半固态处理对Al-50wt%Si合金初晶硅形貌的影响研究

提高初晶硅的收率是Al-Si合金法制备太阳能级多晶硅的研究热点之一。本文对成分为Al-50wt%Si合金在580℃进行半固态热处理,分析初晶硅的形貌以及Al元素含量的变化。结果表明:随半固态处理时间的增加,初晶硅的尺寸逐渐增大,其原因是在熟化机制的作用下,尺寸为0.15~0.7mm的初晶硅的含量显著增加,这一结果导致初晶硅的收率高于理论收率。同时,经过半固态热处理,片状初晶硅之间的富Al层容易酸洗去除,降低了初晶硅中的Al含量。

Effect of Semi-solid Treatment on the Microstructure of Primary Silicon in Al-50wt;Si Alloy

Increasing the recovery rate of primary silicon from solvent refining of Al-Si melt is an important issue in producing solar-grade multi-crystalline silicon feedstock.In this paper,the influence of semi-solid treatment on the evolution of primary silicon and Al content in primary silicon was analyzed.The results show that the diameter of primary silicon increase with increasing the annealing time.This is attributed to the increase content of primary silicon with diameter of 0.15-0.7 mm,depending on the Ostwald ripe mechanism.Thus,the practical recovery rate of primary silicon is higher than the theoretical value.Meanwhile,the Al-rich layer between plate-like primary silicon is easy to remove in the experienced Al-Si ingots,which decreased the Al content in the primary silicon.