A MICROMECHANICAL SOLIDIFICATION HEAT-TRANSFER IN ONE-DIMENSIONAL AL-AL2O3 COMPOSITE AND ITS CONSEQUENCE ON MICROSTRUCTURE EVOLUTION

One dimensional heat transfer during solidification of aluminum melt, with and without alumina particles, has been investigated by the finit e difference technique. The results indicate that in the region surrou nding the particle, the temperatures are higher as compared with those in absence of particles. The solidification front slows down consider ably in the vicinity of alumina particles. A larger particle is more e ffective in slowing down the solidification front than a small particl e or a cluster of two smaller particles of the same total length. The slowing down of the solidification front may be responsible for the ob servation that the alloy around the ceramic dispersoids is the last fr action to freeze.