ICAMS / Interdisciplinary Centre for Advanced Materials Simulation

Mg-Al solidification

Mg-Al solidification (A. Monas and D. Pawlik)

Mg-Al alloys have significant technological and industrial importance due to their weight and cost effectiveness. On the other hand, despite the ease of production of ordinary parts made out of Mg-Al alloys there are significant issues concerning galvanic corrosion. Microgalvanic corrosion induced by more noble precipitates determines the degrading itself, which directly affects the macrogalvanic corrosion properties. This engineering issue takes place at multi material joints and leads to a fast degradation of the light alloy component. One of the solution to this problem is to tailor the alloy in such a way that the secondary beta-phase of Mg-Al wraps the primary HCP Mg-Al dendrites in a thin but closed shell which significantly increase the corrosion resistance. This study is focused on the conditioning of manufacturing parameters by simulations which enable the closed shell beta-phase formation upon solidification. This is done by performing a set of phase field simulations of the Mg-Al alloy solidification including HCP Mg-Al and a consequent beta phase formation at different conditions. The effect of initial melt concentration and the cooling rate on the beta phase mesh-work formation is also considered in this study.