Time-sharing dual electron beam welding of TC4/T2 Joints: Enhanced mechanical properties due to the optimization of Intermetallics Compounds layer achieved by in-situ remelting

Time-sharing Dual Electron Beam (TDEB) welding technology was used to process TC4/T2 joint. The key innovation of TDEB lies in its in-situ remelting capability, where a precisely controlled secondary electron beam dynamically remelts the weld pool. This unique feature enables active intervention in the solidification process, effectively breaking up the IMC layer. The in-situ remelting effect of TDEB achieved exceptional control over the detrimental IMCs layer: the thickness of the IMCs layer of the TC4/T2 joint is uneven with the thinnest area is less than 6 μm, and the average thickness is about 10 μm. The TC4/T2 joints exhibited remarkably enhanced mechanical properties, with a tensile strength of more than 240 MPa and a maximum elongation of 26.8 %. The fracture occurred in the heat-affected zone on the copper side. bypassing the typically brittle IMCs/TC4 interface, which indicates the effectiveness of TDEB in suppressing the IMCs layer's detrimental influence. Furthermore, microstructure analysis revealed that the IMCs layer consisted of a unique mixed structure of brittle CuTi and ductile Cu₃Ti. These ductile Cu₃Ti play a vital role in impeding crack initiation and propagation.