Thin Sample Alloy Solidification in Electromagnetic Driven Convection


Thin Sample Alloy Solidification in Electromagnetic Driven Convection

Kao, A.; Shevchenko, N.; Roshchupinka, O.; Eckert, S.; Pericleous, K.

During the directional solidification of Ga-In25%wt., density variations in the liquid cause plumes of solute to be ejected from the interface through natural convection. This can lead to the formation of chimneys during solidification and ultimately freckles. The application of external magnetic fields can be used to suppress these plumes. Two magnetic systems are considered. The first is a rotating magnetic wheel, which provides conditions analogous to forced convection at the solidification interface. The forced convection causes preferential growth of secondary branches and the plumes to be transported downstream and back into the bulk. The second is the application of a static magnetic field, which interacts with inherent thermoelectric currents, generating a Lorentz force that drives fluid flow within the inter-dendritic region. However, in the bulk, where there are no thermoelectric currents electromagnetic damping dominates and plumes are stunted.

Using a fully coupled transient numerical model a quantitative analysis of each of these systems has been investigated. Figure 1 shows numerical results of the velocity profiles and dendritic morphology for each of these cases. Comparisons to experiments are given for the cases of natural and forced convection. The experimental setup uses a Hele-Shaw cell with an electric heater and Peltier cooler allowing for control over the thermal gradient and cooling rate.

  • Lecture (Conference)
    8th International Congress on Electromagnetic Processing of Materials (EPM2015), 12.-16.10.2015, Cannes, France
  • Contribution to proceedings
    8th International Congress on Electromagnetic Processing of Materials (EPM2015), 12.-16.10.2015, Cannes, France

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Publ.-Id: 21984