Understanding Radiation Induced Transmutation in Tungsten Alloys for Nuclear Fusion

了解核聚变钨合金中的辐射诱发嬗变

• 批准号: 1802461
• 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: 2016
• 资助国家: 英国
• 起止时间: 2016 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=studentship-1802461
• 关键词: Understanding; Radiation; Induced; Transmutation; Tungsten

The development of viable nuclear fusion power plants relies on materials capable of withstanding the combined effects of high neutron irradiation and elevated temperatures in an extreme environment around the fusion plasma. Few materials proposed for plasma-facing components are capable of meeting these demands. Molybdenum, carbon composites and beryllium have all been examined but issues with either activation, tritium retention or sputtering rate exist for all these. Tungsten is now considered the leading candidate for the divertor and possibly all first wall armour. During irradiation with 14MeV neutrons, transmutation effects will alter the composition of any materials, further complicating accurate predictions of lifetime assessment. Previous work has shown that binary tungsten -rhenium and tungsten -tantalum alloys can form nanosized precipitates under irradiative exposures, which harden then ultimately embrittle the materials. However ternary W-Re-Ta and W-Re-Os alloys have been shown to behaviour quite differently under irradiation which raises important questions about the best route for mimicking transmutation pathways using pre-alloyed materials and fundamental questions regarding the mechanisms of precipitation formation in both irradiated and unirradiated alloys. In addition there have been no studies of tungsten-rhenium-tantalum-osmium alloys despite this being the terminal composition, previous studies focused on binary systems only and sometimes with overly high solute contents. This can lead to precipitates being observed that are not expected under operational conditions. In this project, higher-order (both ternary and quaternary alloys from the of tungsten-rhenium-tantalum-osmium systems) alloys representing more accurate transmutation products will be exposed to heavy ion-irradiation, then examined using a multi-technique approach of Atom Probe Tomography, TEM and Nanoindentation Measurements, aiming to link 3D chemical information at the atomic-scale to mechanical properties of these alloys. In particular how thermally stable these clusters are will be studied using thermal aging treatments. There has been no studies performed on this system with respect to this and this will be the first time the dissolution or growth will be observed. Nanoindentation will be used to study the interaction of dislocations with clusters and how this lead to hardening. These experiments are key to understanding if thermal treatments can be used to prolong divertor lifetime in service by annealing out radiation damage.In this manner we hope to obtain a much deeper understanding of interactions between solute additions in these materials following irradiation, better understand the kinetics and thermodynamics of irradiation assisted precipitation and how this alters the mechanical behaviour. This will provide valuable data needed to underpin atomistic simulations being performed at CCFE and eventually lead to better lifeing predictions for the divertor.EPSRC research theme is Energy.

可行的核聚变发电厂的发展依赖于能够承受高中子辐照和聚变等离子体周围极端环境中高温的综合影响的材料。很少有材料能够满足这些要求。钼、碳复合材料和铍都被检测过，但它们都存在活化、氚保留或溅射率的问题。钨现在被认为是主要的候选转向器和可能所有的第一壁装甲。在14MeV中子照射期间，嬗变效应将改变任何材料的组成，进一步使寿命评估的准确预测复杂化。先前的研究表明，钨铼二元合金和钨钽二元合金在辐射照射下可以形成纳米级析出物，这些析出物会变硬，最终使材料脆化。然而，W-Re-Ta和W-Re-Os三元合金在辐照下表现出完全不同的行为，这就提出了关于使用预合金材料模拟嬗变途径的最佳途径的重要问题，以及关于辐照和未辐照合金中沉淀形成机制的基本问题。此外，钨-铼-钽-锇合金虽然是末端成分，但还没有研究，以前的研究只集中在二元体系上，有时溶质含量过高。这可能导致在操作条件下观察到意想不到的沉淀。在这个项目中，代表更精确嬗变产物的高阶（来自钨-铼-钽-锇系统的三元和四元合金）合金将暴露在重离子照射下，然后使用原子探针断层扫描、透射电镜和纳米压痕测量等多技术方法进行检测，旨在将原子尺度上的三维化学信息与这些合金的机械性能联系起来。特别是如何热稳定这些团簇将研究使用热老化处理。目前还没有对这个体系进行过相关的研究，这将是第一次观察到溶解或生长。纳米压痕将用于研究位错与团簇的相互作用以及这如何导致硬化。这些实验是了解热处理是否可以通过退火消除辐射损伤来延长转向器使用寿命的关键。通过这种方式，我们希望更深入地了解辐照后这些材料中溶质添加物之间的相互作用，更好地理解辐照辅助沉淀的动力学和热力学以及这如何改变机械行为。这将为CCFE进行的原子模拟提供有价值的数据，并最终对转向器进行更好的寿命预测。EPSRC的研究主题是能源。

项目成果

Radiation-induced segregation in W-Re: from kinetic Monte Carlo simulations to atom probe tomography experiments

• DOI: 10.1140/epjb/e2019-100244-y
• 发表时间: 2019-10
• 期刊: The European Physical Journal B
• 作者: M. J. Lloyd;R. Abernethy;D. Armstrong;P. Bagot;M. Moody;E. Martínez;D. Nguyen-Manh

Decoration of Voids with Rhenium and Osmium Transmutation Products in Neutron Irradiated Single Crystal Tungsten

• DOI: 10.2139/ssrn.3389518
• 发表时间: 2019-05
• 期刊: AMI: Scripta Materialia
• 作者: M. J. Lloyd;R. Abernethy;I. Griffiths;P. Bagot;M. Moody;D. Armstrong;M. Gilbert