Refining mechanism of solidified structure of alloy by electromagnetic refining process

Refining mechanism of solidified structure in which a static magnetic field and an alternating electrical current are simultaneously imposed on the local area of a metal or an alloy, has been experimentally examined using a Sn-10mass%Pb alloy. The refining period of the structure was examined by changing the imposing period of the electromagnetic vibration on the sample and it was confirmed that the refining period was the initial stage of solidification. The refining region was specified to be around the electrodes by inserting a stainless steel wire net in the sample while it was independent of the inserting position of the electrodes. Convection was induced by the electromagnetic vibration because temperature difference in the sample drastically decreased as soon as the vibration was excited in the sample. From these experimental results, the estimated mechanism in this process is that dendrite tips around the electrodes are cut off by the electromagnetic vibration in the initial stage of the solidification and it spread to the whole area of the sample by the convection induced by the electromagnetic vibration. Furthermore, nucleation is induced by an intense electromagnetic vibration.