Effects of microparticles on deformation and microstructural evolution of fine-grained ice
| Autor: | Koki Nakajima, Tomotaka Saruya, Tomoyuki Homma, Kumiko Goto-Azuma, Nobuhiko Azuma, Morimasa Takata |
|---|---|
| Rok vydání: | 2019 |
| Předmět: |
Dislocation creep
glacial rheology ice crystal studies 010504 meteorology & atmospheric sciences Work hardening Strain rate Deformation (meteorology) 010502 geochemistry & geophysics 01 natural sciences Grain size Grain growth Deformation mechanism Grain boundary Composite material ice dynamics structural glaciology Geology 0105 earth and related environmental sciences Earth-Surface Processes |
| Zdroj: | Journal of Glaciology. 65:531-541 |
| ISSN: | 1727-5652 0022-1430 |
| DOI: | 10.1017/jog.2019.29 |
| Popis: | We investigated the effects of microparticles and grain size on the microstructural evolutions and mechanical properties of polycrystalline ice. Uniaxial compression tests were conducted using fine-grained pure ice and silica-dispersed ice under various conditions. Deformation behavior of fine-grained ice was found to be characterized by stress exponent n ≈ 2 and activation energy Q ≈ 60 kJ mol−1. The derived strain rates of fine-grained ice were ≈ 1 order of magnitude larger than those of coarse-grained ice obtained in previous studies, and they were found to be independent of particle dispersion and dependent on the mean grain size of ice, with grain size exponent p ≈ 1.4. Work hardening was observed in dislocation creep, while the strain rate continued to decrease. These results indicate that the deformation mechanism of fine-grained ice is different from typical dislocation creep, often associated with n = 3. Although microparticles restricted grain growth, there was little direct effect on the deformation of fine-grained ice. Microstructural observations of the ice samples indicated that the grain boundaries were straight and that the subgrain boundary densities increased after deformation. Our experiments suggest that grain size and boundaries play important roles in the deformation processes of polycrystalline ice. |
| Databáze: | OpenAIRE |
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