Ames Laboratory, U.S. Department of Energy, Ames, Iowa 50011, USA.
Department of Physics, Iowa State University, Ames, Iowa 50011, USA.
Phys Rev Lett. 2018 Feb 23;120(8):085703. doi: 10.1103/PhysRevLett.120.085703.
The crystal nucleation from liquid in most cases is too rare to be accessed within the limited time scales of the conventional molecular dynamics (MD) simulation. Here, we developed a "persistent embryo" method to facilitate crystal nucleation in MD simulations by preventing small crystal embryos from melting using external spring forces. We applied this method to the pure Ni case for a moderate undercooling where no nucleation can be observed in the conventional MD simulation, and obtained nucleation rate in good agreement with the experimental data. Moreover, the method is applied to simulate an even more sluggish event: the nucleation of the B2 phase in a strong glass-forming Cu-Zr alloy. The nucleation rate was found to be 8 orders of magnitude smaller than Ni at the same undercooling, which well explains the good glass formability of the alloy. Thus, our work opens a new avenue to study solidification under realistic experimental conditions via atomistic computer simulation.
在大多数情况下，从液体中结晶的晶核非常罕见，以至于在传统的分子动力学（MD）模拟的有限时间尺度内无法观察到。在这里，我们开发了一种“持久晶核”方法，通过使用外部弹簧力防止小晶体晶核熔化，从而促进 MD 模拟中的晶体成核。我们将该方法应用于纯 Ni 的情况，该情况具有适度的过冷度，在传统的 MD 模拟中观察不到成核，并且获得的成核率与实验数据吻合良好。此外，该方法还可用于模拟更缓慢的事件：强玻璃形成 Cu-Zr 合金中 B2 相的成核。在相同过冷度下，成核率比 Ni 小 8 个数量级，这很好地解释了合金良好的玻璃形成能力。因此，我们的工作为通过原子计算机模拟在实际实验条件下研究凝固开辟了新途径。
