This study investigates the material behaviour and processing windows for selective laser melting (SLM), an additive manufacturing (AM) process, to directly fabricate net-shape Al metal matrix composite parts from Al/5wt.%Fe2O3, Al/10wt.%Fe2O3 and Al/15wt.%Fe2O3 powder mixtures. The processing windows of laser powers and scanning speeds are plotted in relation to the resulting surface roughness, density and hardness of SLM specimens. It is found that the in situ reaction of Al/Fe2O3 powder mixtures significantly influences the SLM processability and manipulates the range of applicable processing parameters for the direct production of particle reinforced Al matrix parts. The in situ reaction (affected by the proportion of Fe2O3 additive to the powder mixture) releases extra heat and collaborates with laser energy which can modify the visual surface and microstructural appearance or alter material characteristics in SLM processing windows. Higher Fe2O3 content leads to an increase in hardness, but a decrease in density of the SLM samples may occur. (C) 2012 Elsevier B.V. All rights reserved.