The heterogeneous nature of slip in ice single crystals deformed under torsion

Ice single crystals were deformed under torsion and dislocation arrangements were analyzed by synchrotron topography at ESRF (European Synchrotron Radiation Facility). Profile analysis of the topographs revealed the scale-invariant character of the dislocation arrangement with long-range correlations. Dislocation density gradients are shown to be slightly anti-correlated as the intensity profile is similar to an anti-persistent random walk-like signal. This analysis reveals the influence of internal stresses on dislocation arrangement up to the sample scale. Similar observations in reversed torsion experiments, together with strong hardening behaviour, allow a mechanism of cross-slip of basal dislocations on prismatic planes to be suggested for interpretation of local dislocation interaction behaviour.