基于缺陷捕获和气体释放的新型抗辐照含纳米孔道材料的制备与性能研究

Understanding plasma-surface interactions (PSI) in magnetically confined fusion device is critical in harvesting potential fusion energy. Plasma facing material is subject to unprecedented high thermal heat load, high particle fluxes and neutron damage. W is identified as one of a few materials that may survive harsh plasma conditions. However, recent findings that shows blistering, whisker formation, and even exfoliation on W surface upon fusion plasma bombardment have raised some concerns in this made the fusion community concerned effectiveness damped. In this proposal, facing to the problems appearing in the facing plasma material of W bulk, we propose a new strategy, for the first time, to greatly increase the radiation tolerance by releasing the defects out of the materials instead of absorption and storage of them. The new facing plasma material, nanochannel W films, will be prepared by magnetic sputtering deposition. Such nanochannel W films can suppress the production and growth of bubbles, and greatly increase their stability and lifetime under harsh environment. In this project, we will study the interaction process of plasma and nanochannel W films, systematically analysis the process of absorption of defects and gas atoms by the nanochannels, figure out the key factors which affect the radiation resistant ability, and find out the mechanisms for the radiation tolerance of the new nanochannel W materials. The results of this research offer a candidate facing plasma material for fusion reactor and also provide a new way to prepare swelling resistant materials.

等离子体与面向等离子体壁材料之间的相互作用控制是当前核聚变研究面临的一项巨大技术挑战。本项目针对W块材受高剂量等离子体辐照后表面出现气泡、剥落和形成纳米丝等现象，提出了一种基于纳米孔道自由表面有效缺陷捕获和气体原子释放的抗辐照新策略，制备含纳米孔道W新型面向等离子体抗辐照材料，它能有效抑制W材料中气泡的产生和生长，大大提高面向表面等离子材料的抗辐照稳定性和寿命。通过系统研究等离子体与含纳米孔道W的相互作用过程，分析纳米孔道自由表面吸引、吸收和湮灭缺陷的过程和自由表面演化动力学，明确影响其抗辐照性能的关键因素，揭示该材料在极端条件下抗辐照内在机理。本项目研究将为未来聚变堆提供材料优选方案和技术储备，也为裂变堆抗辐照肿胀材料的研究提供了新的解决思路，将直接服务于我国聚变核能利用计划。

等离子体与面向等离子体的固体壁材料之间的相互作用的控制和高性能面向等离子体材料的研发是当前核聚变研究面临的一项巨大挑战。本项目针对钨块材受高剂量等离子体辐照后表面出现气泡、剥落和形成纳米丝等现象，提出了一种基于纳米孔道有效缺陷捕获和气体原子释放的抗辐照新策略，制备了新型抗辐照面向等离子体含纳米孔道W材料，并开展了系统的性能评价研究。通过在不同温度条件下用不同剂量的高能He+离子辐照实验以及Kr2+、He+ 离子协同辐照实验发现，这种新的利用纳米孔道来提高材料抗辐照性能的策略有别于纳米晶材料、纳米多层膜材料以及氧化物弥散强化材料等抗辐照机制，纳米孔道的不饱和性和开放性使其不仅能够较好的沉降缺陷和氦泡，而且能够有效的释放氦原子，气体最高释放率达到了63.7%。纳米硬度测试显示，纳米孔道材料具有更好的抗辐照硬化和辐照应变能力。在~1018 ions/cm2s大束流低能氦等离子体辐照后发现，相比于块体钨，纳米孔道钨薄膜形成纳米丝的起始剂量高于块材钨近一个数量级，且纳米丝生长速率仅仅只有块体钨的1/4。在保持较好的结构稳定性下，纳米孔道可以及时的释放氦原子使得在如此恶劣的等离子体环境下，钨薄膜仍能具备优良的抗辐照性能。利用正电子湮灭实验技术以及分子动力学和第一性原理的多尺度理论模拟共同分析了氦原子在纳米孔道钨薄膜中的扩散和形成氦团簇的演化过程，同时也揭示了纳米孔道钨表面低的缺陷形成能，使得其能有效吸引空位、气体原子等缺陷并释放，从而实现“自愈合”，大幅提高其抗辐照性能。本项目研究结果不仅为未来聚变堆面向等离子体材料的设计提供了新方案，也为裂变堆抗辐照肿胀材料的研究提供了新思路。.项目执行期间共发表直接相关SCI研究论文9篇，包括Acta Materialia（一区IF6.03）两篇，Nuclear Fusion（二区IF4.06）一篇，Journal of Nuclear Materials（三区IF2.45）4篇；在国际系列学术会议上作邀请报告2个，口头报告2个，国内学术会议上作邀请报告3个，口头报告5个。培养毕业博士研究生3人。承办全国性专业学会会议1次（156人）。