Ames Laboratory – US Department of Energy, Iowa State University, Ames, Iowa 50011, USA.
Sci Rep. 2011;1:194. doi: 10.1038/srep00194. Epub 2011 Dec 23.
The structural description of disordered systems has been a longstanding challenge in physical science. We propose an atomic cluster alignment method to reveal the development of three-dimensional topological ordering in a metallic liquid as it undercools to form a glass. By analyzing molecular dynamic (MD) simulation trajectories of a Cu(64.5)Zr(35.5) alloy, we show that medium-range order (MRO) develops in the liquid as it approaches the glass transition. Specifically, around Cu sites, we observe "Bergman triacontahedron" packing (icosahedron, dodecahedron and icosahedron) that extends out to the fourth shell, forming an interpenetrating backbone network in the glass. The discovery of Bergman-type MRO from our order-mining technique provides unique insights into the topological ordering near the glass transition and the relationship between metallic glasses and quasicrystals.
无序系统的结构描述一直是物理科学的长期挑战。我们提出了一种原子团簇对准方法，以揭示金属液体在过冷形成玻璃时三维拓扑有序的发展。通过分析 Cu(64.5)Zr(35.5)合金的分子动力学（MD）模拟轨迹，我们表明在液体接近玻璃转变时会出现中程有序（MRO）。具体来说，在 Cu 位置周围，我们观察到“伯格曼三十面体”堆积（二十面体、十二面体和二十面体）扩展到第四壳层，在玻璃中形成一个相互贯穿的骨干网络。我们的有序挖掘技术发现的伯格曼型 MRO 为接近玻璃转变时的拓扑有序和金属玻璃与准晶体之间的关系提供了独特的见解。
