Effect of Fe additive on plastic deformation for crush-boxes with closed-cell metal foams, Part I: Al-composite foam compression response

AbstractIn this paper, we investigate effect of Fe–intermetallic compounds on plastic deformation of closed-cell composite Aluminum Foam as filler of thin-walled tubes. However, deformation of the Aluminum foam-filled thin-walled tubes as crushed-box will be presented in Part (II). Composite foams of AlSi7SiC3 and AlSi7SiC3-(Fe) as closed cell were synthesized by powder metallurgy foaming method. Macro and Micro structures of the produced foams revealed a non-homogenous cell 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. Analysis of EDAX results show, 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. %, which presence of them, depended on the cooling rate during solidification of liquid foams. The uniaxial compressive stress–strain curves of the filled thin-walled tubs with the composite closed cell foams will be investigated in next part. The stress-strain curve of the AlSi7SiC3 foam shows a smooth plastic deformation behavior in the plastic region, throughout the compression tests. However with increasing the weight percent of Fe from 1 up to 3%, the curve shows some variety at the slope of curves within the plastic zone. Results shown all of the compression response is due to the micro-porosity in plateau region and presence of the Fe-Al-Si-intermetallic within the cells wall that both them have the role of a stress concentration point during compressive loading.