气候变化领域集成服务门户(CCPortal): Kinking facilitates grain nucleation and modifies crystallographic preferred orientations during high-stress ice deformation

CCPortal

DOI	10.1016/j.epsl.2021.117136
	Kinking facilitates grain nucleation and modifies crystallographic preferred orientations during high-stress ice deformation
	Fan S.; Prior D.J.; Hager T.F.; Cross A.J.; Goldsby D.L.; Negrini M.
发表日期	2021
ISSN	0012821X
卷号	572
英文摘要	Kinking is an important strain-accommodating process during crystal plastic deformation under relatively large stresses and may influence the mechanical properties of the Earth's lithosphere and planetary cryosphere. To better understand the origins, mechanisms, and microstructural effects of kinking, we present detailed microstructural analyses of coarse-grained (∼1300 μm) ice samples deformed under uniaxial compression at -30 °C. Deformed samples show elongated (aspect ratio ≥ 4) kink domains developing within or at the tips of remnant original grains (≥300 μm, aspect ratio < 4). Small, equiaxed subgrains also develop along the margins of remnant grains. Moreover, many remnant grains are surrounded by mantles of small, recrystallized grains (<300 μm, aspect ratio < 4). Together, these observations indicate that grain nucleation is facilitated by both kinking and dynamic recrystallization. Low- (<10°) and high-angle (mostly >10°, many >20°) kink bands within remnant grains have misorientation axes that lie predominantly within the basal plane. The c-axes of most kink domains are oriented sub-perpendicular to the sample compression axis, indicating that kinking may produce or modify a crystallographic preferred orientation. Kink band densities are highest within remnant grains that have basal planes sub-parallel to the compression axis—these data are inconsistent with models suggesting that (if kinking is the only strain-accommodating process) there should be higher kink band densities within grains that have basal planes oblique to the compression axis. One way to rationalize this inconsistency between kink models and experimental observations is that kinking and dynamic recrystallization are both active during deformation, but their relative activities depend on the crystallographic orientations of individual grains. For grains with basal planes sub-parallel to the compression axis, strain-induced grain boundary migration (GBM) is inhibited, and large strain incompatibilities can be relaxed via kinking when other processes such as subgrain rotation (SGR) recrystallization are insufficient. For grains with basal planes oblique to the compression axis, strain-induced GBM might be efficient enough to relax the strain incompatibility via selective growth of these grains, and kinking is therefore less important. For grains with basal planes sub-perpendicular to the compression axis, kink bands are seldom observed—for these grains, the minimum shear stress required for kinking exceeds the applied compressive stress, such that kinks cannot nucleate. © 2021 Elsevier B.V.
关键词	crystallographic preferred orientation (CPO)electron backscatter diffraction (EBSD)ice kinking nucleation
英文关键词	Aspect ratio; Crystal orientation; Crystallization; Dynamic recrystallization; Grain boundaries; Ice; Nucleation; Rotation; Textures; Aspect-ratio; Basal planes; Basal-planes; Compression axis; Crystallographic preferred orientation; Crystallographic preferred orientations; Electron backscatter diffraction; Grain nucleation; Kink bands; Kinking; Strain
语种	英语
来源期刊	Earth and Planetary Science Letters
文献类型	期刊论文
条目标识符	http://gcip.llas.ac.cn/handle/2XKMVOVA/203082
作者单位	Department of Geology, University of Otago, Dunedin, New Zealand; Department of Earth and Environmental Science, University of Pennsylvania, Philadelphia, PA, United States; Department of Geology and Geophysics, Woods Hole Oceanographic Institution, Woods Hole, MA, United States
推荐引用方式 GB/T 7714	Fan S.,Prior D.J.,Hager T.F.,et al. Kinking facilitates grain nucleation and modifies crystallographic preferred orientations during high-stress ice deformation[J],2021,572.
APA	Fan S.,Prior D.J.,Hager T.F.,Cross A.J.,Goldsby D.L.,&Negrini M..(2021).Kinking facilitates grain nucleation and modifies crystallographic preferred orientations during high-stress ice deformation.Earth and Planetary Science Letters,572.
MLA	Fan S.,et al."Kinking facilitates grain nucleation and modifies crystallographic preferred orientations during high-stress ice deformation".Earth and Planetary Science Letters 572(2021).