【作者】 李娜；

【导师】 梅显秀；

【作者基本信息】 大连理工大学 ， 等离子体物理， 2025， 博士

【摘要】 随着聚变能源研究的不断推进,耐辐照材料的开发已成为该领域的核心课题之一,尤其是在面向等离子体材料的选择上。这类材料需要在极端环境下长期稳定运行,面临H、He等离子体辐照、高能中子辐照和强热负荷辐照等多重挑战。金属钨作为面向等离子体材料的主要候选者,在H、He等离子体辐照作用下,会在材料内部产生气泡,进而引发起疱、开裂、表面绒毛等恶化行为;在高能中子辐照下,剧烈的级联损伤造成大量缺陷积累,从而引发材料硬化、脆化等;而强热负荷中的瞬态热负荷则可能导致熔化、喷溅及开裂等破坏行为。这些辐照效应显著制约了材料的性能表现和使用寿命,因此开发具有优异耐辐照性能的材料至关重要。和传统晶体材料相比,非晶合金具有本征的无序结构,包含丰富的自由体积,且无晶界、位错等缺陷,有效避免了由缺陷积累而导致的性能恶化,因而被认为具备优异的耐辐照能力。尽管非晶合金的温度敏感性影响了其应用,但对其在复杂辐照条件下的损伤机制进行研究,有助于为聚变反应堆面向等离子体材料的设计和优化提供理论支持和数据依据。然而,目前非晶合金在多束辐照条件下的损伤机制尚未被充分阐明。基于此,本论文以Zr_63.5Cu₂₃Al₉Fe_4.5和Fe₈₀B₁₃Si₇非晶合金作为主要研究对象,系统研究了非晶合金在单束辐照、“瞬态热负荷和He离子”以及“强级联损伤和He离子”复杂辐照条件下的损伤机制。同时,论文还扩展了对相同成分Zr_63.5Cu₂₃Al₉Fe_4.5晶体合金的辐照响应行为研究,揭示了不同本征结构对辐照损伤机制的影响差异。论文的主要研究内容及结果如下:（1）比较了具有高玻璃形成能力和高热稳定性的Zr_63.5Cu₂₃Al₉Fe_4.5和Fe₈₀B₁₃Si₇非晶合金在单束He²⁺离子辐照条件下的损伤机制差异,发现由于具有较小的原子质量,Fe₈₀B₁₃Si₇非晶合金中的He离子分布更集中;同时,B元素有效抑制了气体原子在材料中的扩散,形成堆积紧密的大尺寸气泡。泡间隙内的原子扩散在较大压应力和过量自由体积的作用下显著增强,导致Fe₈₀B₁₃Si₇非晶合金的泡层区域析出Fe₃B纳米晶。纳米压痕结果显示Zr_63.5Cu₂₃Al₉Fe_4.5非晶合金在2×10¹⁷/cm²辐照后锯齿流动未明显改变,4×10¹⁷/cm²时产生大量<4 nm的小尺寸锯齿,而Fe₈₀B₁₃Si₇非晶合金则在泡层深度形成约30 nm的突跳点。结合He泡行为,揭示了非晶合金变形模式改变的潜在机制:小He泡参与剪切重排造成的局域化变形、大He泡阻碍剪切重排导致的均匀化变形、泡层坍塌诱导的局部断裂。（2）探索了瞬态热负荷和He离子辐照条件下的协同效应影响Fe₈₀B₁₃Si₇非晶合金微观结构演化的内在机制。研究表明,当瞬态热负荷辐照引起的升温超过合金熔点时,快速熔化和冷却过程诱导非晶合金保持无序的非晶结构,并形成更加无序的团簇结构,同时引起大量自由体积的产生。在瞬态热负荷和He离子辐照条件下,He离子诱导Fe₈₀B₁₃Si₇非晶合金的晶化行为显著被抑制,即使在更高剂量的He离子辐照下也未观察到晶化现象。瞬态热负荷辐照也通过增加非晶合金中的自由体积,促进了He泡的生长,并使泡层的位置更加靠近表面。此外,更多的自由体积还可以增强非晶合金容纳入射粒子的能力,有利于提高表面起疱和剥落等损伤的剂量阈值。（3）研究了强级联损伤和He的协同效应对Zr_63.5Cu₂₃Al₉Fe_4.5非晶和晶体合金的影响规律及其内在机制。研究表明Zr_63.5Cu₂₃Al₉Fe_4.5非晶合金在所有辐照条件下均能保持其非晶结构,且元素分布均匀。在两种He辐照条件下,由于元素和结构上的均匀性,非晶合金中的He泡在空间上均匀分布。相比于单束He辐照,强级联损伤的加入显著增加了自由体积含量,促进了He原子和泡的迁移,使得气泡尺寸增加约22%,从而加剧了辐照诱导肿胀行为。在力学性能方面,辐照后非晶合金发生软化,锯齿流动行为减弱,塑性变形更加均匀,但未观察到显著的协同效应。对于晶体合金,所有辐照条件下均发生了非晶化转变,形成Cu、Al、Fe三种元素不均匀分布的非晶结构。在两种He辐照条件下,晶体合金中均观察到气泡,其中富Cu区域的泡尺寸大于富Al和富Fe区域;值得注意的是,在双束辐照条件下,除整体气泡尺寸增大以外,各元素富集区域间的气泡尺寸差异显著减小,这归因于强离位损伤显著增强了原子混合效应,使得晶体合金中三种元素的分布更加均匀。三种辐照条件下的晶体合金均表现出软化,并呈现出轻微的锯齿流动行为。与单束He辐照相比,强级联损伤的加入促进了元素的均匀化分布,减弱了界面应力集中效应,从而表现出更低的硬度和更明显的锯齿流动行为。更多还原

【Abstract】 With the ongoing progress in fusion energy research,the development of irradiation-resistant materials has become one of the core challenges in this field,particularly in the selection of plasma-facing materials（PFMs）.These materials need to maintain long-term structural and functional stability under extreme operational conditions,including hydrogen（H）and helium（He）plasma irradiation,high-energy neutron irradiation,and intense heat loads.Tungsten,as the primary candidate for PFMs,experiences bubble formation under H and He plasma irradiation,leading to degradation behaviors such as blistering,cracking,and surface fuzz.Under high-energy neutron irradiation,severe cascade damage results in the accumulation of numerous defects,leading to material hardening and embrittlement.Additionally,transient heat loads in intense heat flux conditions may cause melting,spattering,and cracking.These irradiation effects significantly limit the materials’performance and service life,highlighting the critical importance of developing materials