An investigation on diffusion bonding of aluminum and magnesium using a Ni interlayer

Diffusion bonding aluminum and magnesium using a Ni interlayer was investigated for the first time. The bonding trials were carried out at 440 °C for different time under 1 MPa in a vacuum of 6 × 10 ^{- 3} Pa. The interfaces were investigated by means of SEM, EPMA, XRD and Vickers hardness test. The results showed that dissimilar metals of Mg/Al could be successfully joined by diffusion bonding with a Ni interlayer and the Mg-Al intermetallic compounds were impeded. From Al side to Mg side, there was Al substrate, Al-Ni reaction layer, Ni interlayer, Mg-Ni reaction layer, Mg substrate. The microhardness in the Al-Ni reaction layer and Mg-Ni reaction layer increased sharply, which were 201.5 Hv and 244.1 Hv. The fracture occurred in the intermetallic compound layer of the Mg-Ni reaction layer, where the Mg ₂Ni phase appeared on both Al and Mg surfaces.