The dependence of the β-AlFeSi to α-Al(FeMn)Si transformation kinetics in Al-Mg-Si alloys on the alloying elements

An homogenisation process is applied to as cast billets Al-Mg-Si alloys in order to improve the extrudability. During this homogenisation, plate-like β-AlFeSi phase transforms to a more rounded α-Al(FeMn)Si phase which are more favourable for the extrusion process. In this paper, the influence of the alloying elements on the rate of the intermetallic β-to-α transformation is studied. A Finite Element Model (FEM) predicts the kinetics of the β-to-α transformation for various Mn and Si concentrations. The software package Thermo-Calc is used to derive the equilibrium solubilities for various alloy compositions. These solubilities are used in the Finite Element Method as boundary conditions for the interfacial concentrations of the intermetallics. Subsequently, the results of the Finite Element Model are validated with experimental data.