Compressive deformation and yielding mechanisms in cellular Al alloys determined using X-ray tomography and surface strain mapping

The mechanisms of compressive deformation that occur in both closed and open cell Al alloys have been established. This has been achieved by using X-ray computed tomography (CT) and surface strain mapping to determine the deformation modes and the cell morphologies that control the onset of yielding. The deformation is found to localize in narrow bands having widths of order of a cell diameter. Outside the bands, the material remains elastic. The cells within the bands that experience large permanent strains are primarily elliptical. A group of cells work collectively to allow large localized deformation. Size does not appear to be the initiator of the deformation bands. Equiaxed cells remain elastic. The implications for manufacturing materials with superior mechanical properties are discussed.