scholarly journals Development of crystallographic preferred orientation and microstructure during plastic deformation of natural coarse-grained quartz veins

2010 ◽  
Vol 115 (B12) ◽  
Author(s):  
Giorgio Pennacchioni ◽  
Luca Menegon ◽  
Bernd Leiss ◽  
Fabrizio Nestola ◽  
Geoffrey Bromiley
Keyword(s):  
Plastic Deformation ◽  
Preferred Orientation ◽  
Coarse Grained ◽  
Crystallographic Preferred Orientation ◽  
Quartz Veins

scholarly journals The microstructural record of porphyroclasts and matrix of partly serpentinized peridotite mylonites – from brittle and crystal-plastic deformation to dissolution–precipitation creep

Solid Earth ◽  
2013 ◽  
Vol 4 (2) ◽  
pp. 315-330 ◽  
Author(s):  
J. Bial ◽  
C. A. Trepmann
Keyword(s):  
Plastic Deformation ◽  
Upper Mantle ◽  
Boundary Migration ◽  
High Stress ◽  
Preferred Orientation ◽  
Dislocation Creep ◽  
Polarization Microscopy ◽  
Crystallographic Preferred Orientation ◽  
Fine Grained ◽  
Serpentinized Peridotite

Abstract. We present microfabrics in high-pressure, metamorphic, partly serpentinized peridotite mylonites from the Voltri Massif, in which porphyroclasts and matrix record independent deformation events. The microfabrics are analysed using polarization microscopy and electron microscopy (SEM/EBSD, EMP). The mylonites contain diopside and olivine porphyroclasts originating from the mantle protolith embedded in a fine-grained matrix consisting mainly of antigorite and minor olivine and pyroxene. The porphyroclasts record brittle and crystal-plastic deformation of the peridotite at upper-mantle conditions and differential stresses of a few hundred MPa. After the peridotites became serpentinized, deformation occurred mainly by dissolution–precipitation creep resulting in a pronounced foliation of the antigorite matrix, crenulation cleavages and newly precipitated olivine and pyroxene from the pore fluid at sites of dilation, i.e. in strain shadows next to porphyroclasts and folded fine-grained antigorite layers. Antigorite reveals a pronounced associated shape preferred orientation (SPO) and crystallographic preferred orientation (CPO) with the basal (001) cleavage plane oriented in the foliation plane. In monomineralic antigorite aggregates at sites of stress concentration around porphyroclasts, a characteristically reduced grain size and deflecting CPO as well as sutured grain boundaries indicate also some contribution of crystal-plastic deformation and grain-boundary migration of antigorite. In contrast, the absence of any intragranular deformation features in newly precipitated olivine in strain shadows reveals that stresses were not sufficiently high to allow for significant dislocation creep of olivine at conditions at which antigorite is stable. The porphyroclast microstructures are not associated with the microstructures of the mylonitic matrix, but are inherited from an independent earlier deformation. The porphyroclasts record a high-stress deformation of the peridotite with dislocation creep of olivine in the upper mantle probably related to rifting processes, whereas the serpentinite matrix records dominantly dissolution–precipitation creep and low stresses during subduction and exhumation.

scholarly journals Recrystallization fabrics of sheared quartz veins with a strong pre-existing crystallographic preferred orientation from a seismogenic shear zone

2016 ◽  
Vol 682 ◽  
pp. 214-236 ◽  
Author(s):  
Nancy A. Price ◽  
Won Joon Song ◽  
Scott E. Johnson ◽  
Christopher C. Gerbi ◽  
Rachel J. Beane ◽  
...  
Keyword(s):  
Shear Zone ◽  
Preferred Orientation ◽  
Crystallographic Preferred Orientation ◽  
Quartz Veins

scholarly journals Electron backscatter diffraction (EBSD) based determination of crystallographic preferred orientation (CPO) in warm, coarse-grained ice: a case study, Storglaciären, Sweden

2020 ◽  
Author(s):  
Morgan E. Monz ◽  
Peter J. Hudleston ◽  
David J. Prior ◽  
Zachary Michels ◽  
Sheng Fan ◽  
...  
Keyword(s):  
Electron Backscatter Diffraction ◽  
Shear Plane ◽  
Preferred Orientation ◽  
Coarse Grained ◽  
Strain History ◽  
Shear Direction ◽  
Preparation Technique ◽  
Crystallographic Preferred Orientation ◽  
Electron Backscatter ◽  
Backscatter Diffraction

