Magnetically Damped Convection During Solidification of a Binary Metal Alloy

Abstract

The transient transport of momentum, energy, and species during solidification of a Pb-19percent Sn alloy is numerically simulated with and without magnetic damping. The system is contained in an axisymmetric, annular mold, which is cooled along its outer vertical wall. Since thermosolutal convection accompanies solidification and is responsible for final macrosegregation patterns, application of a steady magnetic field, which is parallel to the axis of the mold, has the potential to reduce macrosegregation by damping buoyancy-driven flow during solidification. Results show that, during early stages of solidification, the magnetic field significantly affects thermally driven flow in the melt, as well as interactions between thermally and solutally driven flows. However, interdendritic flows and macrosegregation patterns are not significantly altered by moderate magnetic fields. Scaling analysis reveals that extremely strong fields would be required to effectively dampen convection patterns that contribute to macrosegregation.

Modeling and measurements of heat transfer phenomena in two-phase PbSn alloy solidification in an external magnetic field

“…where K0 =2.8.10 -ll m 2 [13]. The solutal and thermal expansion coefficients fls and fir were set 0.354%wt -i and 1.09.10 -4 K -1 respectively.…”

“…In order to define the volume fraction of liquid, the set of equations (6), (8) -(12) is solved iteratively. To avoid oscillations, arising from the volume fraction calculation on the liquid/mush-and solid/mushboundaries, the following relaxation is used: e = (1-aE).e* +ae -e (13) where ae is the relaxation factor which was set equal to 0.5. e* is the liquid volume fraction of the previous iteration.…”

“…The influence of a time-harmonic (a.c.) magnetic field on the Pbl9%wtSn alloy solidification was studied numerically in a 2D geometry in [13]. It was shown that turbulence, induced by the electromagnetic stirring, has a significant effect on solidification.…”

Solidified Structure Control of Metallic Materials by Static High Magnetic Fields

“…Following this attempt, numerous studies were carried out on understanding the mechanism of such effect and its operating parameters using both the numerical simulation [3][4][5][6][7][8] and experimental [9][10][11][12][13][14][15][16] methods. This understanding led to various techniques to improve the quality of the crystal which has an electroconducting or partially electroconducting nature using a magnetic field.…”

Effects of Uniform and Gradient High Magnetic Fields on Gravity Segregation in Aluminum Alloys

“…[7][8][9] The previous studies show that the high magnetic field can affect the solute distribution during solidification process. 8,[10][11][12] Results of experiments using low magnetic fields 13) and numerical modeling 14) indicate that the magnetic field can suppress gravity segregation in term of Lorentz force. The segregation in solidified structure is associated with both the nature of the solute and the magnetic intensity and gradient.…”