本文通過實驗和理論相結(jié)合的方式,研究了 Au55Cu25Si20金屬玻璃的結(jié)構(gòu)特征以及它在高溫和高壓下的行為,同時也探究了Ca,Al金屬液體以及Ca72.7Al27.3金屬合金在高溫高壓下的結(jié)構(gòu)演變。Au55Cu25Si20金屬玻璃的結(jié)構(gòu)特征表現(xiàn)為局域原子的堆積以9,10,11配位的多面體為主,而不是以類二十面體團簇為主,同時這些9,10,11配位的多面體中小尺寸的團簇互相排斥,而大尺寸的團簇互相吸引。這種異常的原子堆積結(jié)構(gòu)限制了該金屬玻璃的玻璃形成能力,并導致了結(jié)構(gòu)因子第一峰出現(xiàn)異常的峰肩。通過用5%的Ag替換Cu,Au55Cu20Ag5Si20金屬玻璃的空間連接性和原子堆積密度得到了大幅度提升,從而提高了玻璃形成能力,這與實驗結(jié)果也是相吻合的。應(yīng)用原位高壓X射線衍射實驗技術(shù)和第一性原理分子動力學模擬,對Au55Cu25Si20金屬玻璃在壓力誘導下的結(jié)構(gòu)變化進行了研究,并持續(xù)加壓到了36.8GPa。研究發(fā)現(xiàn),Au55Cu25Si20金屬玻璃的非晶態(tài)-非晶態(tài)相變發(fā)生在13.1到15.8 GPa之間,并且在降壓的過程中該相變是可逆的。理論研究與實驗研究的結(jié)果相一致,揭示了在高壓和低壓下A... 

【文章頁數(shù)】：177 頁

【學位級別】：博士

【文章目錄】：
Abstract (English)
Abstract (Chinese)
Acknowledgements
Abbreviations
Chapter One
    1 Introduction
        1.1. Introduction to metallic glasses
        1.2. Introduction to metallic liquids
        1.3. Thesis outlines
Chapter Two
    2 Experimental and theoretical methods and setups
        2.1. Samplepreparation
            2.1.1. Preparation of metallic glasses
        2.2. Diamond anvil cell (DAC)
            2.2.1. Principle
            2.2.2. Major components of DAC
            2.2.3. Heating
            2.2.4. Synchrotron radiation
        2.3. Theoretical methods
            2.3.1. First-principles method
            2.3.2. Density functional theory
            2.3.3. Computational framework
            2.3.4. Structural analysis methods
Chapter Three
    3 Structural signature in Au-based metallic glasses
        3.1. Introduction
        3.2. Materials and methods
            3.2.1. Sample preparation
            3.2.2. Simulation details
        3.3. Results and discussion
        3.4. Summary
Chapter Four
    4 Pressure-induced phase transformation in Au_(55)Cu_(25)Si_(20) metallic glass
        4.1 Introduction
        4.2 Experimental and theoretical methods
        4.3 Results and discussion
        4.4 Summary
Chapter Five
    5 Temperature-induced phase transformation in Au_(55)Cu_(25)Si_(20) metallic liquid
        5.1 Introduction
        5.2 Experimental and theoretical methods
        5.3 Results and discussion
        5.4 Summary
Chapter Six
    6 Structural evolution of metallic liquids under pressure
        6.1 Introduction
        6.2 Computational details
        6.3 Results and discussion
        6.4 Summary
Chapter Seven
    7 Conclusions
Bibliography
List of Publications



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