Microstructure Evolution in Solidified Al–Si Hypereutectic Alloys Under the Impact of an Electric Current Pulse
Investigating the structure evolution of silicon phase in Al–Si alloys in the extra energy field is of high importance to understand and control the growth behavior of faceting phases. The present paper focuses on the influence of an electric current pulse (ECP) on the structure of directionally solidified Al–20.5 wt%Si hypereutectic alloy. Experimental results showed that ECP had a great impact on the structures of silicon phase. The interconnected, porous primary silicon structure was observed in the initial growth period, accompanied by a small quantity of eutectic silicon directly growing from the primary silicon. In the following growth period, it was surprisingly found that the numerous complex regular silicon and eutectic silicon structures appear instead of the primary silicon. On the other hand, the reference sample without ECP showeds that the structures were composed of several coarse plate-like primary silicon and eutectic structures. The variation of silicon structures indicated that the solidification behavior of faceting phases was remarkably modified by ECP, which may be due to the forced melt flow generated by the electromagnetic force.
KeywordsAl–Si alloy Structure evolution Solidification Electric current pulse
The authors gratefully acknowledge the financial supports from the Shanghai Sailing Program (Grant no. 17YF1405600), National Natural Science Foundation of China (Grant no. 51704192, 51320105003), Science and Technology Commission of Shanghai Municipality (Grant no. 14DZ2261200).
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