Achieving extraordinary strength–ductility synergy in (Al2O3+Al2Cu)/Al composites though synergetic strengthening effect of in-situ hierarchical Al2O3 nanoparticles and AlCu precipitates

Achieving a desirable combination of strength and ductility in Al–CuO composites reinforced using in situ Al 2 O 3 nanoparticles remains a challenge due to Al 2 O 3 nanoparticle macro-segregation, few intragranular distributions, and poor interfacial bonding in Al/Al 2 O 3 system. Herein we report a novel manufacturing technique for (Al 2 O 3 +Al 2 Cu)/Al composites reinforced with in-situ hierarchical intragranular Al 2 O 3 nanoparticles and AlCu precipitates, which involves the accumulative roll bonding of pure Al and CuO-coated Cu foils and a post heat treatment. The as-prepared (Al 2 O 3 +Al 2 Cu)/Al composite displays a unique multiscale microstructure characterized by equiaxed micrometer-scale Al grains, two types of Al 2 O 3 reinforcing particles dispersed in grain interior, including Al 2 O 3 whiskers and Al 2 O 3 nanoparticles, and high-density, micro/nanosized, plate-like AlCu precipitates. The in-situ hierarchical Al 2 O 3 reinforcing particles and AlCu precipitates can effectively hinder the dislocation motion and increase the accumulation and multiplication of dislocations inside the grains, resulting in a remarkably enhanced strength and strain-hardening capacity. As a result, the obtained (Al 2 O 3 +Al 2 Cu)/Al composites exhibit a high tensile yield strength of 290.2 MPa, ultimate tensile strength of 452.8 MPa, and fracture elongation of 22.5 %; these values are superior to those of numerous Al-Cu alloy matrix composites. This work provides inspirations for fabricating bulk Al-matrix composites with exceptionally high strength and ductility.