Diffusion Welding of Al-Sn Alloy and Copper

The effect of tin addition in aluminum on the diffusion weldability of copper and aluminum has been investigated. The welding was carried out at 773K for 1.8ks, 3.6ks, 7.2ks and 14.4ks under the pressure of about 2.0MPa in a vacuum of 0.1Pa. Tin plays an important role in destroying the aluminum oxide layer, relaxing thermal stress and also in diffusion of the alloying elements (Mg, Zn, In, Bi) to the welding interface. High joint strength is obtained by addition of tin. The dual addition of tin and magnesium to aluminum brings about a joint, the shear strength of which is higher than that obtained by the single addition of tin. Such intermetallic compounds as γ2(Al4Cu9), η2(AlCu) and θ(Al2Cu) forme during diffusion welding of copper and aluminum. Fracture occurres along the original welded interface of joint enclosed by the compound η2.