Fig. 1. Experimentally determined Cu concentration contour plot in the directionally solidified Al-4.5 wt.%Cu alloy under various magnetic fields (GT = 60 K/cm and R = 10 μm/s): (a) and (b) Transverse microstructures and experimentally determined Cu concentration contour plot without and with a 12 T magnetic field; (c) Cu concentration versus solid fraction profiles in the transverse sections of directionally solidified Al-4.5 wt%Cu alloys under various magnetic field intensities. The inset at the top right shows relative solute concentration at a solid fraction of 0.85. The below inset is a magnified solute concentration profiles at initial solidification stage.

Fig. 2. SEM-BSE images on the transverse section in the directionally solidified Al-4.5 wt.%Cu alloy under various magnetic fields: (a) 10 μm/s; (b) 20 μm/s; (a1) and (b1) 0 T; (a2) and (b2) 6 T; (a3) and (b3) 12 T; (c) the volume fraction of the eutectic phase as a function of the growth speed without and with a 12 T magnetic field; (d) volume fraction of the eutectic phase as a function of the magnetic field intensity at a growth rate of 10 μm/s.

Fig. 3. Effect of the magnetic field on the liquid-solid interface and the fraction of the solid phase in the mushy zone in the directionally solidified Al-4.5 wt.%Cu alloy at the growth rate of 10 μm/s: (a) 3D-CT reconstruction structures and (b) the corresponding transverse microstructures under various magnetic fields (i.e., 0 T, 0.1 T, 0.5 T and 10 T); (c) and (d) transverse microstructures at various positions in the mushy zone for the samples solidified without and with a 10 T magnetic field; (e) the volume fraction (f) of the α-Al primary phase in the mushy zone as a function of the distance from the liquid-solid interface (L) measured without and with the magnetic field.

Fig. 4. Effect of the magnetic field on the solute diffusion at the liquid-solid and the dendrite core-segregation zone interfaces during directional solidification: (a) One volume element in the mushy zone; (b) schematic diagram of the solute distribution near the liquid-solid interface without and with the magnetic field; black and yellow lines showing the solute distribution in the solid phase without and with the magnetic field; (c) the distribution of the solute Cu in the Al-0.85 wt.%Cu alloy along the axial direction; (d) schematic illustration of the influence of the TE magnetic effects on the solid diffusion; (e) schematic diagram of the experimental setup for the eliminating grain boundary segregation during the heat treatment process under the temperature gradient and the magnetic field; (f) the distribution of the solute Cu and the corresponding structure in the Al-4.5 wt.%Cu alloy during the heat treatment under the temperature gradient and the magnetic field (GT = 60 K/cm).