Synchrotron X-ray topographic experiments were carried out  in situ  in order to study dislocation transmission through grain boundaries in the initial stages of plastic deformation of bi-crystals. The grain boundaries hindered dislocation motion even in the case of the most favorable slip geometry, where both the Burgers vectors and slip planes were parallel in the 2 grains. Slip transmission was greatly affected by the stresses exerted by dislocations which were stopped at the grain boundaries, and by the local structure of the grain boundary itself. Slip behind the boundary probably began from new dislocation sources which formed under the effect of combined external and internal stresses.

In Situ Observation of Plastic Deformation of Fe-Si Bi-Crystals by White-Beam Synchrotron Radiation Topography M.Polcarová, J.Gemperlová, J.Brádler, A.Jacques, A.George, L.Priester: Philosophical Magazine A, 1998, 78[1], 105-30