Multimaterial Bonding of Additively Manufactured Carbon Fiber-Reinforced Thermoplastics/64 Titanium

The integration of lightweight materials in hybrid structures is critical for achieving energy efficiency in automotive and aerospace industries. This study presents a novel method for directly bonding carbon-fiber-reinforced thermoplastics to Ti6Al4V titanium alloy (64Ti) substrates using fused filament fabrication 3D printing. The technique involves 3D printing short carbon fiber-reinforced polyamide 6 onto sandblasted 64Ti substrates, heated via a hot plate integrated into the 3D printer. Lap-shear tests reveal that adhesion strength improves with increased fusion time, achieving a maximum shear stress of 27.3 ± 2.2 MPa for 60 min welding. Finite element analysis demonstrates stress concentrations at the adhesion edges and highlights the formation of a fracture process zone with localized plastic deformation and microcrack generation. Additionally, the feasibility of fabricating 3D structures and integrating continuous carbon fiber-reinforced thermoplastics onto 64Ti substrates is demonstrated. This study advances hybrid material joining techniques by providing a cost-effective, scalable method for achieving robust metal-composite bonds suitable for structural applications.