On the Theory of Vacancy Diffusion in Alloys
On the Theory of Vacancy Diffusion in Alloys
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合金中空位扩散理论
DOI：
10.1103/physrev.74.1513
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发表时间：
1948
期刊：
影响因子：
--
通讯作者：
F. Seitz
中科院分区：
文献类型：
--
作者：
F. Seitz
本文以晶格空位迁移为基础，讨论了合金中的扩散理论，试图解释Wa Johnson关于金银合金中扩散的实验。假设晶格网络在扩散过程中保持其一致性，即使存在通过任何区域的合成空位电流。还假设晶格中存在两种类型的原子，分别称为A原子和B原子。扩散系数用函数p(n a 1，n a 2)表示，给出了从一个原子平面(表示为平面2)跳到相邻平面(表示为平面1)的空位与A原子互换位置的概率，如果平面1的单位面积上有n个A原子，平面2中有n个a 2 A原子。我们发现，如果放射性示踪剂的扩散系数在没有化学梯度的情况下迁移，则化学扩散系数与函数p的关系与放射性示踪剂的扩散系数的关系是完全不同的。采用复杂性增加的模型来推导函数p的显式表达式。结果发现，Johnson的实验只能用比通常使用的模型更复杂的模型来解释。用空位扩散理论解释了Smielskas和Kirkendall关于铜与黄铜界面上基准标记物在扩散过程中相对位移的实验。提出了一种可以为空位扩散提供绝对检验的实验。
The theory of diffusion in alloys is discussed on the basis of the migration of lattice vacancies in an attempt to interpret the experiments of WA Johnson on diffusion in gold-silver alloys. It is assumed that the lattice network preserves its identity during the diffusion even though there is a resultant vacancy current passing through any region. It is also assumed that two types of atom, designated as A and B atoms, are present in the lattice. The diffusion coefficients are expressed in terms of a function p (n a 1, n a 2) giving the probability that a vacancy in jumping from one atomic plane (designated as plane 2) to a neighboring plane (designated as plane 1) will interchange places with an A atom if there are n a 1 A atoms per unit area of plane 1 and n a 2 A atoms in plane 2. It is found that the chemical diffusion coefficient is related to the function p in a very different way from the diffusion coefficients for radioactive tracers if the latter migrate when no chemical gradient is present. Models of increasing complexity are employed to derive explicit expressions for the function p. It is found that Johnson's experiments can be explained only with the use of models that are more complex than those commonly used. The theory of vacancy diffusion is also employed to interpret the experiments of Smigelskas and Kirkendall concerning the relative displacement during diffusion of fiducial markers placed at the interface between copper and brass. An experiment which could provide an absolute test for vacancy diffusion is proposed.