Fabrication and superior ductility of laminated Ti-TiBw/Ti composites by diffusion welding

Two novel laminated Ti-TiBw/Ti composites, consisting of pure Ti layers with different thicknesses of 200 μm and 400 μm and TiB whisker reinforced Ti (TiBw/Ti) composite layers with a constant thickness of 200 μm, were successfully fabricated by diffusion welding. Herein, the individual thickness of the two layers can be controlled accurately through raw Ti sheets and TiBw/Ti composite sheets. The two prepared laminated composites exhibit higher ultimate tensile strength (625 MPa and 569 MPa, respectively) and higher elongations (19.0% and 27.5%, respectively) compared with pure Ti material (546 MPa, 17.5%). The superior ductility is mainly attributed to the necking delaying effect and delamination shielding effect. Fracture characteristics show that many tunnel cracks were formed in TiBw/Ti composite layer and shear bands were presented in the pure Ti layer. Moreover, interfacial delamination was formed between Ti layer and TiBw/Ti composite layer interface, which is beneficial to toughen the laminated composites.