Improved energy absorption capacity of Al/Al2O3 foams by the ductile/brittle hybrid deformation mode

Abstract

In the present study, Al/Al 2 O 3 foams were prepared to increase the energy absorption capacity by enlarging the densification strain. Analysis of the mechanical characteristics was performed and the energy absorption ability was calculated on the samples. The deformation process of the inner and outer-layer cells was investigated on the micro- and macro-scales to clarify the optimisation mechanism of the densification strain. The stress–strain curves demonstrated that the ceramic/aluminium foam exhibited an extended plateau region (densification strain of 0.63), resulting in high energy absorption capacity and efficiency. Analysis of the deformation process illustrated that the oxide layer played a dominant role in the brittle deformation of the outer-layer cells. The evolution of crack formation, propagation, and coalescence in cells provided randomly distributed “defects” in foams, resulted in the scattered plastic deformation zones in inner cells. The strain hardening effect of the cell wall was suppressed based on this typical deformation mode of foam, which resulted in increased densification strain and improved energy absorption capacity. Moreover, the Al/Al 2 O 3 foams exhibited superior corrosion resistance compared to the Al foams.