Enhanced strength and fracture characteristics of the TiAl/Ti₂AlNb laminated composite

In this study, TiAl/Ti₂AlNb laminated composite has been prepared via vacuum hot-pressing sintering. The composite exhibits a good synergy between bending strength and ductility, with a significantly enhanced bending strength value of 910.25 MPa. The fracture characteristics in the TiAl alloy layer, Ti₂AlNb alloy layer and interfacial α₂-Ti₃Al layer are separately elucidated. It is concluded that the slip bands, tunnel cracks (α₂-Ti₃Al layer), deflected microcracks (Ti₂AlNb alloy layer), and microcracks (TiAl alloy layer) are involved in the fracture process. Moreover, the main deformation behaviors consist of dislocation glide and local microcracking. The formation of stack faults and twins is also observed in the TiAl alloy layer. Furthermore, we focus on revealing the relationship between the deformation behaviors and fracture process of the composite. In particular, the strain partitioning and delayed fracture, multistage synergetic deformation mechanisms, and specific microcrack initiation are discussed. These findings are important for investigating the fundamental mechanisms and serving as a guide for the design of high-performance laminated composites.