The threshold pressure P-0 for infiltration of Al-12 wt.% Si alloy into compacts of mixtures of alumina and silicon carbide particles having largely different size is investigated. The results are in line with those recently derived from infiltrations of Al into bimodal SiC compacts, namely, P-0 remains almost constant for fractions of coarse particles below that which gives the maximum particle volume fraction, decreasing there onwards down to the value corresponding to coarse particles. The experimental data for P-0 can be reasonably fitted by generalizing an approach, recently developed for SiC bimodal compacts, which gives P-0 in terms of the mixture specific surface area calculated by means of the linear rule of mixtures. (C) 2008 Elsevier B.V. All rights reserved.