Microstructure and phase structure of rapidly solidified Al-Si alloy

Rapidly solidified eutectic and hypereutectic Al-Si alloy strips were prepared by rotational quenching technique on a single roller.The microstructure and phase structure of the strips were characterized by means of SEM,TEM and XRD.The results show that the grains are refined obviously after rapid solidification,and eutectic and hypereutectic structure is transformed into hypoeutectic structure.Compared with equilibrium solidification,the nucleation and growth of primary silicon are restrained and the primary silicon can not form.On the other hand,α-Al phase is nucleated prior to eutectic,therefore the microstructure of the strips are composed of primary micro-nanostructure α phase and feather-needle like eutectic(α+si) in the α-Al phase.