Interface microstructure and bond strength of 1420/7B04 composite sheets prepared by diffusion bonding

The effect of temperature on interface microstructure and shear strength of 1420 Al–Li alloy and 7B04 Al alloy composite plates prepared by diffusion bonding were investigated. The results indicate the optimum temperature for bonding the composite plates is 520 °C, a sound bonding interface without continuous intermetallic compound layers and interfacial voids is obtained, and the shear strength value of bond joints can be as high as 190 MPa. An interfacial transition zone is formed due to the alloying elements mutual diffusion during the bonding process. Meanwhile, the effect of temperature on diffusion of alloying elements and interface reaction were discussed in detail, the results show that the higher temperature can increase the diffusion of alloying elements fluxes across the bonding interface, which can accelerate the closure of interfacial voids; meanwhile, when Mg atoms diffuse across the bonding interface, it can react with and break up the surface oxide films into discrete particles, and the removal of interface oxides increases the metal to metal bond areas and improves the bond quality.