Investigation of liquid phase motion generated by the thermoelectric current and magnetic field interaction

I. Kaldre^{1, 2} - Y. Fautrelle¹ - J. Etay¹ - A. Bojarevics² - L. Buligins³

¹ SIMAP-EPM, PHELMA-Campus, BP75, 38402 St Martin d'Heres Cedex, France
² Institute of Physics University of Latvia, 32 Miera str., LV-2169, Salaspils, Latvia
³ University of Latvia, Faculty of Physics and Mathematics, 8 Zellu str., LV-1002, Riga, Latvia

Abstract
At the crystallization front of a metallic alloy, temperature variations can exist on length scales comparable with the dendrite spacing order of magnitude, which means that a large temperature gradient can exist locally. This can lead to a thermoelectric current circulation near the solidification front. When an external magnetic field is applied, a Lorentz force appears and a flow of the liquid phase is initiated (thermoelectromagnetic convection). This flow may influence the heat and mass transfer conditions in the melt, which can eventually lead to changes in the grain and dendrite structure of the metal. Our experiment was prepared to experimentally observe and investigate thermoelectromagnetic convection on the macroscopic scale. The experimental setup consisted of a cobalt needle, which represented the sold phase inhomogeneity and was surrounded by the GaInSn eutectic alloy, which stood for the liquid phase. The magnetic field influence on the temperature distribution was measured using thermocouples, and the current and the temperature distributions were mathematically modeled and theoretically described. Tables 1, Figs 9, Refs 6.