Investigation on process and microstructure of Ti/Ni/Cu joints by electron beam welding

In this article, the electron beam welding of the Cu alloy (QCr0.8) with Ti alloy (TC4) sheet was processed and the joint microstructure as well as the welding process were studied. The results show that brittle reaction layer which was mainly composed of TiCu, Ti₂Cu, Ti₂Cu₃ and TiCu₂ formed at the weld fusion line, regardless of welding on the middle or on the Cu side. The mechanical properties of the joint were severely deteriorated by the layer that tensile strength was only 89.4 MPa for welding on the Cu side. The microstructure of the joint was improved with pure nickel as filler metal for the electron beam welding. The weld was mainly composed of solid solution. Intermetallic compound phase decreased significantly in fusion line compared with the joint without filler metal. The mechanical properties of the joint were obviously improved that the average tensile strength was 205.2 MPa and the bending strength was 413.3 MPa with 0.5 mm offset of electron beam on the Cu side.