Infiltrations of SiC powder (SiCp) preforms by a series of Al-based melts have been carried out in a pressure vessel. Effects of alloying additions (Pb, Mg, Cu and Si) on amount of porosity in the infiltrated preforms were investigated. The porosity measurements were carried out by image analysis using an optical microscope in conjuction with a computer having image analysis software programs. The relationship between the amount of porosity was evaluated in the lights of present understanding of the wetting behaviour of the components. Additions of Pb, increased the porosity while Cu, and Si addition did not effect it appreciably. The porosity were significantly reduced by increasing Mg content of Al. (c) 2005 Elsevier B.V. All rights reserved.