The shear response of the Σ9⟨110⟩{221} symmetrical tilt grain boundary in three face-centered cubic metals Cu, Al and Ni was studied by atomistic simulation methods with the embedded atom method for interatomic potentials and with a bicrystal model. By applying an energy minimization procedure, it was found that there were two optimized structures of this particular grain boundary at zero temperature for all the three metals studied. Shear of bicrystals at room temperature was studied by the molecular-dynamics simulation method. Various kinds of structure evolution behavior were found for this grain boundary depending upon the shear direction: pure grain-boundary sliding, grain-boundary atomic shuffling accompanied by lattice dislocation emission from the grain boundary and grain-boundary migration coupled with grain boundary sliding, namely, grain boundary coupling motion. The grain boundary coupling motions could differ in the direction and distance of the grain boundary migration depending on the shear direction. An analysis with the aid of the coincidence site lattice theory indicates that the structure evolution behavior could be attributed to several elementary structure transformations inherent to this particular grain boundary. A pair parameter (λ,κ) was proposed to describe the grain boundary coupling motions.

Shear Response of the Σ9 <110>{221} Symmetric Tilt Grain Boundary in FCC Metals Studied by Atomistic Simulation Methods. L.Wan, S.Wang: Physical Review B, 2010, 82[21], 214112