Grain rotation mediated by grain boundary dislocations in nanocrystalline platinum

作者：Lihua Wang, Jiao Teng, Pan Liu, Akihiko Hirata, Evan Ma, Ze Zhang, Mingwei W. Chen, Xiaodong Han · 发表于：Nature Communications · 年份：2014 · DOI：10.1038/ncomms5402 · 被引用次数：444 · 研究领域：Microstructure and mechanical properties、Advanced materials and composites、Ion-surface interactions and analysis

Grain rotation is a well-known phenomenon during high (homologous) temperature deformation and recrystallization of polycrystalline materials. In recent years, grain rotation has also been proposed as a plasticity mechanism at low temperatures (for example, room temperature for metals), especially for nanocrystalline grains with diameter d less than ~15 nm. Here, in tensile-loaded Pt thin films under a high-resolution transmission electron microscope, we show that the plasticity mechanism transitions from cross-grain dislocation glide in larger grains (d>6 nm) to a mode of coordinated rotation of multiple grains for grains with d<6 nm. The mechanism underlying the grain rotation is dislocation climb at the grain boundary, rather than grain boundary sliding or diffusional creep. Our atomic-scale images demonstrate directly that the evolution of the misorientation angle between neighbouring grains can be quantitatively accounted for by the change of the Frank-Bilby dislocation content in the grain boundary.