Influence of competition between intragranular dislocation nucleation and intergranular slip transfer on mechanical properties of ultrafine-grained metals

Tsuru, Tomohito   ; Aoyagi, Yoshiteru*; Kaji, Yoshiyuki  ; Shimokawa, Tomotsugu*

Mechanical properties of the bulk nanostructured metals, in which the volume fraction of the grain boundary is remarkably increased, cannot be explained by the average quantity of dislocation motion as predicted in conventional course-grained metals. Therefore, it is necessary to understand the effect of each grain and dislocation motion on macroscopic mechanical properties. In the present study, large scale atomistic simulations are performed to investigate the activation process of both intergranular and intragranular dislocations. A dipole of Frank-Read source was modeled as a dislocation source and bow-out motion was simulated to investigate the effect of grain size and orientation on the critical shear stress and macroscopic plastic deformation.