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properties
of moving solid/liquid interfaces
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| The
kintetics of equilibrium adjustment at solid/liquid interfaces differs
considerably depending on the direction of motion, i.e. there are
significant differences for solidification and melting. The aysmmetry
in the phase transformation of melting and solidification is
studied in the present project, with the aim of establishing models
that in turn provide the means of describing liquid/solid phase
transformations in a wide range of conditions, including conditions
with discontinuities of the chemical potential at the
interface. |
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fragmentation
of dendrites
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| Solidification
of metal alloys occurs in the vast majority of cases in the form of
dendrites. According to an estimation, 1012
metallic dendrites per second are grown from metals worldwide. This
morphology is caused by the complex interaction of temperature and
concentration distribution in both the liquid and the solid phase. By a
combination of a cellular automaton and a solution of the differential
equation for heat or mass transport it is possible to predict these
distributions and simulate dendritic growth. Fragmentation of dendrites
can occur under certain conditions at late stages of a solidification
process. This stage can only be studied numerically with a fast and
effective algorithm which is developed in this project. |
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nuclation
controlled structures in Sn-Cu-alloys
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| Alloys
in the Cu-Sn are used as structural material with high Cu content
(bronze), as functional material with high Sn content (solder alloys).
This alloy system is not only interesting because of the possible
technical applications. There are some fundamental questions that can
be answered by carrying out experiments in the medium concentration
range in between the technical applications. One of the key features of
the phase diagram is a metatectic equilibrium, at which a solid phase
decomposes to a second solid phase and liquid phase. Microstructure
evolution is mostly nucleation controlled in some concentration ranges.
This is investigated by carefully controlled heat treatments and
subsequent rapid quenching. |
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