金属玻璃储能行为研究

发布时间：2022-02-12 08:45

　　金属玻璃的屈服应力和弹性应变极限远远超过传统的多晶合金,但具有应变软化和拉伸时灾难性失效（零延展性）的缺陷。对于块状金属玻璃,应变软化和脆性是其作为结构材料更广泛应用的主要障碍。改善机械性能的主要方法之一是通过热机械加工实现再生以获得更高能量状态的金属玻璃。金属玻璃的热机械加工可以显著地诱导其结构和性质的变化,即使热机械加工施加的宏观应变完全在弹性体系内时依然有效。这种处理可以使得金属玻璃达到更高能量的“回复”状态或更低能量的“老化”状态,因为回复状态能使非晶合金力学性质得到改善,因此金属玻璃的回复受到了广泛的关注。研究普遍认为,热机械加工导致的结构和性质的变化会随着加工程度的变化而单调变化。在本论文中,我们用超声锤击方法处理各种金属玻璃,结果表明通过强烈的超声弹性处理,（i）损伤和（ii）通过增加原子迁移率促进回复之间的内在结构竞争可以导致振荡形式的能量储存。这一现象和在玻璃形成液体的粘性流动中看到的情况类似,但是在弹性状态下处理玻璃会产生更高的振荡幅度。我们在La基金属玻璃的低温热循环过程中观察到能量振荡,这表明在高频率弹性处理过程中能量振荡是MG的一般特征。存储能量的振荡行为的发... 

【文章来源】：中国科学院大学(中国科学院物理研究所)北京市

【文章页数】：99 页

【学位级别】：博士

【文章目录】：
摘要
Abstract
Chapter1 Introduction
    1.1 Metallic glasses and their unique properties
    1.2 Achilles’heel in mechanical performance of MGs
    1.3 Methods to improve room temperature plasticity in MGs
        1.3.1 Fabrication of amorphous/(nano)crystalline composites
        1.3.2 Design of BMGs with specific compositions
        1.3.3 Size reduction of MGs
        1.3.4 Thermomechanical processing of MGs
    1.4 Rejuvenation of MGs induced by TMP
    1.5 Relaxation of MGs induced by TMP
    1.6 Motivation and objectives
Chapter2 Experimental methods
    2.1 Selection of materials
    2.2 Preparation of MGs
    2.3 Treatment of MGs
        2.3.1 Ultrasonic hammering(UH)process
        2.3.2 Cryogenic thermal cycling(CTC)
    2.4 Characterization of MGs
        2.4.1 X-ray diffraction(XRD)
        2.4.2 Transmission electron microscopy(TEM)
        2.4.3 Differential scanning calorimetry(DSC)
        2.4.4 Resonant ultrasound spectroscopy(RUS)
        2.4.5 Compression tests
        2.4.6 Scanning electron microscope(SEM)
        2.4.7 Vickers microhardness
        2.4.8 Temperature measurements in UH process
        2.4.9 Dynamic mechanical analysis(DMA)
Chapter3 Deformation behavior during UH
    3.1 Elastic deformation in Zr-based MGs
    3.2 Thermoplastic deformation in Pd-based and La-based MGs
    3.3 Correlations between glass properties and deformation behavior
        3.3.1 Correlations between fragility and energy dissipation
        3.3.2 Correlations betweenβ-relaxation and the extent of flow
    3.4 Summary
Chapter4 Energy storage oscillation induced by UH
    4.1 Relaxation enthalpy variations induced by UH treatment
        4.1.1 Effect of static force
        4.1.2 Effect of hammering time
        4.1.3 Effect of thermal history of as-cast MGs
    4.2 Structure-property correlations in UH-treated MGs
    4.3 Oscillatory energy storage induced by UH treatment
    4.4 Stored energy of cold work through different processing routes
    4.5 Summary
Chapter5 Finite element simulation of UH process
    5.1 Non-linear vibration due to hammering
    5.2 Finite-element-method modelling
    5.3 FEM simulation results and discussion
        5.3.1 Horn vibrations prior to loading
        5.3.2 Disk vibrations during UH
        5.3.3 Effect of static force on disk vibration
        5.3.4 Non-linear variations of the work done
    5.4 Summary
Chapter6 Energy storage behavior during CTC
    6.1 Oscillatory energy storage induced by CTC
    6.2 Effect of thermal history on energy storage evolution
    6.3 Effect of chemical heterogeneity on cryogenic rejuvenation
        6.3.1 Lanthanum impurity contents
        6.3.2 Relaxation enthalpy variations
        6.3.3 Mechanical performance
        6.3.4 Effect of chemical heterogeneity on microstructure
        6.3.5 Effect of impurity on thermomechanical properties
    6.4 Summary
Chapter7 Summary and outlook
References
个人简历及发表文章目录
Acknowledgements


【参考文献】：
期刊论文
[1]Serrated magnetic properties in metallic glass by thermal cycle[J]. 李明哲,Sajad Sohrabi,丁大伟,董帮少,周少雄,汪卫华.  Chinese Physics B. 2017(06)



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