Observation of giant diffusivity along dislocation cores
Observation of giant diffusivity along dislocation cores
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DOI：
10.1126/science.1151771
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发表时间：
2008-03-21
期刊：
影响因子：
56.9
通讯作者：
Balk, T. John
中科院分区：
文献类型：
--
作者：
Legros, Marc;Dehm, Gerhard;Balk, T. John
原子在晶格中的扩散是一个热激活过程，可以通过诸如晶界或位错的缺陷来强烈加速。当由位错携带时，这种基本机制被称为“管道扩散”。管道扩散已被用来解释蠕变过程中的异常扩散、科特雷尔气氛和位错-沉淀物相互作用，尽管这更多地依赖于推测而不是直接证明。最近，通过原位透射电子显微镜观察和控制铝薄膜中硅纳米沉淀物之间的位错运动。我们观察到了管道扩散现象，并测量了沿着单个位错线的扩散率。它被发现，位错加速扩散的杂质的近三个数量级相比，体扩散。
Diffusion of atoms in a crystalline lattice is a thermally activated process that can be strongly accelerated by defects such as grain boundaries or dislocations. When carried by dislocations, this elemental mechanism is known as "pipe diffusion." Pipe diffusion has been used to explain abnormal diffusion, Cottrell atmospheres, and dislocation- precipitate interactions during creep, although this rests more on conjecture than on direct demonstration. The motion of dislocations between silicon nanoprecipitates in an aluminum thin film was recently observed and controlled via in situ transmission electron microscopy. We observed the pipe diffusion phenomenon and measured the diffusivity along a single dislocation line. It is found that dislocations accelerate the diffusion of impurities by almost three orders of magnitude as compared with bulk diffusion.