부산대학교 도서관

The solidification processes for Sn-2Ag alloy and Sn-2Ag-0.6Zn alloy have been directly observed in-situ using time-resolved X-ray imaging at SPring-8. In case of low cooling rate, the solidification condition is in coupled zone, the primary (β-Sn) has been overgrown by the eutectic structure. In case of other cooling conditions, the solidification of primary (β-Sn) dendrites and interdendritic eutectic structure have been observed. The dendrite tip radii have been characterized. It was found that the dendrite tip radius decreased as the growth velocity increased. The tip radius in Sn-2Ag-0.6Zn alloy is found to be smaller than that in Sn-2Ag alloy, when the growth velocity is the same. The values of tip radius agreed well with the previous results which were obtained using the unidirectional solidification and quenching technique.