Control of solidified structure of cast metal by imposing electromagnetic field

In order to improve the quality of cast metal and to control solidification of metals, two new casting processes controlling metal solidification by imposing electromagnetic field are developed. One is simultaneous imposition of multiple-electromagnetic fields from the outside of a cold-crucible copper mold during continuous casting of Sn-4.5 mass% Pb alloy, and the other is the imposition of a rotating magnetic field during the unidirectional solidification to make in situ surface composite with special mechanical and physical properties. The experimental results show that multiple-electromagnetic fields can not only eliminate surface defects, but also improve solidification structure of cast metal. Moreover, a new kind of composite pipe and gear of Al-12.6 mass% Si eutectic alloy was made by imposing electromagnetic stirring during unidirectional solidification. This suggests a new method of making surface composite with special mechanical and physical properties. It is also found that a separated eutectic occurs in the anomalous eutectic and the separated phase is the leading faceted phase with solution entropy over 23 J/mol K.