Microstructure and mechanical properties of laminated Ti-TiBw/Ti composites fabricated by wire arc additive manufacturing

To achieve the synergetic improvement of the strength and ductility of titanium matrix composites (TMCs), in this study, flux-cored wires were customized and combined with the wire arc additive manufacturing (WAAM) process to fabricate laminated Ti-TiBw/Ti composites. The diffusion behavior of the reinforcement during the WAAM deposition process was studied in detail. By optimizing the process parameters to regulate the distribution of the reinforcement, the composites presented a laminated structure on the macroscale and a non-uniform distributed network structure on the microscale. Compared with pure titanium, the ultimate tensile strengths and ductility of the laminated Ti-TiBw/Ti composites have both improved. The ultimate tensile strengths of the composites with 5 vol% and 10 vol% TiBw/Ti layers are 574 MPa and 663 MPa, respectively, and the fracture elongation are 27.74 % and 24.95 %, respectively. This heterogeneous structure of TMCs reconciles the contradiction between strength and ductility, mainly attributed to the strengthening effect of in-situ synthesized TiBw and the toughening effect of the laminated structure and the TiBw network structure.