Interaction of slip dislocations with grain boundaries in body-centered cubic bicrystals

Bulk bicrystals of Fe–4 at.% Si of Σ9 or Σ15 type, oriented for single slip and deformed in compression were studied by conventional transmission electron microscopy. The deformation was limited to early stages. In both bicrystals, the deformation proceeded by independent slip in both grains. In the Σ9 bicrystal, a small fraction of deformation was attributed to the transfer of slip from one grain to the other leaving residual grain boundary dislocations. In the Σ15 bicrystal, dislocations of both signs of Burgers vectors were observed in the grains. The movement of dislocations from the boundary was initiated by dislocation sources formed in the boundary. Jogs on screw dislocations may support the formation of sources.