Directional solidification apparatus with liquid metal cooling medium of Sn was employed to study influence of varied withdrawal rates on directional solidification structure of blade.The results indicate that withdrawal rates play a significant role in directional crystallization structure of blade.The blades formed well with withdrawal rates of 6 mm/min or 8 mm/min.The columnar grains with regular array along longitudinal direction are straight,and the grain size is uniform.With increasing withdrawal rate...