A model for distribution of aluminum in silicon refined by vacuum directional solidification

We propose a simple numerical model for distribution of Aluminum (Al) in silicon ingot during vacuum directional solidification, including segregation from silicon crystal to silicon melt as well as evaporation from silicon melt to vacuum atmosphere. According to the model, the effective segregation Keff and the total evaporation coefficient kT(Al)of Al under the experimental conditions are 0.0137 and 2.6755 × 10−6 m·s−1, respectively. In comparison with experimental results, the segregation of Al is dominated at the beginning of solidification, whereas at the last stage of solidification the removal of Al is mainly depended on the evaporation. It is also found that the critical influences on aluminum removal during vacuum directional solidification are temperature and solidification rate. ▶ We propose a distribution model of Al in Si by vacuum directional solidification. ▶ The model includes two parts: segregation of Al and evaporation of Al. ▶ The validity of the model is conformed by comparing with the experiment results. ▶ The Al content in Si ingot decreases with increasing temperature. ▶ Solidification rate mainly affect the segregation of Al.