Behavior of particles in front of metallic solid/liquid interface in electromagnetic field
(Shanghai Enhanced Laboratory of Ferrous-Metallurgy, Shanghai University, Shanghai 200072, China)
Abstract: The first part deals with the behavior of particles theoretically, and the critical electromagnetic force needed to alter the behavior of particles was deduced under different conditions. It was proposed that applying electromagnetic force would change the distribution coefficient of the particles. By using the data from literatures, the migrating rate of SiC particle by electromagnetic force was calculated, which is far more than the critical rate of solidifying interface which will result in the engulfment of the SiC particle in the Al-SiC matrix metal. Therefore the possibility of controlling the behavior of the particles in front of the solidifying interface by electromagnetic field was confirmed. In the second part, by using simulative experiments, the man-made alternation of the behavior of the particles in front of the solidifying interface under electromagnetic field was observed, and the idea of changing the distribution of the particles in solidified metal by electromagnetic force was verified experimentally. It is shown that, the particle, which would be engulfed by the solidifying interface, would escape from the interface under electromagnetic buoyant force (EMBF), and the particles adherent to the interface would migrate toward it and be engulfed finally under EMBF. Further more, the particles being pushed by the interface would stay at the interface, the repulsive force exerted on the particles would be counteracted by EMBF, and then the particle would turn to be engulfed. Adjusting the direction and magnitude of EMBF could alter the distribution of the particles in the solidifying metal.
Key words: solidification; particle; electromagnetic field; pushing/engulfment; distribution of particles