Structural signature in Au-based amorphous alloys
Structural signature in Au-based amorphous alloys
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DOI：
10.1016/j.actamat.2017.08.020
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发表时间：
2017-11
期刊：
影响因子：
9.4
通讯作者：
S. Khan;X. D. Wang;Q. Cao;D. X. Zhang;J. Jiang
中科院分区：
文献类型：
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作者：
S. Khan;X. D. Wang;Q. Cao;D. X. Zhang;J. Jiang
本文阐明了au55cu25si20非晶合金（AA）结构因子第一个主峰左侧的异常肩是由aus单键dau键的填充引起的，而第一个主峰主要是由aus单键dau、aus单键cu和aus单键si键的贡献引起的。这种玻璃的局部原子填充主要由9、10和11个配位多面体组成，而不是像二十面体一样的团簇，其中小的团簇倾向于相互避开，大的团簇倾向于相互连接。这种异常的原子堆积结构限制了其玻璃化形成能力，并导致结构因子第一峰的异常肩。用5个at替换。结果表明，当Cu原子被Ag原子取代时，Au55Cu20Ag5Si20AA中的空间连通性和原子堆积密度大大增加，从而使原子结构均匀化，至少达到第二近邻，从而抑制了竞争性晶状核的几何结构，从而增强了GFA。这项工作说明了元素取代如何改变金基玻璃中的原子填充，并从原子尺度上理解高GFA，从而开发具有更大临界尺寸的新型原子吸收剂。
Here we elucidated that the anomalous shoulder at the left side of first main peak in structural factor is resulted from packing of Ausingle bondAu bonds in the Au55Cu25Si20amorphous alloy (AA), while the first main peak is largely from contributions of Ausingle bondAu, Ausingle bondCu and Ausingle bondSi bonds. Local atomic packing of this glass is mainly composed of 9, 10 and 11-coordinated polyhedra rather than icosahedral-like clusters, in which the small sized clusters prefer avoiding each other while large ones prefer connecting themselves. This anomalous atomic packing structure limits its glass forming ability (GFA) and results in the anomalous shoulder of the first peak in structural factor. With the replacement of 5 at.% Cu atoms by Ag atoms, the spatial connectivity and the atomic packing density in Au55Cu20Ag5Si20AA are largely increased, which homogenize atomic structures at least up to the second nearest neighbors and frustrate the geometry of competing crystalline-like nuclei, consequently, enhancing the GFA, as observed in experiments. This work illustrates how the atomic packing in an Au-based glass is altered by element substitution and sheds new insights to understanding of high GFA from the atomic scale and thus developing novel AAs with larger critical sizes.