Optimising diffusion bonding parameters to maximize the strength of AA6061 aluminium and AZ31B magnesium alloy joints

The main difficulty when joining magnesium (Mg) and aluminium (Al) alloys lies in the existence of formation of oxide films and brittle intermetallic in the bond region. However diffusion bonding is a suitable process to join these two materials. The diffusion bonding process parameters such as bonding temperature, bonding pressure, holding time and surface roughness of the bond specimen play a major role to determine the joint strength. In this investigation an attempt was made to develop empirical relationships to predict the lap shear strength and bonding strength of diffusion bonding of AZ31B magnesium and AA6061 aluminium alloys, incorporating above said parameters. Response surface methodology (RSM) was applied to optimise the diffusion bonding process parameters to attain the maximum shear strength and bonding strength of the joint. From this investigation, it is found that the bonds fabricated with the bonding temperature of 430 °C, bonding pressure of 13.84 MPa, holding time of 32.50 min and surface roughness of 0.12 μm exhibited maximum shear strength and bonding strength of 49.39 and 70.04 MPa respectively.

► Joining of AZ31B magnesium and AA6061 aluminium alloys.
► An empirical relationship was developed to predict the lap shear and bonding strengths.
► Response surface methodology was applied to optimise the diffusion bonding process parameters.