Separation of Silicon from Coarse Al-Si Melts under Alternating Electromagnetic Field with Varying Frequencies

The separation behaviour of primary silicon from high-silicon Al-Si melts during the directional solidification under alternating electromagnetic field with varying frequencies and pulling rates is investigated. Results show that the separation of Si from Al-Si melts significantly depends on the electromagnetic frequency and the solidification rate of the melts as well. Moreover, the separation and enrichment effects of Si electromagnetic frequency with 3 kHz was superior to 30 kHz during the electromagnetic separation process, which was independent on the initial concentration. The flat and distinct separation interfaces could be formatted by using a relatively low pulling rate of 5 μm/s and a frequency of 3 kHz. Finally, the differential scanning calorimetry analysis showed that the alloy section had good thermal stability in the whole electromagnetic separation process. This method has the prospect and potential of becoming the method for manufacturing low-cost Al-Si alloys after the electrothermal process.