含纳米孔道钨-铼面向等离子体材料的氢/氘同位素滞留行为研究

Nuclear fusion is regarded as one of the important ways to solve the problems of human energy and environment. In the process of realizing stable operation of controlled thermonuclear fusion reactor, the plasma facing material (PFM) is one of the key problems that need to be solved urgently. Tungsten (W) is considered as the best candidate PFM for its excellent physical and chemical properties. However, the harsh fusion service environment also introduces to W many problems such as bubbles/fuzz formation, hydrogen isotopes retention, cascade damage and so on. This project mainly focuses on the problems of hydrogen isotopes retention, transmutation metal rhenium element and their synergistic effect faced by W as PFM. Combined with the advantages of nanomaterials in radiation resistance, tungsten-rhenium (W-Re) alloy thin films with different mass fraction of rhenium are prepared by magnetron sputtering and ordered nanochannel structures with unsaturated and open properties are introduced into the films. The influence of nanochannel and rhenium element on the hydrogen isotopes retention behaviors are deeply investigated by using the low-flux, middle energy hydrogen/deuterium ions and high-flux, low-energy deuterium plasma irradiation experiments. The micro-mechanism of radiation resistance of nanochannel W-Re film is revealed, providing a new idea for the design of PFM.

核聚变能目前被认为是最终解决人类能源和环境问题的重要途径之一。在实现可控热核聚变堆稳定运行的进程中，面向等离子体材料是其中亟待解决的关键问题之一。金属钨因其优异的物理化学性质被认为是最佳的面向等离子体候选材料，然而恶劣的聚变服役环境给钨材料也带来了诸多难题，如气泡/纳米丝的形成、氢同位素滞留、级联损伤等。本项目主要针对钨作为面向等离子体材料所面临的氢同位素滞留、嬗变金属铼元素及其协同作用等问题开展相关研究。结合纳米材料在抗辐照方面的优势，利用磁控溅射技术制备含不同质量分数铼的钨-铼合金薄膜，并向其中引入具有不饱和性和开放性的有序纳米孔道结构。利用低束流中能氘/氚离子和高束流低能氘等离子体辐照实验，深入探究纳米孔道结构和铼元素对氢、氘同位素滞留行为的影响。揭示纳米孔道钨-铼合金薄膜抗辐照的微观机理，为面向等离子体材料的设计提供新的思路。

面向等离子体材料要遭受极端恶劣的服役环境，其成败密切关系到反应堆中等离子体的稳定、第一壁结构材料和元件免受等离子体轰击等问题。因此，针对复杂聚变环境引发的离子及其热负荷效应与材料之间的相互作用，厘清其中的辐照损伤机制对先进抗辐照损伤的面向等离子体材料的设计起到至关重要的作用。本项目首先从实验角度出发深入研究了纳米孔道钨薄膜中的纳米孔道结构对氦-空位缺陷演化和氦滞留的影响，发现在氦泡形成初期纳米孔道结构帮助薄膜释放辐照引入的氦原子，延缓氦-空位缺陷的长大；其次利用高频脉冲电子束和离子束模拟聚变堆中的瞬态热负荷冲击，继续研究了纳米孔道钨薄膜的抗瞬态热负荷性能，发现纳米孔道结构为钨薄膜提供足够的空间容纳热瞬态冲击引发的热胀冷缩，有效减缓了热载荷下应力的聚集，从而抑制了裂纹的扩展；最后将具有优异氦调控和抗瞬态热应力能力的纳米孔道结构引入到自身性能优异的高熵合金中，研究了纳米孔道Al0.1CoCrFeNi高熵合金薄膜的抗氦辐照性能和塑性能力，同样进一步证实了纳米孔道结构在抗辐照损伤方面具有显著优势的普适性。