The influence of strain rate and presence of dispersed second phases on the deformation behaviour of polycrystalline D2O ice

Christopher J.L. Wilson, Nicholas J.R. Hunter, Vladimir Luzin, Mark Peternell, Sandra Piazolo

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3 Citations (Scopus)

Abstract

This contribution discusses results obtained from 3-D neutron diffraction and 2-D fabric analyser in situ deformation experiments on laboratory-prepared polycrystalline deuterated ice and ice containing a second phase. The two-phase samples used in the experiments are composed of an ice matrix with (1) air bubbles, (2) rigid, rhombohedral-shaped calcite and (3) rheologically soft, platy graphite. Samples were tested at 10°C below the melting point of deuterated ice at ambient pressures, and two strain rates of 1 × 10−5 s−1 (fast) and 2.5 × 10−6 s−1 (medium). Nature and distribution of the second phase controlled the rheological behaviour of the ice by pinning grain boundary migration. Peak stresses increased with the presence of second-phase particles and during fast strain rate cycles. Ice-only samples exhibit well-developed crystallographic preferred orientations (CPOs) and dynamically recrystallized microstructures, typifying deformation via dislocation creep, where the CPO intensity is influenced in part by the strain rate. CPOs are accompanied by a concentration of [c]-axes in cones about the compression axis, coinciding with increasing activity of prismatic-<a> slip activity. Ice with second phases, deformed in a relatively slower strain rate regime, exhibit greater grain boundary migration and stronger CPO intensities than samples deformed at higher strain rates or strain rate cycles.
Original languageEnglish
Pages (from-to)101-122
Number of pages22
JournalJournal of Glaciology
Volume65
Issue number249
DOIs
Publication statusPublished - Feb 2019

Keywords

  • ice crystal studies
  • ice rheology
  • structural glaciology

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