The resistance to the glide of lattice dislocations between adjacent crystal grains due to the presence of a grain boundary was investigated. By using the combination of molecular dynamics simulations and a line tension model, those geometrical parameters were identified that were relevant to the description of the process. In the molecular dynamics simulations, the slip transmission of dislocation loops nucleated from a crack tip near to a series of pure tilt grain boundaries in Ni was observed. The results were rationalized in terms of a line tension model for the activation of a Frank-Read source in the presence of a grain boundary. It was found that the slip transmission resistance was a function of only 3 variables. One was the ratio of the resolved stress on the incoming slip system to that on the outgoing slip system. The second was the magnitude of any residual Burgers vector content left in the grain boundary. The third was the angle between the traces of the incoming and outgoing slip planes in the grain boundary plane. A comparison with molecular dynamics simulations and experimental data showed that the line tension model captured the essential energetics of slip transmission, and suggested

relatively simple functional relationships between the grain boundary geometry and the loading conditions on the one hand, and slip transmission resistance on the other.

Modelling Grain-Boundary Resistance in Intergranular Dislocation Slip Transmission. M.De Koning, R.Miller, V.V.Bulatov, F.F.Abraham: Philosophical Magazine A, 2002, 82[13], 2511-27