Study on the Solidification Structures of Al-Fe-Si Alloy under DC and AC Magnetic Fields

The effects of DC and AC magnetic field on the phase composition, morphology and distribution of the ternary Al-Fe-Si alloy were investigated. The solidification structures of the alloy solidified with and without the application of magnetic fields were confirmed by DSC and structural measurements. The results showed that, in this Al-Fe-Si alloy the fine needle-like Al(3)Fe phase dominated the microstructure at the grain boundaries with the minor amount of Chinese script-like alpha-AlFeSi. Distribution of Al(3)Fe phase was almost homogeneous in the volume of the sample when alloy was solidified in the conventional condition. When the DC magnetic field was imposed, distribution of Al(3)Fe phase was more homogeneous. However, the Al(3)Fe and alpha-AlFeSi phases were accumulated towards the center of the sample with the application of the AC magnetic field. This is due to the difference of Lorentz force between Al matrix and iron-containing intermetallics. Furthermore, the amount of Chinese script-like alpha-AlFeSi was increased remarkably under AC magnetic field.