Diffusion Bonding Process and Interface Performance of 2198 Al-Li Alloy

The diffusion bonding process can take full advantage of 2198 Al-Li alloy to produce high-efficiency integral structures. However, the dense and stable oxide layer on the surface to be bonded seriously hinders the diffusion bonding process. The suitable surface treatment method was selected to remove the oxide layer. Furthermore, the effects of bonding temperature, time and pressure on interface performance were studied. Optical microscopy (OM) and scanning electron microscope (SEM) are used to observe the bonded interface and fracture surface after the shear test. The maximum shear strength and strength ratio reach up to 131 MPa and 96%, respectively. In general, shear fracture surfaces account for the majority of bonded interfaces, which show ductile areas with dimples and brittle regions with quasi-cleavage behavior. This study indicates 2198 Al-Li alloy can be well bonded by suitable surface treatment and process parameters.