Lab 2b- Recrystallisation in analogue materials.
VIEPS/Mainz Microstructure Course
| TOC
| Lecture 1
2
3
4 a
b
5 a
b
| Lab 1 a
b
c
2 a
b
c
3 a
b
4 a
b
5 a
b
| Glossary Table
1
2
3
4
5
Index
|
We have four movies of static, dynamic, and metadynamic recrystallisation
in octachloropropane.
A) Grain Growth.
In this experiment, we start out with a nice foam texture, and end up
with a nice foam texture, and in between we have a nice foam texture. This
is characteristic of static grain growth.
-
What are the characteristics of the grain boundary
geometries seen in this experiment?
-
Is there a relationship between the number of sides
a grain has and the curvature of its boundaries?
-
What is the driving force for grain boundary migration
in this experiment?
-
What is the relationship between grain size and whether
a grain shrinks or grows?
B) Dynamic recrystallisation. This movie is an extended version
of one of the movies in the first lab. Now we can find out if your predictions
for further microstructural development are true. The white areas that
develop around grains show areas where the grain boundary is no longer
perpendicular to the surface of the glass, so that you are looking through
two grains separated by a grain boundary.
-
Sketch the grains A & B at 4 stages of this experiment,
and label the deformation processes involved in the evolution of grains
A & B.
-
Look at Grain C and its neighbours below it, how
does the grain boundary change through the experiment, and why might this
change occur?
C) Dynamic and meta-dynamic recrystallisation. In this pair of movies
we start off with a foam texture, deform it in pure shear, stop the deformation,
and watch it return to a foam texture. At the end of this first movie the
motor was stopped and the further evolution of the microstructure is controlled
by its internal state at that time.
-
Using the dust particles as markers of material points,
how much shortening has the sample undergone by the end of the first movie?
-
What is the direction of maximum flattening, and
is this parallel to the grain shape foliation orientation?
Pure shear deformation of OCP
-
In the second movie (below) the behaviour of the
aggregate is very different in the first half of the movie than in the
second half, how and why does the behaviour change (eg why might the driving
forces evolve even though the motor has been turned off) ?
Post deformation behaviour of OCP following pure shear as seen above