Shan Zhiwei, Knapp J A, Follstaedt D M, Stach E A, Wiezorek J M K, Mao S X
Department of Mechanical Engineering and Materials Science, University of Pittsburgh, Pittsburgh, Pennsylvania 15261, USA.
Phys Rev Lett. 2008 Mar 14;100(10):105502. doi: 10.1103/PhysRevLett.100.105502. Epub 2008 Mar 12.
In situ tensile straining transmission electron microscopy tests have been carried out on nanocrystalline Ni. Grain agglomerates (GAs) were found to form very frequently and rapidly ahead of an advancing crack with sizes much larger than the initial average grain size. High-resolution electron microscopy indicated that the GAs most probably consist of nanograins separated by low-angle grain boundaries. Furthermore, both inter- and intra-GA fractures were observed. The observations suggest that these newly formed GAs may play an important role in the formation of the dimpled fracture surfaces of nanocrystalline materials.
已对纳米晶镍进行了原位拉伸应变透射电子显微镜测试。发现晶粒团聚体（GAs）在扩展裂纹前方非常频繁且迅速地形成，其尺寸远大于初始平均晶粒尺寸。高分辨率电子显微镜表明，这些晶粒团聚体很可能由被低角度晶界分隔的纳米晶粒组成。此外，还观察到了晶粒团聚体之间和内部的断裂。这些观察结果表明，这些新形成的晶粒团聚体可能在纳米晶材料的韧窝断裂表面形成过程中起重要作用。
