Mushy zone morphology during directional solidification of Pb-5.8 wt pct Sb alloy

The Pb-5.8 wt pet Sb alloy was directionally solidified with a positive the rmal gradient of 140 K cm(-1) at a growth speed ranging from 0.8 to 30 mu m s(-1), and then it was quenched to retain the mushy zone morphology. The m orphology of the mushy zone along its entire length has been characterized by using a serial sectioning and three-dimensional image reconstruction tec hnique. Variation in the cellular/dendritic shape factor, hydraulic radius of the interdendritic region, and fraction solid along the mushy zone lengt h has been studied. A comparison with predictions from theoretical models i ndicates that convection remarkably reduces the primary dendrite spacing wh ile its influence on the dendrite tip radius is not as significant.