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2D Model for homogenisation and precipitation

The pseudo-front tracking model used to describe the formation of microstructure during solidification also applies to homogenisation. This 2-dimensional model can describe the evolution of the primary precipitates, which formed in the interdendritic regions during solidification. The model predicts the amount and the type of primary precipitates as a function of temperature and solute distribution in the matrix during homogenisation. It is based on the assumptions of diffusion controlled phase transformations and local equilibrium at the interfaces. The equilibrium conditions are obtained either by direct calls to the phase diagram software Thermo-Calc or from tabulated phase diagrams.

The model is presently operational for multicomponent alloys in the direct coupling mode and for binary alloys in the tabulation mode. Comparisons with experimental data have been performed but remain limited if not coupled to a precipitation model.
A preliminary coupled version of the present homogenisation model with the INPL precipitation model has been developed and applied to the 3003 alloys for a 1D geometry. Results are promising, although the extension of the coupled model to 2D would require the development of optimisation methods to reduce the computation time.

Reported by

Ecole Polytechnique Fédérale de Lausanne
Laboratoire de métallurgie physique
1015 Lausanne