结构无序的非晶合金以及化学无序的高熵合金作为两种典型的无序合金，由于复杂的化学成分和特殊的结构拥有优秀的综合性能，在新型金属材料中脱颖而出。与传统合金不同，高熵合金由于其每种主元的元素克分子数相等，因此具有高熵效应、迟滞扩散效应、严重的晶格畸变以及性能上的“鸡尾酒”效应。这些效应使高熵合金具有良好的力学性能和热力学稳定性，因此可用作极端环境下的结构材料的备选材料。高熵非晶合金是高熵合金与非晶合金的交叉产物，它在拥有紧密拓扑结构的同时还存在着高度的化学无序状态，使其兼具高熵合金和传统非晶的综合特点，并且在一些性能上会更加优异。

    本论文的工作研究了几种典型高熵合金和高熵非晶合金在离子辐照后的结构和性能响应，以期探索这些新型材料在核反应堆和空间辐照环境下的潜在应用。重点研究了三种典型的高熵合金——传统的CoCrFeCuNi高熵合金、NbTiVTa难熔高熵合金和CoCrFeCuNb_0.65共晶高熵合金，探究并比较其微观结构演变和力学行为差异；并以ZrTiHf系高熵非晶合金作为研究对象，探索了其辐照响应和抗辐照机理及力学行为演变。主要研究工作内容及结果如下：

（1）利用100 keV He⁺离子室温下辐照三种典型的高熵合金，并通过形貌表征和纳米压痕测试评价了辐照引起的表面损伤和力学性能。结果表明，高熵合金中不同元素相之间的辐照肿胀程度存在差异，且高剂量下样品表面发生起皮。在CoCrFeCuNb_0.65共晶高熵合金中，发现低应力区引起的氦泡聚集现象。随辐照剂量增加，高熵合金均发生先硬化后软化，符合辐照诱导位错滑移“障碍”的硬化模型及长期的热峰效应引起的粘性软化模型。

（2）对ZrTiHf系高熵非晶合金和同体系的高熵合金在He离子作用下的抗辐照性和力学行为进行了对比研究。发现ZrTiHfCuBeNi高熵非晶合金的临界起皮剂量高于其他两种合金。辐照后高熵非晶合金发生软化，锯齿流变现象减弱，可归因于辐照诱导类液区模型或者高浓度原子尺度缺陷；辐照后蠕变弛豫峰强度和弛豫时间并未发生明显变化，通过Kelvin粘弹性模型两项指数拟合计算解释了辐照诱导类液区变化和弛豫过程的关系。

（3）系统研究了高熵非晶合金He离子辐照后的局部硬化行为。发现随着辐照剂量增加，硬化峰向右移动，并伴随着氦泡的形核和生长。另外，在氦泡层的中心区域观察到氦泡的聚集和重叠。He离子作用引起的局部硬化行为符合基于氦泡的大小和密度的半定量模型及氦泡相互作用产生的内应力模型。

（4）借助透射电镜进一步研究了高熵非晶合金的高温Xe离子辐照后的微观结构演变和力学行为，探索辐照对晶化的影响机制。发现与单一热退火不同，高温辐照不仅导致样品晶化，而且还引入了更复杂的金属间化合物；通过辐照诱导应力模型解释了纳米晶中形成非边缘断裂位错的现象；发现了辐照后高熵非晶合金的塑性有所改善，归因于晶化行为及材料内部的原子间距的变化。此外，通过Hertzian弹性接触理论估算了辐照后剪切转变区的体积变化，符合持续辐照期间类液区结构的重排和含量变化规律。

    Structurally disordered metallic glass (MG) and chemically disordered high-entropy alloy (HEA) are two typical disordered alloys. Due to their complex chemical composition and special structure, they have excellent comprehensive performance and stand out among new metal materials. Being different from the conventional alloys, compositions in HEAs are complex due to the equimolar concentration of each component, which results in four core effects for HEAs: high entropy effects, sluggish diffusion, severe lattice distortion, and cocktail effects in properties. These effects compel HEAs to have good mechanical properties and thermodynamic stability, proposing them as structural materials in extreme environments. High-entropy metallic glass (HE-MG) is a cross product of HEA and MG. HE-MGs exhibit the characteristics of a long-range disordered atomic arrangement, similar to that of traditional MGs and also contain an equimolar ratio of constituents similar to that of crystalline HEAs. Because of their unique structural and compositional features, HE-MGs exhibit peculiar physical, chemical, and mechanical properties.

    In this dissertation, in order to explore the potential application of these materials in irradiation environments, e.g. those in the nuclear industry, the ion irradiation responses of typical HEAs and HE-MGs will be investigated, focusing mainly on three typical HEAs: traditional CoCrFeCuNi HEAs, NbTiVTa refractory high-entropy alloys (RHEAs) and CoCrFeCuNb_0.65 eutectic high-entropy alloys (EHEAs), as well as the representative ZrTiHf-based HEAs and HE-MGs. Their microstructure evolution, irradiation damages and the corresponding mechanical behaviors upon ion irradiation are systematically studied as follows:

（1）Three typical high-entropy alloys were irradiated with a 100 keV He⁺ ion beam. The surface damage and mechanical properties caused by irradiation were evaluated by morphology characterization and a nanoindentation test. The results show that there are differences in the degree of irradiation swelling between different element phases in HEAs, and peeling and blistering, occurring on the surface at high fluence. Especially in CoCrFeCuNb_0.65 EHEAs, He bubble accumulation caused by low stress zones was found. In addition, all three HEAs show a process of hardening first and then softening, due to the dislocation-dominated irradiation hardening model and the viscous softening model caused by the long-term thermal peak effect.

（2）ZrTiHf-based HE-MGs and HEAs were selected and compared with He⁺ ion irradiation at room temperature. It was found that the ZrTiHfCuBeNi HE-MG showed excellent resistance to irradiation, and its critical peeling fluence was higher than that of others. He ion irradiation led to an obvious softening of the samples, and distinctly weakened the serrated flow feature during plastic deformation. The change of the deformation behavior is attributed to the introduction of excess liquid-like zones or atomic-scale defects by ion irradiation. The relaxation peak intensity and relaxation time of HE-MG did not change significantly after irradiation, and the relation between the variation of irradiation-induced liquid-like zone and the relaxation process has been explained by the two-exponential fitting of Kelvin viscoelastic model.

（3）The local hardening behavior of HE-MG after He irradiation has been studied systematically. The peak of local hardening moves to the right, accompanied by nucleation and growth of helium bubbles. In addition, coalescence and overlapping of the He bubbles were observed in the central of the bubble layer at the highest fluence. The localized hardness change is quantified by a model based on the size and density of the He bubbles and the internal stress model of He bubble interaction.

（4）Transmission electron microscopy (TEM) were used to further study the microstructure evolution and mechanical behavior of HE-MGs. Unlike traditional thermal annealing, high-temperature irradiation not only caused the sample to crystallize, but also introduced more complex intermetallic compounds. Based on the radiation-induced stress model, irradiation can also cause non-edge-on faulted dislocation in the formed nanocrystals. It was found that the plasticity of the sample after irradiation was improved, due to the formation of nanocrystals and the change of the interatomic distance within the MGs. In addition, the Hertzian elastic contact theory is used to estimate the volume evolution of the shear transition zone after irradiation, which is consistent with the law of rearrangement and content change of the liquid-like zone during continuous irradiation.