抄録
Thermit reaction was induced in molten aluminium silicon alloy by addition of coarse silica particles with stirring. Exothermic reaction commenced in the Al-Si eutectic melt at 1023 K. All silica particles were reduced into silicon in a brief period. Reduced silicon resolved into matrix melt. This thermit reaction produced α-alumina particles. These oxides were as large as added silica particles. After solidification, microstructures of specimens exhibited eutectic matrix, large primary silicon crystals and the oxide particles. A series of experiments were executed with magnesium addition before silica particles mixing. Magnesium quickened the dispersion of silica particles into matrix melt. So the thermit reaction occurred more rapidly and the highest temperature attained by the reaction was higher than those attained by the experiments without magnesium addition. The oxide particles resulted by experiments with magnesium showed a proof that the thermit reaction took place from outside to inside of silica particles gradually under high temperature.
