Effect of cenosphere content on the compressive deformation behaviour of aluminum-cenosphere hybrid foam

Al-cenosphere closed cell hybrid foams (HFs) of varying relative densities were made by melt foaming method through stir casting technique. In order to investigate the effect of cenosphere content on the compressive deformation behaviour of HFs, varying amounts of cenospheres (18, 25, 30 and 35 vol%) was used as thickening agent and CaH2 (0.6 wt% of alloy) was used as foaming agent. Two types of pores come in this hybrid foam: (i) micropores due to the hollow cenosphere and (ii) macropores due to the entrapment of gas generated. The results showed that the cenospheres particles were uniformly distributed in the cell wall. It was noted that the addition of cenospheres improved the yield strength, the plateau stress, and the energy absorption capacity of HFs, up to a 30 vol% of cenosphere. Further increase in cenosphere content leads to reduction in the plateau stress and the energy absorption capacity of HFs. It is interestingly noted that the densification strain is almost invariant to the cenosphere volume fraction. Attempts are also made to empirically correlate the deformation response with the cenosphere volume fraction and relative density.