Morphology Evolution Mechanism of α-Al Dendrite of Hypoeutectic Al-7%Si Alloy Regulated by Low Voltage Alternating Current Pulse
LI Ning 1, ZHANG Limin1, XING Hui1, ZHANG Rong1, YIN Pengfei2, WU Yaoyan1, WANG Juan1, LIU Hainan1
1 Key Laboratory of Space Applied Physics and Chemistry, Ministry of Education, School of Science, Northwestern Polytechnical University, Xi’an 710072; 2 College of Science, Sichuan Agricultural University, Ya’an 625014
Abstract: The α-Al dendrite morphology evolution law of hypoeutectic Al-7% Si alloy under low voltage alternating current pulse (LACP) has been investigated in this paper. The distribution of current pulse and electromagnetic force in the alloy melt were numerically simulated. LACP of different current density was imposed in whole solidification process of the alloy and the wire metal tube was embedded in sand mould to restrain the melt convection. The mechanism of microstructure regulated by LACP was analyzed. The results show that the degree of refining of α-Al dendrite was aggravated with the increase of current pulse density in cas-ting samples of without wire metal tube and outside of wire metal tube and inside of wire metal tube. However, some of α-Al dendrites turn into rosiness from dendritic is related to the current density of LACP and location. There were significant differences in the morphology of the α-Al dendrite between casting samples of without wire metal tube and outside of wire metal tube and inside of wire metal tube. The analysis suggests that the change of α-Al dendrite was caused by melt convection resulted from the pulse electromagnetic force. The α-Al morphology can be predicted through calculating the Reynolds number of alloy melt, after Al-7% Si alloy was treated with different current density LACP.
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2018, Vol. 32 
