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

Journal article
Authors Christopher J.L. Wilson
Nicholas J.R. Hunter
Vladimir Luzin
Mark Peternell
Sandra Piazolo
Published in Journal of Glaciology
Volume 65
Issue 249
Pages 101-122
ISSN 0022-1430
Publication year 2019
Published at
Pages 101-122
Language en
Links https://www.cambridge.org/core/prod...
Keywords ice crystal studies, ice rheology, structural glaciology
Subject categories Geology, Climate Research, Geosciences, Multidisciplinary, Endogenous earth sciences, Other Earth and Related Environmental Sciences

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- 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.

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