Heterogeneous configuration induced strengthening in aluminum matrix composites via exciting back stress

Abstract

Heterogeneous configuration design has shown attractive effectiveness in addressing the significant plastic inversion problems in traditional aluminum matrix composites (AMCs). The significance of heterogeneous configuration design on the strengthen and toughening of metals and metal-composites has been increasingly recognized. However, the quantitative correlation between heterogeneous structural parameters and mechanical properties in AMCs remains incomplete. Here, a novel strategy was proposed to verify the effectiveness of heterogeneous configuration by adjusting the morphology of the fine-grained domain area. By verifying the effectiveness of heterogeneous structure characteristics on material strengthening, configuration optimization was achieved, resulting in significant strengthening of (SiCnp + GNS)/Al composites. Based on zonal ball milling, the multimodal (SiCnp + GNS)/Al composites containing Silicon carbide nanoparticles (SiCnp)-enriched fine-grained region, Graphene nanosheets (GNS)-enriched transition-grained region, and pure Al as coarse-grained region were prepared. Stearic acid was used as process control agent (PCA) for high energy ball milling process of Al and SiCnp. The various heterogeneous configurations in the composites was realized by adjusting the PCA content of Al and SiCnp during high-energy ball milling to tailor the cold welding degree in fine-grained Al deformed particles. The results show that the distribution of strip-shaped fine-grained region with large aspect ratio can significantly stimulate back stress in composites, being approximately 12 % and 24 % higher than that of the island -shaped fine-grained region configuration and uniform structures, respectively. This contributes to continuous strain hardening and achievement of favorable comprehensive properties, and its elongation is increased by more than 40 % compared to the composites with island-shaped fine-grained region.