The Processing and Bulk Properties of New Low-Activation High-Entropy Alloys

实现净零发电对英国的能源安全和减少气候变化的影响至关重要。核聚变发电是未来长期生产绿色电力的主要候选者。许多现有的金属合金已被提议用于未来的聚变反应堆，包括在经历最具挑战性条件的面向等离子体的组件中。然而，仍然存在这些合金不适合在这样的环境中使用的真实的可能性，因为它们没有在它们将面临的极端条件下进行测试（即，快中子的高通量和高于500 ℃的温度）。因此，有一个强有力的论点，即新的聚变聚焦合金的设计和研究，以最大限度地提高我们的成功结果的机会。高熵合金（HEAs）是一个相对较新的一类合金，近年来在材料科学界产生了很大的兴趣。而不是基于一种主要合金元素（例如，钢中的Fe），它们包含高浓度的多种元素。这种设计理念开辟了一个巨大的合金成分，以前没有探索过。已经开始了一些设计用于聚变的低活化HEA的工作，即，合金在暴露于聚变反应堆条件后较长时间内不太可能具有放射性（因此不必作为长寿命放射性废物处理）。该项目将“扩大”已经显示出一定前景的新型低活化HEA成分的工作，特别关注VCrMnFeAlx合金套件（其中x在0和1之间变化）。这些合金已被证明具有良好的热稳定性，有些还表现出一些有趣的微观结构，可以导致高温强度。然而，迄今为止，这些组合物仅使用非常少量的材料进行评估，因此它们的整体机械性能（例如，应力-应变曲线、高温性能）尚未测量。它们对大规模生产过程中可能使用的批量热机械处理也没有反应。因此，本项目将使用更大的铸件（几公斤的规模）来评估这些性能。先进的高分辨率表征技术将与传统的机械测试一起使用。这些测试产生的所有结果都是新颖的，因为这些合金之前没有测量过。重要的是，这些结果应该表明这些材料是否可能适用于未来的聚变反应堆。

Moving towards net-zero electricity production is critical for the UK's energy security and to reduce the impact of climate change. Nuclear fusion power is a prime candidate for long-term production of green electricity in the future. A number of existing metallic alloys have been proposed for use inside future fusion reactors, including in the plasma-facing components that experience the most challenging conditions. However, there remains a real possibility that these alloys are not suitable for use in such environments, since they have not been tested under the extreme conditions they will face (i.e., a high flux of fast neutrons and temperatures above 500C). Hence, there is a strong argument that new fusion-focussed alloys be designed and investigated to maximise our chances of a successful outcome.High-entropy alloys (HEAs) are a relatively new class of alloys that have generated a lot of interest in the materials science community over recent years. Instead of being based around one principal alloying element (e.g., Fe in steels), they comprise multiple elements in high concentrations. This design philosophy has opened up a huge range of alloy compositions that have not been explored before. Some work has been started on designing low-activation HEAs for fusion, i.e., alloys are less likely to become radioactive for a long period of time following exposure to fusion reactor conditions (and hence won't have to be deposed of as long-life radioactive waste).This project will 'scale-up' work on new low-activation HEA compositions that have already shown some promise, with particular focus on the VCrMnFeAlx suite of alloys (where x varies between 0 and 1). These alloys have been shown to exhibit good thermal stability, and some also exhibit some interesting microstructures that could lead to high-temperature strength. However, to date these compositions have only been assessed using very small quantities of material, so their bulk mechanical properties (e.g., stress-strain curves, high-temperature properties) have not been measured. Neither have their responses to bulk thermomechanical treatments that might be used during their large-scale manufacture. Hence, this project will use larger castings (on the scale of a few kgs) to assess such properties. Advanced high-resolution characterisation techniques will be used alongside conventional mechanical testing. All the results that are produced from these tests will be novel, since they have not been measured before for these alloys. Importantly, the results should indicate whether these materials are likely to be suitable for use in future fusion reactors.