Morphological evolution of solidification microstructure of binary alloy under stirring

Morphological evolutions during the solidification of succinonitrite-5%water (atomic fraction) transparent alloy and Sn-15%Pb (mass fraction) alloy under mechanical stirring were investigated experimentally by in situ observation and quenching, separately. The results showed that the primary solidified microstructures have a globular shape when the strong convection was induced by mechanical stirring. According to the morphological stability theory, the formation mechanism of globular microstructure was discussed. The analysis indicated that the rotation of primary microstructure in a shear flow induced a stabilizing effect on the morphological instability at the solid-liquid interface and promoted the globular growth of solidification microstructure.