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论文类型：期刊论文

发表时间：2014-10-25

发表刊物：JOURNAL OF ALLOYS AND COMPOUNDS

收录刊物：SCIE、EI、Scopus

卷号：611

页面范围：267-272

ISSN号：0925-8388

关键字：Si purification; Impurity contamination; Si-Al alloy; Zn

摘要：During solidification refining of Si, the eutectic alloy ultimately solidifies and becomes enriched with impurity elements according to their small segregation coefficients, which may contaminate the primary Si through the cooling process. Combined with analysis of the morphology of the primary Si, the contamination mechanism was verified for a Si-63.8 wt%Al alloy using various cooling rates in the final cooling stage (873-293 K). By a quenching treatment, the B content in Si was decreased from the initial content of 14.8 to 1.4 ppmw, which is quite close to the value predicted by Scheil's equation. Si cooled down at a rate of 1 K/min showed an increase in impurity content (e.g., B: 4.2 ppmw) owing to solid-state back-diffusion. In order to prevent such contamination, Zn was added to the Si-Al melt at 873 K, which decreased the eutectic temperature and separated Si from the alloy. A final Si amount of 94.1 wt% was recycled without further contamination. (C) 2014 Elsevier B.V. All rights reserved.