also transmission Kikuchi diffraction which is much less applied to studying radiation damage but has the advantage of simpler and cheaper imagining equipment. We expected that byt the end of the project we will have gnateatered a range of microstructures, irradiated them, mechanically tested them and related the hardening to the observed microstructures. This will then be inputed to newly developed models at UKAEA. The project is in collaboration with the UKAEA/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.

核聚变现在正被认真考虑作为2050年后的未来能源，诺丁汉郡最近宣布的STEP建设就证明了这一点。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。如果不了解中子损伤对材料的影响，就没有切实可行的方法来提升部件，因此也就没有反应堆。然而，我们不能仅仅建造一个反应堆来测试材料，然而，研究辐照材料的成本很高，从它们产生机械数据也很困难。中子损伤可以用离子辐照来模拟，但损伤层很薄-200 nm到100微米。因此，不能使用传统的机械测试方法，必须进行新的微观机械测试。这导致由于测试小材料体积所固有的尺寸效应而难以解释结果。正在开发的力学模型将包括辐射损伤对演变的机械性能的影响，但这些模型需要大量的实验输入，以表征和从机理上了解不同的微观结构特征(空洞、沉淀物、环路)如何控制辐射诱导的硬化。该项目旨在利用对一系列模型合金的微观机械测试来揭示不同微观结构特征的影响。这些合金将在铸造时控制铬、碳和钒的含量，以控制固溶体、间隙和碳化物强化。样品将同时受到重离子和氦的照射，以产生空洞和位错环。将在室温和工作温度下使用纳米压痕来研究硬化。室温下的纳米压痕是研究辐照硬化的标准方法，但利用纳米压痕研究高温辐照硬化的工作要少得多。我们预计，使用牛津大学开发的新开发的计算塑性有限元方法，我们将不仅看到辐射损伤对屈服应力的影响，还将看到加工硬化的影响。为了了解原始组织、辐照下的组织演变以及闪光位错与显微组织特征的相互作用，将使用先进的电子衍射成像。这将包括用于研究这种微结构的衍射对比透射电子显微镜，以及传输菊池衍射，它在研究辐射损伤方面的应用要少得多，但具有更简单和更便宜的成像设备的优势。我们预计，到项目结束时，我们将研磨一系列微结构，对它们进行辐照，对它们进行机械测试，并将硬化与观察到的微结构联系起来。然后，这将被输入到英国航空航天局新开发的模型中。该项目与UKAEA/库勒姆聚变能源中心合作，DPhil学生将成为EPSRC聚变科学与技术CDT的一部分。该研究方案与EPSRC的“能源”组合主题以及“聚变”和“核能”分主题保持一致。“工程”这一主题也与“材料工程--金属和合金”研究领域相关。