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Optimising diffusion bonding process parameters to attain maximum strength in Al - Cu dissimilar joints using Response Surface Methodology

The principal difficulty when joining aluminium (Al) and copper (Cu) lies in the existence of formation of oxide films and brittle intermetallics in the bond region. However, diffusion bonding can be used to join these alloys without much difficulty. Temperature, pressure and holding time are the three main variables, which govern the integrity of the diffusion bond. This paper highlights the application of Response Surface Methodology (RSM) to develop empirical relationships to predict diffusion layer thickness (DL), hardness and strength of AA2024 aluminium alloy?copper alloy dissimilar joints. The experiments were conducted based on three-factor, five-level and central composite, rotatable design with full replications technique. The developed empirical relationships were used to optimise diffusion layer thickness, hardness and strength using RSM. From this investigation, it is found that the bonds fabricated with the bonding temperature of 503°C, bonding pressure of 11.6 MPa and holding time of 46 min attained maximum strength. [Received 28 June 2008; Revised 21 February 2009; Accepted 24 August 2009]