Interactions between dislocations and boundaries in polycrystalline ice were studied  in situ  by means of synchrotron X-ray topography. It was found that the grain boundaries acted as sources of lattice dislocations and as obstacles to dislocation motion. Three key features were considered here. These were nucleation, glide and piling-up of basal dislocations; nucleation and glide of non-basal dislocations; and slip transmission through grain boundaries. The latter phenomenon was observed in only 4% of the experiments. The grain boundaries generally acted as effective sources of lattice dislocations at the beginning of deformation, and as strong obstacles to dislocation motion in the later stages of deformation. Slip usually occurred on the basal plane, but non-basal slip was observed when basal slip was suppressed.

I.Baker, F.Liu, K.Jia, X.Hu, M.Dudley: Materials Science Forum, 1996, 207-209, 581-4