Verification of thermoelectric magnetohydrodynamic flow effects on dendritic tip kinetics by in-situ observations

Magnetohydrodynamic flows can be driven by Lorentz forces acting on thermoelectric currents. Their effects on tip velocities of Pd dendrites solidifying from an undercooled melt under magnetic field intensities of up to 6 T were investigated by in-situ observations using a high-speed camera. At low undercoolings, the tip velocities are depressed by magnetic fields of low and high intensities, but recover under an intermediate magnetic field intensity. At high undercoolings, the tip velocities are also depressed, but their recovery is shifted to a higher magnetic field intensity. These observations on Pd dendrites support and extend the findings obtained in previous studies on Ni and Fe dendrites, and fully verify the convection effects on dendritic growth due to three thermoelectric magnetohydrodynamic flow patterns as predicted in recent numerical simulations. Crown Copyright (C) 2019 Published by Elsevier Ltd. All rights reserved.