Modelling particle dissolution and nucleation during the heat
treatment of commercial aluminum alloys
Jos de Zwaan
Site of the project:
Corus
Postbox 10.000
1970 CA IJmuiden
start of the project: August 2005
In December 2005 the
Interim
Thesis has been appeared
and a
presentation has been given.
The Master project has been finished in August 2006
by the completion of the
Masters Thesis and a final presentation has been given.
For working address etc. we refer to our
alumnipage.
Summary of the master project:
Inhomogeneities in the microstructure of commercial aluminum alloys are
the main cause for
heat-cracks, orange-skin metallic surfaces and many other material
failures. Therefore,
the alloys are subject to a thermal treatment at a high temperature
just beneath the
melting temperature in order to taylor the microstructure in terms of
particles.
During this heat treatment two important processes, among other
processes, take place:
- Dissolution of large (primary) particles with a size in the
order of a micrometer;
- Formation (nucleation) and growth of tiny (secondary)
particles with a size in the
order of a nanometer.
The primary and secondary particles have a different composition.
The purpose of this MSc project is to model the combination of the two
abovementioned
processes. The first process is modelled as a Stefan problem,
which is a diffusion
problem (like a heat problem) with a moving boundary (compare with a
solidification
or melting problem). The second process is modelled by the use of a
concentration dependent
nucleation rate from thermodynamic principles. The problems are
coupled by the addition of
a reactive term to the Stefan problem resulting from a mass-balance.
The combination of
the two models is a novelty in the modelling of dissolution of primary
particles combined with
nucleation of tiny secondary particles.
Contact information:
Kees
Vuik
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