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

Mark Peternell and Christopher J. L. Wilson
Effect of strain rate cycling on microstructures and crystallographic preferred orientation during high-temperature creep
Geology (Boulder) (February 2016) Pre-Issue Publication

Abstract

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
EISSN: 1943-2682
Coden: GLGYBA
Serial Title: Geology (Boulder)
Serial Volume: Pre-Issue Publication
Title: Effect of strain rate cycling on microstructures and crystallographic preferred orientation during high-temperature creep
Affiliation: University of Mainz, Institute of Geosciences, Mainz, Germany
Published: 20160224
Text Language: English
Publisher: Geological Society of America (GSA), Boulder, CO, United States
References: 24
Accession Number: 2016-025827
Categories: Structural geology
Document Type: Serial
Bibliographic Level: Analytic
Annotation: GSA Data Repository item 2016086
Illustration Description: illus. incl. 1 table
Secondary Affiliation: Monash University, AUS, Australia
Country of Publication: United States
Secondary Affiliation: GeoRef, Copyright 2017, American Geosciences Institute. Reference includes data from GeoScienceWorld, Alexandria, VA, United States. Reference includes data supplied by the Geological Society of America, Boulder, CO, United States
Update Code: 201613
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