Characterization of Zr-Containing Dispersoids in Al-Zn-Mg-Cu Alloys by Small-Angle Scattering

Abstract

Small-Angle X-ray Scattering (SAXS) and Small-Angle Neutron Scattering (SANS) were compared to Scanning Electron Microscopy (SEM) and Transmission Electron Microscopy (TEM) in their capability to characterize Zr-containing dispersoids in aluminum alloys. It is demonstrated that both scattering techniques are suitable tools to characterize dispersoids in a multi-phase industrial 7xxx series aluminum alloy. While SAXS is more sensitive than SANS due to the high electron density of Zr-containing dispersoids, SANS has the advantage of probing a much larger sample volume. The combination of both allowed verifying that the scattering contribution from dispersoids can be safely separated from other precipitate phases like S-phase or GP-zones. Size distributions obtained from SAXS/SANS and TEM and SEM show good agreement taking the resolution-limited restrictions of the different techniques properly into account.

Keywords: Small-Angle Scattering, Al3Zr, dispersoid, Al-Zn-Mg-Cu, size distribution