Experimental study of particle incorporation during dendritic solidification

The attainable undercooling and the solidification microstructures of several combinations of liquid Cu and liquid Ni with different nonmetallic particle dispersions have been studied with respect to the process of particle incorporation. The interaction between the particles and an advancing smooth solidification front is theoretically described by several models, which consider different materials parameters of the liquid and the dispersoids. The results show that some of the model predictions qualitatively hold also for the case of a dendritic solidification front — as present during the solidification process of an undercooled liquid. However the critical velocities for particle engulfment are more than three orders of magnitude larger than predicted by the current models. Moreover, the results indicate that the morphology of the solid/liquid interface and its dependence on undercooling are crucial parameters for the different interaction modes which are not included in the theoretical models for the incorporation process.