Macrosegregation of a Sn–Pb Alloy under Imposition of Oscillating Electromagnetic Force

Abstract

Recycling of metallic products is one of the important technologies for the formation of a resource-recycling society to reduce carbon dioxide emissions. Because most metal waste is an alloy and it usually consists of various elements, an efficient method to separate these elements from the metal waste is required. Separation of solid and liquid under two phase co-existing condition is one of the promising methods since their chemical components are different. Electromagnetic separation is expected for this purpose because large difference between the solid and the liquid in electrical conductivity induces relatively large difference in the electromagnetic force than that in the gravitational force. Thus, solidification experiment using a low melting point binary Sn-10 mass% Pb alloy under different electromagnetic field imposition conditions has been done, and eutectic ratio adopted as an index of solute separation or segregation was evaluated. Obvious segregation was not observed under a static magnetic field imposition condition because it has a flow suppression function. Segregation was enhanced under the condition of simultaneous imposition of the static magnetic field and an alternating current. The degree of the segregation under the no-electromagnetic field condition was intermediate between those under the magnetic field imposition condition and the simultaneous imposition condition. The eutectic size under the simultaneous imposition condition was larger and this might become easier the liquid motion in the latter stage of the solidification.