Microscopic Crystal Defects Induced by Intense Pulsed Electron Beams and Their Effects on the Diffusion Bonding Performance of Cu-316 L Stainless Steel

This article uses a high current pulsed electron beam (HCPEB) for electron irradiation pretreatment on the surface of Cu and 316 L stainless steel, followed by vacuum diffusion welding treatment of the two. The welding temperature is 800℃ and 850℃, the welding pressure is 5 MPa, and the welding time is 40 minutes. The microstructure changes of 316 L stainless steel after HCPEB irradiation were observed using scanning electron microscopy (SEM), transmission electron microscopy (TEM), and other instruments. Microscopic observation shows that after HCPEB irradiation, the initial coarse grains of 316 L stainless steel significantly transform into fine grains with a large number of crystal defects. Diffusion welding of non-irradiated Cu and 316 L revealed that the welding area of the prepared original joint was not fully welded. In contrast, the samples pretreated with HCPEB showed a good bonding interface after diffusion welding, and the diffusion coefficient of Cu at the interface also significantly increased. The increase in diffusion coefficient is attributed to the large number of crystal defects induced by irradiation, which provides a fast diffusion channel for atomic diffusion and enhances the diffusion ability of atoms. The bonding strength results indicate that the shear strength of the Cu-316 L joint pretreated with HCPEB for diffusion welding is much higher than that of the original joint.