Metallurgical joining of aluminium and copper using resistance spot welding: microstructure and mechanical properties

Abstract

This paper investigates the melting phenomena, joining mechanism, microstructure evolution, and mechanical properties of the Al/Cu dissimilar joints made using resistance spot welding. A metallurgical bonding between Al and Cu is achieved via the reaction-diffusion between liquid Al and solid Cu (i.e. brazing mechanism). The reaction layer was featured by the in-situ formation of an ultra-thin Cu-rich Al-Cu intermetallic compound at the joint interface, on-cooling formation of coarse and thick θ-Al 2 Cu as the primary phase for hyper-eutectic solidification and formation of ultrafine lamellar α-Al/θ -Al 2 Cu eutectic structure. It is shown that the peak load and energy absorption of the Al/Cu joints are controlled by the effective length of the solid/liquid reaction zone and the thickness of the θ -Al 2 Cu primary solidification phase.

Effect of Ni Addition on the Interfacial Strength of Al/Cu Dissimilar Welds Produced by Friction Stir Lap Welding

“…Because FSW is a low-heat-input joining process, it effectively reduces the thickness of the IMC layer. Many previous studies concluded that a reduction in the IMC layer thickness at the dissimilar interface improves the weld strength [13,31,32]. Thus, the thin IMC layer formed at the Al/Cu interface during FSLW might be a microstructural factor causing the strength of the Al/Cu weld produced by FSLW to be higher than that of the weld obtained by GTAW.…”

“…Zhou et al [12] examined the relationship between the thickness of the IMC layer and the welding current (heat input) during pulsed double-electrode gas metal arc welding (DE-GMAW)-brazing of Al to Cu and concluded that the thickness of the IMC layer increased with an increase in the welding current over 35 A, which decreased the Al/Cu weld strength. Zare et al [13] examined the interfacial microstructure and mechanical properties of Al/Cu dissimilar welds produced by resistance spot welding and reported that an increase in the welding current beyond a critical value decreased the Al/Cu weld strength owing to the formation of a large amount of the CuAl 2 phase at the weld interface. Therefore, there have been many attempts to improve the weld strength by controlling the thickness of the IMC layer using a low-heat-input welding process.…”

Spinodal liquid phase separation enabling dissimilar resistance spot welding of immiscible iron and copper alloy system

“…However, the application of RSW for the joining of very dissimilar metals (e.g. Al/Fe [23], Al/Cu [24], and Fe/Cu) is challenging. Due to the very low electrical resistivity of pure copper, less heat is generated in the Cu sheet.…”

The Electrical and Mechanical Aspects of Aluminum and Copper Resistance Spot Weld Joints

“…In line with the automotive industry's objectives to reduce weight, enhance safety, and improve fuel efficiency, carefully considering material cost and mechanical properties has led to the use of Cu and Al-alloys. These materials possess high electrical conductivity, making them advantageous for electric automobiles [3,6,17]. It is still challenging to weld metals with higher thermal conductivity, lower resistance, and high conductivity, such as non-ferrous group metals.…”