Interatomic repulsion softness directly controls the fragility of supercooled metallic melts
Interatomic repulsion softness directly controls the fragility of supercooled metallic melts
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DOI：
10.1073/pnas.1503741112
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发表时间：
2015-11-10
影响因子：
11.1
通讯作者：
Zaccone, Alessio
中科院分区：
文献类型：
--
作者：
Krausser, Johannes;Samwer, Konrad H.;Zaccone, Alessio
我们提出了一种分析方案，将金属玻璃的脆性和粘弹性与金属中的有效离子-离子相互作用联系起来。这是通过对相互作用的短程排斥部分进行近似，结合非仿射晶格动力学来获得离子-离子相互作用的剪切模量、粘度和脆性的解析表达式来实现的。通过将理论模型与实验数据进行拟合，我们能够将离子间斥力的陡度与托马斯-费米屏蔽库仑斥力和各种合金的玻恩-迈耶价电子重叠斥力联系起来。结果是根据几个关键的原子尺度相互作用和非谐参数，对过冷液态金属的脆性进行了简单的封闭式表达。特别是，在脆性与屏蔽库仑和电子重叠排斥的能量尺度之间发现了线性关系。这种关系为通过根据一般原理合理调整合金的化学成分来制造具有定制热弹性和脆性的合金提供了机会。这里提出的分析提供了一种新的方式来研究金属和准金属的外壳电子结构与其粘弹性和脆性之间的联系。
We present an analytic scheme to connect the fragility and visco-elasticity of metallic glasses to the effective ion-ion interaction in the metal. This is achieved by an approximation of the short-range repulsive part of the interaction, combined with nonaffine lattice dynamics to obtain analytical expressions for the shear modulus, viscosity, and fragility in terms of the ion-ion interaction. By fitting the theoretical model to experimental data, we are able to link the steepness of the interionic repulsion to the Thomas-Fermi screened Coulomb repulsion and to the Born-Mayer valence electron overlap repulsion for various alloys. The result is a simple closed-form expression for the fragility of the supercooled liquid metal in terms of few crucial atomic-scale interaction and anharmonicity parameters. In particular, a linear relationship is found between the fragility and the energy scales of both the screened Coulomb and the electron overlap repulsions. This relationship opens up opportunities to fabricate alloys with tailored thermoelasticity and fragility by rationally tuning the chemical composition of the alloy according to general principles. The analysis presented here brings a new way of looking at the link between the outer shell electronic structure of metals and metalloids and the viscoelasticity and fragility thereof.