Foamed materials are widespread in industry applications. While polymeric foams have been applied for many years foamed metals are now beginning to move into the focus of interest. A powder metallurgical method which allows for the production of aluminium foams with porosity levels up to 90 % is described. The foams typically have closed pores and densities ranging from 0.4 to 1g/cm3, so that these foamed metals float upon water. The unique mechanical properties of metal foams are described. The density dependence of metal foam properties is shown with the Young' modulus, flexural strength and compression strength as examples. A non-linear dependency of these properties on the density is found and discussed The discussion then focuses on the energy absorption properties of aluminium foams and tools to select appropriate foams for a given energy absorption task.
