Abstract: Al/Ti dissimilar alloys joining components have potential to be widely used. But the oxidation film on the material surface，the property differences between Al/Ti alloys and the brittle intermetallic compound form in the welding process are the key factors to increase the difficulties of joining these two alloys. The electron beam welding-brazing is used to joining 5A06 Al alloy to TC4 Ti alloy for controlling the liquid-to-solid interalloying reaction and the forming of brittle intermetallic compound to as small extent as possible. The welded seam appearance and the microstructure as well as the mechanical properties of the joints are analyzed. The results show that the welded seam is good shape as well as the back of the joint. A 1.0-1.6 mm thickness reaction zone is generated on the welding-brazing interface where Al and Ti element fully diffuse. The metallurgically bonded joint is gained during the electron beam welding-brazing and a transition layer formed in the TC4 side, while many small Ti-Al intermetallic compounds dispersed in the 5A06 side. The no-defect joints are gained and the maximum tensile strength of Al/Ti dissimilar alloy joints is up to 180 MPa.

Key words: Al alloy, Electron beam, Ti alloy, Welding-brazing