In this study mechanical and corrosion behaviours of Al-12Si-XMg alloys (where Mg contents varied up to 20%) have been investigated. The alloys were prepared by casting followed by extrusion at 300 degrees C with a ratio of 1.6. Precipitation of the Mg2Si phases was observed in the Mg containing Al-12Si alloy matrix with two different morphologies; i.e. as a polyhedral primary particle and as a Chinese script. The amount and size of the primary Mg2Si particles increased with increasing the Mg content, which was accompanied by an improvement in hardness and wear resistance but a reduction in corrosion resistance. (C) 2008 Elsevier B.V. All rights reserved.