Does the Permanent Creep-Rate of Polycrystalline Ice Increase with Crystal Size?

Duval, Paul; Gac, H. Le

doi:10.1017/s0022143000010364

Cited by 50 publications

(14 citation statements)

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“…Moreover, the results of these tests suggest that finegrained polycrystalline ice may, as a result of more rapid recrystallization, approach steady-state tertiary creep more rapidly than coarser-grained ice and support earlier observations (e.g. Duval and Le Gac, 1980; Jacka, 1984). Both the polycrystalline and layered ice exhibited approximately the same ductility in the tertiary creep regime.…”

Section: Discussionsupporting

confidence: 84%

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Ice deformed in compression and simple shear: control of temperature and initial fabric

Wilson¹,

Peternell²

2012

J. Glaciol.

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Layered and polycrystalline ice was experimentally deformed in general shear involving axial compression (strain magnitude 0.5-17%) and simple shear (strain magnitude = 0.1-1.4). As the temperature is increased from -208 8C to -28C, there is at least a twofold enhancement in octahedral shear strain rate, which coincides with the onset of extensive dynamic recrystallization and a change in grain-size distribution at -158C. Between -158C and -108C the c-axis preferred orientation rapidly evolves with the initiation of two-maxima fabrics in shear zones. From -108C to -28C there is progressive evolution of a final c-axis pattern that is asymmetric with respect to the direction of shortening, with a strong maximum at $58 to the pole of the shear zone, a sense of asymmetry in the direction of the shear, and a secondary maximum inclined at $458 to the plane of shearing. An initial c-axis preferred orientation plays a critical role in the initial mechanical evolution. In contrast to established ideas, a strong alignment of basal planes parallel to the plane of easy glide inhibited deformation and there was an increased component of strain hardening until recrystallization processes become dominant.

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Section: Discussionsupporting

confidence: 84%

“…The results here also support the conclusions of other workers (e.g. Duval and Le Gac, 1980; Jones and Chew, 1983; Jacka, 1984), who found that the creep rate was independent of crystal size.…”

Section: Mechanical Behavioursupporting

confidence: 92%

Ice deformed in compression and simple shear: control of temperature and initial fabric

Wilson¹,

Peternell²

2012

J. Glaciol.

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“…As already mentioned, ~ is very small in ice. Although the grainsize dependence of in ice polycrystals from monotonic loading tests is still unexplored, Duval and co-workers [118,119] reported a decreasing primary creep rate with decreasing grain size that might be related with such Hall-Petch mechanism [16].…”

Section: Grain Boundariesmentioning

confidence: 99%

Ice: the paradigm of wild plasticity

Weiss

2019

Phil. Trans. R. Soc. A.

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Ice plasticity has been thoroughly studied, owing to its importance in glaciers and ice sheets dynamics.In particular, its anisotropy (easy basal slip) has been suspected for a long time, then fully characterized 40 years ago. More recently emerged the interest of ice as a model material to study some fundamental aspects of crystalline plasticity. An example is the nature of plastic fluctuations and collective dislocation dynamics. 20 years ago, acoustic emission measurements performed during the deformation of ice single crystals revealed that plastic "flow" proceeds through intermittent dislocation avalanches, power law distributed in size and energy. This means that most of ice plasticity takes place through few, very large avalanches, thus qualifying associated plastic fluctuations as "wild". This launched an intense research activity on plastic intermittency in the Material Science community. The interest of ice in this debate is reviewed, from a comparison with other crystalline materials. In this context, ice appears as an extreme case of plastic intermittency, characterized by scale-free fluctuations, complex space and time correlations as well as avalanche triggering. In other words, ice can be considered as the paradigm of wild plasticity.*Author for correspondence (jerome.weiss@univ-grenoble-alpes.fr). Phil. Trans. R. Soc. A.crystal/sample scale) dynamics of plastic deformation. We show that ice plastic "flow" actually occurs in a strongly spatially heterogeneous and intermittent way, through dislocation avalanches spanning a huge range of size. We relate this with the plastic anisotropy mentioned above that maximizes the role of long-range elastic interactions in collective dislocation dynamics, and discuss the link with the absence of significant isotropic hardening in ice or of development of an internal characteristic microstructural length scale.This "wild" dynamics, characterized by power law distributions of plastic fluctuations (with infinite variance) [17], strongly contrasts with the plasticity of FCC and BCC metals characterized, for sample sizes larger than few μm, by "mild" (finite variance, Gaussian-like) fluctuations, the development of dislocation sub-structures (e.g. dislocation cells) and isotropic hardening. In this context, ice appears as the paradigm for wild plasticity, including at bulk (>mm) scales. 2.Some specificities of ice plasticityThe fundamentals of ice plasticity have been extensively detailed elsewhere [16,18,19]. Here, the goal is not to give such overview, but instead to focus on some specificities of ice plasticity that are playing a key role in collective dislocation dynamics. Plastic anisotropyAs already stressed above, plastic anisotropy is the most prominent characteristic of ice plasticity. This has been exemplified by the creep tests reported by Duval and others [6] showing, for a given resolved shear stress, basal slip creep rates orders of magnitude larger than non-basal slip creep rates. It is related to the hexagonal structure of ice Ih, shared with

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“…These experiments give some insight into more complicated histories (Bindschadler and others, 2013). Similarly the effect of strain rate and initial grain size in pure ice may influence primary creep rates, whereas subsequent tertiary creep appears to be unaffected by the initial grain size (Duval and Le Gac, 1980). However, there is still a lack of data on grain size effects in ice containing dispersed phases, which can be explained by arguments related to the operation of dislocation mechanisms rather than from elastic anisotropy (Schulson and Duval, 2009).…”

Section: Introductionmentioning

confidence: 99%

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

et al. 2018

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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.

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Does the Permanent Creep-Rate of Polycrystalline Ice Increase with Crystal Size?

Cited by 50 publications

References 10 publications

Ice deformed in compression and simple shear: control of temperature and initial fabric

Ice deformed in compression and simple shear: control of temperature and initial fabric

Ice: the paradigm of wild plasticity

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

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Does the Permanent Creep-Rate of Polycrystalline Ice Increase with Crystal Size?

Cited by 50 publications

References 10 publications

Ice deformed in compression and simple shear: control of temperature and initial fabric

Ice deformed in compression and simple shear: control of temperature and initial fabric

Ice: the paradigm of wild plasticity

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

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