Department of Mechanical and Industrial Engineering, Ryerson University, Toronto, Ontario, CanadaM5B 2K3.
Phys Chem Chem Phys. 2010 Nov 7;12(41):13835-48. doi: 10.1039/c0cp00781a. Epub 2010 Sep 20.
In this paper following the linear non-equilibrium thermodynamics approach, an expression is derived for the calculation of the thermodiffusion factor in binary liquid metal alloys. The expression is comprised of two terms; the first term accounts for the thermally driven interactions between metal ions, a phenomenon similar to that of the non-ionic binary mixtures, such as hydrocarbons; the second term is called the electronic contribution and is the mass diffusion due to an internal electric field that is induced as a result of the imposed thermal gradient. Both terms are formulated as functions of the net heats of transport. The ion-ion net heat of transport is simulated by the activation energy of viscous flow and the electronic net heat of transport is correlated with the force acting on the ions by the rearrangement of the conduction electrons and ions. A methodology is presented and used to estimate the liquid metal properties, such as the partial molar internal energies, enthalpies, volumes and the activity coefficients used for model validation. The prediction power of the proposed expression along with some other existing thermodiffusion models for liquid mixtures, such as the Haase, Kempers, Drickamer and Firoozabadi formulas are examined against available experimental data obtained on ground or in microgravity environment. The proposed model satisfactorily predicts the thermodiffusion data of mixtures that are composed of elements with comparable melting points. It is also potentially and qualitatively able to predict a sign change in thermodiffusion factor of Na-K liquid mixture. With some speculation, the sign change is attributed to an anomalous change in thermoelectric power of Na-K mixture with composition.
本文采用线性非平衡热力学方法，推导出了计算二元液态金属合金热扩散系数的表达式。该表达式由两项组成：第一项是金属离子间热驱动相互作用的表达式，这一现象类似于非离子二元混合物，如碳氢化合物；第二项称为电子贡献项，是由于热梯度引起的内部电场引起的质量扩散。这两项都被表示为输运净热的函数。离子-离子输运净热通过粘性流动的活化能来模拟，而电子输运净热与传导电子和离子重新排列对离子作用的力相关联。提出了一种方法，并用于估计液态金属的性质，如偏摩尔内能、焓、体积和用于模型验证的活度系数。提出的表达式与其他一些现有的液态混合物热扩散模型（如 Haase、Kempers、Drickamer 和 Firoozabadi 公式）的预测能力，与地面或微重力环境下获得的实验数据进行了比较。该模型对由熔点相近的元素组成的混合物的热扩散数据进行了满意的预测。它也有可能定性地预测 Na-K 液态混合物的热扩散系数符号发生变化。根据一些推测，这种符号变化归因于 Na-K 混合物的热电势随成分的异常变化。
