Enhancement of strength-plasticity matching in multimodal grained (SiCnp + GNS)/Al composites

• Multimodal configuration was realized by zonal ball milling to create regionally enriched distribution of SiCnp and GNS. • Multimodal (SiCnp + GNS)/Al contained SiCnp-rich fine grain zones, GNS-rich transition grain zones and coarse Al grain zones. • Com40-40-20 showed doubled elongation of 7.1% and enhanced strength by 12% compared to the homogeneous composite counterpart. • Simultaneous enhanced strength and elongation was attributed to the rational distribution of grain zones. To address the strength-plasticity inversion in conventional Al matrix composites (AMCs), two strategies—hybrid reinforcement and heterogeneous configuration—have been proposed. However, excessive reinforcements in hybrid composites can lead to cracking, while coarse grains in heterogeneous composites improve plasticity but reduce strength. This study combines hybrid reinforcement with heterogeneous configurations for fine structural design of multimodal grained composites using a zonal ball milling process. The reinforcements were selected and the zonal ball milling process was tuned to create three grain zones: (1) nano grain zones enriched with hard SiCnp from high-energy ball milling, (2) submicron grain zones uniformly dispersed by flexible GNS as a transition, and (3) micro grain zones primarily composed of pure Al. The multimodal grained (SiCnp + GNS)/Al composites were produced with grain zone ratios of 35:35:30 and 40:40:20. Results showed that the size and distribution of nano grain zones significantly influenced the strengthening effect of the heterogeneous composites. Com40-40-20 exhibited strong bonding between grain zones, enhancing strain compatibility. Compared to homogeneous (SiCnp + GNS)/Al, Com40-40-20 demonstrated approximately 122 % improved plasticity and about 12 % increased strength without any loss. This refined grain zone design offers valuable insights for optimizing high-performance heterogeneous Al matrix composites.