Huang Xiaoxu, Hansen Niels, Tsuji Nobuhiro
Center for Fundamental Research: Metal Structures in Four Dimensions, Materials Research Department, Risø National Laboratory, DK 4000 Roskilde, Denmark.
Science. 2006 Apr 14;312(5771):249-51. doi: 10.1126/science.1124268.
We observe that a nanostructured metal can be hardened by annealing and softened when subsequently deformed, which is in contrast to the typical behavior of a metal. Microstructural investigation points to an effect of the structural scale on fundamental mechanisms of dislocation-dislocation and dislocation-interface reactions, such that heat treatment reduces the generation and interaction of dislocations, leading to an increase in strength and a reduction in ductility. A subsequent deformation step may restore the dislocation structure and facilitate the yielding process when the metal is stressed. As a consequence, the strength decreases and the ductility increases. These observations suggest that for materials such as the nanostructured aluminum studied here, deformation should be used as an optimizing procedure instead of annealing.
我们观察到，纳米结构金属可通过退火硬化，而在随后变形时会软化，这与金属的典型行为相反。微观结构研究表明结构尺度对位错-位错和位错-界面反应的基本机制有影响，即热处理会减少位错的产生和相互作用，导致强度增加和延展性降低。随后的变形步骤可能会恢复位错结构，并在金属受力时促进屈服过程。因此，强度降低而延展性增加。这些观察结果表明，对于此处研究的纳米结构铝等材料，应将变形用作优化工艺而非退火。
