Heterostructured magnesium alloys demonstrate superior mechanical performance. A novel bottom-up fabrication strategy of heterostructures was proposed by preconstructing multiple heterogeneities in rheo-squeeze casting AZ91 billets. The primary α 1 -Mg and α 2 -Mg secondary matrices in the billet exhibited multiple heterogeneities in grain morphology, composition, and β-Mg 17 Al 12 phase (β-phase) distribution. During extrusion, the β-phase governed the dynamic recrystallization and grain growth behaviors through particle-stimulated nucleation and pinning effects. These effects were further modulated by the heterogeneity of β-phase distribution in billets. The secondary matrix exhibited higher β-phase density, consequently enhancing these effects and refining recrystallized grains relative to the primary matrix. This research helps to expand the design strategies for heterostructured alloys.
Zhao et al. (Sun,) studied this question.