EBSD Study on the Effect of a Strong Axial Magnetic Field on the Microstructure and Crystallography of Al-Ni Alloys During Solidification

The effect of a strong magnetic field on the microstructure and crystallography of the primary and eutectic Al₃Ni phases in Al-Ni alloys was investigated by using EBSD. The results show that the magnetic field significantly affected the microstructures and crystallography during both volume and directional solidification. As a result, the Al₃Ni primary phases were aligned with the 〈001〉 crystal direction along the magnetic field and formed a layer-like structure. The magnetic field intensity, solidification temperature, growth speed, and alloy composition played important roles during the alignment process of the Al₃Ni primary phase. Indeed, the alignment degree increased with the magnetic field and the solidification temperature during normal solidification. Moreover, the effect of the magnetic field on the crystallography of the Al-Al₃Ni eutectic in the Al-Ni alloys was also studied. The applied magnetic field modified the orientation of the preferred growth direction of the Al₃Ni eutectic fiber and the crystallographic orientation relationship of the Al-Al₃Ni eutectic. The orientation of the preferred growth direction of the Al₃Ni eutectic fiber depended mainly on the solidification direction and the alignment of the Al₃Ni primary phase. Furthermore, a method for controlling the crystallization process by adjusting the angle between the solidification direction and the magnetic field was proposed.