Comparison of infiltration length of Al-Cu-Si/0•12Al2O3 composites and maximum fluidity length of unreinforced matrix alloys

Saffil alumina fibre preforms were infiltrated with Al-Cu-Si alloys, with 5-21 wt-%Cu, to study the effect of Si variation on the microstructure and fluidity along the length of preforms. The fluidity is measured in terms of a classic foundry practice, i.e. the length that liquid metal flows while solidifying, in a channel packed with an alumina chopped fibre preform. The results for fluidity versus composition, combined with microstructural observations, are explained using information from the phase fields indicated by the equilibrium diagram. These are compared with fluidity tests for unreinforced Al-Cu-Si alloys. Although different, both the composites and unreinforced alloys show similar trends, suggesting that the infiltrated length in the preform can be related to the fluidity values of eutectics that complete solidification and the latent heat of the proeutectic phases, which contributes to maintaining the fluid life of the alloy. (C) 2004 W. S. Mancy Son Ltd.