Effect of strain rate cycling on microstructures and crystallographic preferred orientation during high-temperature creep

Strain rate histories and strain magnitude are two crucial factors governing the evolution of dynamic recrystallized grain size and crystallographic preferred orientation (CPO) in rocks and ice masses. To understand the effect of cyclic variations in strain rate or non-steady state deformation, we c...

Full description

Saved in:
Bibliographic Details
Published in:Geology (Boulder) 2016-04, Vol.Pre-Issue Publication (4), p.279-282
Main Authors: Peternell, Mark, Wilson, Christopher J. L
Format: Article
Language:English
Subjects:
Annan geovetenskap och miljövetenskap
Climate Research
creep
crystal structure
Crystallography
deformation
Earth and Related Environmental Sciences
Effects
experimental studies
fabric
Geologi
Geology
Geovetenskap och miljövetenskap
grain size
High temperature
ice
Klimatforskning
laboratory studies
Materials creep
Microstructure
Other Earth and Related Environmental Sciences
P-T conditions
polycrystalline materials
preferred orientation
rates
strain
Strain rate
stress
structural analysis
Structural geology
temperature
Citations: Items that this one cites
Items that cite this one
Online Access:Get full text
Tags: Add Tag
No Tags, Be the first to tag this record!
Description
Summary:Strain rate histories and strain magnitude are two crucial factors governing the evolution of dynamic recrystallized grain size and crystallographic preferred orientation (CPO) in rocks and ice masses. To understand the effect of cyclic variations in strain rate or non-steady state deformation, we conducted two-dimensional, coaxial plane strain experiments with time-lapse observations from a fabric analyzer. There is a continuous reequilibration of microstructure and CPO development associated with constant and oscillating strain rate cycles. These can be correlated with c-axis small circle distributions, diagnostic of dynamic recrystallization involving new grain nucleation and grain boundary migration (GBM) as observed in the high-temperature deformation of ice and quartz. Inhomogeneous stress distribution can lead to grain size reduction for relatively slower strain rates and GBM for relatively faster rates within a long-interval cycling event, a behavior that contradicts the classic view for dynamic recrystallization processes. Where there is a rapid short-term cycling of strain rate, GBM is hampered and nucleation dominates, accompanied by a marked reduction of grain size and no new CPO development. During such short-term cycling, GBM and crystallographic change is impeded not by impurities, but by an inability of newly nucleated grains to grow.
ISSN:0091-7613
1943-2682
1943-2682
DOI:10.1130/G37521.1