Mapping local orientation and strain fields around intermetallic particles in an Al2050 alloy during elastic tensile loading by scanning 3DXRD and DCT

Intermetallic phases are known to significantly influence the evolution of the local microstructure in Al alloys during processing and thus affect their mechanical properties. However, non-destructively mapping the local orientation and strain fields around intermetallic particles remains technically challenging. Here, we present a multi-modal synchrotron X-ray study on an Al2050 alloy to map the orientations and strains in both Al grains and secondary-phase particles as a function of tensile loading in the elastic regime. Combined with phase contrast tomography (PCT), we visualize the spatial distribution of the secondary phases and pre-existing pores together with the 3D Al grain structure characterized by diffraction contrast tomography (DCT), while higher resolution mappings of orientations and strains for both Al and secondary phase particles (Al 7 Cu 2 Fe) are resolved by Scanning 3D X-Ray Diffraction (s3DXRD). This multi-modal approach not only allows comprehensive microstructure characterization, but also cross-validates the grain orientation reconstruction. The results show that during tensile loading, the intermetallic particles undergo a compressive strain and induce a high stress gradient and unexpected lattice rotation in a local area of an Al grain. This highlights the presence of grain plasticity at only 55% of the yield stress influenced by the intermetallic particles. We demonstrate that studying the evolution of the matrix-precipitates microstructure greatly benefits from the multi-modal approach of combining PCT, DCT and s3DXRD. • Synchrotron grain mapping and tomography is combined to study Al2050 alloy • Variations in grain orientations are quantified between scanning 3DXRD and DCT • Scanning 3DXRD is able to reconstruct Al 7 Cu 2 Fe intermetallic grains successfully • Strain maps of Al and secondary phases characterized by s3DXRD • Local build-ups of stresses and lattice rotation of Al around the intermetallics