Simultaneous Removal of Silicon and Iron-Rich Phases from Coarse Al-Si Alloys Using Manganese Under Electromagnetic Fiel
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UCTION
CAST Al-Si alloy, due to its high strength, good stiffness, excellent casting and processing performance, has become one of the most widely used materials of cast aluminum alloy and is used for manufacturing various kinds of precision parts, which can be mainly reflected in automobile manufacturing, electronics, aerospace, refrigeration equipment and other fields.[1] At present, the production method of cast Al-Si alloy in
YU BAO, YIBO WANG, TING XIAO, YUNFEI HE and YUFENG ZHANG are with the Faculty of Metallurgical and Energy Engineering, Kunming University of Science and Technology, Kunming, 650093, China, with the The National Engineering Laboratory for Vacuum Metallurgy, Kunming University of Science and Technology, Kunming, 650093, China, and with the Engineering Research Center for Silicon Metallurgy and Silicon Materials of Yunnan Provincial Universities, Kunming, 650093, China. GUOQIANG LV, YUN LEI, and WENHUI MA are with the State Key Laboratory of Complex Nonferrous Metal Resources Cleaning Utilization in Yunnan Province, Kunming, 650093, China, with the Faculty of Metallurgical and Energy Engineering, Kunming University of Science and Technology, with the National Engineering Laboratory for Vacuum Metallurgy, Kunming University of Science and Technology, and with the Engineering Research Center for Silicon Metallurgy and Silicon Materials of Yunnan Provincial Universities. Contact e-mail: [email protected] Manuscript submitted May 27, 2018.
METALLURGICAL AND MATERIALS TRANSACTIONS B
China mainly depends on mixing high-purity aluminum and high-purity silicon proportionally. However, this method incurs higher production costs and greater energy consumption. Low-grade bauxite is industrially adopted as raw materials to produce coarse Al-Si alloys through carbon electro-thermal reduction, and then coarse Al-Si alloys are purified to obtain cast Al-Si alloys, the aluminum content of which is usually more than 55 pct, laying a good foundation of using lowgrade bauxite to produce cast Al-Si alloy. This production process greatly saves electricity energy, the iron content obtained by this method, however, is more than 5 pct, which fails to meet the standards of cast Al-Si alloy.[2] Iron phase is the main harmful impurity in cast Al-Si alloys, penetrating the Al crystal grain in the form of thick acicular structure, which greatly weakens the alloy matrix and impairs the mechanical properties and casting performance of Al-Si alloys. Whereas, there has not been a widely accepted or relatively effective method to remove iron from Al-Si alloy at a low cost in Al industry. Also, every time there is a necessary re-melt procedure of Al-Si alloy, there exists the possibility of increased iron content in the alloy. In Al-Si alloy with different silicon contents, iron-rich phases can exist in the form of Al3Fe and Al6Fe. Generally, there are three main phases combined by Fe, Al, and Si in Al-Si alloy, the phases of Al8Fe2Si and Al5FeSi, which are referred to the a-iron phase and b-iron phase, respectively.[3] The
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