Nondestructive observation of pore structure deformation behavior of functionally graded aluminum foam by X-ray computed tomography

Cellular materials are expected to be used for the components of automobiles and as railway and building materials owing to their lightweight structures and desirable mechanical properties. The newest class of cellular materials consists of functionally graded aluminum (FG Al) foams, in which the properties vary with the position. In this study, closed-cell FG Al foam with a varying pore structure was fabricated and its deformation behavior during the compression tests was nondestructively observed by X-ray computed tomography (X-ray CT). The fabricated FG Al foam had different pore structures (different densities) in the same Al foam. The FG Al foam initially started to deform only in the low-density region, which was followed by deformation in the high-density region. The deformation of the FG Al foam indicated its novel mechanical properties, such as multiple plateau stresses, corresponding to the pore structures of the regions where deformation occurred. Consequently, it was shown that the FG Al foam with a varying pore structure and a seamless bonding interface has the potential to be deformed at a controlled and desired location and with a desired plateau stress.