Lun Yang, Yunzhu Ma, Liu W
The integration of dissimilar metals is a key strategy for developing lightweight structural materials, where the reliability of interfacial bonding critically determines mechanical performance. In Ti–Al systems, intermetallic compounds (IMCs) govern load transfer and fracture behavior. However, their evolution in Mg-containing Al alloys remains insufficiently understood, despite Mg being a common alloying element. In this work, solid-state diffusion bonding between TC4 Ti alloy and 2A12 Al alloy was conducted at 475-550 °C to investigate the evolution of interfacial microstructures and their correlation with mechanical performance. A double-layered interfacial structure consisting of Al 3 Ti and Al 18 Ti 2 Mg 3 was formed. With increasing temperature, the interfacial structure evolves from an Al 18 Ti 2 Mg 3 -dominated configuration to an Al 3 Ti-dominated configuration, which is associated with enhanced Ti diffusion. This transition leads to distinct fracture behavior under different loading conditions. Under shear loading, the fracture-controlling region shifts to the Al 3 Ti layer as it becomes continuous, accompanied by an increase in shear strength from 81.54 MPa to 127.62 MPa. In contrast, under tensile loading, crack propagation preferentially occurs along the Al 18 Ti 2 Mg 3 layer, which provides a relatively continuous path for crack growth along the interface. This behavior reflects that interfacial fracture behavior in Mg-containing Ti–Al systems is closely related to phase competition and the structural continuity of interfacial phases