Influence of a high magnetic field on the precipitation behavior of the primary Al3Fe phase during the solidification of a hypereutectic Al-3.31 wt% Fe alloy

Influences of high magnetic fields on the precipitation behavior of the primary Al3Fe phase during the solidification of a hypereutectic Al-3.31 wt% Fe are investigated. Under the uniform field the primary crystals tend to be distributed homogeneously, whereas under the positive gradient field they move upward in the specimen. Under both cases, they tend to align with [100] parallel to the field direction. The field also induces axial bifurcation of the primary crystals, gives rise to the formation of transverse cracks in the primary crystals and increases the number of nuclei. The homogeneous distribution of the primary crystals in the uniform field and the upward movement in the gradient field are attributed to the respective magnetic viscosity resistance force and the magnetization force. The alignment results from the magnetic torque due to the magnetic anisotropy of the primary crystals. The bifurcation and the cracks are related to the thermoelectric magnetic force and the linear shrinkage coefficient difference between the Al solid solution and the primary Al3Fe phase. The increased number of nuclei arises from the detachment of the primary crystals and the suppression of the descent of the original primary crystals in the initial material and the Fe solute diffusion by the field.

► Effect of high magnetic field on precipitation behaviors of Al3Fe phase is studied.
► Uniform magnetic field tends to homogenize distribution of Al3Fe.
► Field tends to align Al3Fe with [100] parallel to the field direction.
► Field induces bifurcation, cracks and increase of nucleation amount of Al3Fe.
► Twinning, heat flow and preferred extension direction affect orientation of Al3Fe.