New approach to lightweight construction: Light aluminium extruded profiles with magnesium core
23.09.08 -A research team from TU Berlin is currently developing materials based on aluminium and magnesium aimed at reducing weight. Practical applications are envisaged in car bodies, which still account for 30 per cent of the total weight of an average vehicle. About half of this figure is attributable to structural parts that could be designed to be much lighter with magnesium components. Prof. Walter Reimers from the Institute of Materials Science and Technologies at TU Berlin is conducting research in this field.
Although considerable weight savings can be made in the body using aluminium profiles, the researchers see potential for further savings. If a magnesium billet is clad with aluminium and then extruded, a lighter profile is produced that still has the good processing characteristics of aluminium. In this way, flat dies could also be used to produce initial shapes for subsequent rolling.
In the transition zone between the two materials, pressure and temperature lead to the formation of an intermetallic phase that is extremely thin; one such phase comprises 17 magnesium atoms to every 12 aluminium atoms. Computer-generated forming parameters are subjected to optimisation in the extrusion press until an intermetallic phase is obtained that provides the best possible bond between the aluminium shell and the magnesium core and the aluminium completely encases the magnesium core to protect it against corrosion. Reimers promises engineers a material that looks like aluminium and can be processed like aluminium, but which is almost as light as pure magnesium.