The Effect of Fe Additive on Plastic Deformation for Crush-Boxes with Closed-Cell Metal Foams, Part I: Al-Composite Foam Compression Response

In this study, the effect of Fe–intermetallic compounds on plastic deformation of closed-cell composite Aluminum Foam as the filler of thin-walled tubes is investigated. Composite foams of AlSi7SiC3 and AlSi7SiC3-(Fe) as a closed cell were synthesized through powder metallurgy foaming method. Macro and Micro structures of the produced foams revealed a non-homogenous cell which is dependent on Fe-rich intermetallic compounds. The cellular structure of AlSi7SiC3 foam shows a non-uniform and small size of bubbles with a few central big voids in comparison with the AlSi7SiC3-(Fe) foams. The analysis of EDAX (Energy Dispersive Analysis of X-rays) indicate that there are (α+β)-Fe- intermetallic compound within foams with Fe 2 wt. %, and (α+δ)-Fe-intermetallic compound for the foams with Fe 2 wt. %, in which their presence depend on the cooling rate during the solidification of liquid foams. The stress-strain curve of the AlSi7SiC3 foam shows a smooth plastic deformation behavior in the plastic region, throughout the compression tests. However, by increasing the weight percent of Fe from 1 up to 3%, the curve shows some variation at the slope of ln(σ)-ln(ε) curves within the plastic zone. The results obtained indicated that all of the compression response is due to the micro-porosity in plateau region and the presence of the Fe-Al-Si-intermetallic within the cell wall revealed that both of them have the role of a stress concentration point during the compressive loading.