PREFERRED CRYSTALLOGRAPHIC ORIENTATION IN THE ICE-I-]II TRANSFORMATION AND THE FLOW OF ICE-II

The preferred crystallographic orientation developed during the ice I --> II transformation and during the plastic flow of ice II was measur ed in polycrystalline deuterium oxide (D2O) specimens using low-temper ature neutron diffraction. Samples partially transformed from ice I to II under a non-hydrostatic stress developed a preferred crystallograp hic orientation in the ice II. Samples of pure ice II transformed from ice I under a hydrostatic stress and then when compressed axially, de veloped a strong preferred orientation of compression axes parallel to (10 (1) over bar 0). A match to the observed preferred orientation us ing the viscoplastic self-consistent theory was obtained only when (10 (1) over bar 0) [0001] was taken as the predominant slip system in ic e II.