Investigation of the microstructure of aluminum and magnesium joints during diffusion welding

The influence of temperature and chemical composition of intermediate layers on the for­mation of welded joints structure made of AMg2 aluminum and MA2-1 magnesium alloys is investigated. It is found that during thermo-deformation welding cycle at T = 400°C, a diffusion zone with a thickness of ~ 80 mm is formed bet­ween magnesium and aluminum alloys, with a microhardness in the central part of 2160 MPa, where the cracking occurs. To reduce the intensity of diffusion pro­cesses at the interface and prevent the formation of brittle intermetallic phases between the alloys, nickel or titanium foil with a thickness of 30 mm was used as a barrier layer. In the magnesium-aluminum joints obtained using a tita­nium foil layer, intermetallic layers do not form. Mechanical bending and tensile tests showed that the strongest mag­nesium-aluminum joints (sB = 138–142 MPa) were obtai­ned when using titanium layers.