Interfacial evolution and bonding mechanisms in γ -TiAl/Al explosive welding: a molecular dynamics study

Abstract The explosive welding (EXW) of γ -TiAl to Al offers a promising route to fabricate lightweight, high-strength hybrid structures, yet the atomic-scale bonding mechanisms remain unclear. In this work, large-scale molecular dynamics simulations were performed to investigate the effects of flyer velocity (1.5–2.9 km s −1 ) and collision angle (10°–40°) on the thermal response, diffusion behavior, phase evolution, and mechanical performance of γ -TiAl/Al EXW. Increasing flyer velocity drives a transition from solid–solid contact to solid–liquid and ultimately liquid–liquid mixing, accompanied by elevated interfacial temperature, thicker diffusion layers, and extensive amorphization. During cooling, the Al base exhibits strong face-centered cubic recrystallization but retains vacancy defects, whereas the γ -TiAl flyer preserves stable HCP bands and quenched disorder. Mechanical tests reveal that a flyer velocity of 2.5 km s −1 achieves the best strength-ductility balance (∼5.1 GPa peak stress, ∼0.08 fracture strain) through the formation of a well-mixed interface. At this velocity, increasing the collision angle from 10°–30° gradually improves joint strength and ductility by promoting more uniform defect evolution and plastic deformation, whereas an excessive angle (40°) induces shear-driven separation that weakens bonding. These findings elucidate the fundamental atomic processes governing γ -TiAl/Al EXW and provide quantitative guidance for optimizing processing parameters in advanced lightweight structural applications.