Investigation of Thermo-Electro-Magnetic force on equiaxed grain motion during upward directional solidification

It has been shown that the coupling between the magnetic field and the temperature gradient generates a Thermo-Electro-Magnetic (TEM) Force that dramatically modifies the trajectory of the equiaxed grains during solidification of Al -10 wt%Cu metallic alloys. We analyze the motion of equiaxed grains both experimentally by Synchrotron X-ray radiography, and theoretically by numerical modeling. The time evolution of trajectory characteristics, like the deviation angle of the equiaxed grain and the grain velocities, were determined as a function of the temperature gradient, the cooling rate and the direction of the magnetic field. By means of numerical modeling, we performed calculations of the Thermo-Electro-Magnetic (TEM) force and Thermo-Electro-Magnetic-Convection (TEMC) in the liquid acting on a solid particle which mimics an equiaxed envelope. Numerical calculations of the viscous drag force were performed firstly on a dendrite envelope, considering the wall confinement. This allowed us to calculate the terminal grain velocity. It was found that the measured grain velocities, as well as their deflection angle measurements were in good agreement with the numerical predictions.