In most wrought aluminium alloys, high strength is achieved through a combination of precipitation hardening, work hardening, and solid solution strengthening. These mechanisms rely on the coherency of nanoscale precipitates, which interact with dislocation motion and are carefully controlled through precise composition and processing conditions. However, in recycled alloys made from low-grade scrap, the high impurity levels lead to the formation of large intermetallic compounds (IMCs) at the micro- and millimeter scales during the casting process. Although it is well known that these coarse IMCs degrade the material's elongation and formability, the specific mechanisms of plastic deformation in the presence of these large compounds are not yet fully understood.
The project will investigate the micromechanics and plasticity of alloys containing large inclusions, whether at low volume fractions or in large fractions like eutectic alloys. A combination of ex-situ and in-situ characterization methods will be used including nanoindentation, electron microscopy and Artificial Intelligence X-ray Imaging (AIXI). A strengthening model will be developed to describe the macro-mechanical behaviour of recycled alloys. This model will help clarify the relationship between the morphology of secondary phases and the alloys' ductility and plasticity. The ultimate goal is to enhance the processability of these alloys during thermomechanical processing by optimizing their cast microstructure.
