Evaluation of the formation of the silicon-rich area of hypereutectic aluminum-silicon melts treated with alternating electromagnetic directional solidification

Abstract In order to replace the high energy consumption and high-polluting Siemens method, aluminum-silicon (Al-Si) solvent refining was used by many researcher to manufacture purified silicon. Aiming at evaluating the formation of the Si-rich areas of hypereutectic aluminum-silicon (Al-Si) melt materials, a series of experiments on the effects of silicon separation from hypereutectic aluminum-silicon under different conditions was carried out. Currently, some researchers used the mechanism to explain silicon formation and separation from hypereutectic Al–Si melts during directional solidification (DS), based on Fick's second law. However, the mechanism cannot explain some experimental phenomena. In the present study, the deficiencies of the mechanism were examined and are presented. To explain the formation of Si-rich areas in detail, combinations of hypereutectic aluminum-silicon melts were analyzed to obtain a better understanding of the properties of hypereutectic aluminum-silicon melts. The experiments were used to confirm that the Si separate from hypereutectic Al-Si melts is also a purification process. Moreover, when the sample dealt with a 0.9 mm/min pulling speed under 3 kHz, the silicon content of the Si-rich areas can reach over 80 wt%. Finally, a novel optimized device was developed to obtain better Si separation from the hypereutectic Al-Si melts.