The transmission of an incoming dislocation through a symmetrical low-angle tilt grain boundary was studied for {110}<111> slip systems in body-centered cubic metals using discrete dislocation dynamics simulations. The transmission resistance was quantified in terms of the different types of interactions between the incoming and grain boundary dislocations. Five different dislocation interaction types were considered: co-linear, mixed-symmetrical junction, mixed-asymmetrical junction, edge junction, and co-planar. Mixed-symmetrical junction formation events were found not only to cause a strong resistance against the incident dislocation penetration, but also to transform the symmetrical low-angle tilt grain boundary into a hexagonal network (a general low-angle grain boundary). The interactions between the incident dislocation and the grain boundary dislocations could form an array of <100> dislocations (binary junctions) in non-coplanar interactions, or a single <100> dislocation in co-planar interaction. It was determined how the transmission resistance depended upon the mobility of <100> dislocations. The <100> dislocations had usually been treated as immobile in dislocation dynamics simulations. Here, the mobility law for <100> dislocations was implemented. As an example, it was reported how the mobility of <100> dislocations affected the equilibrium configuration of a ternary dislocation interaction.

Dislocation Interactions and Low-Angle Grain Boundary Strengthening. B.Liu, D.Raabe, P.Eisenlohr, F.Roters, A.Arsenlis, G.Hommes: Acta Materialia, 2011, 59[19], 7125-34