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Mechanism of fast diffusion of substitutional solute atoms in FCC crystals

机译：FCC晶体中置换溶质原子快速扩散的机理

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In the alloy systems of face-centred cube (FCC) structure, the diffusivities of some solute atoms are several orders of magnitude more than those of the matrix atoms, such as Au and Ag in Pb, S in Ni, as well as B in gamma-Fe. Many people think that these solute atoms with anomalously fast diffusivities diffuse as interstitial atoms. So far this theory has been widely used. For example, the latest edition of Metal Reference Book says, about diffusion in metals, that some solutes "may dissolve interstitially, at least in part, and diffuse by an interstitial-type process, This belief stems from the very large anomalous diffusion rates of solutes in these solvents". In another new book about diffusion, the "interstitial diffusion in substitutional alloys" is even taken as a title of a chapter in which the anomalously fast diffusion is discussed. However, if we take a quantitative discussion in the above alloys, we would find that the diffusivities calculated by interstitial diffusion disagree not onlywith the orders of magnitude but also with some experimental results. In this note, complex diffusion mechanism (CDM) is used to explain this phenomenon, which has recently been used to explain the non-equilibrium segregation. Hereinafter it is used tocalculate the diffusion activation energies and diffusion coefficients for all of the substitutional solute atoms with anomalously fast diffusion as known so far. The theoretical results agree very well with the experimental ones.
机译：在面心立方（FCC）结构的合金系统中，某些溶质原子的扩散率比基体原子的扩散率高几个数量级，例如Pb中的Au和Ag，Ni中的S和Ni中的B。 γ-铁。许多人认为具有异常快速扩散性的这些溶质原子会以间隙原子的形式扩散。到目前为止，该理论已被广泛使用。例如，最新版的《金属参考书》说到金属中的扩散，某些溶质“可能至少部分地溶解于间隙中，并通过填隙型过程扩散。这种信念源于极大的异常扩散速率”。这些溶剂中的溶质”。在另一本有关扩散的新书中，“替代合金中的间隙扩散”甚至被用作讨论异常快速扩散的一章的标题。但是，如果我们对上述合金进行定量讨论，我们会发现，通过间隙扩散计算出的扩散率不仅与数量级不一致，而且与一些实验结果不一致。在本说明中，复杂扩散机制（CDM）用于解释此现象，最近已将其用于解释非平衡偏析。在下文中，它被用来计算到目前为止已知的具有异常快速扩散的所有取代溶质原子的扩散活化能和扩散系数。理论结果与实验结果非常吻合。

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