Sub-structure characterization of experimentally and naturally deformed ice using cryo-EBSD

Area of Science:

• Materials Science
• Glaciology
• Crystallography

Background:

• Internal stresses in ice result from strain incompatibility between grains.
• Understanding ice deformation and annealing processes is crucial for glaciology and materials science.

Purpose of the Study:

• To present the first high-resolution electron backscatter diffraction (EBSD) results for ice.
• To investigate lattice distortions and their relation to deformation and annealing processes in ice.

Main Methods:

• High-resolution EBSD with a spatial resolution down to 0.25 micrometers.
• Analysis of two polycrystalline ice samples: natural polar ice (Vostok ice core) and experimentally deformed laboratory ice.

Main Results:

• Inhomogeneous deformation leads to lattice distortions concentrated at grain boundaries and triple junctions in both ice types.
• Distortions manifest as continuous lattice distortions or distinct tilt boundaries and sub-grains (10-50 micrometers) in experimental ice.
• Sub-grains form via rearrangement of basal edge dislocations into low-energy configurations (tilt boundaries).

Conclusions:

• EBSD is a powerful tool for studying ice microstructure and deformation mechanisms.
• Lattice distortions at grain boundaries provide insights into stress build-up and annealing in ice.
• The findings advance the understanding of polycrystalline ice behavior under stress.