We examine vacancy-assisted diffusion in the 57 random, equimolar alloys that can be formed from Cu, Ag, Au, Ni, Pd, and Pt based on the well-tested embedded atom method functions of Foiles, Baskes, and Daw [Phys. Rev. B 33, 7983 (1986)]. We address the suggestion [Yeh et al., Adv. Eng. Mater. 6, 299 (2004)] that increasing the number of constituents causes diffusion to be “sluggish” in random, equimolar alloys. Using molecular dynamics (MD) simulations of random alloys with a single vacancy, combined with calculations of vacancy formation, we extract vacancy-assisted diffusivities in each alloy. After developing and applying several possible criteria for evaluating “sluggishness,” we find that only a small minority (from 1 to 8, depending on how sluggishness is defined) of the alloys exhibit sluggish diffusion whereas in the large majority of alloys diffusion is faster and in quite a few cases ought to be considered vigorous (that is, faster than in any of the constituents). We correlate diffusivity with a combination of the mean of the constituent diffusivity and a simple function of lattice mismatch. We conclude that simply increasing the number of constituents in such alloys does not systematically alter the diffusion, but that instead lattice mismatch plays a primary factor; sluggish diffusion is more likely to occur in a window of small lattice mismatch (1–3%) even in binary alloys. Quantitatively, our calculated diffusivities correlate with a combination of (1) rule of mixtures of the diffusivities of the constituents, and (2) a simple function of the lattice mismatch; this accounts for the large majority of our calculated diffusivities to within a factor of 2 (over a range of three orders of magnitude). We also find that while lattice mismatch on the order of 1–3% is necessary for sluggish diffusion, it is not sufficient.

中文翻译：

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随机等摩尔FCC合金中的扩散缓慢

我们基于经过充分测试的Foiles，Baskes和Daw [Phys。Phys.Lett。，1991，5，3，5，6]的嵌入原子方法功能，研究了由Cu，Ag，Au，Ni，Pd和Pt形成的57种无规，等摩尔合金中的空位辅助扩散。版本B 33，7983（1986）]。我们解决了这个建议[Yeh等。，高级 。母校 6，299（2004）]认为增加成分的数量会使扩散在无规等摩尔合金中“缓慢”进行。使用具有单个空位的随机合金的分子动力学（MD）模拟，并结合空位形成的计算，我们提取了每种合金中的空位辅助扩散系数。在制定并应用了几种评估“迟滞”的可能标准后，我们​​发现只有一小部分（从1到8，取决于迟缓的定义）合金表现出缓慢的扩散，而大多数合金的扩散更快且在相当多的情况下，应该被认为是有力的（也就是说，比任何成分都快）。我们将扩散系数与组成扩散系数的平均值和晶格失配的简单函数相结合。没有系统地改变扩散，而是晶格失配是主要因素；即使在二元合金中，小晶格失配（1-3％）的窗口中也更容易发生缓慢的扩散。从数量上讲，我们计算出的扩散率与以下各项的组合相关：（1）成分扩散率的混合规则，以及（2）晶格失配的简单函数；这占我们计算出的大部分扩散系数的2倍以内（在三个数量级的范围内）。我们还发现，尽管对于缓慢的扩散而言，晶格失配在1-3％左右是必要的，但这还不够。