In this study, by the technique of mechanical alloying (MA), aluminium-based composite reinforced contained various amounts of Al4C3 particles, depending on MA time, were produced. The machinability of metal-matrix composites (MMCs) was characterised by the investigation of chip formation, cutting forces and surface roughness. XRD, SEM and mechanical properties of the block samples produced by powder metallurgy technique were investigated. It was found that increasing the duration of mechanical alloying resulted in the formation higher amounts of Al3C4 particles which therefore raised the hardness, but on the contrary decreased the transverse rupture strength of the samples. During the machining of MMCs, elemental and arc chips formation were observed. High volume fraction of Al4C3 in the matrix decreased formation of built-up edge (BUE) and surface roughness at high cutting speeds. Furthermore, it was concluded that the effect of Al4C3 on the crack formation in shear plane, reduced the cutting force, shortened the chip contact length and the chip segment thickness. (C) 2002 Elsevier Science Ltd. All rights reserved.