Effects of Electromagnetic Vibration Frequencies on Microstructure and Tensile Properties of Al-15 Wt Pct Sn Alloy in Se
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AL-SN alloys are well known for their excellent tribological and mechanical properties,[1] which require Sn-rich phases to be distributed in the Al matrix uniformly.[2] However, due to the limited solubility of Al-Sn alloys, strong sedimentary and inverse segregation tendency will come out in the conventional casting of Al-Sn alloys.[3,4] In order to produce the Al-Sn alloy with a homogeneous microstructure, different preparation methods[5–8] have been developed. It was found that the imposition of the electromagnetic vibration (EMV) had positive effects in weakening the segregation and refining the grains during the solidification process. Vives[9,10] applied the EMV technique to process Al-based alloys. He found that the equiaxed grains with small size rather than the coarse dendrites appeared when the amplitude of electromagnetic pressure reached
YUNBO ZHONG, HUAI WANG, YINGBIN WANG, JIANG WANG, ZHE SHEN, TIANXIANG ZHENG, DONGSHENG ZHU, WEILI REN, ZUOSHENG LEI, ZHONGMING REN, and JINGWEN HUANG are with the State Key Laboratory of Advanced Special Steels, Shanghai University, Shanghai 200072, China. Contact e-mail: yunboz@staff.shu.edu.cn Manuscript submitted October 5, 2016. METALLURGICAL AND MATERIALS TRANSACTIONS A
to a specific value. Moreover, this technique was applied in the continuous casting of Al-based alloys. Li et al.[11,12] found that the refined equiaxed grains were yielded in a specific frequency range when the EMV was imposed in the solidification process of the Mg alloy and the Al alloy. Zhao et al.[13,14] found that the dendritic grains were refined at a low frequency of the electromagnetic field. The macrosegregation and solute content inside the grains were improved after the continuous casting process of the Al alloys. Due to the difficulties in applying a whole domain EMV in the large industrial casting process, a local EMV technique was proposed.[15–17] In this technique, the magnetic field and the current were applied in a local volume of the melt, which had evidently refined the grains in Sn-10 wt pct Pb and Al-6 wt pct Si alloys. The refined microstructure appeared at the vicinity of the electrodes during the initial stage of the solidification process. Meanwhile, the local EMV can inhibit the segregation of the Sn-10 wt pct Pb alloy.[18] However, the affected zone of the local EMV on the grain refinement was still limited to a certain extent near the electrodes. If the size of the ingot becomes larger, the solidification process will not synchronize at different locations. Therefore, it is necessary to impose the EMV on the multi-position of the melt.
In this paper, the slabs of the Al-15 wt pct Sn alloy were produced by the semi-continuous casting. The technique of the multi-position EMV with different current frequencies was imposed during the semi-continuous casting process. The metallographic structure, inverse segregation, and tensile properties of the slabs obtained under different conditions were analyzed. The effects of the EMV with different frequencies on the refinement of the macrostructu
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