It is a challenge work for joining of Al to Cu by conventional fusion welding method. This study investigates butt joining of 6061 Al alloy to pure copper using cold metal transfer (CMT) process in asymmetrical V-groove configuration. The microstructure and mechanical properties of Al/Cu butt joints are revealed. The microstructure in the fusion zone mainly consists of α (Al) and Al2Cu phase accompanied with Si phase. The two-layer intermetallic compound (IMC) layers are exhibited at the Al/Cu interface. The first IMC layer near the copper is a thin layer in thickness of less than 5 μm. The second IMC layer is in the irregular non-linear and zigzag shape with some particles dispersed at the boundaries. XRD analysis shows that the IMCs in the joints mainly contain Al2Cu, AlCu, Al3Cu4 and Al4Cu9 phase. The ultimate tensile strength (UTS) of the joints could reach 108 MPa. The fracture paths of the joints are along the Al/Cu interface. The pores and IMCs are main factors to determine the strength of the joints. Since the pores are at the Al/Cu interface, the UTS of the joint is lowered at low wire feed rate. The joints break along the Al/Cu interface due to the brittle IMC layer at high wire feed rate. It can be achieved Al/Cu butt joints with sufficient strength in asymmetrical V-groove configuration.
Cold metal transfer (CMT) technique is developed for lap joining of titanium (Ti) alloy to stainless steel (SS) with CuSi3 filler wire. The effect of welding speed on the microstructure and mechanical properties of Ti/SS lap joints is investigated. The results indicate that the wetting angle of the lap joints gradually increases and the weld width decreases with increasing the welding speed. It is found that many coarse phases in the fusion zone are rich in Ti, Fe and Si etc, inferring as Fe–Si–Ti ternary phase and/or Fe2Ti phase at low welding speed. Many fine spherical particles in the fusion zone are considered as iron-rich particles at high welding speed. The transition layer are exhibited at the Ti–Cu interface. With increasing the heat input, the intermetallic layer becomes thicker. A variety of brittle intermetallic compounds (IMCs) are identified in the lap joints. The shear strength of the joints increases with increasing the welding speed. Two fracture modes occur in the lap joints at low welding speed. Thicker reaction layer causes brittle fracture and poor joint strength. The Fe–Ti–Si and Fe2Ti phase within the fusion zone are detrimental to the joint strength. The fracture surface of the joints is dominated by smooth surface and tear pattern at high welding speed. The fracture mode of the joints is merely along the Ti–Cu interface.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.