Thermoelectric current and magnetic field interaction influence on the structure of directionally solidified Sn–10 wt.%Pb alloy

• Directional solidification of Sn–10 wt.%Pb alloy under magnetic field.
• Thermoelectromagnetic velocity order of magnitude is estimated.
• At low pulling velocities structure change due to magnetic field is more profound.
• Significant segregation appears perpendicular to field direction in transverse field.

In this experimental work Sn–10 wt.%Pb alloy is directionally solidified in Bridgman setup at various growth velocities (from 0.5 μm/s to 20 μm/s) under transverse 0.4 T magnetic field. Temperature gradient of 8 K/mm is maintained perpendicular to the solidification direction during experiments. Liquid phase convection and its influence on the structure and segregation of an alloy, caused by magnetic field and thermoelectric current interaction (thermoelectromagnetic convection or TEMC) is studied experimentally and estimated theoretically in this work. Detailed velocity order of magnitude estimation is carried out. Besides optical microscopy, component distribution along the diameter of the sample is quantitatively measured by scanning electron microscopy. Results show that significant influence on the macrosegregation and dendrite spacing of a metallic alloy is achieved if sample is solidified with applied transverse magnetic field at low solidification velocity.

Structure of directionally solidified Sn–10 wt.%Pb alloy at solidification velocity of 0.5 μm/s. (a) without magnetic field; (b) with 0.4 T transverse field.Figure optionsDownload as PowerPoint slide