Effects of the heat treatments of solution (T4) and aging (T6) on the variations of the microstructure and the compressive properties of the open-cellular SG91A Al foams are investigated. The Al foams after heat treatments exhibit more stable deformation behavior than that of the as-cast foam. Microstructural observations reveal that the T4 and T6 heat-treatments were over-done in the Al foams, suggesting that the standard heat treatments conditions of the bulk Al alloy are not necessarily suitable for the cellular alloy. A discrepancy between the strength of the cellular Al foams and the bulk Al alloys after heat treatments is observed, that is, the strength of the Al foams decreased after heat treatments. However, the densification strains of the three kinds of foams are approximately identical. Results indicate that the densification strain is independent of the microstructure of cell edge solids. The plateau stresses of the open-cellular SG91A Al foams agree with the Gibson and Ashby model.
International Journal of Materials and Product Technology,
special issue, vol. 2, (2001), pp. 574-579