Subgrain boundaries in Antarctic ice quantified by X-ray Laue diffraction
Subgrain boundaries in Antarctic ice quantified by X-ray Laue diffraction
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DOI：
10.3189/002214311795306628
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发表时间：
2011-03
影响因子：
3.4
通讯作者：
I. Weikusat;A. Miyamoto;S. H. Faria;S. Kipfstuhl;N. Azuma;T. Hondoh
中科院分区：
文献类型：
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作者：
I. Weikusat;A. Miyamoto;S. H. Faria;S. Kipfstuhl;N. Azuma;T. Hondoh
摘要极地冰盖中的冰在流向海岸的过程中会发生变形。利用升华边缘样品表面的高分辨率光学显微镜(显微组织图谱)，可以观察和记录变形和再结晶组织，如亚晶界。通过显微组织图谱观察到的亚晶界揭示了其特有的形状和排列方式。由于这些排列与基面取向有关，因此需要完整的晶体取向测量来进一步表征和解释亚晶界类型。X射线劳厄衍射测量验证了不同边界类型的敏感性，并通过微结构映射用于分类。X射线劳厄衍射提供了所有四个晶轴的取向错位值。通过显微组织映射预先定位的亚晶界的线扫描可以确定旋转轴和角度。再加上亚晶界的取向，这就产生了有关位错类型的信息。发现了由基面位错组成的倾斜和扭曲边界，以及由非基位错组成的倾斜边界。统计分析表明，非基位错在所有亚晶界的形成中起着重要作用。
Abstract Ice in polar ice sheets undergoes deformation during its flow towards the coast. Deformation and recrystallization microstructures such as subgrain boundaries can be observed and recorded using high-resolution light microscopy of sublimation-edged sample surfaces (microstructure mapping). Subgrain boundaries observed by microstructure mapping reveal characteristic shapes and arrangements. As these arrangements are related to the basal plane orientation, full crystallographic orientation measurements are needed for further characterization and interpretation of the subgrain boundary types. X-ray Laue diffraction measurements validate the sensitivity of different boundary types with sublimation used by microstructure mapping for the classification. X-ray Laue diffraction provides misorientation values of all four crystal axes. Line scans across a subgrain boundary pre-located by microstructure mapping can determine the rotation axis and angle. Together with the orientation of the subgrain boundary this yields information on the dislocation types. Tilt and twist boundaries composed of dislocations lying in the basal plane, and tilt boundaries composed of nonbasal dislocations were found. A statistical analysis shows that nonbasal dislocations play a significant role in the formation of all subgrain boundaries.