Crystallographic effect of a high magnetic field on a solidified hypoeutectic Zn–Al alloy

Hypoeutectic Zn–4.45 wt% Al solidified under a high magnetic field was investigated crystallographically. With the field, the primary zinc-rich β phase is distributed homogeneously and orients with thecaxis perpendicular to the magnetic field direction. These results are attributed to the magnetic viscosity resistance force and the magnetocrystalline anisotropy of zinc, respectively. The orientation modification also leads to a preferential alignment of the flat-shaped primary β dendrites. Furthermore, with the field, the eutectic β phase shows an orientation character similar to that of the primary β phase. This arises from its continuous growth with the primary β phase. In addition, a specific crystallographic orientation relationship ({0001}β||{111}α, 〈1\overline 210〉β||〈110〉α) exists in some of the eutectics (between the eutectic zinc-rich β and aluminium-rich α phases). However, this orientation relationship is related to the distribution of primary β dendrites, which originates from the independent nucleation of the pseudo-primary α phase attached to the primary β dendrites.