Dissimilar welding of magnesium alloy to aluminium alloy: a review

Aluminium alloys and magnesium alloys offer superior properties with less density that allow designing structures with reduced cost, high efficiency, and material optimisation. Increasing usage of aluminium and magnesium alloys in industries like automobile, aerospace, railway, shipbuilding and marine requires their fabrication. At the same time, aluminium and magnesium joining is challenging due to detrimental effect of hard and brittle intermetallic compound (IMC) (Mg₁₇Al₁₂ and Mg₂Al₃) formation. Addition of interlayer or filler of chosen composition limit formation of Al/Mg IMCs by controlling IMC dispersal and variety (retarding amount of Al/Mg IMC and preferentially forming other less brittle IMCs). Fast welding processes; limit energy input and reactivity time to avoid IMC formation. Controlled heat input; maintain lower processing temperature to avoid IMC formation. These three individually or in combination are possible ways to tackle the formation of Al/Mg IMCs. Dissimilar Al-Mg joining by methods like Gas Tungsten Arc Welding, Diffusion Bonding, Laser Welding and Laser Weld Bonding, Cold Metal Transferand Friction Stir Welding have been discussed in detail. The effects of modification implemented on the material response in terms of resultant joint properties, microstructure and metallurgical relations are emphasised. Furthermore, the future scope for dissimilar Al/Mg welding has been deliberated.