Formation and transition of solidification structure in high undercooled Ni-P eutectic alloy

The high undercooling of the NiP eutectic alloys was achieved by glass fluxing technique. With increasing undercooling, the solidification microstructures of the alloys have changed, for example, grain refinement, transformation from regular rod eutectic structure to spherical anomalous eutectic grain structure with particulate morphology; while at higher undercooling, fine regular eutectic structure was observed. The reason of formation of anomalous eutectic group can be explained by the model of single dendritic eutectic phase growth and fusion. Fine regular cellularlike eutectic microstructure formed at high undercooling can be depicted by solid/liquid interface stability theory.