Effects of process parameters and alloy compositions on the pore structure of foamed aluminum

A study was carried out to understand the dependence of the structures of foamed aluminum (FA) on the process variables and to seek an effective measure to overcome the difficulties in preparation of FA by melt foaming process. The following variables were examined: thickening-stirring time, addition of thickening agent, foaming temperature, addition of foaming agent, and the solidification behavior of the alloy. It was found that the slurry viscosity and foaming temperature have very strong effects on the density of FA. Selecting a suitable thickening agent for a required density is very important. Excessive high foaming temperature would result in unnecessarily large pores and non-uniform distribution. It may become easier to obtain a uniform pore distribution if selecting an alloy that has a wider solidification range.