Application of electromagnetic separation of phases in alloy melt to produce In-situ surface and functionally gradient c
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6/28/03
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Application of Electromagnetic Separation of Phases in Alloy Melt to Produce In-Situ Surface and Functionally Gradient Composites ZHENMING XU, TIANXIAO LI, and YAOHE ZHOU The principle of electromagnetic separation of phases (primary phase) in alloy melt is that the electromagnetic force scarcely acts on the primary phases due to its low electric conductivity as compared to the melt. As a result, a repulsive force acts on the primary iron-rich phases to push them to move in the direction opposite to that of the electromagnetic force. The in-situ surface composite and the functionally gradient composite reinforced by primary Si are produced when the hypereutectic Al-Si alloy solidifies under electromagnetic force induced by static magnetic field and DC current. Similarly, the Al-Si-1.20 pct Fe-1.60 pct Mn alloy in-situ surface composite reinforced by primary iron-rich phase is produced. Based on this, a new method for production of in-situ multigradient composite with several layers, by electromagnetic separation of phases and directional solidification technique, is proposed.
I. INTRODUCTION
AT present, the main processes for producing surface composite and functional gradient composite during solidification are casting infiltration,[1,2] electromagnetic stirring to separate eutectic process of the eutectic alloy,[3,4] electromagnetic centrifugal casting,[5,6,7] and centrifugal casting.[8,9] These processes, however, are complicated and require complex equipment. Therefore, they are limited in application. When the alloy melt with low electric conductivity phases solidifies under an electromagnetic field, the electromagnetic force scarcely acts on the low electric conductivity phases because of the different conductivities between the phase and the melt. Thus, the low electric conductivity phase is moved in the direction opposite to that of the electromagnetic force.[10–13] Therefore, in this article, we have studied a new method of the in-situ surface and functional gradient composites produced by the electromagnetic separation of phases. Furthermore, an in-situ multigradient composite with several layers produced by electromagnetic separation of phases and the directional solidification technique is proposed. The aim of this research is to develop a new method for production of the in-situ surface and functional gradient composites by electromagnetic separation of phases. II. EXPERIMENTAL PROCEDURE A. Principle of Proposed Method Fig. 1(a) shows a schematic illustration of the experimental equipment. The principle of an electromagnetic method for producing in-situ surface and functional gradient ZHENMING XU, Associate Professor, TIANXIAO LI, Lecturer, and YAOHE ZHOU, Professor, are with the School of Materials Science and Engineering, and the State Key Laboratory of MMCs, Shanghai Jiao Tong University, Shanghai 200030, People’s Republic of China. Contact e-mail:[email protected] Manuscript submitted September 12, 2002. METALLURGICAL AND MATERIALS TRANSACTIONS A
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