Abstract
Shear stress driven grain boundary (GB) migration was found to be a ubiquitous phenomenon in small grained polycrystalline materials. Here we show that the GB displacement shift complete (DSC) dislocation mechanism for GB shear coupled migration is still functioning even if the geometry orientation of the GBs deviates a few degrees from the appropriate coincidence site lattice (CSL) GBs. It means that any large angle GB can have a considerable chance to be such a “CSL-related GB” for which the shear coupled GB migration motion can happen by the GB DSC dislocation mechanism. We conclude that the CSL-DSC bi-crystallographic lattice structure in GB is the main reason that GB can migrate under shear stress.
Highlights
Shear stress driven grain boundary (GB) migration was found to be a ubiquitous phenomenon in small grained polycrystalline materials
The grain growth in these circumstances has been proved to be largely attributed to the GB migration motion under shear stress[7]
The magic of the coincidence site lattice (CSL)-displacement shift complete (DSC) lattice lies in the fact that, in a crystallographic sense, GBs can migrate by shear stress as long as the atoms in GB move according to a set of displacement vectors which connect the lattice sites of the neighboring grains in the GB zone correspondingly
Summary
Shear stress driven grain boundary (GB) migration was found to be a ubiquitous phenomenon in small grained polycrystalline materials. The shear stress induced GB migration behavior can serve as a strain accommodation mechanism during mechanical loading of the materials[12,13]. Both effects should have profound influence on the mechanical performance of the small grained polycrystalline materials. The magic of the CSL-DSC lattice lies in the fact that, in a crystallographic sense, GBs can migrate by shear stress as long as the atoms in GB move according to a set of displacement vectors which connect the lattice sites of the neighboring grains in the GB zone correspondingly. It is not yet well known if the vicinal GBs in general can migrate under shear stress, and if the GB DSC dislocation mechanism still functions in shear of these vicinal GBs
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