高频应力驱动非晶合金快速回春行为研究

非晶合金由于拥有独特的长程无序原子排列结构而具备很多优异性能，然而制约非晶合金应用的最大问题是其宏观脆性。回春是一种新型原子构型激励方法，通过提升非晶合金能量状态来提高结构中流变单元数量，进而大幅改善非晶合金塑性变形能力。本项目计划采用新开发的高频应力预压方法开展非晶合金回春研究：首先通过调整预压频率、应力、振幅、时间，确立过程参数对非晶合金回春的影响规律，揭示高频应力能够加速回春实现的内在机制；然后通过对比分析初始铸态、弛豫低能态、回春复原态非晶合金热焓演变曲线和动态力学响应曲线，明确回春的热力学和动力学特征，结合高分辨率原子力显微镜和透射电镜非均匀结构观察结果，探究回春的物理本源；最后测量不同回春状态非晶合金宏观压缩力学性能，阐明回春能够提高非晶合金塑性变形能力的机理。项目的实施将开发一种新型高效回春方法，加深人们对非晶合金回春行为的理解，并为回春调控非晶合金力学性能提供理论基础。

Due to long-range disordered microstructure, metallic glasses (MGs) process many excellent properties, thus have wide application prospect in many fields. However, the greatest limiting factor for their application is the macroscopic brittleness. Rejuvenation is a new configurational excitation method, it raises the energy state of MGs so that there are more flow units in the structure, leading to great improvement of the plastic deformation ability of MGs. Using new developed high frequency stress precompression, we plan to investigate the rejuvenation of MGs. First, by adjusting the frequency, stress, amplitude, time of the precompression, we aim at establishing the relation between the precompression factors and the rejuvenation states, and revealing the underlying mechanism of accelerated rejuvenation induced by the high frequency stress precompression. Second, through comparative analysis of structural enthalpy evolution and dynamic mechanical response of the as-cast, relaxed low energy state and rejuvenation recovered MGs, we aim at unearthing the thermodynamic and dynamic features of rejuvenation, combined with the heterogeneous microstructure observation using high resolution atom force microscope and transmission electron microscope, revealing the physical origin of rejuvenation. Last, by performing macroscopic compression test using different rejuvenated MGs, we aim at revealing the underlying relationship between the rejuvenation and deformation ability of MGs. The above research will provide us high-efficient rejuvenation method, improve our understanding of the rejuvenation, and offer theoretical basis for tailoring the mechanical properties of MGs.