Solidification fronts in supercooled liquids: How rapid fronts can lead to disordered glassy solids
Solidification fronts in supercooled liquids: How rapid fronts can lead to disordered glassy solids
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DOI：
10.1103/physreve.86.031603
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发表时间：
2012-09-21
影响因子：
2.4
通讯作者：
Knobloch, E.
中科院分区：
文献类型：
--
作者：
Archer, A. J.;Robbins, M. J.;Knobloch, E.
我们确定的速度结晶（或，更一般地说，固化）前，因为它前进到均匀的液相后，系统已淬火到结晶区的相图。我们通过假设系统的动态密度泛函理论（DDFT）模型和应用边际稳定性准则来计算前速度。我们的研究结果也适用于相场晶体（PFC）凝固模型。随着凝固前沿进入不稳定液相，前沿后面的密度分布产生密度调制，并且这些调制的波长是动态选择的量。对于浅猝灭，所选择的波长恰好是晶相的波长，因此形成了良好有序的晶态。然而，当系统被深度淬火时，我们发现这个波长可以与晶体的波长有很大的不同，因此凝固前沿自然会在系统中产生无序。随后必须发生显着的重排和老化的系统，以形成规则的有序晶体，对应于自由能最小值。每当一个锋从随机的初始条件发展起来时，就会引入额外的无序。我们用PFC模型得到的模拟结果来说明这些发现。
We determine the speed of a crystallization (or, more generally, a solidification) front as it advances into the uniform liquid phase after the system has been quenched into the crystalline region of the phase diagram. We calculate the front speed by assuming a dynamical density functional theory (DDFT) model for the system and applying a marginal stability criterion. Our results also apply to phase field crystal (PFC) models of solidification. As the solidification front advances into the unstable liquid phase, the density profile behind the advancing front develops density modulations and the wavelength of these modulations is a dynamically chosen quantity. For shallow quenches, the selected wavelength is precisely that of the crystalline phase and so well-ordered crystalline states are formed. However, when the system is deeply quenched, we find that this wavelength can be quite different from that of the crystal, so the solidification front naturally generates disorder in the system. Significant rearrangement and aging must subsequently occur for the system to form the regular well-ordered crystal that corresponds to the free energy minimum. Additional disorder is introduced whenever a front develops from random initial conditions. We illustrate these findings with simulation results obtained using the PFC model.