Insights into strain partitioning and void nucleation in recycled aluminium alloy: The role of Fe-rich intermetallic

Recycled aluminium alloys inevitably contain a high density of Fe-rich intermetallic (IMC) particles that introduce pronounced microstructural heterogeneity, yet the micromechanical role of these particles in governing strain partitioning and particle-induced damage during plastic deformation remains insufficiently understood. This study combines in situ high-resolution digital image correlation (HRDIC) and EBSD to directly quantify strain partitioning and deformation incompatibility in a recycled 6xxx alloy produced from post-consumer scraps. Compared with commercial baseline AA6111, the recycled IBA6111 alloy exhibits a transition in dominant strain localisation sites from grain-boundary-mediated to particle-controlled heterogeneous plastic deformation. The rigid and brittle Fe-rich IMC particles generate strong local strain gradients, asymmetric lattice rotations, and elevated dislocation densities in the surrounding matrix, ultimately triggering void nucleation through particle cracking. Tracking individual particles in situ , the critical local strain associated with particle cracking is quantified and reveals that cracking susceptibility is governed cooperatively by particle morphology, orientation, and spatial configuration rather than size alone. Particle cracking triggers pronounced strain redistribution in the surrounding matrix and amplifies deformation incompatibility, which accelerates further damage formation within particle clusters. These findings indicate a mechanistic understanding that linking Fe-rich IMC particles to strain partitioning and particle-induced damage in recycled aluminium alloys and providing guidance for impurity-tolerant alloy design.