A Model of the β-AlFeSi to α-Al(FeMn)Si Transformation During Homogenization in 6xxx Alloys
F. J. Vermolen, C. Vuik, and S. van der Zwaag, Delft University of Technology, Delft, The Netherlands,
N.C.W. Kuijpers, Delft University of Technology, Netherlands Institute for Metals Research (NIMR), Delft, The Netherlands
P.T.G. Koenis and K.E. Nilsen, BOAL BV, de Lier, The Netherlands
Track: BILLET PROCESS AND EQUIPMENT - Homogenization
ABSTRACT --- One of the physical processes during the homogenization treatment
of 6xxx aluminum alloys is the transformation of plate-like β-Al5FeSi particles to more
rounded shaped α-Al12(FeMn)3Si particles. The rate of this transformation determines
the homogenization time. Mathematically the β to α transformation is treated as a
Stefan problem where the concentration and the position of the interfaces, separating
the Aluminum phase and the α or β phase, have to be determined. The boundary
conditions are obtained from thermodynamical calculations, using the ThermoCalc
package. A Finite element model and an analytical model, which mimic the growth of
an α particle on a dissolving β plate, are proposed and compared. Finally, some
metallurgical implications are given.
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