Simulation of nuclei morphologies for binary alloy
Simulation of nuclei morphologies for binary alloy
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DOI：
10.1007/s11425-010-4019-2
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发表时间：
2010-07
期刊：
影响因子：
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通讯作者：
Daming Li;Pingwen Zhang
中科院分区：
文献类型：
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作者：
Daming Li;Pingwen Zhang
我们用弦方法研究了二元合金的临界形核形态。在给定的温度下，连接亚稳态相(液体)和稳定相(固体)的弦的动力学方程由二元合金系统的亥姆霍兹自由能所支配。如果弦的松弛时间足够大，则得到通过临界核(鞍点)的定常弦。计算了具有各向同性界面能的纯合金二维和三维形核的临界形核半径和形核能垒，与经典形核理论相一致。临界形核形态对合金的界面能各向异性强度和界面厚度在二维和三维方向上都很敏感。随着界面能各向异性强度的增加，形核的临界核和成核势垒变小，这意味着如果考虑界面能的各向异性，则更容易形成稳定的核。
We study the critical nuclei morphologies of a binary alloy by the string method. The dynamic equation of the string, connecting the metastable phase (liquid) and stable phase (solid), is governed by Helmholtz free energy for the binary alloy system at a given temperature. The stationary string through the critical nucleus (saddle point) is obtained if the relaxation time of the string is sufficiently large. The critical nucleus radius and energy barrier to nucleation of a pure alloy with isotropic interface energy in two and three dimensions are calculated, which are consistent with the classical nucleation theory. The critical nuclei morphologies are sensitive to the anisotropy strength of interface energy and interface thickness of alloy in two and three dimensions. The critical nucleus and energy barrier to nucleation become smaller if the anisotropy strength of the interface energy is increased, which means that it is much easier to form a stable nucleus if the anisotropy of the interface energy is considered.