High-Precision Nucleation Rate Measurements for Higher Melting Metals
High-Precision Nucleation Rate Measurements for Higher Melting Metals
复制标题
高熔点金属的高精度成核率测量
DOI：
10.1007/s11837-014-1027-7
复制
发表时间：
2014
期刊：
影响因子：
2.6
通讯作者：
G. Wilde
中科院分区：
文献类型：
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作者：
Joachim Bokeloh;G. Wilde
在高熔点面心立方金属过冷熔体中，晶体的成核问题在过去经常被研究。然而，现有的数据不够精确，而且只涵盖了很小范围内的成核率，无法对基本过程的性质以及原则上可以从这种分析中扣除的固液界面自由能等重要参数作出精确的结论。在实验条件良好的条件下，通过进行统计上显著数量的重复单液滴实验，可以避免歧义并分析成核动力学。应用适当的统计分析可以得到独立于特定成核模型的成核速率。根据这种方法对纯模型材料进行的第一次研究表明，这种方法是有效的。结果与应用于实验数据的经典形核理论得到的结果相当，并且表明人们可能需要重新考虑非均相形核几乎总是导致凝固开始的共同假设。目前的结果还表明，常用的固液界面自由能模型可能会导致高估的值。
Nucleation of a crystal in undercooled melts of higher melting face-centered-cubic-metals has often been studied in the past. However, the data available were not of sufficient accuracy and only covered nucleation rates in too small of a range to allow precise conclusions concerning the nature of the underlying process as well as concerning important parameters such as the solid–liquid interface free energy that can in principle be deducted from such analyses. One way to circumvent ambiguities and analyze nucleation kinetics under well-defined conditions experimentally is given by performing statistically significant numbers of repeated single droplet experiments. Application of proper statistics analyses yields nucleation rates that are independent of a specific nucleation model. The first studies that were conducted in accordance with this approach on pure model materials revealed that the approach is valid. The results are comparable to those obtained by classic nucleation theory applied to experimental data, and it was shown that one might need to rethink the common assumption that heterogeneous nucleation is almost always responsible for solidification initiation. The current results also show that often-used models for the solid–liquid interface free energy might lead to overestimated values.