Measurements and full-field predictions of deformation heterogeneities in ice

• Published in: Earth and Planetary Science Letters
• Main Authors: Montagnat, M., Blackford, J. R., Piazolo, S., Arnaud, L., Lebensohn, R.A.
• Other Authors: EDGe, Laboratoire de glaciologie et géophysique de l'environnement (LGGE), Observatoire des Sciences de l'Univers de Grenoble (OSUG), Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national des sciences de l'Univers (INSU - CNRS)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB Université de Savoie Université de Chambéry )-Centre National de la Recherche Scientifique (CNRS)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national des sciences de l'Univers (INSU - CNRS)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB Université de Savoie Université de Chambéry )-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS)-Observatoire des Sciences de l'Univers de Grenoble (OSUG), Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national des sciences de l'Univers (INSU - CNRS)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB Université de Savoie Université de Chambéry )-Centre National de la Recherche Scientifique (CNRS)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national des sciences de l'Univers (INSU - CNRS)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB Université de Savoie Université de Chambéry )-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), School of Engineering - Institute of Materials and Processes, University of Edinburgh (Edin.), Department of Geology and Geochemistry Stockholm, Stockholm University, CLIPS, Materials Science and Technology Division, Los Alamos National Laboratory (LANL), Swedish Research Council VR 621-2004-5330, Knut and AliceWallenberg Foundation, department INSIS of CNRS, France Royal Society European Science Foundation (ESF), European Project:
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2011
• Subjects: Columnar Ice; Polar Ice; Numerical Simulations; Electron Backscatter Diffraction; Modeling Viscoplastic Behavior; Self-Consistent Approach; Dynamic Recrystallization; Polycrystalline Ice; Deformation heterogeneities; Kink bands; Full-field approach; [SDU.STU.GL]Sciences of the Universe [physics]/Earth Sciences/Glaciology; [SDU.STU.GP]Sciences of the Universe [physics]/Earth Sciences/Geophysics [physics.geo-ph]; Ice Sheet
• Online Access: https://insu.hal.science/insu-00605029; https://insu.hal.science/insu-00605029/document; https://insu.hal.science/insu-00605029/file/Montagnat2011.pdf; https://doi.org/10.1016/j.epsl.2011.02.050

International audience We have made creep experiments on columnar grained ice and characterised the microstructure and intragranular misorientations over a range of length scales. A FFT full-field model was used to predict the deformation behaviour, using the experimentally characterised microstructure as the starting material. This is the first time this combination of techniques has been used to study the deformation of ice. The microstructure was characterised at the cm scale using an optical technique, the automatic ice texture analyser AITA and at the micron scale using electron backscattered diffraction EBSD. The crystallographic texture and intragranular misorientations were fully characterised by EBSD (3 angles). The deformed microstructure frequently showed straight subgrain boundaries often originating at triple points. These were identified as kink bands, and for the first time we have measured the precise misorientation of the kink bands and deduced the nature of the dislocations responsible for them. These dislocations have a basal edge nature and align in contiguous prismatic planes enabling deformation along the c-axis. In addition, non-uniform grain boundaries and regions of recrystallization were seen. We present coupling between fine scale characterization of intragranular misorientations, from experiments, and prediction of internal stresses that cause it. The model predicts the morphology of the observed local misorientations within the grains, however it over predicts the misorientation values. This is because the annealing and recrystallization mechanisms are not taken into account in the model. Ice is excellent as a model material for measuring, predicting and understanding deformation behaviour for polycrystalline materials. Specifically for ice this knowledge is needed to improve models of ice sheet dynamics that are important for climatic signal interpretation.