Effect of interface on mechanical properties and formability of Ti/Al/Ti laminated composites

Abstract

Ti/Al/Ti laminated composites were prepared by hot-pressing and hot-rolling. Subsequent annealing was used to adjust Ti/Al interface. Then the influence of interface on the mechanical properties and formability of Ti/Al/Ti laminated composites was investigated. The results indicate that the diffusion rate between Ti and Al atoms increases with the increase of annealing temperature, which widens the diffusion layer and promotes the formation of TiAl 3 phase. The Ti/Al interfacial bonding strength enhances gradually as the annealing temperature increased from 200 to 400 °C. However, the bonding strength is deteriorated significantly as the annealing temperature exceeds 400 °C owing to the coarse TiAl 3 phase. The strength of Ti/Al/Ti laminated composites decreases gradually, whereas the elongation and Erichsen cupping formability are greatly affected by the interfacial bonding strength with the increase of annealing temperature. As the temperature increased from 200 to 400 °C, the increased interfacial bonding strength is beneficial to delay the premature necking and fracture of Ti/Al/Ti laminated composites, thereby improving their ductility. The coarsened TiAl 3 phase is easy to induce interfacial debonding with the further increase of annealing temperature. The crack deflection and passivation at the debonding can effectively suppress the crack propagation, which improves the ductility and formability of Ti/Al/Ti laminated composites unexpectedly. Especially the thick and coarse TiAl 3 phases are generated for Ti/Al/Ti laminated composites when annealed at 550 °C, but they show excellent elongation and formability. Which is attributed to the energy consumption by crack initiation at Ti/Al interface, thus the fracture failure of Ti/Al/Ti laminated composites is delayed.