Aluminium Alloys: moving boundary problems ( figures)
Pierre Pinson

Delft University of Technology

Start of the project: September 2001.
End of the project: February 2002.
Here is the literature study and the final report. This project is done within the Erasmus exchange programme with Institut National des Sciences Appliquees ( INSA) Toulouse.

Summary of the master project:
As-cast aluminum alloys often contain particles and other inhomogeneities, which deteriorate the mechanical properties both for further processing and final use. These inhomogeneities can be removed with a thermal treatment, during which the metallurgical state of the material changes. These changes can either involve the dissolution or morphology of the various phases.

Recently we started to study morphology changes of the various phases. We consider the transformation of plate-shaped particles (Al5FeSi) into spherical-shaped particles (Al12Fe3Si). For this problem two or three dimensional configurations are required. We have done some numerical experiments to approximate the moving boundary.

During this stage work has been done on the following subjects: compare the numerical solution with measurements (form of the boundary via photos of the micro-structure, concentrations, etc.). A comparison of the numerical solution with an analytical solution for a simple geometry. Finally we have observed (as expected) instabilities in the form of the moving boundary. The question is does these instabilities occur always, or is there some parameter, which influences the occurrence of instabilities?



Alpha particle on beta plate                   Faceted particle on beta plate

Results of numerical simulations

Instabilities in the growing particle. When the Gibbs-Thomson effect is included in the mathematical model the curves are smooth.


Growth of the particle - position         Concentration profile at the end

Contact information: Kees Vuik

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