Microstructure Simulation for Solidification of Magnesium-Zinc-Yttrium Alloy by Multi-phase-field Method Coupled with CALPHAD Database

The Mg-Zn-Y alloys show a good mechanical strength which can be achieved with the precipitation hardening by intermediate phases (X Wand / phase) in Mg solid solution (a phase) However an accurate control of the microstructure formation is required in order to obtain good mechanical properties In this study experimental observations of microstructures of the Mg-Zn-Y system have been performed Then we have focused on developing CALPHAD (CALculation of PHAse Diagrams) thermodynamic database to obtain the Gibbs free energy to draw phase diagram of the system and to understand the precipitation behavior of the intermediate phases In order to understand the formation of microstructures we have performed simulations of solidification of the alloy with use of multi-phase-field method At the beginning the solidification process has been calculated for a large area then the zoomed in region of the lamellar structures of the a phase and the W phase have been analyzed Resulting optimum lamellar spacing reproduce experimental one well