- 著者
- Wataru SHIGEYAMA(繁山航) Naoko NAGATSUKA(永塚尚子) Tomoyuki HOMMA(本間智之) Morimasa TAKATA(高田守昌) Kumiko GOTO-AZUMA(東久美子) Ilka WEIKUSAT Martyn R. DRURY Ernst-Jan N. KUIPER Ramona V. MATEIU Nobuhiko AZUMA(東信彦) Dorthe DAHL-JENSEN Sepp KIPFSTUHL
- 出版者
- 公益社団法人 日本雪氷学会
- 雑誌
- Bulletin of Glaciological Research (ISSN:13453807)
- 巻号頁・発行日
- vol.37, pp.31-45, 2019 (Released:2019-12-17)
- 参考文献数
- 64
- 被引用文献数
- 4
Mass loss from ice sheets contributes to global sea level rise, and accelerated ice flow to the oceans is one of the major causes of rapid ice sheet mass loss. To understand flow dynamics of polar ice sheets, we need to understand deformation mechanisms of the polycrystalline ice in ice sheets. Laboratory experiments have shown that deformation of polycrystalline ice occurs largely by dislocation glide, which mainly depends on crystal orientation distribution. Grain size and impurities are also important factors that determine ice deformation mechanisms. Compared with ice formed during interglacial periods, ice formed during glacial periods, especially ice that forms cloudy bands, exhibits finer grain sizes and higher impurity concentrations. A previous report suggests the deformation rate of ice containing cloudy bands is higher than that of ice without cloudy bands. To examine the microstructures and deformation histories of ice in cloudy bands, we applied the electron backscatter diffraction (EBSD) technique to samples from the Greenland Ice Sheet using an environmental scanning electron microscope (ESEM) equipped with cold stages. Prior to the EBSD analysis, we optimised our ESEM/EBSD system and performed angular error assessment using artificial ice. In terms of c- and a-axis orientation distributions and grain orientation spread, we found little difference between samples taken from a cloudy band and those taken from an adjacent layer of clear ice. However, subgrain boundary density and orientation gradients were higher in the cloudy band, suggesting that there are more dislocations in the cloudy band than in the clear ice layer.
1 0 0 0 OA 電子線後方散乱回折(EBSD)法を用いた氷の結晶方位測定の検討
- 著者
- 繁山 航 永塚 尚子 本間 智之 高田 守昌 東 久美子 R.V. Mateiu 東 信彦
- 出版者
- 公益社団法人 日本雪氷学会/日本雪工学会
- 雑誌
- 雪氷研究大会講演要旨集 雪氷研究大会(2015・松本) (ISSN:18830870)
- 巻号頁・発行日
- pp.161, 2015 (Released:2016-02-29)
1 0 0 0 OA 時効析出型高強度展伸用マグネシウム合金の開発
自動車用鋼板のような大型部材として用途のある展伸用Mg合金の開発を目指し、圧延・押出などの熱間加工後、時効処理により強化できるような時効硬化型Mg合金の研究を行った。時効析出型のMg-Ca合金はAlやInの微量添加により時効硬化性が改善される。Al添加合金では底面上にGPゾーンが形成され、In添加合金では柱面上に板状析出物の形成が確認された。この柱面析出物は析出強化に有効に働くとされており、新しい時効硬化型マグネシウム合金開発に期待される。さらに、これらの結果に基づいてMg-Al-Ca-Mn合金の熱間押出し材を作製し、400MPaを超える高い引張耐力を示す材料の開発に成功した。