This study investigated the Laser Beam Welding (LBW) of Ti6Al4V and Nitinol alloys, with and without a copper interlayer, using a pulse current of 110 A, a pulse duration of 8 ms, a pulse frequency of 12 Hz, and a welding speed of 3.4 mm/s. The microstructure and mechanical properties of the welds were characterized using scanning electron microscopy (SEM), energy-dispersive spectroscopy (EDS), tensile testing and hardness profiling. Direct joints were prone to cracks, high concentration of Ti 2 Ni intermetallic, and low tensile strength (∼110 MPa). The insertion of a copper interlayer altered the interfacial reactions by promoting the formation of Ti 2 Cu intermetallic phases while reducing the concentration of brittle Ti 2 Ni, which resulted in crack-free joints with significantly improved tensile strength (∼250 MPa). This represents approximately 40% of the strength of the Nitinol-Nitinol similar joint (630 MPa). Fractographic analysis revealed brittle fracture in direct joints, while interlayered joints showed mixed fracture modes with ductile features. Hardness profiling revealed a reduction in peak hardness from 600 HV in direct welds to 430 HV in interlayered welds, confirming the beneficial role of the copper interlayer in enhancing overall mechanical performance.
Yaseen et al. (2026) studied this question.