Atomistic computation of liquid diffusivity, solid-liquid interfacial free energy, and kinetic coefficient in Au and Ag
Atomistic computation of liquid diffusivity, solid-liquid interfacial free energy, and kinetic coefficient in Au and Ag
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DOI：
10.1103/physrevb.65.214106
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发表时间：
2002-06-01
影响因子：
3.7
通讯作者：
Asta, M
中科院分区：
文献类型：
--
作者：
Hoyt, JJ;Asta, M
使用嵌入原子方法的原子间势对纯银和金进行了分子动力学模拟，以计算枝晶凝固连续介质建模所需的材料参数。已经确定了熔点附近温度的液态扩散系数，并且发现与 Ag 的实验数据非常吻合。 Au 和 Ag 的动力学系数是通过监测固液界面速度随过冷度的变化而确定的。 100 和 110 方向的结晶速率与 Broughton、Gilmer 和 Jackson [Phys.莱特牧师。 49, 1496 (1982)] 而 111 方向表现出较慢的生长速率，这与固液边界上堆垛层错簇的存在一致，堆垛层错簇在凝固过程中退火。通过监测界面位置的平衡波动，获得了Ag和Au的固液界面自由能及其各向异性。波动谱技术可以准确测定界面能量中非常小的各向异性，我们发现 Ag 的各向异性因子为 1.0+/-0.3%，Au 的各向异性因子为 1.6+/-0.3%。
Molecular-dynamics simulations using interatomic potentials of the embedded atom method have been performed on pure Ag and Au to compute materials parameters which are necessary for continuum modeling of dendritic solidification. The liquid state diffusion coefficient has been determined for temperatures in the vicinity of the melting points and good agreement with experimental data available for Ag is found. The kinetic coefficients for Au and Ag have been determined by monitoring the velocity of the solid-liquid interface as a function of undercooling. Rates of crystallization for the 100 and 110 directions agree well with a model proposed by Broughton, Gilmer and Jackson [Phys. Rev. Lett. 49, 1496 (1982)] whereas the 111 direction exhibits a slower growth rate consistent with the presence of stacking fault clusters on the solid-liquid boundary, which anneal out during solidification. The solid-liquid interfacial free energy and its anisotropy have been obtained for Ag and Au by monitoring equilibrium fluctuations in the interface position. The fluctuation spectrum technique allows for an accurate determination of very small anisotropies in the interfacial energy and we find an anisotropy factor 1.0+/-0.3% for Ag and 1.6+/-0.3% for Au.