一种呈现脆强玻璃转变的金属玻璃形成材料中的超均匀性逼近
Approach to Hyperuniformity in a Metallic Glass-Forming Material Exhibiting a Fragile to Strong Glass Transition
AI总结：
本文通过分子动力学模拟研究金属玻璃形成材料 Al90Sm10 的脆强玻璃转变，量化超均匀性指数 H 并与德拜-沃勒参数比较，揭示其临界值与林德曼判据的类比关系，并将脆强玻璃形成和液-液相分离归因于协同组装过程。
摘要：
我们通过分子动力学模拟研究了一种呈现脆强（FS）玻璃形成的金属玻璃形成（GF）材料（Al90Sm10），以更好地理解这种高度独特的玻璃形成模式。在这种模式中，许多描述普通玻璃形成液体弛豫时间和扩散的常见唯象关系不再适用，取而代之的是在响应函数中观察到真正的热力学特征，而在玻璃转变温度 Tg 处几乎没有热力学特征。鉴于这种金属玻璃形成材料的热力学和动力学与水之间存在许多意想不到的相似之处，我们首先关注该液体中的反常静态散射，这延续了近期对水、硅和其他脆强玻璃形成液体的研究。特别地，我们量化了我们液体的“超均匀性指数”H，它提供了分子“堵塞”的定量度量。为了深入了解 H 的温度依赖性和大小，我们还估计了另一种更熟悉的粒子局域化度量，即德拜-沃勒参数 $<u^2>$，它描述了在快弛豫时间量级的时间尺度上的均方粒子位移，并且我们还计算了加热晶态 Cu 的 H 和 $<u^2>$。这种对晶态材料和金属玻璃材料的 H 与 $<u^2>$ 的比较分析使我们能够理解 H 的临界值在 $10^{-3}$ 量级，这类似于晶体熔化和玻璃“软化”的林德曼判据。我们进一步将这类液体中脆强玻璃形成和液-液相分离的出现解释为源于玻璃形成液体中的一种协同组装过程。
英文摘要：
We investigate a metallic glass-forming (GF) material (Al90Sm10) exhibiting a fragile-strong (FS) glass-formation by molecular dynamics simulation to better understand this highly distinctive pattern of glass-formation in which many of the usual phenomenological relations describing relaxation times and diffusion of OGF liquids no longer apply, and where instead genuine thermodynamic features are observed in response functions and little thermodynamic signature is exhibited at the glass transition temperature, Tg. Given the many unexpected similarities between the thermodynamics and dynamics of this metallic GF material with water, we first focus on the anomalous static scattering in this liquid, following recent studies on water, silicon and other FS GF liquids. In particular, we quantify the 'hyperuniformity index' H of our liquid which provides a quantitative measure of molecular 'jamming'. To gain insight into the T-dependence and magnitude of H, we also estimated another more familiar measure of particle localization, the Debye-Waller parameter $<u^2>$ describing the mean-square particle displacement on a timescale on the order of the fast relaxation time, and we also calculate H and $<u^2>$ for heated crystalline Cu. This comparative analysis between H and $<u^2>$ for crystalline and metallic glass materials allows us to understand the critical value of H on the order of $10^{-3}$ as being analogous to the Lindemann criterion for both the melting of crystals and the 'softening' of glasses. We further interpret the emergence of FS GF and liquid-liquid phase separation in this class of liquids to arise from a cooperative assembly process in the GF liquid.
机构、总结、中文摘要均由AI分析而来，可能存在错误，请以论文正文为准。
