Analogue Modelling at the University at Albany, State
University of New York
Youngdo Park, Jin-Han Ree & Win Means
Introduction
There are 15 time-lapse movies on this page, which show the experimental
deformation or post-deformation behaviour of octachloropropane (C3Cl8).
Most of the experiments on this page were performed during December 1995,
when JHR was visiting Albany. Feel free to download these movies for teaching.
The order of the movies is such that the experimental strain rate decreases
and temperature increases.
Octachloropropane (OCP hereafter) is an organic material with hexagonal
crystal symmetry. Polycrystalline OCP shows "similar(?)" microstructures
to those found in quartzite. The material has been used to study various
deformation processes by many workers (Win Means, Janos Urai, Mark Jessell,
Jin-Han Ree, Paul Bons, Coen ten Brink, Cees Passchier), and is probably
being used for the same purpose, even now somewhere on Earth (see Ree,
1994, J. Struct. Geol. vol. 16, 403-418 for details of the experiments).
Nearly simple shearing grips (grips imposing simple shearing with a
small "transpressional" component) were used for deformation, except in
Movie 04 which shows a pure shear deformation experiment.
The horizontal dimension of the movies is ~1.5 mm.
Movie Format
Each experiment has been converted into QuickTime format.
The QuickTime versions can be viewed
directly assuming you have an QuickTime viewer attached to your browser.
Hints:
a) The movies display better if the monitor set to more than 256 colours.
b) Set the QuickTime player to display All Frames
In order to download any one of these movies, simply click on the icon
to the right of the sample frames.
Movie 00: Cataclastic deformation
The sample is already deformed at beginning of movie. A sub-horizontal
high strain rate zone or fault, marked by darker color, develops in the
lower part of field. Some high strain rate zones, oriented at high angles
to the shear direction, show the opposite sense of shear to that expected.
Although concentrated shearing probably takes most of the bulk straining,
some grains still deform internally. The last frame in the movie was taken
with plane polarized light and shows the void spaces created during deformation.
In this movie 
becomes 
387k
Movie 01: Grain boundary opening
In the lower part of the pictures, grain boundary starts to open at expected
orientation during sinistral shearing. Near the end of the movie, a feature
which resembles transform fault connecting two openings (ridges) develops.
Incipient opening at grain boundaries can also be seen at the end.
In this movie 
becomes 
314k
Movie 02: Formation of subgrains by rotational recrystallization
Irregular grain boundaries and small subgrains near grain boundaries form
during deformation. The grain near the center of the field of the view,
becomes sigmoidal in shape as deformation progresses. The grains in the
top right of the movie show extensive grain boundary sliding as the experiment
progesses. Also follow the behaviour of these two grains in the bottom
right 
as the boundary
between them switches from a grain boundary migration process to a grain
boundary sliding process.
In this movie 
becomes 
861k
Movie 03: Post-deformational, microstructural changes of the sample of
Movie 02
This movie records changes of microstructures after deformation. Can you
tell the shear sense from the last pictures? How do the grains that survive
until the end of movie originate? Observed at the same temperature as the
preceding deformation.
In this movie 
becomes 
598k
Movie 04: Subgrain boundary formation and grain boundary migration
Sets of subgrain boundaries form within grains. The trace of these subgrain
boundaries is subparallel to the c-axis orientation. Grain boundary migration
can also be seen.
In this movie 
becomes 
234k
Movie 05: Post-deformational, microstructural changes of the sample of
Movie 04
Grains change into nearly equilibrium texture of polycrystalline material
in the end. There is also mysterious vertical lengthening (~5%) while the
motor was off. Observed at the same temperature as the preceding deformation.
In this movie 
becomes 
458k
Movie 06: Contrast in deformation microstructures among domains of different
strain rate
In this movie, a strain rate gradient in the vertical direction can be
seen. Differences in microstructures such as foliation intensity, orientation
and subgrain boundary density can be seen along the direction of strain
rate gradient.
In this movie 
becomes 
629k
Movie 07: Post-deformational, microstructural changes of the sample of
Movie 06
This movies shows how the rates of grain growth - strain energy driven
or surface energy driven, are different for the strain rate domains of
Movie 06. At the beginning, the process of grain growth in the high strain
rate domain seems to be faster than that of low strain rate domain. However,
with time, the rate of grain growth seems to be faster in the low strain
rate domain, resulting in coarser grained texture in this domain in the
end. Observed at the same temperature as the preceding deformation.
In this movie 
becomes 
1707k
Movie 08: Nearly identical rates of subgrain boundary migration across
grain boundaries
This feature can be seen in the grains near the center of the field.
In this movie 
becomes 
166k
Movie 09: Development of high strain rate zones and formation of "ribbons"
in the zones
Shearing is localized in the two zones near the top and bottom of the field.
In these zones, subvertical alignment of subgrain boundaries can be seen.
At the end, nearly single grain, at least in c-axis orientations, forms,
which resembles ribbons.
In this movie 
becomes 
1961k
Movie 10: Subgrain boundary migration and grain size increase
Subgrain boundaries, oriented subvertically, migrate during deformation.
Subhorizontal relative motions of markers within some grains can be seen,
and this suggests that the slip planes of these grains are also subhorizontal
or perpendicular to the subgrain boundaries. Since the traces of subgrain
boundaries are subparallel to the c-axes, the observed motion of markers
suggests slip on the basal planes.
In this movie 
becomes 
986k
Movie 11: Post-deformational, microstructural changes of the sample of
Movie 10
In contrast to the previous examples, the microstructure of this sample
remains about the same. This suggests that (1) microstructures with high
subboundary density may be stable, or (2) microstructures in this sample
do not change due to the starting low defect density acquired during low
strain rate deformation. Observed at the same temperature as the preceding
deformation.
In this movie 
becomes 
739k
Movie 12: Grain boundary migration during high temperature deformation
High mobility of grain boundaries can be seen in this experiment performed
near the melting point. This experiment also shows reversal of shear-sense,
obtained by reversing the drive motor. Microstructures do not seem to have
good memory of old shear-sense.
In this movie 
becomes 
538k
Movie 13: Grain growth at zero strain rate
The numbers at the bottom right indicate time (hr:min:sec) after the first
frame of the movie. Can you find an area which was swept twice by migrating
grain boundaries?
In this movie 
becomes 
493k
Movie 14: Grain growth in a partial melt system
Some of the grain boundaries in this movie are wet by a melt, which is
OCP saturated acetone. Similar grain growth to that of Movie 13 can be
seen. Is the wetting angle changing during migration of boundaries? "Marker"
particles that drift across the field of view are probably in melt film
between sample and glass.
In this movie 
becomes 
213k
We thank our teacher, Professor W.D. Means for bringing us into this
interesting field and his continuous support while we were at Albany. This
work was supported by NSF grants to EAR-9017478 & EAR-9404872 to W.D.
Means, and KOSEF grant 941-0400-003-2 to J.-H. Ree.
This page was assembled by Mark Jessell and any mistakes are probably
his fault. 19/6/96