Studies of Nanovoids in Quenched Aluminum Using SAXS Techniques

A small angle X-ray scattering (SAXS) study of quenched-in nanovoids in 99.988 and 99.995 at.% aluminum (Al) is presented. Nanovoids are agglomerations of point defects in the metallic host. SAXS is a non-destructive, dynamic probe which is ideally suited to characterize nanoscale electron density inhomogeneities, e.g., electron density difference between void and metal matrix. Previous SAXS studies of nanovoid structures in metals were limited by the presence of multiple scattering from the metal matrix. In this study, meticulous material processing methods were applied to induce a significant nanovoid concentration in nominally pure Al while minimizing the introduction of multiple scattering artifacts through sample deformation. Absolute intensity calibration with a secondary glassy carbon standard was performed. SAXS analyses were used to estimate void size, void-metal interface structure, void number distribution and void volume fraction in quenched aluminum samples. Also, preliminary aging studies of nanovoids in Al revealed some interesting trends in the kinetic properties of the nanovoids. These information has the potential to be used to develop novel aluminum alloy alloys.