非晶合金由于其独特的长程无序结构、优异的力学和物理性能，在国防、空天等领域显示出广泛的应用前景。在这些领域的应用过程中，非晶合金易受到高能激光辐照而发生烧蚀失效。同时，非晶合金在激光烧蚀下的材料与结构响应本身也极具科学意义。因此，近年来，非晶合金的激光烧蚀得到了越来越多的关注。本文以一种典型锆基非晶合金(Vitreloy 1)为模型靶材料，开展了大气和水下两种环境的纳秒脉冲激光辐照实验，围绕烧蚀过程和机制，取得了以下几个方面的研究进展：

(1) 开展了纳秒脉冲激光在大气环境下对非晶合金靶及其对应晶态合金的烧蚀实验。通过超高速相机捕捉到了激光在非晶合金表面诱发的等离子体，以及等离子体在空气中激发的冲击波，和靶表面的爆炸沸腾现象。分析表明，等离子体通过动量传递激发冲击波的形成，二者动力学过程均满足Taylor-Sedov理论中关于理想球面波的描述，并与靶体的拓扑结构无关。爆炸沸腾诱导非晶合金靶表面形成分层微纳米结构：微米级的烧蚀凹坑和纳米孔洞。非晶无序结构抑制了激光热量向试样内部的传播，而更多沉积在烧蚀表面，这导致在爆炸沸腾中非晶合金有更高的表面过热程度和更浅的热影响区。因此，非晶合金烧蚀形貌的纳米孔洞直径和烧蚀坑深度均小于晶态合金。

(2) 开展了纳秒脉冲激光在水环境下烧蚀非晶合金实验。采用不同时间分辨率的超高速相机澄清了水下烧蚀的全过程。首次捕捉到激光诱导的非晶合金等离子体，以及一系列在水中传播的冲击波和在试样表面形成的空化气泡。分析表明，在水中的系列冲击波源于等离子体的直接激发或在不同介质中的多次反射和透射。空化气泡的成核源于等离子的热效应，但是气泡的长大动力学偏离经典Rayleigh-Plesset理论的预测。实验发现，这种偏离是由于爆炸沸腾模式的烧蚀物质喷发与空化气泡在时间和空间上存在重叠，导致提前进入水中的烧蚀物质抑制了气泡的长大。

(3) 实验确定了非晶合金纳秒激光水下烧蚀产物。通过高分辨透射电镜，对由于爆炸沸腾而进入水中的烧蚀产物进行了精细表征，发现烧蚀产物中存在多种不同结构的纳米颗粒：完全非晶、非晶-晶体复合和多晶。非晶纳米颗粒的组分均匀且尺寸较小；后两种纳米颗粒表现出独特的核-壳结构并存在明显的组分偏析。纳米颗粒结构的差异取决于烧蚀物质进入水中的方式：在空化气泡成核前直接进入还是经过气泡后延时进入。在不同入水方式中，烧蚀产物的冷却速率和玻璃形成能力存在显著差异，从而形成不同结构的纳米颗粒。

(4) 探究了大气环境和水下纳秒脉冲激光烧蚀对非晶合金内部结构的影响。研究表明，爆炸沸腾中剧烈的热效应只聚集在烧蚀表面，其极快的升温和降温过程不会引发非晶合金内部结构的明显变化。等离子体激发的压缩冲击波会增大试样次表面剪切转变区（STZ）的激活体积，该压缩波经边界反射后会形成拉伸波并对次表面造成二次作用，导致STZ激活体积减小，激活数量增加，从而使次表面区域的硬度降低。冲击波两次作用效果的强弱与冲击波的初始幅值有关，水下烧蚀中的高幅值冲击波会导致非晶合金试样次表面出现一个软化层，但空气中的低幅值冲击波却不足以对试样内部结构或微观力学性能造成影响。

