Nanostructure distribution in multilayered Al alloy sheets analyzed by quantitative small-angle X-ray scattering tomography

For composites composed of similar/dissimilar metallic materials, the local strength is determined by their local micro/nanostructures. In this study, two square pillars cut from Al/Al-Zn/Al and Al-Mg/Al-Zn/Al-Mg multi-layered sheets are investigated nondestructively by small-angle X-ray scattering (SAXS) tomography utilizing a pencil beam with a diameter of 20 mu m. The absolute values of the attenuation coefficients are estimated successfully without standard specimens on 20-mu m-thick cross sections of the pillars. The absolute SAXS intensity profiles are reconstructed for the first time on both multilayers. The distributions of the constituent elements and local nanostructure parameters are assessed subsequently. The results indicate that the nanostructures in the multilayered sheets fluctuate two-dimensionally on the cross sections. The local hardness distributed on the same cross section is estimated using the results for the binary multilayer. This study shows that SAXS tomography is a promising method for investigations on composites with nanostructures fluctuating on a mesoscopic scale.