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

Abstract : 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.