Removal of aluminum from silicon by electron beam melting with exponential decreasing power

• Directional solidification of silicon was achieved by electron beam with exponential decreasing power.
• The removal efficiency of aluminum was improved by this method.
• The loss of silicon was reduced by more than 52%.
• The energy consumption was reduced by more than 54%.

Aluminum is one of the main impurities in silicon, which can be separated and eliminated by electron beam melting. However, high removal efficiency can be obtained only by increasing melt temperature or extending refining time, resulting in high energy consumption. In this work, the directional solidification of silicon was achieved by electron beam with exponential decreasing power, considering that aluminum has both characteristics of segregation and evaporation. The distributions of aluminum show increasing trend from the bottom to the top of the electron beam melted silicon ingot, which is the same as that after traditional directional solidification. The removal efficiency is improved by the coupling of segregation and evaporation. Compared with traditional electron beam melting, the loss of silicon reduced by more than 52% and the energy consumption reduced by more than 54%. This method is more effective to remove aluminum from silicon with low energy consumption.