Aluminium foams for lighter vehicles

Metallic foams have become an attractive research field both from the scientific viewpoint and the prospect of industrial applications. Various methods for making such foams are available. Some techniques start from specially prepared molten metals with adjusted viscosities. Such melts can be foamed by injecting gases or by adding gas-releasing blowing agents which decompose in-situ, causing the formation of bubbles. A further way is to start from solid precursors containing a blowing agent. These can be prepared by mixing metal powders with a blowing agent, compacting the mix and then foaming the compact by melting. Alternatively, casting routes can be used to make such precursors. The unique properties of foams promise a variety of applications in vehicle design ranging from light-weight construction, impact energy absorption to various types of acoustic damping and thermal insulation. Four applications are discussed, including a lifting arm on a lorry, an automobile and a train crash box, and a motor bracket.