Formation of two glass phases in binary Cu-Ag liquid
Formation of two glass phases in binary Cu-Ag liquid
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DOI：
10.1016/j.actamat.2020.05.060
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发表时间：
2020-08-15
期刊：
影响因子：
9.4
通讯作者：
Goddard, William A., III
中科院分区：
文献类型：
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作者：
An, Qi;Johnson, William L.;Goddard, William A., III
玻璃化转变可以被描述为动态转变，其中存在动力学的急剧减慢，或者作为热力学相变。为了研究易碎Cu-Ag液体玻璃化转变的物理起源，我们对32,000至2,048,000个原子的系统进行了分子动力学（MD）模拟。令人惊讶的是，我们发现了从液体(L)到亚稳异质类固体相的一级冻结转变，表示为g -玻璃，当过冷液体在深度过冷时低于其熔化温度等温演变。相比之下，当液体以10(11)K/秒的快速冷却速率连续淬火至室温时，可以获得更均匀的液体状玻璃，称为l -玻璃。我们报道了L-G跃迁的热力学描述，并表征了g玻璃中异质结构的相关长度。g-玻璃的剪切模量明显高于l -玻璃，表明一阶L-G跃迁与g-玻璃中涉及基本构型激发的长程弹性有根本联系。(C) 2020材料学报Elsevier Ltd.出版。版权所有。
The glass transition is alternatively described as either a dynamic transition in which there is a dramatic slowing down of the kinetics, or as a thermodynamic phase transition. To examine the physical origin of the glass transition in fragile Cu-Ag liquids, we employed molecular dynamics (MD) simulations on systems in the range of 32,000 to 2,048,000 atoms. Surprisingly, we identified a 1st order freezing transition from liquid (L) to metastable heterogenous solid-like phase, denoted as the G-glass, when a supercooled liquid evolves isothermally below its melting temperature at deep undercooling. In contrast, a more homogenous liquidlike glass, denoted as the L-glass, is achieved when the liquid is quenched continuously to room temperature with a fast cooling rate of similar to 10(11) K/sec. We report a thermodynamic description of the L-G transition and characterize the correlation length of the heterogenous structure in the G-glass. The shear modulus of the G-glass is significantly higher than the L-glass, suggesting that the first order L-G transition is linked fundamentally to long-range elasticity involving elementary configurational excitations in the G-glass. (C) 2020 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.