Piazolo S, Montagnat M, Blackford J R
Department of Geology and Geochemistry, Stockholm University, Stockholm, Sweden.
J Microsc. 2008 Jun;230(Pt 3):509-19. doi: 10.1111/j.1365-2818.2008.02014.x.
In this work, we present first results of high-resolution EBSD for ice with a spatial resolution down to 0.25 microm. The study highlights the potential of EBSD to significantly increase our understanding of deformation and annealing processes associated with the build-up of internal stresses due to strain incompatibility between grains. Two polycrystalline samples were analyzed: a natural sample of polar ice from the Vostok ice core (Antarctica) and an experimentally deformed sample of laboratory grown columnar ice. In summary, we observe the following: (1) inhomogeneous deformation through the grains is translated into lattice distortions that are concentrated mainly at grain boundaries and triple junctions (natural and experimental sample), (2) these distortions may be continuous (natural and experimental sample) or may form distinct tilt boundaries and sub-grains of 10-50 microm size (experimental sample). These form mainly by rearrangement of basal edge dislocations into low-energy configurations (i.e. tilt boundaries) in various prism planes. Continuous lattice distortions originate from screw or mixed edge and screw dislocations lying in the basal plane.
在这项工作中，我们展示了空间分辨率低至0.25微米的冰的高分辨率电子背散射衍射（EBSD）的初步结果。该研究突出了EBSD在显著增进我们对由于晶粒间应变不相容而产生的内应力积累相关的变形和退火过程理解方面的潜力。分析了两个多晶样品：一个来自沃斯托克冰芯（南极洲）的极地冰天然样品和一个实验室生长的柱状冰的实验变形样品。总之，我们观察到以下情况：（1）晶粒内部的不均匀变形转化为主要集中在晶界和三叉晶界处的晶格畸变（天然样品和实验样品），（2）这些畸变可能是连续的（天然样品和实验样品），或者可能形成10 - 50微米大小的明显倾斜边界和亚晶粒（实验样品）。这些主要通过基面边缘位错在各种棱柱面中重排为低能量构型（即倾斜边界）而形成。连续的晶格畸变源自位于基面中的螺旋位错或混合的刃型位错和螺旋位错。
