Efficient local atomic packing in metallic glasses and its correlation with glass-forming ability
Efficient local atomic packing in metallic glasses and its correlation with glass-forming ability
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DOI：
10.1103/physrevb.80.014202
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发表时间：
2009-07
影响因子：
3.7
通讯作者：
D. Ma;A. Stoica;Xun-li Wang;Zhaoping Lu;M. Xu;M. Kramer
中科院分区：
文献类型：
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作者：
D. Ma;A. Stoica;Xun-li Wang;Zhaoping Lu;M. Xu;M. Kramer
液体在冷却时绕过结晶而冻结成玻璃。原子在液体中移动的速度越慢，原子就越有可能逃脱结晶的捕获。在玻璃形成液体如聚合物和二氧化硅液体中，而不是单独的无规行走，原子被困在分子单元中（如液体二氧化硅中的SiO4四面体[1]），以集体运动的方式，大大降低了原子的迁移率。[2]因此，这些局部结构单元解释了液体优异的玻璃形成能力，并保持为聚合物和二氧化硅玻璃的构建单元。[2，3]类似地，金属玻璃也表现出局部结构单元的迹象，如短程有序（SRO）（或溶质中心原子簇），如最近的结构建模和计算机模拟工作中提出的。[4-6]然而，金属玻璃中的局部原子结构缺乏关键的实验测定，并且局部原子堆积与玻璃形成能力之间的相关性多年来尚未得到实验证明。在这项工作中，我们探讨了本地原子结构的金属玻璃使用飞行时间中子和同步辐射X射线衍射技术与高分辨率。我们的研究结果提供了一个新的计划，有效的本地原子包装的原子团簇更多»包括多种类型的原子在第一配位壳层的证据。我们还展示了第一个实验证据的不同原子键的数量和玻璃形成能力之间的明确的相关性。我们的发现对理解金属玻璃、液体和其他无序材料的原子结构具有重要意义，并可能为广泛的科学问题提供见解，在这些问题中，通过填充球体进行有效的空间填充至关重要。«少
A liquid freezes into a glass when bypassing crystallization upon cooling. The slower an atom moves around in the liquid, the more likely the atom escapes the capture of crystallization. In glass-forming liquids such as polymer and silica liquids, rather than individual random walk, atoms are encaged in molecular units (such as the SiO4 tetrahedra in liquid silica[1]) which, in a collective motion manner, reduce dramatically the atomic mobility.[2] These local structural units thus account for the excellent glass-forming ability of the liquids, and remain as the building blocks of polymer and silica glasses.[2, 3] Analogously, metallic glasses also exhibit signs of local structure units such as short range orders (SROs) (or solute-centered atomic clusters), as proposed in recent works of structural modeling and computer simulation.[4-6] However, there is a lack of key experimental determination of local atomic structure in metallic glasses, and the correlation between local atomic packing with glass-forming ability has yet to be demonstrated experimentally over the years. In this work, we have probed local atomic structure of metallic glasses using time-of-flight neutron and synchrotron X-ray diffraction techniques with high resolution. Our results provide evidence for a new scheme of efficient local atomic packing where atomic clustersmore » encompass multiple types of atoms in the first coordination shell. We also demonstrate the first experimental evidence of a clear correlation between the number of unlike atom bonds and the glass-forming ability. Our findings have important implications for understanding atomic structure of metallic glasses, liquids and other disordered materials, and may provide insights into a broad range of scientific problems where efficient space filling by packing spheres is essential.« less