In the present study, the in situ powder metallurgy (IPM) process was employed to prepare a powder feedstock for the fabrication of Al/SiC nanocomposites. Commercially pure (CP) aluminum and Al-2.5 Mg powders accompanied with different contents (0-7 wt.%) of nanosized SiC particles were used as the starting materials. The different chemical compositions of the metallic materials affected their wettability with SiC nanoparticles. This led to different types of participation of reinforcing material in the powder mixture (e.g. blended with the CP Al powders or embedded within Al-2.5 Mg powders). The effects of morphology, microstructure, size, apparent density, flowability, and hardness of the produced powder mixtures on their compaction behavior were investigated. It was concluded that the chemical composition and the percentage of nanometric SiC particles involved in the process affected their aforementioned characteristics. These in turn influenced the powder compaction behavior considerably. The increased reinforcement content reduced the densification of CP Al and Al-2.5 Mg based composite powders differently. The density-pressure data were fit reasonably with all the compaction equations explored, but the highest correlation factor was obtained by the Ge equation. The plastic deformation capacity of powders could be predicted reasonably by using the Heckel and Panelli-Ambrozio Filho equations. (C) 2013 Elsevier B.V. All rights reserved.