Tagungsbeiträge

The first time metallic foams were mentioned was in 1926 by Alexandre Meller. Since then the understanding of the behavior has developed so the material can be used for special applications. Nevertheless the mechanical properties are bad compared to solid material. Because of the mean variation of the pore size the strength underlays a variation too. A solution can be to reinforce the matrix with fibers so the mechanical properties can be improved and the variation can be reduced. In a first attempt the aluminum powder is mixed with 2 weight percent cleaned glass fibers and a blowing agent (TiH2) and were compacted with a heated compressing tool. After that the preform can be foamed by an alloy adapted heat-treatment. The preform expands to about 500 percent of the primary volume while the fibers are orientated randomly in the metal matrix so the composite keeps its isotropic behavior. Referring to compression tests the mechanical properties improved. The composite is 20% stiffer and 8% stronger than the non-reinforced foam having the same density. Analyzing the failure behavior, all of the fibers got pulled out of the matrix. To reach higher strength and stiffness the adhesion of the matrix and fibers must be improved. A solution can be to use e.g. carbon fibers or other fibers which can build a compound with the matrix material. Combined with a higher share and longer fibers the reinforced foam can be stiffer stronger and level out the influences of the mean variation of the pore size.