Influence of Ni interlayer on microstructure and mechanical properties of laser welded joint of Al/Cu bimetal

The dissimilar joint consists of 6061 aluminum and 110 copper with a Ni foil interlayer. The influence of Ni element on the interfacial microstructure composition and bonding properties of the Al/Cu bimetal was systematically investigated. The study results demonstrate that the Ni element can inhibit the diffusion of Al, and fine the microstructure of deleterious phase IMC at the interface zone. The tensile strength of joints with Ni foil increases firstly and then decreases with the increase of laser power, and the maximum is about 126.9 MPa which improves about 27.1 % than that of Al/Cu joints without Ni foil. The fracture surface mainly passes through the (Cu) solid solution and the Al2Cu + AlNi IMCs zone due to the presence of hard and brittle IMCs severely deleterious the joining strength of joints.