Enhancing Strength and Toughness of Aluminum Laminated Composites through Hybrid Reinforcement using Dispersion Engineering

In order to address the challenge of balancing strength and ductility, we propose a novel approach of creating a hybrid aluminum matrix composite with a combination of in-situ and ex-situ reinforcement. This approach aims to achieve a uniform distribution of reinforcements and establish strong bonding between the reinforcements and the matrix. To harness the advantages of both intergranular and intragranular dispersion of reinforcements, we have synthesized nano-sized Al3BC particles in-situ within ultrafine-grained (UFG) aluminum. This in-situ synthesis was accomplished by incorporating carbon nanotubes (CNTs) into the elemental powder mixture, followed by mechanical activation and subsequent annealing. The resulting in-situ nano-scaled Al3BC particles were uniformly dispersed within the elongated UFG aluminum grains, effectively impeding dislocation movement and preserving their strength under stress. This led to enhanced strength and strain hardening. Compared to the counterpart material without the in-situ nano-Al3BC reinforcement, the fabricated (Al3BC, CNT)/UFG Al composite exhibited simultaneous improvements in both strength (394 MPa) and total elongation (19.7%). These results demonstrate the promising reinforcing effects of the in-situ/ex-situ approach, which benefits from the uniform dispersion of reinforcements and the establishment of a strong semi-coherent interface with the matrix. A novel hybrid nanoreinforcing via elemental powder mixture was adopted to the first time to achieve an excellent strength-ductility combination in CNT/Al composites.