On the dendritic tip stability parameter for aluminium alloy solidification

The dendritic tip stability parameter σ∗ is estimated for two aluminium alloys, namely Al–4 wt.%Cu and Al–2 wt.%Si, based on recently measured values of their crystal-melt surface energy anisotropy strength and linear scaling of the microscopic solvability theory. The influence of the stability parameter on columnar dendritic growth models of solidification, and consequently on columnar to equiaxed transition (CET), is determined, with the help of modified Hunt CET maps and meso-scale front tracking simulations.