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2D and 3D Grain Growth Modeling and Simulation

Luis Antonio Barraales Mora (Autor)

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ISBN-10 3867276846
ISBN-13 9783867276849
Sprache Englisch
Seitenanzahl 148
Auflage 1 Aufl.
Band 0
Erscheinungsort Göttingen
Promotionsort Aachen
Erscheinungsdatum 13.08.2008
Allgemeine Einordnung Dissertation
Fachbereiche Mathematik
Physik
Bergbau- und Hüttenwesen
Beschreibung

Grain growth is the result of the collective migration of the grain boundaries of a
polycrystal. Since grain boundaries are very complex elements, grain growth is
complex as well. The mathematical description of the grain boundary requires four
parameters in the two-dimensional case and eight parameters in the threedimensional
one. The evolution of the microstructure in the course of grain growth is
determined by the grain boundary mobility and energy; both properties depend on all
the parameters for the definition of the grain boundary. Since triple lines, quadruple
points and chemical composition play an important role, grain boundary becomes
even more complex.
The modeling of the grain growth requires the consideration of all the factors that
affect grain growth. In the present dissertation, a Vertex Model for the simulation of
two- and three-dimensional grain growth is implemented. The two-dimensional model
was corroborated with classic basic theories on grain growth. Simulation on normal
grain growth showed scaling behavior und a deviation of less than 1% when
compared with the von Neumann-Mullins relationship. Furthermore, the model
validated the theory on the finite mobility of the triple junctions from Gottstein and
Shvindlerman and with this the model showed its applicability for the simulation of
more complex granular aggregates with a finite triple junction mobility. The model
also allows the use of experimental data. For instance, it was utilized for the
reproduction of an experimental setting of magnetic influenced grain growth in pure
titanium samples. The results of the simulation demonstrated that a magnetic field
can determined the texture and grain growth kinetics of magnetic anisotropic metals.
Simulation can also help to understand unexpected experimental results. For
example, it was explained by means of molecular static and vertex model simulation
the faceting of certain grain boundaries in aluminum. For this purpose, the grain
boundary energy was obtained from molecular-static simulation and subsequently
used in Vertex simulation. The results showed that the faceting of the grain
boundaries can be attributed to the anisotropy of the grain boundary energy with the
inclination angle.
In turn, the 3D model was utilized to study the effect of the boundary junctions on
three-dimensional grain growth. For this purpose a special configuration that allows
the steady-state motion of the grain boundaries was used. The simulation results
showed a very good agreement with the theoretical expectations and demonstrated
that the finite mobility of the quadruple junctions can drag grain boundary migration.
However, it was also found that triple lines drag more effectively grain growth.