Dendritic to seaweed morphology transition in isothermal solidification of Al–Cu alloys: II. Flow effects

A phase-field model for diffusion-limited crystal growth is extended by a lattice-Boltzmann approach to investigate isothermal solidification of aluminum-copper (Al-Cu) alloys under a constant cooling rate, including effects of the melt flow. In particular, we study the influence of convection on a morphological transition from dendritic to seaweed growth, previously established for purely diffusive growth, that arises when the undercooling exceeds a critical threshold. The results reinforce the importance of side-branching activity in the morphology transition, as both side branching and the transition can be suppressed by melt flow under certain conditions. Implications for the theory of morphology transitions and the nature of the phase transition are outlined.