Phase-field modelling of zinc dendrite growth in ZnAlMg coatings
Résumé
A phase-field model for dendritic solidification is applied to hot-dip ZnAlMg coatings, in order to study the morphology of zinc dendrites and the solute segregation leading to the formation of eutectics. These aspects define the microstructure that conditions the corrosion resistance and the mechanical behaviour of the coating. The model implemented is partially coupled with the tracking of crystal orientation in solid grains, which allows anisotropy effects to be considered in multidendrite simulations. For this purpose, the composition of a hot-dip ZnAlMg coating is assimilated to a dilute pseudo-binary system. 1D and 2D simulations of isothermal solidification are performed in a finite element solver, and the results are compared with analytical solutions for growth velocity and concentration profiles.