Fabrication and compression properties of functionally graded foam with uniform pore structures consisting of dissimilar A1050 and A6061 aluminum alloys

Functionally graded aluminum foam (FG Al foam) is a new type of Al foam and is expected to improve the performance of Al foam. FG Al foam with a pore structure that varies with the position has been fabricated in the past decade. However, there have been few reports on the fabrication of FG Al foam with varying base materials. In this study, A1050–A6061 FG Al foam with an almost uniform pore structure was successfully fabricated by a friction stir welding (FSW) route precursor foaming method. Stepwise compression tests and continuous X-ray CT nondestructive observation of the pore structures revealed that the deformation of the fabricated FG Al foam started from the A1050 Al foam layer then spread to the A6061 Al foam layer. The stress–strain curves during compression tests revealed differences in compression properties depending on the type of Al alloy in the deformed Al foam layer. The plateau stress was lower during the deformation of the A1050 Al foam layer than during the deformation of the A6061 Al foam layer. The plateau stresses during such deformations were almost the same as those of uniform A1050 and A6061 Al foams. Consequently, it was shown that FG Al foam with varying base materials has the potential to exhibit novel mechanical properties, such as multiple plateau stresses, and controlled deformation behavior, depending on only the strength of the base materials.