| Project/Area Number |
12640438
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Geology
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| Research Institution | The University of Tokyo |
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Principal Investigator |
SHIMIZU Ichiko Graduate School of Science, Research Associate, 大学院・理学系研究科, 助手 (40211966)
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| Project Period (FY) |
2000 – 2002
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| Project Status |
Completed (Fiscal Year 2002)
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| Budget Amount *help |
¥3,700,000 (Direct Cost: ¥3,700,000)
Fiscal Year 2002: ¥700,000 (Direct Cost: ¥700,000)
Fiscal Year 2001: ¥1,500,000 (Direct Cost: ¥1,500,000)
Fiscal Year 2000: ¥1,500,000 (Direct Cost: ¥1,500,000)
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| Keywords | dynamic recrystalization / rock deformation / stress / rheology / anisotropy / texture / grain size distribution / 動的再結晶組織 / 結晶粒径分布 / 核形成-成長モデル / 石英 / オリビン / 結晶方位定向配列 / 高温高圧実験 / 核形成-成長理論 / カンラン石 / 核形成 / 粒界移動 / 漸移クリープ / 数値シミュレーション |
|---|
| Research Abstract |
Dynamic recrystallization (DRX) is characterized by cyclic events nucleation and grain growth during plastic deformation. The evolution of grain size distribution in dynamic recrystallization was investigated by a stochastic model of nucleation-and-growth. Scaling relations representing characteristic grain size and recrystallization cycle were derived from nucleation rate and growth rate. The grain size evolve from an initial distribution to a steady-state one that is approximated by a lognormal distribution. A universal relation between deformation conditions (i.e., stress and temperature) and the steady-state grain size were formulated for recovery creep of minerals. The influence of DRX on texture (or lattice preferred orientation, LPO) development is an important issue in considering seismic anisotropy in the Earth mantle. Since a grain with 'favorable' orientation (soft grain) has larger dislocation energy than that with 'unfavorable' orientation (hard grain), soft grains are replaced with hard grains by grain boundary migration. Therefore, the LPO produced by crystalline slip becomes weak or diminished by grain growth. On the contrary, strain-free nuclei have nearly the same orientation as their host grains, hence nucleation would enhance the LPO dominated by soft grains. Textures between the above two end-members are possible for DRX
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