Effect of a transverse magnetic field on the macrosegregation and the growth of the Sn dendrite in the directionally solidified Sn-Pb alloys was investigated experimentally. The results indicated that the magnetic field modified the shape of the liquid/solid interface and the dendrite morphology significantly. Indeed, the application of the magnetic field caused the formation of the sloping interface and the refinement of the dendrite. It is also found that the magnetic field decreased the mushy zone length. These effects were enhanced with the increase of the magnetic field intensity and the decrease of the growth speed. Further, the Seebeck thermoelectric force (E-s) at the liquid/solid interface in the Sn-20 wt %Pb alloy was measured in-situ and the results indicated that the value of the Seebeck thermoelectric force was about 1 mu V. The modification of the solidification structure during directional solidification under the magnetic field may be attributed to the interclendritic thermoelectric magnetic convection (TEMC). (C) 2014 Elsevier BM. All rights reserved.