Interface microstructures and mechanical properties of foamable precursor sandwiches and aluminum foam sandwiches

In this paper, the aluminum foam sandwich (AFS) was obtained from foamable precursor sandwich (FPS) through a foaming process, in which the preparation of FPS was achieved by compound casting with hot rolling. The effects of rolling and foaming on the interface microstructures and mechanical properties were investigated. Furthermore, the interface bonding mechanisms and strengthening mechanisms were revealed. For FPSs, increasing the rolling pass increased the interface thermodynamic energy, which was beneficial to the achievement of a more effectively bonded interface. Meanwhile, the grains were refined, the fraction of low angle grain boundaries ( f LGABs ) and average geometrically necessary dislocation density ( ρ ¯ GND ) at the interface increased, which collectively contributed to the enhancement of interface bonding strength and ductility. In the foaming process, although the interface thermodynamic energy led to a reduction in the original interface defects and an enhancement in elements diffusion at the pre-existing well-bonded interface, AFSs displayed lower interface bonding strength and ductility compared to their corresponding FPSs due to coarse grains, decreased f LGABs and ρ ¯ GND . Moreover, an analysis of interface strengthening mechanisms revealed that the increase of rolling pass for FPS resulted in an improvement in the interface bonding strength and ductility of the corresponding AFS.