Effect of Zn addition on primary silicon morphology and B distribution in Si–Al alloy

Abstract

Si–Al–Zn alloy melts were used for silicon purification by the solvent refining process. The effect of metal Zn addition on alloy macrostructure, primary Si morphology, as well as B distribution in Si–Al alloy during solvent refining process was studied in this work. The three main results were as follows. First, with the increasing of Zn content in Si–Al alloy, the primary silicon changed from slender plate-like to irregular and short, meanwhile the distribution of primary silicon changed from bottom to central and top. Second, the more Zn content in Si–Al alloy, the more inclusions of eutectic melts will be in primary silicon, which results in diffusion difficulty of impurity B in inclusions. Third and last, with increasing Zn content, the refining ratio of B increased gradually and removal fraction of B decreased accordingly.