nn7b06605_si_001.pdf (1.17 MB)
Mechanically Driven Grain Boundary Formation in Nickel Nanowires
journal contribution
posted on 2017-11-13, 00:00 authored by Lihua Wang, Deli Kong, Yin Zhang, Lirong Xiao, Yan Lu, Zhigang Chen, Ze Zhang, Jin Zou, Ting Zhu, Xiaodong HanMetallic nanomaterials are widely
used in micro/nanodevices. However,
the mechanically driven microstructure evolution in these nanomaterials
is not clearly understood, particularly when large stress and strain
gradients are present. Here, we report the in situ bending experiment of Ni nanowires containing nanoscale twin lamellae
using high-resolution transmission electron microscopy. We found that
the large, localized bending deformation of Ni nanowires initially
resulted in the formation of a low-angle tilt grain boundary (GB),
consisting of randomly distributed dislocations in a diffuse GB layer.
Further bending intensified the local plastic deformation and thus
led to the severe distortion and collapse of local lattice domains
in the GB region, thereby transforming a low-angle GB to a high-angle
GB. Atomistic simulations, coupled with in situ atomic-scale
imaging, unravelled the roles of bending-induced strain gradients
and associated geometrically necessary dislocations in GB formation.
These results offer a valuable understanding of the mechanically driven
microstructure changes in metallic nanomaterials through GB formation.
The work also has implications for refining the grains in bulk nanocrystalline
materials.