with superior irradiation resistance.In contrast to conventional crystalline materials,amorphous alloys are featured with their intrinsically disordered atomic structure,abundant free volume,and absence of crystalline defects such as grain boundaries and dislocations,which effectively prevent performance degradation caused by defect accumulation.Consequently,amorphous alloys are considered to exhibit excellent irradiation resistance.Although the temperature sensitivity of amorphous alloys impacts their practical applications,investigating their damage mechanisms under complex irradiation conditions is crucial.Such studies provide essential theoretical insights and experimental data to support the design and optimization of plasma-facing materials for fusion reactors.However,the damage mechanisms of amorphous alloys under multi-beam irradiation conditions have not been fully elucidated.Thus,this study focused on Zr_63.5Cu₂₃Al₉Fe_4.5 and Fe₈₀B₁₃Si₇ amorphous alloys as the primary research subjects.It systematically investigated the irradiation damage mechanisms of these alloys under single ions beam irradiation,and complex irradiation conditions of“transient heat load and He”as well as“strong cascade damage and He”.Additionally,comparative studies with compositionally equivalent Zr_63.5Cu₂₃Al₉Fe_4.5crystalline alloy further revealed the influence of intrinsic structure on irradiation damage mechanisms.The main research content and results are as follows:（1）The damage mechanisms of Zr_63.5Cu₂₃Al₉Fe_4.5（with high glass-forming ability）and Fe₈₀B₁₃Si₇（with high thermal stability）amorphous alloys were compared under single-beam He ions irradiation.It was found that Fe₈₀B₁₃Si₇ amorphous alloy with lower atomic mass exhibited a more concentrated distribution of He ions.Additionally,the presence of boron（B）effectively suppressed the diffusion of gas atoms within the material,leading to the formation of tightly packed,large-sized bubbles.The diffusion of atoms within the bubble gaps was significantly enhanced under high compressive stress and excess free volume,leading to the precipitation of Fe₃B nanocrystals in Fe₈₀B₁₃Si₇ amorphous alloy.Nanoindentation experiments showed that serrated flow of Zr_63.5Cu₂₃Al₉Fe_4.5 amorphous alloy did not change obviously after irradiation with the dose of 2×10¹⁷/cm²,and a large number of small-sized pop-in<4 nm produced at 4×10¹⁷/cm²,while a displacement burst sized with about 30 nm occurred in the bubbles layer depth in Fe₈₀B₁₃Si₇ amorphous alloy.Combined with the He bubble distribution characteristics,physical mechanisms of deformation modes changes in the amorphous alloy after He ions irradiation were revealed:localized deformation caused by small He bubbles participating in shear rearrangement,homogeneous deformation caused by large He bubbles hindering rearrangement,and localized fracture induced by bubble layer collapse.