Gradient solute cluster evolution and strengthening in a cyclic torsion-baked dilute Mg alloy

Solute clustering provides a promising route to overcome the strength-ductility trade-off, yet controlled formation of such clusters remains challenging in Mg alloys. Here, cyclic torsion (CT) followed by bake treatment is employed to promote cluster formation in a dilute Mg alloy. CT introduces a radial gradient in substructure and dislocation density, accompanied by Ca-Ca clusters. Subsequent baking further increases the cluster density, size, and compositional complexity. These clusters synergize with heterogeneous deformation to enhance both hetero-deformation-induced and cluster strengthening, enabling a ∼66 MPa yield strength increase without sacrificing ductility, thus confirming the efficacy of CT-assisted clustering as a strengthening mechanism.