Effect of a Weak Transverse Magnetic Field on the Microstructures in Directionally Solidified Zn-2.2 at.% Cu Peritectic Alloy

摘要

Effect of a weak transverse magnetic field (B ≤ 0.7 T) on the microstructures in directionally solidified Zn-2.2 at.% Cu peritectic alloy has been investigated experimentally. The results indicate that the magnetic field causes the formation of a transition from the primary dendrite to peritectic phase, macrosegregation of the Cu solute in the primary dendrite, a change in the volume fraction of the primary phase, and the refinement of the primary dendrite. Furthermore, energy dispersive spectrometer (EDS) analysis reveals that the magnetic field increases the Cu solute content in the solid and front of the solid/liquid interface. The Seebeck voltage near the solid/liquid interface in directionally solidified Zn-2.2 at.% Cu alloy at various growth speeds is measured in situ, and the result shows that a thermoelectric current exists near the solid/liquid interface. The thermoelectric magnetic convection (TEMC) in the liquid under the magnetic field is numerically simulated, and the result reveals that a unidirectional TEMC forms in the liquid near the solid/liquid interface during directional solidification under the transverse magnetic field. The modification of the microstructures in directionally solidified Zn-2.2 at.% Cu alloy under the transverse magnetic field should be attributed to the TEMC driven solute transport.