Effect of interfacial transition layer with CNTs on fracture toughness and failure mode of carbon fiber reinforced aluminum matrix composites

In this work, a strategy is proposed to construct an interfacial transition layer with CNTs to simultaneously strengthen and toughen composites. Combining CNTs with carbon fiber reinforcements in the aluminum matrix through electrophoretic deposition, and a multiscale hierarchical Cf/Al composite structure is fabricated by pressure infiltration. The mechanical response and failure modes of the composites were investigated. The results indicate that (I) both the strength and weibull modulus of fiber bundles grafting by CNTs were improved and the fiber bundles exhibited the characteristic of progressive failure during the failure process. (II) The tensile strength, fracture toughness and fracture work of the composites grafted with CNTs increased by 128%, 21.6% and 113% respectively, while the ILSS was slightly decreased. The CNTs/Al interfacial transition layer acts as a "fence" to hinder cracks from splitting the fiber bundle structure, and promoting energy dissipation through extensive debonding of the fiber bundle, which also reduces the risk of brittle fracture.