Institut für Festkörperforschung, Forschungszentrum Jülich GmbH, D-52425 Jülich, Germany.
Nat Mater. 2010 Apr;9(4):332-6. doi: 10.1038/nmat2713. Epub 2010 Feb 28.
In simple crystalline materials, plastic deformation mostly takes place by the movement of dislocations. Although the underlying mechanisms in these materials are well explored, in complex metallic alloys--crystalline solids containing up to thousands of atoms per unit cell--the defects and deformation mechanisms remain essentially unknown. Owing to the large lattice parameters of these materials, extended dislocation concepts are required. We investigated a typical complex metallic alloy with 156 atoms per unit cell using atomic-resolution aberration-corrected transmission electron microscopy. We found a highly complex deformation mechanism, based on the movement of a dislocation core mediating strain and separate escort defects. On deformation, the escort defects move along with the dislocation core and locally transform the material structure for the latter. This mechanism implies the coordinated movement of hundreds of atoms per elementary glide step, and nevertheless can be described by simple rearrangement of basic structural subunits.
在简单的晶体材料中，塑性变形主要通过位错的移动来实现。尽管这些材料的潜在机制已经得到了很好的研究，但在复杂的金属合金中——每个晶胞包含多达数千个原子的晶体固体——缺陷和变形机制仍然基本未知。由于这些材料的晶格参数较大，需要扩展位错的概念。我们使用原子分辨率的像差校正透射电子显微镜研究了一个典型的具有 156 个原子/单位胞的复杂金属合金。我们发现了一种高度复杂的变形机制，其基础是位错核心介导应变和单独的护送缺陷的运动。在变形过程中，护送缺陷与位错核心一起移动，并为后者局部改变材料结构。这种机制意味着每一个基本的滑移步骤都有数百个原子的协调运动，但仍然可以通过基本结构亚单位的简单重排来描述。
