Effect of Intermetallic Phases and Compounds on the Compressive Behavior and Fracture Mechanism of Al–Si–Zn Foams.

In this study, the effects of alloy elements, oxide phases, and created intermetallic compounds of aluminum alloy foams with different percentages of silicon, zinc, and combinations of both these elements were investigated on the compressive properties and fracture behavior of these foams. The results showed that the addition of alloying elements formed intermetallic compounds in the structure of the foam, and the number of intermetallic compounds increased with increasing the percentage of these elements which causes inconsistency between these compounds and base materials. All these factors changed the failure mechanism of these foams so that the failure behavior of pure aluminum foam and zinc-containing foams was a ductile failure, whereas the failure behaviors of silicon-containing foam samples were brittle. The Al–4%Si–4%Zn sample had the highest compressive strength among all of the fabricated samples due to the uniformly distributed intermetallic compounds in the cell wall of these samples, whereas the Al–8%Si, Al–8%Si–4%Zn, and Al–8%Si–8%Zn foam samples were more brittle than the other fabricated foam samples due to the more formation of brittle compounds such as CaAl2Si2 and their accumulation in a certain area which reduced the compressive strength of these foams. Also, it was observed that the energy absorption capacity and yield strength of pure aluminum foam generally increased with the addition of alloy elements due to the increase in the amount of created intermetallic compounds in the structure of these foams. [ABSTRACT FROM AUTHOR]