The microstructure and electrical conductivity of aluminum alloy foams

Closed-cell aluminum alloy foams were produced by applying the powder metallurgical technique, i.e. by mixing metal powders and foaming agent (titanium hydride powder) and compacted them into a dense foamable precursor and the foamable precursor material expanded by heating it up to above its melting point. The important geometric parameter that affects the properties of foams, such as cell diameter, edge thickness and edge length, has been examined. The effect of porosity and cell diameter on the electrical conductivity of foams was investigated and the results were compared with a number of models. It was found that the percolation theory can be successfully applied to describe the dependence of the electrical conductivity of aluminum alloy foams on the relative density. The cell diameter has a negligible effect on the electrical conductivity of foams.