Study on the mechanism of synergistic improvement of bonding strength and elongation of Ti/Al composite plates by annealing treatment

Titanium/aluminum (Ti/Al) composite plates with good flatness and excellent comprehensive mechanical properties were prepared by differential temperature rolling with mobile induction heating and annealing processes. This study investigated the impact of various annealing times on the microstructure and mechanical properties of the composite plates. The findings indicate that the Ti6O oxide layer inhibits the growth of TiAl3 compounds, allowing oxygen atoms from the oxide layer to dissolve into the matrix and generate atomic vacancies. This results in the formation of concave-convex features at the Ti6O/Al interface, thereby increasing the contact area and establishing a metallurgical interlocking structure. After 60 min of annealing, an Al18Ti2Mg3 phase forms near the interface with the Al layer, the strong chemical interactions among Ti-Al-Mg atoms enhance both the confinement effect and plasticity at the interface while also disrupting the crystal lattice and widening the transition region. The three-dimensional (3D) interfacial transition zone is characterized by dispersed dislocations, which significantly improve the comprehensive mechanical properties of the composite plates. However, following 90 min of annealing, the increased Mg atomic content accelerates the decomposition of the oxide film and reduced the oxygen concentration, thereby reducing its inhibitory effect on Ti/Al atom diffusion. This resulted in the formation of brittle TiAl3 compounds at the Al18Ti2Mg3/Al interface, leading to a decrease in mechanical properties of the Ti/Al composite plates.