    Amorphous alloys have shown wide applications in the fields of defense and aerospace due to their unique long-range disordered structure and excellent mechanical and physical properties. In these applications, amorphous alloys are susceptible to ablation failure under the irradiation of high-energy laser. Meanwhile, the material and structure responses of amorphous alloys under laser ablation are also of great scientific significances. Therefore, laser ablation of amorphous alloy has received more and more attention in recent years. In this dissertation, a typical Zr-based amorphous alloy (Vitreloy 1) is used as a model target material to carry out nanosecond pulse laser irradiation experiments in both atmospheric and underwater environments. Focusing on the ablation process and mechanism, several advances have been achieved in the following:

(1) The ablations of nanosecond pulse laser on the Vitreloy 1 target and its crystalline counterpart are carried out in the atmospheric environment. The ultra-high-speed camera captures the laser-induced plasma of the amorphous alloy, the plasma-excited shock wave in the air, and the explosive boiling phenomenon on the target surface. The analysis shows that the plasma stimulates the shock waves through momentum transfer. The dynamic processes of both plasma and shock wave satisfy the description of ideal spherical waves in Taylor-Sedov theory, and it is independent of the topological structure of the target material. Explosive boiling leads to the formation of hierarchical micro-nano structures on the surface of the amorphous alloy: micro-scale ablation crater containing nanovoids. The disordered structure of amorphous alloy suppresses the diffusion of laser heat into the inside of the target, and more deposits on the ablated surface. This results in a higher degree of surface superheating and a shallower heat affected zone in the amorphous alloy during explosive boiling. Therefore, the diameter of nanovoids and the depth of ablation crater of the amorphous alloy are smaller than those of the corresponding crystalline counterpart.

(2) The nanosecond pulse laser ablation of the Vitreloy 1 target is carried out in water. The ultra-high-speed cameras with different time resolutions are used to clarify the entire process of underwater ablation. It is the first time to capture laser-induced plasma for amorphous alloy, as well as a series of shock waves propagating in water and the cavitation bubble formed on the target surface. Analysis shows that the series of shock waves in water originate from direct excitation of plasma or multiple reflections and transmissions in different media. The nucleation of cavitation bubble comes from the thermal effect of plasma, but the growth of the bubble deviates from the prediction of the classical Rayleigh-Plesset theory. Experimental results have shown that this deviation is due to the spatiotemporal overlap of the explosive boiling induced ejection of ablation products and the cavitation bubble, leading to the ablation products entering the water in advance to inhibit the bubble growth.

(3) The structure and composition of the ablation products for amorphous alloy under the nanosecond laser in water are confirmed experimentally. The ablation products entering the water due to explosive boiling are finely characterized by the high-resolution transmission electron microscopy, and it is found that there are many kinds of nanoparticles with different structures in the ablation products: completely amorphous, amorphous-crystal composite and polycrystalline. The amorphous nanoparticles have uniform compositions and smaller sizes, and the latter two kinds of nanoparticles show the unique core-shell structure with obvious component segregation. The difference in nanoparticle structure depends on the ways that ablation material enters the water: it enters directly before the nucleation of cavitation bubble or lingeringly enters after the bubble collapse. There are significant differences in the cooling rate and glass forming ability for the ablation products that enter the water in different ways, resulting in the formation of nanoparticles with different structures.

(4) The influence of nanosecond pulse laser ablation on the internal structure of amorphous alloys is explored in both atmospheric and water environment. Studies have shown that the violent thermal effect of explosive boiling is only concentrated on the ablation surface, and the extremely rapid heating and cooling process in explosive boiling will not cause obvious changes in the internal structure of amorphous alloys. The compressive shock wave excited by the plasma will increase the activation volume of the shear transition zone (STZ) in the subsurface of sample. After the compressive wave is reflected from the boundary, it will form a tensile wave and cause a secondary effect on the subsurface. This secondary effect from tensile wave reduces the activation volume of STZ while increase their quantity, thus leads to the decrease of hardness of the subsurface area. The strength of the two-step effect from shock wave is related to its initial amplitude. The high-amplitude shock wave in underwater ablation will cause a softened layer on the subsurface of the sample, but the low-amplitude shock wave in the air is not enough to affect the internal structure or micromechanical properties of the sample.