Morphological evolution of non-dendritic microstructure during solidification under stirring

Morphological evolution of non-dendritic microstructure during the solidification of succinonitrile-5%water(SCN-5%Wat) transparent alloy under mechanical stirring was experimentally investigated.The incubation time for the formation of non-dendritic microstructures decreased rapidly and the microstructure was gradually refined with the increase of stirring rate and cooling rate.When the stirring rate and cooling rate were low,the incubation time for the formation of non-dendritic microstructures decreased obviously with the increase of the melt undercooling.When the stirring rate was high,the effect of the melt undercooling on the incubation time for the formation of non-dendritic microstructures was weak.The morphology of primary microstructures had an important influence on the subsequent morphological evolution of these microstructures during the isothermal holding of the melt without stirring.It was found that when there were dendrites in the undercooled melt,the dendrites would be dissolved and the final microstructure would be replaced by the re-nucleated globular crystals if the stirring time was long enough.