（2）The synergistic effects of transient heat load and He dual-beam irradiation on the microstructural changes of Fe₈₀B₁₃Si₇ amorphous alloy were further explored.The study demonstrated that when the temperature rose induced by transient heat load irradiation exceeded the melting point of the material,the rapid melting and cooling process preserved the disordered amorphous structure in amorphous alloy,introduced a large amount of free volume and formed more disordered cluster structure.Under the transient heat load and He dual-beam irradiation conditions,crystallization behavior induced by He ions irradiation was significantly suppressed in Fe₈₀B₁₃Si₇ amorphous alloy,even under higher doses of He ions irradiation.Furthermore,the free volume increased in the amorphous alloy after transient heat load irradiation,which promoted the growth of He bubbles and caused the bubble layer to shift closer to the surface.Additionally,the increased free volume enhanced the ability to accommodate incident particles,thereby raising the damage dose threshold for surface blistering and spallation.（3）The research explored the synergistic effects of strong cascade damage and He on Zr_63.5Cu₂₃Al₉Fe_4.5 amorphous and crystalline alloys,as well as the underlying mechanisms.The study showed that Zr_63.5Cu₂₃Al₉Fe_4.5 amorphous alloy maintained its amorphous structure and exhibited homogeneous elemental distribution under all irradiation conditions.Under two He irradiation conditions,due to the uniformity in both composition and structure,He bubbles distributed homogeneously in the amorphous alloy.Compared to single-beam He ions irradiation,the addition of strong cascade damage significantly increased the free volume content,promoting the migration of He atoms and bubbles,which led to about 22%increase in bubble size and exacerbated irradiation-induced swelling.In terms of mechanical properties,the amorphous alloy softened after irradiation,with a weakened serrated flow behavior and more homogeneous plastic deformation,although no significant synergistic effects were observed.For the crystalline alloy,amorphization occurred under all irradiation conditions,resulting in the amorphous structure with the inhomogeneous distribution of Cu,Al,and Fe elements.Under both single and dual He ions irradiation,bubbles were observed in crystalline alloys,with larger bubble sizes in Cu-rich regions compared to Al-rich and Fe-rich regions.Notably,under dual-beam irradiation,in addition to an overall increase in bubble size,the differences in bubble size among regions enriched with different elements were significantly reduced.This phenomenon was attributed to the strong displacement damage under dual-beam irradiation,which substantially enhanced atomic mixing and led to a more homogeneous distribution of Cu,Al,and Fe elements within the crystalline matrix.All irradiated crystalline alloys exhibited softening and slight serrated flow behavior.Compared to single He ions irradiation,the presence of strong cascade damage promoted elemental homogenization and mitigated interfacial stress concentration,thereby resulting in lower hardness and more pronounced serrated flow behavior.更多还原