铸态亚共晶Al-Si合金中初生硅的生长机制(英文)

利用光学显微镜和电子背散射衍射技术观察亚共晶Al-10%Si合金的微观结构特征。结果表明,在亚共晶合金内很容易发现初生硅颗粒。研究亚共晶Al-10%Si合金溶液中初生硅析出过程中的晶核形成和生长机制,发现硅原子容易偏析并形成Si-Si簇,即使在共晶和亚共晶合金内,这一现象也会导致初生硅的形成。另外,由化学驱动力和较大的堆积碰撞或溶质的凝固偏析等原因引起的溶质再分配在初生硅的形成过程中也起着重要的作用,其中溶质再分配方程由Jackson-Chalmers方程推导而出。一旦硅溶质浓度超过共晶成分,在固/液界面的前端就会析出初生硅。

Growth mechanism of primary silicon in cast hypoeutectic Al-Si alloys

The microstructural features of hypoeutectic Al 10%Si alloy were observed using optical microscopy and electron backscatter diffraction.The results show that primary silicon particles are frequently found in hypoeutectic alloys.Hence,the nucleation and growth mechanisms of the precipitation of primary silicon of hypoeutectic Al 10%Si alloy melts were investigated.It was discovered that Si atoms are easy to segregate and form Si Si clusters,which results in the formation of primary silicon even in eutectic or hypoeutectic Al Si alloys.In addition,solute redistribution caused by chemical driving force and large pile-ups or micro-segregation of the solute play an important role in the formation of the primary silicon,and the solute redistribution equations were derived from Jackson-Chalmers equations.Once Si solute concentration exceeds eutectic composition,primary silicon precipitates are formed at the front of solid/liquid interface.