Abstract. Microstructures provide key insights into understanding the mechanical behavior of ice. Crystallographic preferred orientation (CPO) develops during plastic deformation as ice dynamically recrystallizes, with the dominance of intracrystalline glide on the basal plane. CPO patterns in fine-grained ice have been relatively well characterized and understood in experiments and nature, whereas CPO patterns in "warm" (T > −10 ºC), coarse-grained, natural ice remain enigmatic. Previous microstructural studies of coarse-grained ice have been limited to c-axis orientations using light optical measurements. We have developed a new sample preparation technique, by constructing composite sections, to allow us to use electron backscatter diffraction (EBSD) to obtain a representative, bulk CPO on coarse-grained ice. We suggest that a grain sampling bias of large, branching crystals that appear multiple times as island grains in thin section may result in the typical multiple maxima CPOs previously identified in warm, coarse-grained ice that has been subjected to prolonged shear. CPOs combined from multiple samples of highly sheared ice from Storglaciären provide a more comprehensive picture of the microstructure and yield a pronounced cluster of c-axes sub-normal to the shear plane and elongate or split in a plane normal to the shear direction, and a concomitant girdle of a-axes parallel to the shear plane with a maximum perpendicular to the shear direction. This pattern compares well with patterns produced by sub-sampling data sets from experimentally sheared ice at high homologous temperatures up to strains of ~ 1.5. Shear strains in the margin of Storglaciären are much higher than those in experimental work. At much lower natural strain rates, dynamic recrystallization, particularly grain boundary migration, may have been more effective so that the CPO has been continuously reset and represents a smaller, final fraction of the shear history, rather than the entire finite strain history.

Lattice preferred orientation in CaIrO3 perovskite and post-perovskite formed by plastic deformation under pressure

2007 ◽  
Vol 34 (9) ◽  
pp. 679-686 ◽  
Author(s):  
Ken Niwa ◽  
Takehiko Yagi ◽  
Kenya Ohgushi ◽  
Sébastien Merkel ◽  
Nobuyoshi Miyajima ◽  
...  
Keyword(s):  
Plastic Deformation ◽  
Preferred Orientation ◽  
Lattice Preferred Orientation

Structure and Hardness of Cryorolled and Heat-Treated 2xxx Aluminum Alloy

2010 ◽  
Vol 667-669 ◽  
pp. 925-930
Author(s):  
S.V. Krymskiy ◽  
Elena Avtokratova ◽  
M.V. Markushev ◽  
Maxim Yu. Murashkin ◽  
O.S. Sitdikov
Keyword(s):  
Heat Treatment ◽  
Solid Solution ◽  
Plastic Deformation ◽  
Aluminum Alloy ◽  
Severe Plastic Deformation ◽  
Coarse Grained ◽  
Aging Response ◽  
Heat Treated ◽  
Aluminum Solid Solution ◽  
A Cell

The effects of severe plastic deformation (SPD) by isothermal rolling at the temperature of liquid nitrogen combined with prior- and post-SPD heat treatment, on microstructure and hardness of Al-4.4%Cu-1.4%Mg-0.7%Mn (D16) alloy were investigated. It was found no nanostructuring even after straining to 75%. Сryodeformation leads to microshear banding and processing the high-density dislocation substructures with a cell size of ~ 100-200 nm. Such a structure remains almost stable under 1 hr annealing up to 200oC and with further temperature increase initially transforms to bimodal with a small fraction of nanograins and then to uniform coarse grained one. It is found the change in the alloy post–SPD aging response leading to more active decomposition of the preliminary supersaturated aluminum solid solution, and to the alloy extra hardening under aging with shorter times and at lower temperatures compared to T6 temper.

Modern Models of Grain Boundary Diffusion

2011 ◽  
Vol 312-315 ◽  
pp. 1116-1125
Author(s):  
Vladimir V. Popov
Keyword(s):  
Plastic Deformation ◽  
Grain Boundary ◽  
Severe Plastic Deformation ◽  
Nanocrystalline Materials ◽  
Boundary Diffusion ◽  
Grain Boundary Diffusion ◽  
Coarse Grained ◽  
Gas Condensation ◽  
Non Equilibrium

Recent models of grain-boundary diffusion are briefly reviewed. Models of diffusion along equilibrium boundaries of recrystallization origin in coarse-grained materials and along non-equilibrium boundaries in nanocrystalline materials obtained by gas condensation and compacting or by severe plastic deformation are considered separately.

Sign in / Sign up

Export Citation Format

Share Document