Effect of a high magnetic field on the microstructure in directionally solidified Al–12 wt%Ni alloy

Abstract

Influence of an axial high magnetic field (up to 12 T) on the microstructure of the hypereutectic Al–12 wt%Ni alloy has been investigated. Results show that the magnetic field has affected the dendritic arrays significantly. As a consequence, Al 3Ni phases are aligned in such a way that the planes of the primary Al 3Ni phase are perpendicular to the magnetic field direction. Further, X-ray diffraction (XRD) results show that the 〈0 0 1〉-crystal direction of the Al 3Ni crystal orients along the magnetic field direction. During directional solidification under an axial magnetic field, the regular sandwich structure between the primary Al 3Ni phase and the eutectic Al/Al 3Ni phase is formed, and with the increase of growth speed, the size of the Al 3Ni phase and the layer spacing decreases. The above experimental results have been discussed from magnetic and growth anisotropy of the crystal. Moreover, a method to control the crystallization process by means of magnetic field during directional solidification is proposed.