Flow Effects on Mush Coarsening

Gradient annealing experiments of a near-eutectic AlCu30 alloy with artificial stirring induced by a rotating magnetic field (RMF) of 6 mT were performed. The specific surface area of the primary phase was measured on metallographic sections perpendicular to the sample axis with a fixed amount of fraction solid. The variation of the specific surface area with fluid flow is compared to flow free experiments: the specific surface area varies as the inverse cube root of annealing time if no RMF is applied, but varies as an inverse forth root at 6 mT. The experimental procedure and results are presented in detail and discussed with models of convective coarsening of dendrites.